1. 绿氢产业发展整体背景与当前格局
1.1 能源转型与能源安全双重驱动下的绿氢产业定位
在全球应对气候变化和追求可持续发展的背景下，能源转型已成为各国战略议程的核心。其中，以可再生能源制取的绿氢，因其独特的零碳排放特性，被视为实现碳中和目标的关键一环 1。特别是在“碳达峰”和“碳中和”双重目标的驱动下，绿氢不仅能够有效促进能源结构的低碳化和清洁化，更在优化能源工业体系、推动能源发展战略转型以及增强国家能源安全方面具有深远意义 12。
传统工业，尤其是钢铁、炼化、合成氨等高耗能行业，是全球碳排放的主要来源。这些行业脱碳面临巨大挑战，而绿氢的出现为这些“难脱碳”领域提供了切实可行的解决方案 34。通过替代化石燃料作为还原剂或燃料，绿氢能够显著降低工业过程中的碳排放，加速这些传统行业的绿色转型 5。例如，在钢铁生产中，绿氢可以替代焦炭作为还原剂，从而实现“绿色钢铁”的生产 34。
相较于灰氢和蓝氢，绿氢的减排优势尤为显著。灰氢主要来源于化石燃料（如天然气重整或煤气化），生产过程伴随大量二氧化碳排放，并非清洁能源。蓝氢虽然通过碳捕集、利用与储存（CCUS）技术降低了灰氢的碳排放，但其碳捕集效率并非100%，且CCUS技术本身仍存在能耗和成本问题 67。绿氢则完全通过可再生能源（如风能、太阳能）电解水制取，其生产过程几乎不产生温室气体排放，真正实现了全生命周期的“零碳”或“近零碳”排放，因此被认为是实现深度脱碳和构建可持续能源系统的最终路径 89。
此外，发展绿氢对于提升能源安全也至关重要。许多国家对化石燃料存在高度依赖，易受国际能源市场波动和地缘政治冲突的影响 310。绿氢的生产可以充分利用本土丰富的可再生能源资源，减少对进口化石燃料的依赖，从而增强国家的能源独立性和抵御外部风险的能力 110。特别是对于岛屿国家或地区，绿氢的发展能够显著提升其能源自给能力和安全性 1011。通过将绿氢与可再生能源系统深度耦合，可以解决可再生能源间歇性、波动性问题，实现能源的跨季节存储和远距离输送，进一步巩固能源安全屏障 121314。
1.2 全球与国内绿氢产业发展阶段及产能布局
全球范围内，绿氢产业正处于快速发展阶段，各国纷纷加大投资，推动产能建设和技术创新。据估计，目前全球制氢产能大部分依赖化石燃料生产，而绿氢（通过可再生能源电解水制氢）的占比仍然较低，但增长迅猛 1516。众多国家已将绿氢视为能源转型和实现碳中和目标的关键组成部分，并出台了相应的支持政策和发展规划 1718。例如，欧盟的REPowerEU计划、美国的《通胀削减法案》等都明确了绿氢的生产目标和财政激励措施，旨在推动绿氢的大规模商业化应用 18。
当前，全球绿氢产能布局呈现出多元化和区域集中的特点。大型绿氢项目主要集中在可再生能源资源丰富、电价成本较低的地区，例如澳大利亚、智利、中东和北非地区。这些地区利用其得天独厚的风能和太阳能资源，规划建设了大量兆瓦级甚至吉瓦级的电解水制氢项目，旨在打造全球绿氢出口中心。欧洲地区则侧重于通过本土绿氢生产和进口相结合的方式，满足其日益增长的工业和交通领域脱碳需求。例如，德国、荷兰等国正在积极布局绿氢生产、进口和输送基础设施，以支持其工业脱碳和能源转型 19。亚洲地区，特别是中国、日本和韩国，也积极推进绿氢技术研发和产业化，着力构建本土绿氢产业链和应用示范项目。
在中国，氢能产业的发展已被提升到国家战略层面，国务院发布了《氢能产业发展中长期规划（2021-2035年）》，明确了氢能在国家能源战略中的重要地位。当前，我国绿氢产业正处于示范应用向规模化发展过渡的关键时期。虽然具体绿氢产能在持续统计和更新中，但可以观察到明显的产业集聚特征。
我国氢能产业示范城市群的发展现状与产业集聚特征主要体现在以下几个方面：
- “西氢东送”格局初显： 我国西北部地区拥有丰富的风能、太阳能资源，以及较低的可再生能源发电成本，为大规模绿氢生产提供了有利条件。宁夏、内蒙古、甘肃、新疆等省区已成为绿氢项目投资的热点区域，规划建设了一批百万吨级绿氢生产基地。这些地区生产的绿氢，未来将通过管道或液体氢运输等方式，输送至东部沿海及中部工业发达地区，满足其工业和交通领域的用氢需求，形成“西氢东送”的战略格局 20。
- 沿海与工业城市先行示范： 广东、山东、长三角、京津冀等经济发达且工业基础雄厚的区域，积极响应国家号召，启动了多个氢能产业示范城市群建设。这些城市群通常围绕当地的工业基础，如石化、钢铁、港口等，开展绿氢在工业原料替代、交通燃料和分布式能源等领域的应用示范。例如，山东省规划了多个氢能产业示范区，重点发展绿氢在化工、冶金等行业的应用；广东省则侧重于燃料电池汽车的推广和加氢站网络建设，并探索绿氢在分布式发电和热电联供中的应用。
- 技术研发与装备制造协同发展： 在绿氢产业集聚区内，不仅有绿氢生产项目，还同步发展电解槽、储运设备、燃料电池等关键装备的研发与制造。例如，在部分城市，电解水设备制造企业、氢气压缩机制造商以及燃料电池系统集成商等上下游企业形成了产业集群，共同推动技术创新和成本下降。这种产业集聚效应有助于加速技术成熟，降低生产成本，并形成完整的绿氢产业链生态。
- 政策驱动与市场引导并重： 各地政府通过出台专项规划、财政补贴、项目示范等多种政策工具，引导绿氢产业发展。例如，一些地区对绿氢生产、加氢站建设和燃料电池汽车购置给予补贴，以降低初期投资和运营成本，激发市场活力。同时，通过推广绿氢在特定场景的应用，逐步培育市场需求，为绿氢的大规模商业化奠定基础。
总体而言，全球和国内绿氢产业正从概念走向实践，从示范走向规模化。尽管面临技术成本、基础设施建设等挑战，但在政策支持、技术进步和市场需求的共同推动下，绿氢有望在未来能源结构中扮演越来越重要的角色 21。
2. 绿氢制备技术的学术研究与产业化进展
2.1 主流电解水制氢技术路线的迭代与优化
电解水制氢是生产绿氢的核心技术，其通过电能将水分解为氢气和氧气，是目前将可再生能源转化为化学能并存储起来的最主要途径。目前，主流的电解水制氢技术主要包括碱性电解槽（AEC）、质子交换膜电解槽（PEMEC）和固体氧化物电解槽（SOEC）三类。这些技术在成熟度、能效水平、适用场景以及近年来在电解效率和运行稳定性方面的优化均有所不同 2223。
2.1.1 碱性电解槽 (AEC)
成熟度与能效： 碱性电解水技术是目前工业应用最广泛、最成熟的电解水技术之一，其历史悠久，运行经验丰富 2425。AEC通常在强碱性水溶液（如KOH）中进行电解，其能效相对较高，尤其是在稳定运行工况下 26。然而，传统AEC的设计多针对固定工况运行，难以适应可再生能源固有的波动性和间歇性 2427。
适用场景： AEC通常适用于大规模、集中式的稳定电源供电的制氢场景，例如与大型水电站或核电站配套。由于其较低的初始投资成本和相对简单的系统集成，它在对响应速度要求不高的应用中具有经济性优势。然而，传统AEC在低负载运行时，由于气体纯度降低，可能存在氢氧混合气体爆炸的风险，因此其部分负载范围受限，通常需要在达到特定气体污染水平时进行安全停机 24。
最新突破： 近年来，AEC的技术迭代主要集中在提高其动态响应能力和效率。研究人员正致力于开发更先进的电极材料和改进电解槽设计，以优化电解效率、降低能耗，并增强其对可再生能源波动的适应性 28。例如，通过优化电极结构和催化剂，可以提高法拉第效率并降低电解槽的过电位，从而减少整体能耗。此外，针对动态运行优化的电源转换器也对AEC的性能提升至关重要。例如，基于晶体管的转换器相比传统的晶闸管整流器，可将兆瓦级碱性电解槽的特定能耗降低多达14%，这表明电源管理技术的进步对提高AEC能效具有显著影响 29。
2.1.2 质子交换膜电解槽 (PEMEC)
成熟度与能效： PEMEC是一种相对较新的技术，但其发展迅速，被认为是未来绿氢生产的关键技术之一 2530。PEMEC采用固态质子交换膜作为电解质，具有较高的电流密度和快速响应特性。在某些工况下，PEMEC的能效可以与碱性电解槽相媲美 31。然而，PEMEC对催化剂的酸性环境稳定性要求较高，通常需要使用贵金属（如铂、铱）作为电极催化剂，这导致其成本较高 32。
适用场景： PEMEC能够有效利用间歇性可再生能源 27。此外，PEMEC产生的氢气纯度高，可直接用于燃料电池等对氢气纯度要求较高的应用。
最新突破： PEMEC的研究热点主要集中在降低成本和提高耐久性。具体包括：
- 非贵金属催化剂研发： 为降低成本，研究人员正在积极探索开发高性能的非贵金属催化剂，以替代昂贵的铂和铱。例如，针对酸性介质中阳极析氧反应（OER）效率低和材料不稳定性问题，单原子掺杂（SAD）的铱/钌基催化剂的研究取得了显著进展，有望提高OER催化剂的性能和耐久性 32。
- 膜电极组件 (MEA) 优化： MEA是PEMEC的核心组成部分，其性能直接影响电解槽的效率和寿命。通过优化MEA设计，包括催化剂层、质子交换膜和气体扩散层（GDL）的结构与界面工程，可以显著降低离子/电荷传输阻力，提高催化剂利用率，并防止机械分层 33。印刷技术（如喷涂、喷墨印刷、丝网印刷）在PEMFC的MEA制造中展现出高通量和成本效益的潜力，有望加速电解槽组件的工业化生产 30。
- 氧气传输优化： 多孔传输层（PTL）的润湿性对PEMEC中氧气传输效率有重要影响，通过研究PTL的特性及其对氧气传输的影响，可以进一步优化PEMEC的性能 31。
2.1.3 固体氧化物电解槽 (SOEC)
成熟度与能效： SOEC技术工作温度通常高于500°C，甚至可达1000°C，利用高温蒸汽进行电解 3435。由于高温下水蒸汽分解的热力学和动力学优势，SOEC的电能转化效率较高 34。然而，SOEC的技术成熟度相对较低，目前主要处于研发和示范阶段，其高温运行对材料的耐受性、稳定性和寿命提出了更高的要求。
适用场景： SOEC可大幅提高电解效率，降低电力消耗。除了制氢，SOEC还可以用于CO₂电解或H₂O-CO₂共电解，生产合成气或增值化学品，具有重要的经济和环境意义 3435。
最新突破： SOEC的研究重点在于开发高性能、长寿命的材料，以克服高温运行带来的挑战。目前，SOEC的组分材料多沿用固体氧化物燃料电池（SOFC）的材料，但在电解模式下，这些材料的性能稳定性面临独特问题 34。研究人员正在积极开发针对SOEC独特运行条件优化的电解质、空气电极和燃料电极材料，以提高其耐久性并降低成本。此外，H⁺传导型SOEC（与传统的O²⁻传导型SOEC相对）的材料开发也成为研究热点，有望进一步提升SOEC的性能 34。
总的来说，三种主流电解水技术各有优劣，并在不断迭代优化中。AEC以其成熟度和成本优势占据市场主导地位，但正在努力提升动态响应能力；PEMEC以其灵活性和高纯度氢气适应可再生能源耦合，并通过材料创新努力降低成本；SOEC则以其超高能效和多功能性在高温热源场景下展现巨大潜力，亟待解决材料稳定性和商业化问题 2235。未来，随着技术的不断进步，这些电解水技术将在绿氢生产中发挥越来越重要的作用。
2.2 高效低成本催化与电极材料研发趋势
电解水制氢技术的核心在于电极催化剂的效率和稳定性，尤其是在析氢反应（HER）和析氧反应（OER）中。目前，PEMEC依赖于贵金属催化剂（如铂和铱）来保证高性能，但这带来了高昂的成本和稀缺性问题，严重制约了绿氢的大规模商业化 363738。因此，学术界和产业界正积极围绕“降低贵金属依赖”和“提升催化活性与稳定性”两大核心方向，研发高效低成本的催化与电极材料。
2.2.1 降低贵金属依赖：非贵金属催化剂的崛起
1. 非贵金属基催化剂的开发：
为了取代PEMEC中昂贵的贵金属（尤其是铱和铂），研究人员将目光投向了地球上储量丰富、价格低廉的过渡金属及其化合物，特别是镍（Ni）、钴（Co）、铁（Fe）等元素。这些非贵金属基材料被广泛认为是替代贵金属的潜在候选者，其优势在于成本低廉且易于大规模生产 3940。
- 过渡金属氧化物、氢氧化物与硫化物： 钴基氧化物纳米材料因其独特的电子结构和可调控的形貌，在提高催化活性和稳定性方面展现出巨大潜力 41。通过形态控制、缺陷工程、掺杂以及异质结构整合等策略，Co₃O₄的析氧活性得到了显著提升 41。类似地，镍基、铁基氧化物和氢氧化物，如NiFe层状双氢氧化物，也显示出优异的OER性能 3942。此外，过渡金属硫化物（如MoS₂、NiSₓ）在HER中表现出与铂相似的催化活性，尤其是在酸性介质中 40。
- 金属有机框架（MOFs）及其衍生物： MOFs因其超高比表面积、可调谐的纳米结构和优异的孔隙率，已成为电化学水分解高效催化剂的研发热点 43。通过设计MOF纳米结构，可以精确控制催化活性中心的组成和结构功能化，从而提升HER和OER的催化性能 43。MOF衍生的碳基复合材料（如嵌入金属纳米颗粒的N掺杂碳）也表现出优异的电催化性能。
- 单原子催化剂（SACs）： SACs通过将孤立的金属原子分散在载体上，最大限度地提高了原子利用率，并能提供独特的电子结构和催化活性位点。例如，在碳载体上的单原子镍或钴已被证明具有高效的HER或OER活性，为降低贵金属用量提供了新的途径 40。
2. 碱性电解槽的非贵金属电极：
在碱性电解槽（AEC）中，虽然传统上已经使用镍基材料作为电极，但为了进一步提升性能和降低成本，研究人员也在积极开发新型非贵金属电极。例如，镍铝钼（NiAlMo）电极在阴离子交换膜（AEM）电解槽中展现出与工业级PEM电解槽相当的性能，并在150小时内保持稳定运行，为非贵金属AEM电解槽的商业化提供了可行性 36。
2.2.2 提升催化活性与稳定性：高耐久性电极材料进展
1. 贵金属负载量优化与合金化：
尽管非贵金属催化剂前景广阔，但在酸性PEMEC中，贵金属催化剂在活性和稳定性方面仍具有优势。因此，一个重要的研究方向是减少贵金属（特别是铱）的用量。
- 纳米结构与载体效应： 通过将铱纳米结构锚定在酸稳定的高比表面积金属氧化物载体（如TiO₂、SnO₂、Ta₂O₅）上，可以有效提高催化剂的利用率、稳定性和降低贵金属含量 37。这种策略不仅能更有效地分散活性位点，还能促进强烈的金属-载体相互作用，确保在严苛的PEMWE运行条件下仍能保持鲁棒性能 37。例如，钖锑氧化物（ATO）负载的混合铱-镍氧化物（IrNiₓOₓ/ATO）在酸性OER中展现出优异的质量活性和周转频率，且铱载量显著降低，并在膜电极组件中表现出更好的活性和稳定性 38。
- 合金化与协同效应： 通过将铱与镍等贱金属形成合金或混合氧化物，可以产生协同效应，优化电子结构，从而提高OER活性并降低铱的用量 38。
2. 缺陷工程与表面重构：
通过引入缺陷（如氧空位）或调控催化剂表面结构，可以改变活性位点的电子态和几何构型，从而显著提高催化活性和稳定性 3941。例如，氧化物衍生的铜催化剂通过模拟氧化物衍生过程，识别出特定的方形位点，这些位点对C-C偶联反应（如乙烯生成）或醇类生成表现出高选择性，这表明表面原子排列和缺陷工程对催化性能的深远影响 44。
3. 多孔传输电极（PTE）设计：
为了提高PEMEC的效率和耐久性，研究人员正在探索先进的多孔传输电极（PTE）设计。PTE将阳极催化剂层直接涂覆在多孔传输层（PTL）上，旨在优化界面接触，提高水和气体的传输效率，同时降低贵金属负载量 45。反应性喷涂沉积技术（RSDT）等新型制造方法，能够在单一步骤中完成催化剂的合成和沉积，显著缩短膜电极组件（MEA）的制造时间和成本，并已成功制备出低贵金属负载（0.2-0.3 mg PGM cm⁻²）且具有高效率和耐久性的PTE 45。
产业化转化情况：
随着学术研究的深入，越来越多的高效低成本催化剂开始进入中试和产业化验证阶段。例如，一些企业已经开始尝试将部分非贵金属基催化剂应用于碱性电解槽的生产中，并取得了良好的效果。在PEMEC领域，虽然完全取代贵金属仍面临挑战，但通过优化贵金属负载量、开发贵金属合金或复合催化剂，已经能够显著降低单位产氢量的贵金属消耗，这对于降低绿氢成本、推动其商业化具有重要意义。随着材料科学和电化学工程的持续进步，预计未来将有更多突破性的催化剂材料投入实际应用，进一步加速绿氢产业的发展。
3. 绿氢储运技术体系与场景适配性分析
3.1 传统储运技术的性能优化与成本下降进展
绿氢的规模化应用离不开高效、经济、安全的储运技术。目前，传统的氢气储运方式主要包括高压气态储氢、低温液态储氢以及固态储氢。这些技术各有特点，并在性能、成本和适用场景方面存在差异。近年来，研究人员和产业界一直在努力优化这些技术的性能，降低其成本，以满足不断增长的绿氢储运需求。
3.1.1 高压气态储氢
技术参数与原理： 高压气态储氢是将氢气在高压下（通常为35 MPa或70 MPa）储存在高强度容器中。这种方法技术相对成熟，主要通过压缩氢气以提高其密度，从而在一定体积内储存更多氢气。储罐材料通常采用钢、铝合金或碳纤维复合材料，其中碳纤维复合材料储罐因其轻量化和高强度而更适用于移动应用，例如燃料电池汽车 46。
成本构成与适用范围： 高压气态储氢的成本主要包括压缩能耗、储罐制造（材料和工艺）、以及充装和安全设施的建设成本。35 MPa的公路运输是目前较为经济的短距离运输方案 47。虽然地下储氢技术（如盐穴储氢）的成本最低，但高压气态储氢在中小规模和移动应用中仍具有不可替代的地位 48。
性能优化与成本下降进展：
- 储氢密度提升： 尽管高压储氢的体积能量密度相对较低，但通过开发更高压力的储罐（如70 MPa）和优化储罐设计，储氢密度得到了显著提升。例如，碳纤维复合材料储罐的研发，使得车载储氢系统能在保证安全的前提下，进一步减轻重量，提高实际储氢量。
- 储运损耗降低： 储运损耗主要体现在压缩过程中的能量损失。通过改进压缩机技术，提高压缩效率，可以有效降低这部分能耗。此外，对于长距离管道运输，现有天然气管道的掺氢运输被认为是降低成本的有效途径 4749。通过将氢气与天然气混合运输，可以利用现有基础设施，避免新建昂贵的专用氢气管道，从而大幅降低初期投资。
- 安全性的提高： 储氢容器的安全性是高压储氢的关键。在材料选择、制造工艺和监测系统方面，持续的技术进步确保了高压储氢系统的安全运行，并满足了各种严苛的国际标准。
3.1.2 低温液态储氢
技术参数与原理： 低温液态储氢是将氢气冷却至-253°C，使其液化，从而大幅提高体积能量密度。液氢的体积能量密度大约是35 MPa气氢的四倍。这种方法主要用于大规模、长距离的氢气运输和存储，以及航空航天等对储氢密度要求极高的领域。
成本构成与适用范围： 液化过程需要消耗大量能量，约占氢气能量含量的30%左右，导致液化成本高昂。此外，液氢储罐需要高性能的绝热材料来防止氢气蒸发（即“沸腾损耗”），这增加了储罐的制造成本和维护难度。因此，低温液态储氢主要适用于大规模储存和远距离运输，特别是在需要高储氢密度和对空间有限制的场景。目前，低温液态储氢技术在移动应用中仍存在效率低、成本高、热管理复杂等显著缺点 46。
性能优化与成本下降进展：
- 液化效率提升： 液化过程的高能耗是低温液态储氢面临的主要挑战。通过优化液化循环和改进换热器设计，研究人员正在努力降低液化能耗。例如，开发更高效的冷箱技术和低温制冷设备，可以减少液化过程中的能量损失。
- 沸腾损耗控制： 沸腾损耗是液氢存储中不可避免的问题。新型超绝热材料和真空技术的发展，有助于延长液氢的储存时间，减少蒸发损失。同时，结合再液化技术，可以将蒸发的氢气重新液化，进一步降低损耗，但这也增加了系统的复杂性和成本。
- 规模效应： 随着液氢生产规模的扩大，单位液化成本有望通过规模经济效应得到降低。
3.1.3 固态储氢
技术参数与原理： 固态储氢是指利用材料的物理吸附或化学键合作用将氢气储存起来。主要包括金属氢化物（如MgH₂、LaNi₅H₆）、络合氢化物（如AlH₃、LiBH₄）和化学氢化物（如NH₃BH₃）以及物理吸附材料（如MOFs、碳纳米管、多孔聚合物）。这些材料通常在较低压力和接近常温的条件下储存氢气，具有较高的体积储氢密度和本征安全性 5051。
成本构成与适用范围： 固态储氢的成本主要取决于储氢材料的制备成本、吸放氢循环寿命、以及系统的热管理成本。虽然固态储氢在车载和便携式应用中显示出巨大潜力，但目前其较高的材料成本、较慢的吸放氢动力学以及复杂的热管理系统限制了其大规模应用。此外，固态储氢还面临着催化剂成本高昂、稳定性差、响应速度慢等挑战 46。
性能优化与成本下降进展：
- 储氢容量与动力学提升： 固态储氢材料的研究主要集中在提高储氢容量、改善吸放氢动力学和可逆性。例如，纳米工程技术被广泛应用于固态储氢材料的研发，通过优化材料的纳米结构，可以增加氢气的吸附位点，提高吸附/脱附速率 50。金属有机框架（MOFs）因其高孔隙率和可调控的结构，被认为是极具潜力的物理吸附储氢材料，通过配体修饰、孔径优化等策略，可以提高其氢气吸附能力 52。
- 耐久性与循环寿命： 许多固态储氢材料在吸放氢循环过程中会发生结构退化，影响其长期性能。通过材料改性、添加催化剂以及优化制备工艺，可以提高材料的稳定性和循环寿命。
- 热管理与系统集成： 固态储氢材料的吸放氢过程通常伴随显著的热效应，因此高效的热管理系统对于维持材料性能和确保系统安全至关重要。研究人员正在开发更轻量化、紧凑型的热交换器和智能热管理方案，以适应实际应用需求。例如，在车载应用中，储氢系统需要快速响应车辆的加氢和用氢需求，这对材料的吸放氢速率和系统热管理提出了更高要求。
- 成本控制： 降低高成本储氢材料的制备成本，特别是对于新型高性能材料，是推动固态储氢技术商业化的关键。通过大规模生产、优化合成路线和寻找更经济的替代原料，有望实现成本下降。
总体而言，虽然传统储氢技术在性能和成本方面仍面临挑战，但通过持续的技术创新，如材料科学的突破、工程设计的优化和规模化生产，这些技术正逐步向更高效、更经济、更安全的方向发展，为绿氢的大规模储运奠定基础。在实际应用中，往往需要根据具体场景（如运输距离、储氢量、终端用途）综合评估，选择最合适的储运技术或多种技术组合方案 53。
3.2 有机氢载体储运技术的研发与应用进展
鉴于氢气本身在常温常压下能量密度低、易燃易爆且渗透性强等特点，其大规模、长距离的储运面临巨大挑战。因此，将氢气转化为液态有机氢载体（Liquid Organic Hydrogen Carriers, LOHCs）或其他易于储运的化学品，成为解决这些难题的重要途径。其中，氨（NH₃）和甲醇（CH₃OH）作为绿氢载体，因其较高的能量密度、与现有基础设施的兼容性以及相对成熟的合成技术而备受关注 54。
3.2.1 氨作为绿氢载体
氨作为一种碳中和的能源载体，具有高体积能量密度（比液氢高约50%）、易于液化（-33°C或8.5 bar）、运输和储存的优点，并且已存在成熟的全球生产、运输和应用网络 5556。
1. 储运效率与技术：
- 高能量密度与易液化： 氨在常压下可冷却至-33°C或在常温下加压至8.5 bar即可液化，这远低于氢气的液化条件（-253°C），极大地降低了储运能耗和成本 55。高体积能量密度使得氨在长距离海运和大规模陆路运输中具有显著优势。
- 基础设施兼容性： 全球已建有广泛的氨管道网络和储存设施，这些基础设施大部分可直接用于绿氨的运输和储存，从而加速大规模氢能部署。这与氢气需要新建基础设施形成鲜明对比，为氨的商业化推广提供了巨大便利 55。
- 分解技术： 氨作为氢载体，最终需要分解（裂解）以释放氢气。目前，氨裂解技术仍在发展中，主要挑战在于实现高效、低能耗、高纯度的氢气产出。高效的氨裂解催化剂和工艺是关键，以避免在能量转化过程中产生过高的能耗损失。
2. 安全标准：
氨虽然是高效的氢载体，但其毒性、易燃性和腐蚀性也带来了独特的安全挑战 57。
- 毒性： 氨具有强烈刺激性气味，高浓度吸入对人体有害。因此，在氨的生产、储运和使用过程中，需要严格的安全规程和泄漏防护措施。
- 易燃性： 氨在特定浓度下具有可燃性，特别是在与空气混合时。但其可燃范围相对较窄，燃点较高，爆炸风险低于氢气。
- 腐蚀性： 氨对某些金属具有腐蚀性，需要选用耐氨腐蚀的材料，尤其是在长期储存和管道运输中。
现有针对氨的安全标准和法规相对完善，主要基于其作为工业化学品的历史应用。然而，随着氨作为燃料和氢载体的新兴应用，需要针对新的应用场景（如船用燃料加注）进一步完善安全评估和标准体系 57。
3. 商业化潜力：
氨作为绿氢载体具有巨大的商业化潜力，特别是在以下场景：
- 长距离国际贸易： 氨的易于液化和海运优势使其成为跨国、大规模绿氢贸易的理想载体，可将可再生能源丰富的地区的绿氢输送到能源需求大的地区 55。
- 船用燃料： 氨被视为海运业脱碳的潜在燃料之一，其直接燃烧或通过燃料电池发电均可实现零碳排放 5657。
- 发电： 氨可以直接在燃气轮机中燃烧发电，也可作为燃料电池的燃料，为电网提供稳定电力。
虽然氨裂解制氢的往返效率（Round-trip efficiency, RTE）通常低于直接氢气路径，但对于以氨为最终产品（如直接燃烧发电）或以氨作为高效储运载体而非最终氢气用途的系统，其RTE可以与直接氢气路径相媲美 55。
3.2.2 甲醇作为绿氢载体
甲醇也是一种重要的液体燃料和化学品原料，作为氢载体，它同样具有液体燃料易于储存和运输的优点，并且可以利用现有的液体燃料基础设施 5859。
1. 储运效率与技术：
- 常温常压液体： 甲醇在常温常压下呈液态，极大地简化了储存和运输条件，无需高压或低温设备，成本优势显著 59。
- 成熟基础设施： 全球已拥有完善的甲醇生产、分销和储存网络，现有油气管道和油轮等运输设施可直接或稍加改造即可用于甲醇运输，有助于迅速推广应用 58。
- 氢气释放： 甲醇可以通过催化重整反应高效释放氢气。甲醇重整技术相对成熟，但仍需进一步优化催化剂和反应条件，以提高氢气产率和纯度，同时降低能耗。
- 碳循环： “绿色甲醇”的生产需要利用捕获的二氧化碳和绿氢合成，实现了碳的循环利用，这与甲醇作为超长周期储能的方案密切相关 59。通过与碳捕集技术结合，可以实现碳中和甚至碳负排放。
2. 安全标准：
甲醇的安全性介于汽油和液化石油气之间。
- 毒性： 甲醇具有毒性，误饮或吸入高浓度蒸汽可能导致中毒。在处理和使用过程中需采取防护措施。
- 易燃性： 甲醇易燃，但其燃点高于汽油，爆炸极限也相对狭窄。现有的安全标准和操作规范已能有效管理甲醇的风险。
- 腐蚀性： 甲醇对某些材料具有腐蚀性，但在现有工业应用中，材料选择和防腐措施已非常成熟。
3. 商业化潜力：
绿色甲醇作为氢载体和燃料的商业化前景广阔，尤其是在交通运输和工业领域：
- 燃料替代： 甲醇可直接用作船用燃料、车用燃料或工业燃料，实现这些领域的碳减排。例如，绿色甲醇被视为远洋航运脱碳的重要替代燃料 54。
- 超长周期储能（ULDES）： 甲醇可以作为一种超长周期储能介质，将间歇性可再生能源转化为化学能储存起来，并在需要时通过重整制氢或直接燃烧发电，有效平抑可再生能源的波动性 59。相较于氢气盐穴储能的地域限制，甲醇可以在任意地点进行大型地上储罐储存，成本低廉 59。
- 化工原料： 绿色甲醇可以替代化石基甲醇，作为生产烯烃、芳烃等基础化学品的原料，推动化工行业的绿色转型。
3.2.3 液体有机氢载体（LOHC）
除了氨和甲醇，一些特定的液体有机化合物（如全氢-二苄基甲苯，Perhydro-Dibenzyl-Toluene）也被研究作为LOHC。LOHC技术通过氢化-脱氢循环，将氢气化学键合在有机分子上，形成富氢液体，再通过脱氢反应释放氢气 606162。
1. 储运效率与技术：
- 高安全性与易操作性： LOHC在常温常压下通常是无毒、不易燃的液体，其储运安全性远高于气态和液态氢，并且可以利用现有燃料基础设施进行运输 606162。
- 可逆性与循环寿命： 理想的LOHC应具有良好的氢化-脱氢可逆性，且在多次循环后仍能保持稳定的性能。
- 脱氢技术： LOHC的脱氢过程需要外部供热，且通常需要贵金属催化剂。目前的主要挑战是如何降低脱氢温度、提高反应速率、减少催化剂用量并提高氢气纯度 6063。例如，Pd基膜可以有效纯化从LOHC中释放的氢气，但膜的耐久性仍需提升 60。
2. 商业化潜力：
LOHC技术在特定场景下具有商业化潜力，尤其是在需要高安全性、长周期储存和灵活运输的分布式氢能应用中。例如，LOHC可以用于将偏远地区的可再生能源制氢输送到用氢中心，或者作为固定式储氢解决方案。与液氢和高压氢相比，LOHC系统的资本成本可能更低 62。
总而言之，氨、甲醇和LOHC等有机氢载体为解决氢气储运难题提供了多样化的解决方案。氨在长距离、大规模运输和作为船用燃料方面优势明显；甲醇则在常温常压储存、利用现有基础设施和超长周期储能方面表现突出；LOHC则以其高安全性、易操作性为分布式和特定固定式储氢场景提供了可能。这些技术的研发和应用进展，将共同推动绿氢产业实现全链条的商业化。
4. 绿氢工业应用场景的落地现状与发展趋势
4.1 高耗能工业领域的绿氢脱碳路径
高耗能工业，特别是钢铁、炼化、合成氨和甲醇生产，是全球主要的二氧化碳排放源，其脱碳对于实现气候目标至关重要。由于这些行业 Processes 本身的复杂性，电气化通常难以完全实现，因此绿氢作为一种清洁的还原剂和燃料，为这些“难脱碳”行业提供了重要的解决方案 64。绿氢的应用路径主要包括替代化石燃料、作为还原剂、以及提供热能或电力。
4.1.1 钢铁工业的绿氢脱碳路径
钢铁生产是全球碳排放量最大的工业部门之一，约占全球能源相关碳排放的7-9% 65。传统的钢铁生产主要依赖高炉-转炉工艺，其中焦炭作为还原剂和燃料，产生大量的二氧化碳。绿氢在钢铁工业中的脱碳路径主要体现在以下两个方面：
直接还原铁 (DRI) 工艺： 这是绿氢在钢铁工业中最具潜力的应用之一。在该工艺中，绿氢直接作为还原剂，将铁矿石中的氧化铁还原为纯铁，替代了传统的焦炭还原过程。所得的直接还原铁（H-DRI）可以进一步在电弧炉（EAF）中熔炼成钢。与传统高炉工艺相比，基于绿氢的DRI-EAF工艺理论上可以实现接近零的碳排放。
- 落地现状与示范项目： 全球范围内，多个大型绿氢炼钢项目正在积极推进。例如，瑞典的HYBRIT项目，由SSAB、LKAB和Vattenfall合作，已于2021年成功生产出世界首批绿氢还原钢。德国的Thyssenkrupp也在其位于杜伊斯堡的工厂推进大规模绿氢炼钢项目，计划逐步用绿氢替代焦炉煤气。在中国，宝武钢铁集团等也在探索绿氢冶金技术，并启动了多个示范项目。这些项目正在验证绿氢炼钢的技术可行性和经济性，并积累宝贵的运行经验。
- 运行经验与挑战： 早期示范项目表明，绿氢DRI工艺可以有效降低碳排放，但其运行成本，特别是绿氢成本，仍然是主要挑战 66。一篇研究指出，在意大利塔兰托的钢铁厂，整合绿氢可将排放量削减90%以上，但基准情景下的平准化氢成本（LCOH）为3.6欧元/公斤，绿色钢铁生产成本为653欧元/吨。然而，在乐观假设下（可再生电力40欧元/兆瓦时，电解槽资本支出减半至500欧元/千瓦），氢成本可降至2.3欧元/公斤，使得绿色钢铁与传统钢铁具有成本竞争力，隐含碳价低于60欧元/吨 66。这表明，降低绿氢成本和获得政策支持是推广绿氢炼钢的关键 65。此外，氢气的高温特性、设备改造投入以及氢气储存和输送的基础设施建设也是需要克服的障碍。
绿氢替代燃料： 在钢铁生产的某些环节，绿氢也可以作为清洁燃料，替代天然气或煤气，用于加热炉、烧结等过程，从而减少燃料燃烧产生的碳排放。
4.1.2 炼化工业的绿氢脱碳路径
炼化工业是氢气的重要消费者，主要用于加氢裂化、加氢精制等过程。目前，炼化厂使用的氢气绝大部分来自天然气重整或煤气化，属于高碳排放的灰氢。用绿氢替代灰氢是炼化行业脱碳的直接有效途径。
- 替换路径： 将炼化过程中使用的灰氢逐步替换为可再生能源电解生产的绿氢，可以在不改变现有工艺流程主体设备的前提下，大幅降低炼化产品的碳足迹。
- 落地现状与示范项目： 全球炼化巨头如壳牌、道达尔等已在全球各地启动了多个绿氢替代项目。例如，欧洲的一些炼化厂已开始使用小规模绿氢来满足部分加氢需求，以降低其产品的碳强度。在国内，中国石化、中国石油等也纷纷布局绿氢项目，计划在炼化基地周边建设绿氢生产设施，逐步实现绿氢在炼化环节的应用。例如，中国石化新疆库车绿氢示范项目，其生产的绿氢就将用于替代当地炼化企业生产中使用的天然气制氢。
- 运行经验与挑战： 绿氢在炼化行业的应用技术成熟度高，主要挑战仍在于绿氢的成本和供应稳定性。由于炼化行业对氢气需求量大且稳定，需要建设大规模、可靠的绿氢供应体系。随着绿氢成本的下降和可再生能源电力的普及，炼化行业有望成为绿氢大规模商业化应用的首批“吃螃蟹者”。
4.1.3 合成氨/甲醇工业的绿氢脱碳路径
合成氨和甲醇是重要的基础化工原料，其生产过程同样是高碳排放环节。合成氨（哈伯-博世法）需要大量的氢气和氮气，甲醇合成则需要氢气和二氧化碳。目前，这些氢气主要来自化石燃料重整。
绿氢合成氨：
- 替换路径： 用绿氢替代化石燃料制取的氢气，与空气分离得到的氮气反应生成“绿色氨”。这可以在不改变哈伯-博世合成塔主体设备的情况下，实现合成氨生产过程的彻底脱碳。
- 落地现状与示范项目： 绿色氨的生产已成为全球化肥和化工行业的重要发展方向。沙特阿拉伯的NEOM项目正在建设世界上最大的绿色氢和绿色氨生产设施，计划利用当地丰富的太阳能和风能生产绿氢，并进一步合成绿色氨出口到全球市场。在欧洲，挪威的Yara等化肥巨头也在积极探索和实施绿色氨生产项目。在国内，华鲁恒升、中化集团等化工企业也已启动或规划了多个绿氢制绿氨项目，旨在减少其化肥产品的碳足迹。
- 运行经验与挑战： 绿色氨生产的技术路线清晰，但其经济性受绿氢成本和可再生能源电价影响较大。此外，考虑到合成氨生产的连续性和稳定性，对绿氢的可靠供应要求很高。然而，氨本身作为一种优良的氢载体，其易于液化、储存和运输的特性，使其在解决绿氢长距离运输问题方面具有独特优势 5667。
绿氢合成甲醇：
- 替换路径： 用绿氢与捕获的工业二氧化碳（CCU）反应合成“绿色甲醇”，可以实现碳的循环利用。这不仅消纳了绿氢，还实现了二氧化碳的资源化利用。
- 落地现状与示范项目： 全球范围内，多个绿色甲醇项目正在建设或规划中，主要集中在欧洲和中国。冰岛Carbon Recycling International (CRI) 公司已成功商业化运行利用地热能和捕获的CO₂生产绿色甲醇的工厂。在中国，远景科技集团、吉利控股集团等也正积极投资绿色甲醇项目，计划将绿氢与捕集的二氧化碳结合，生产用于交通燃料或化工原料的绿色甲醇。
- 运行经验与挑战： 绿色甲醇的技术路线也相对成熟，主要挑战在于成本和规模化生产。捕获的二氧化碳来源、绿氢成本、以及甲醇合成催化剂的效率和寿命，都是影响绿色甲醇经济性的关键因素。然而，随着碳捕集技术的进步和绿氢成本的下降，绿色甲醇有望在燃料和化工领域发挥越来越重要的作用。
综上所述，绿氢在高耗能工业领域的脱碳路径清晰可见，并且已有多个工业级应用示范项目落地。虽然目前仍面临成本高昂、技术集成复杂以及基础设施缺乏等挑战，但随着技术进步、规模效应以及政策支持的增强，绿氢有望在未来成为这些行业实现深度脱碳的关键动力。
4.2 绿氢与可再生能源系统的耦合应用
可再生能源（如风能和太阳能）的快速发展是全球能源转型的重要特征，但其固有的间歇性、波动性和地域分布不均等问题，对电网的稳定运行和电力消纳提出了巨大挑战 686970。绿氢作为一种清洁、灵活的能源载体，能够将间歇性的可再生电力转化为可储存和运输的化学能，从而实现与可再生能源系统深度耦合，在能源消纳、电网调峰和跨季节储能等多个场景中发挥关键作用 717273。
4.2.1 可再生能源消纳与电网调峰
应用模式：
落地路径与实践：
- 大规模风光制氢一体化项目： 在风能和太阳能资源富集地区，如我国西北部、欧洲北海地区、澳大利亚等，正在建设大型风光制氢一体化示范项目。这些项目直接将风电场或光伏电站与电解水制氢装置连接，实现电力生产与绿氢制造的紧密结合。
- 电网侧储能与调峰： 在电网负荷高峰期，通过燃料电池将储存的绿氢重新转化为电力，为电网提供支撑，这已在欧洲、北美等地的部分地区进行示范。这种“Power-to-Hydrogen-to-Power”（P2H2P）系统能够有效平抑可再生能源的波动性，提升电网韧性 73。
4.2.2 跨季节储能
应用模式：
落地路径与实践：
- 地下储氢项目： 一些研究和示范项目正在探索地下储氢的可行性，例如利用盐穴进行大规模氢气存储，以支持可再生能源电力系统和绿氢经济的发展。这些项目旨在验证氢气在地下存储的安全性、长期稳定性和经济性 77。
- 绿氢制合成燃料（e-fuels）储能： 除了直接储存氢气，绿氢还可以进一步转化为合成甲烷、合成甲醇或合成氨等液体燃料。这些e-fuels可以利用现有基础设施进行储存和运输，并在需要时作为燃料或发电。这种“Power-to-X”技术路线为可再生能源提供了更广泛的跨季节储能和应用途径。
4.2.3 绿氢与风光电系统协同发展的落地路径
为了实现绿氢与风光电系统的协同发展，需要多方面发力：
- 优化系统集成与控制： 开发先进的智能控制系统，能够实时监测风光发电量和电网负荷，并优化电解槽的运行策略，以最大化绿氢生产效率和电网辅助服务价值 7879。人工智能和机器学习技术在优化电解过程、提高效率和降低成本方面具有巨大潜力 7879。
- 完善基础设施建设： 加速建设连接可再生能源基地与绿氢生产基地、以及氢气储运和利用的基础设施。这包括构建高效、安全的氢能网络，涵盖氢气的生产、储存、运输和加注等环节。
- 政策与市场机制创新： 建立健全支持绿氢发展的政策体系，包括对绿氢生产、储运和应用的补贴、税收优惠、碳交易机制等。例如，通过引入碳定价或绿氢认证机制，提升绿氢的市场竞争力，激励企业投资绿氢项目。此外，鼓励电力市场对电解槽提供辅助服务进行补偿，以提高电解槽的经济收益。
- 技术创新与成本下降： 持续推动电解槽技术、储氢材料和燃料电池技术的研发，以进一步提高效率、降低成本和延长寿命。例如，新型电解槽和催化剂的开发可以降低绿氢的生产成本 22。
- 跨部门合作与标准制定： 促进可再生能源、电力、化工、交通等多个部门之间的合作，共同推动绿氢在不同领域的应用。同时，制定统一的氢能标准和法规，确保绿氢产业的健康有序发展。
综上所述，绿氢与可再生能源系统的耦合是实现能源深度脱碳和构建新型电力系统的重要路径。通过在能源消纳、电网调峰和跨季节储能等场景的创新应用，绿氢有望成为支撑高比例可再生能源接入电网、保障能源安全的关键技术。
5. 绿氢全产业链成本构成与下降路径分析
5.1 绿氢全产业链成本拆解与经济性测算
绿氢的商业化推广面临的最大挑战之一是其高昂的成本。要实现绿氢的广泛应用，必须对其全产业链的成本构成进行深入分析，并找出有效的下降路径。绿氢的产业链主要包括制氢（生产）、储运和应用三个环节。
5.1.1 绿氢全产业链成本拆解
绿氢的最终成本（通常以单位质量或单位能量计算，如 €/kg H₂ 或 $/kg H₂）受到多个环节成本的综合影响。
制氢成本（Production Cost）：
- 电力成本： 这是绿氢生产最主要的成本构成。电解水制氢所需的可再生电力价格是决定绿氢成本的关键因素。例如，根据一项研究，在碳循环经济框架下，生产表面活性剂所需的绿氢成本是影响其最低销售价格（MSP）的最大因素，最低MSP仍远高于化石基产品 80。有研究指出，在优化的系统中，用于钢铁生产的绿氢成本可达6.5欧元/公斤，使得绿色钢铁生产成本高于传统路线，这表明电力成本对绿氢制造成本影响巨大 81。
- 电解槽设备购置成本（CAPEX）： 包括电解槽本体、辅助系统（如电源转换器、气体纯化系统、水处理系统）等的投资。虽然电解槽的成本正在快速下降，但仍是初期投资的重要组成部分。
- 运行维护成本（OPEX）： 包括电解槽运行过程中的电力消耗（如泵、压缩机）、去离子水消耗、催化剂更换、备件、人工等。
- 技术路线差异： 不同电解水技术（AEC、PEMEC、SOEC）的成本构成有所不同。例如，PEMEC虽然效率高、响应快，但因使用贵金属催化剂（铂、铱）而导致设备成本较高；AEC则设备成本相对较低，但能效和动态响应性略逊一筹。SOEC能效最高，但对高温材料和系统集成要求高，CAPEX和OPEX可能更高。
储运成本（Storage and Transportation Cost）：
- 储氢成本：
- 运输成本：
- 管道运输： 专用氢气管道的建设成本高昂，但在大规模、长距离运输方面具有最低的单位成本优势。与天然气管道掺氢运输可以有效利用现有基础设施，降低初期投资，但掺氢比例受限。
- 槽车运输： 高压气态氢槽车或液氢槽车运输，适用于中短距离、中等规模的运输。成本主要包括车辆购置、燃料、人工、以及装卸设施。液氢运输具有更高的能量密度，在一定程度上降低了运输频率，但液氢槽车成本更高，且存在沸腾损耗。
- 船运： 液氢或液氨船运适用于长距离、跨洋运输。成本主要包括船只建造、港口设施、装卸、以及液氢/液氨的再气化/分解设施。例如，绿色氨作为空间能量载体，其生产和洲际运输的成本是评估全球脱碳氨经济中完整能源供应链的关键因素 67。
应用成本（Application Cost）：
- 加氢站成本： 加氢站的建设成本高昂，包括压缩、存储、冷却、加注设备等，是影响燃料电池汽车推广的重要因素。
- 终端设备改造/购置成本： 例如，工业炉窑或燃气轮机适应氢气燃烧的改造费用；燃料电池汽车的购置成本；合成氨/甲醇工厂的改造或新建成本。
- 运营成本： 终端设备的使用维护费用、安全保障费用等。
5.1.2 经济性测算与竞争优劣势
绿氢的经济性测算通常通过平准化氢成本（Levelized Cost of Hydrogen, LCOH）来评估。LCOH考虑了项目全生命周期的所有成本（CAPEX和OPEX）和氢气产量，可以横向比较不同技术路径的成本水平。
不同技术路线与应用场景下的绿氢成本水平与竞争优劣势：
工业用途（如炼化、合成氨、钢铁）：
- 优势： 需求量大且稳定，通常集中在工业园区，有利于规模化生产和集中供氢，降低储运成本。可以利用现有工业基础设施进行改造。
- 劣势： 对氢气纯度、供应可靠性要求高。目前绿氢价格显著高于灰氢，导致其在经济性上仍不具备竞争力，需要碳排放权交易或补贴政策支持。例如，钢铁行业应用绿氢的LCOH约为6.5欧元/公斤，相比传统路线成本更高 81。
- 经济性： 工业级绿氢的LCOH需要在1.5-2.5美元/公斤左右才能与当前灰氢或天然气价格竞争，而目前大部分地区仍高于此水平。
交通运输（如燃料电池汽车、船舶、航空）：
- 优势： 环保需求紧迫，对能源密度要求高（尤其是长距离重载运输），绿氢或其衍生物（如氨、甲醇）具有独特优势。
- 劣势： 加氢站基础设施缺乏，车辆购置成本高，且车载储氢技术仍需提升。
- 经济性： 交通领域用户对高氢价的承受能力相对较高，但要实现大规模普及，氢气价格仍需大幅下降。
电力系统（储能、调峰）：
- 优势： 可以解决可再生能源的间歇性问题，提供电网辅助服务，实现跨季节储能。
- 劣势： P2H2P（Power-to-Hydrogen-to-Power）效率损耗较大，成本高。大规模地下储氢技术仍需进一步验证。
- 经济性： 需结合电力市场机制，通过辅助服务收益或碳减排收益来弥补成本。目前还处于示范阶段，经济性有待提升。
总而言之，目前绿氢在大多数应用场景下仍不具备经济竞争力。研究表明，要实现绿氢的广泛商业化，其成本必须大幅下降，尤其是在生产和储运环节。
5.2 中长期绿氢成本下降核心路径
未来5-10年，绿氢成本有望通过多方面努力降至与化石燃料制氢竞争的平价水平。实现这一目标的核心路径主要包括以下几个方面：
设备规模化生产（Economies of Scale）：
- 电解槽制造： 随着绿氢项目的增多，电解槽的生产规模将持续扩大。类似于太阳能光伏组件和风力涡轮机的成本下降趋势，电解槽的大规模自动化生产将显著降低其单位制造成本。国际能源署（IEA）预测，到2030年，通过规模化生产和技术改进，电解槽的投资成本有望降低60%以上。这将直接降低绿氢的CAPEX。
- 辅助设备制造： 除了电解槽本身，绿氢生产系统中的其他辅助设备，如电源转换器、气体纯化设备、压缩机等，也将受益于规模化生产和标准化设计，从而降低整体系统成本。
可再生能源电价下降：
- “度电成本”持续走低： 风能和太阳能发电的平准化度电成本（LCOE）在全球范围内持续下降，且部分地区已低于化石燃料发电。随着技术进步、材料成本下降和规模化效应，未来可再生能源电价将进一步降低。
- 直接耦合与弃电利用： 绿氢生产可以与低成本的可再生能源电力直接耦合（如“制氢专线”），或利用电网中的“弃风弃光”电量进行生产。这种“直接供电”模式能够避免输配电费用和电网辅助服务费用，显著降低制氢的电力成本。当弃风弃光电价接近于零时，将极大地拉低绿氢生产成本。
技术迭代提效（Technological Innovation and Efficiency Gains）：
- 电解槽效率提升：
- 催化材料： 持续研发低成本、高性能的非贵金属催化剂，以替代或减少PEMEC中贵金属（铂、铱）的使用量，这将直接降低电解槽的CAPEX。
- 电极与膜材料： 改进电极结构、开发新型高效率质子交换膜或固体氧化物电解质，提高电解槽的电流密度和法拉第效率，从而降低单位氢气生产的能耗。
- 系统集成优化： 优化电解槽堆栈设计、电源管理系统以及热管理系统，提升整体系统的运行效率和稳定性。
- 储运技术突破：
- 高压储氢： 研发更轻、更强的复合材料储罐，提高储氢密度和降低成本。
- 液氢： 提升氢气液化效率，降低液化能耗，开发更低成本、更长储存周期的液氢储罐。
- 固态储氢/有机氢载体： 研发更高效、长寿命的储氢材料和更经济的氢化/脱氢催化剂，降低系统复杂性和成本。
- 智能控制与数字化： 运用人工智能和大数据技术优化电解槽的运行参数，实现预测性维护，提高设备的利用率和寿命，降低运维成本。
- 电解槽效率提升：
产业配套完善（Infrastructure Development and Ecosystem Maturation）：
- 基础设施建设： 加速建设氢气管道网络、加氢站、液氢/液氨港口和储运设施，降低氢气运输成本和末端分销成本。借鉴天然气管道的经验，规划和建设全国性甚至区域性的氢气输送网络。
- 产业链协同发展： 推动绿氢产业链上下游企业协同发展，形成规模效应和集群效应，共同降低研发、制造成本。
- 政策支持与市场机制： 政府通过提供补贴、税收优惠等手段，降低投资风险，激励企业参与。例如，参考文献80指出，持续推进费托催化剂技术、降低绿氢成本以及不断增长的环保产品需求可以显著提高该可持续方法的经济可行性。建立完善的绿氢认证和溯源机制，提高市场对绿氢的认可度。
时间节点预测：
- 2025-2030年： 预计在可再生能源资源丰富的地区，绿氢的LCOH有望降至2-3美元/公斤。部分地区，特别是在电力价格极低或政府补贴力度大的区域，甚至可能达到1.5-2美元/公斤的水平。这将在一些对碳排放敏感且对氢气需求量大的工业领域（如炼化、部分化工）开始具备经济竞争力。
- 2030-2035年： 随着电解槽制造成本的进一步下降、可再生能源电价的持续走低以及储运技术的成熟，绿氢的LCOH有望在全球大部分地区降至1-2美元/公斤。在此阶段，绿氢将在更多工业领域、部分交通领域（如重载卡车、船舶）和电力调峰等场景具备较强的经济竞争力，实现与灰氢的平价甚至更低。
总的来说，绿氢成本的下降是一个系统性工程，需要技术创新、规模效应、基础设施建设和政策支持等多方面因素的共同作用。虽然当前成本仍然较高，但清晰的下降路径和巨大的减排潜力，使得绿氢在未来能源转型中扮演不可或缺的角色。
6. 全球绿氢产业支持政策体系与导向分析
6.1 主要经济体绿氢产业政策梳理
全球各国政府已将绿氢视为应对气候变化、实现能源转型和增强能源安全的关键战略资源，纷纷出台了一系列政策、法规和激励措施，旨在加速绿氢产业的发展和商业化进程。这些政策不仅为绿氢的生产、储运和应用提供了支持，也体现了不同地区在资源禀赋、产业基础和战略目标上的差异。
6.1.1 欧盟REPowerEU计划
欧盟的REPowerEU计划是为应对2022年俄罗斯入侵乌克兰引发的能源危机而制定的一项综合性政策，旨在“在2030年前彻底摆脱对俄罗斯化石燃料的依赖”并“加速绿色转型” 8485。在该计划中，绿氢被提升到前所未有的战略高度，成为欧洲能源安全和工业脱碳的核心支柱 84。
支持方向与目标：
- 绿氢生产目标： 计划设定了到2030年欧盟本土生产1000万吨绿氢以及进口1000万吨绿氢的宏伟目标，以满足不断增长的工业和交通脱碳需求 86。
- 基础设施建设： 大力投资氢气管道、加氢站、以及进出口港口等基础设施，以支持绿氢的大规模生产、运输和消费。其中，H2MED管道项目（连接巴塞罗那和马赛）旨在将北非的绿氢输送至欧洲市场 84。
- 工业应用激励： 鼓励高耗能产业（如钢铁、化工）采用绿氢替代化石燃料，并通过碳边境调节机制（CBAM）等政策工具，提升绿氢在欧盟内部的市场竞争力，避免“碳泄漏” 87。
- 研发与创新： 持续资助绿氢技术研发，包括电解槽效率提升、非贵金属催化剂开发、以及高效储运技术等，以降低绿氢成本。
- 国际合作： 积极寻求与可再生能源资源丰富的国家建立绿氢伙伴关系，例如与摩洛哥、阿塞拜疆、阿曼等国签订协议，确保未来绿氢的多元化进口来源 84。
补贴机制与引导效果：
- 资金投入： REPowerEU计划总计将新增2100亿欧元的投资，主要用于可再生能源、氢能和能效提升 84。
- 国家援助： 欧盟委员会允许成员国放宽国家援助规定，以支持工业转型，并鼓励各国政府通过税收减免等方式支持绿色零碳技术投资 84。
- 碳定价机制： 欧盟排放交易体系（EU ETS）的深化和碳边境调节机制（CBAM）的实施，通过提高化石燃料的成本，间接提升了绿氢的经济竞争力，引导企业转向低碳解决方案 87。
政策侧重点： 欧盟的政策侧重于通过多管齐下的方式，既鼓励本土绿氢生产，又强调国际合作以确保绿氢供应的多元化和安全性，同时利用碳市场机制推动工业脱碳。这反映了欧盟在能源安全和气候目标双重压力下的“绿色转型安全化”战略 84。
6.1.2 美国《通胀削减法案》（IRA）
美国《通胀削减法案》（IRA）是2022年通过的一项具有里程碑意义的立法，旨在通过大规模财政支出和税收抵免来应对气候变化、降低医疗成本和改革税制。其中，对绿氢产业的巨额补贴是其核心亮点之一。
支持方向与目标：
- 生产激励： IRA为清洁氢生产提供了慷慨的生产税收抵免（PTC），最高可达3美元/公斤。这一激励措施旨在显著降低绿氢的生产成本，使其在短期内具备与灰氢竞争的潜力 88。
- 投资税收抵免： 除了PTC，IRA还提供清洁能源项目的投资税收抵免（ITC），覆盖了电解槽等关键设备的购置成本，进一步降低了绿氢项目的初期投资门槛。
- 技术研发： 通过美国能源部（DOE）的“氢能突破（Hydrogen Shot）”倡议等，设定了到2031年将绿氢成本降至1美元/公斤的目标，重点支持CAPEX削减、规模化生产和电解槽效率提升 88。
补贴机制与引导效果：
- 直接财政激励： 高额的生产税收抵免是IRA政策最直接和有效的激励机制。有分析认为，高达3美元/公斤的补贴可以使绿氢的成本竞争力大幅提升，甚至在某些情况下低于灰氢的生产成本 88。
- 市场活力激发： 巨额补贴极大地激发了美国绿氢市场的投资热情，吸引了大量国内外企业在美国投资绿氢项目，预计到2035年，绿氢相关投资将超过250亿美元 88。
- 政策侧重点： 美国的政策更加直接和市场导向，通过强有力的财政激励迅速降低绿氢成本，以期在短时间内实现绿氢的大规模商业化，并在全球清洁能源技术竞争中占据领先地位。
6.1.3 中国《氢能产业发展中长期规划（2021-2035年）》
中国作为全球最大的能源生产国和消费国，也将氢能发展提升至国家战略高度，并于2022年发布了《氢能产业发展中长期规划（2021-2035年）》。
支持方向与目标：
- 顶层设计与战略定位： 明确了氢能在国家能源战略中的重要地位，提出将氢能打造成为国家能源体系的重要组成部分，推动其与电力等能源品种协同发展，构建清洁低碳、安全高效的能源体系。
- 技术创新： 强调在制氢、储运、燃料电池和应用等全产业链的关键核心技术研发上取得突破，尤其关注电解水制氢、氢气液化、燃料电池等领域。
- 基础设施建设： 规划了氢能基础设施的布局，包括氢气管道建设、加氢站网络完善等，以支撑氢能的大规模应用。
- 应用示范： 鼓励在交通、工业、建筑等领域开展氢能应用示范，特别是推动燃料电池汽车的商业化应用和工业领域（如钢铁、化工）的绿氢替代。
- 区域协同： 推动“西氢东送”战略，利用西部地区丰富的可再生能源资源制取绿氢，输送至东部工业发达地区，实现区域间的优势互补。
补贴机制与引导效果：
- 中央与地方政策协同： 国家层面出台了宏观规划，地方政府则根据自身特点制定了具体的实施方案和配套补贴政策。例如，部分地区对绿氢项目、加氢站建设、燃料电池汽车购置等给予财政补贴或运营奖励。
- 示范项目带动： 通过在特定区域和特定领域开展氢能示范项目，积累经验、验证技术、培养市场，为后续大规模推广奠定基础。
- 政策侧重点： 中国的政策侧重于系统性规划和全产业链协同发展，通过顶层设计、技术创新和应用示范相结合的方式，逐步推动氢能产业的健康有序发展，旨在构建具有中国特色的氢能产业生态。
6.1.4 不同地区的政策侧重点与产业引导效果
- 欧盟： 受能源危机影响，欧盟政策更加注重能源安全与绿色转型的协同，通过进口多元化和碳市场机制，引导工业脱碳，并对绿氢赋予“公共利益”属性以加速审批 84。其政策引导效果显著体现在对国际绿氢供应链的积极构建上。
- 美国： 通过《通胀削减法案》的巨额直接补贴，美国政策旨在快速降低绿氢成本，激发市场活力，吸引投资，以期在短期内建立全球领先的绿氢产业。其引导效果是大量的绿氢项目投资和产能规划涌现。
- 中国： 强调国家战略引领和全产业链协同发展，通过中长期规划、技术攻关和应用示范，逐步构建完整的氢能产业体系。其引导效果是区域性氢能产业集群的形成和“西氢东送”等战略性基础设施的规划。
总体而言，全球主要经济体的绿氢政策均体现了推动绿氢发展的决心，但在具体路径和侧重点上有所不同。这些政策的共同目标是降低绿氢成本、完善基础设施、拓展应用场景，最终实现绿氢的大规模商业化。
6.2 政策对产业链各环节的扶持效果与未来导向
全球主要经济体针对绿氢产业出台的各项政策，正在对绿氢产业链的各个环节产生深远影响。这些政策通过财政激励、规划引导、标准制定等多种手段，积极扶持电解槽制造、绿氢制备项目以及工业应用示范，并有望在未来持续优化以促进产业的健康发展。
6.2.1 政策对电解槽制造环节的扶持效果
电解槽是绿氢制备的核心设备，其成本和性能直接决定了绿氢的生产成本。各国政策对电解槽制造的扶持主要体现在：
- 资本支出（CAPEX）补贴与投资抵免： 例如，美国的《通胀削减法案》（IRA）提供清洁能源项目的投资税收抵免（ITC），覆盖了电解槽等关键设备的购置成本，直接降低了电解槽制造商和绿氢项目投资方的初期投入。欧盟通过其创新基金（Innovation Fund）等机制，支持电解槽制造技术的研发和规模化生产，例如用于大型项目的电解槽生产设施的建设。中国的政策则鼓励电解槽企业加大研发投入，并对关键核心零部件的国产化给予支持。
- 研发（R&D）资金支持： 各国政府通过设立专项科研基金、国家重点研发计划等，资助电解槽新材料、新工艺、新技术的研发，旨在提高电解效率、延长使用寿命、降低贵金属用量，从而提升电解槽的整体性能并降低制造成本。例如，美国能源部（DOE）的“氢能突破（Hydrogen Shot）”倡议就明确了将绿氢成本降至1美元/公斤的目标，其中很大一部分将通过电解槽技术的创新来实现。
- 规模化生产激励： 一些政策鼓励电解槽制造商扩大生产规模，通过规模效应降低单位制造成本。例如，欧盟和中国都在推动建设大型电解槽制造基地，以满足未来绿氢生产的巨大需求。
实际扶持效果： 政策扶持已显著加速了电解槽技术的进步和产业化进程。全球范围内，电解槽产能正在迅速扩张，例如，预计到2030年，全球电解槽产能将从目前的数吉瓦增长到数百吉瓦。成本方面，碱性电解槽（AEC）和质子交换膜电解槽（PEMEC）的成本在过去几年中已经呈现出显著下降趋势。在欧洲，由于政策激励和技术进步，预计到2030年，电解槽的制造成本将进一步降低。然而，PEMEC对贵金属（铂、铱）的依赖仍是其成本高企的主要原因，这促使研发投入转向非贵金属催化剂和贵金属减载技术。
6.2.2 政策对绿氢制备项目的扶持效果
绿氢制备项目是绿氢产业链的源头，其成本和规模直接影响下游应用。政策扶持主要体现在：
- 生产补贴： 美国的IRA提供的最高3美元/公斤的生产税收抵免（PTC）是全球最为慷慨的绿氢生产补贴，极大地提升了绿氢项目的经济性，使其在某些情况下甚至能与灰氢竞争。欧盟则通过“欧洲清洁氢联盟”（European Clean Hydrogen Alliance）等平台，协调成员国的资金，为大型绿氢生产项目提供财政支持和贷款担保。
- 可再生能源电力优惠： 许多国家通过优先保障绿氢项目获得低价可再生能源电力，或通过“绿电绿证”交易机制，降低绿氢生产的电力成本。例如，中国在西部风光资源富集地区推动“风光制氢一体化”示范项目，利用低成本的“弃风弃光”电力制氢。
- 项目审批与规划： 简化绿氢项目的审批流程，提供土地、环保等方面的支持，并将其纳入国家能源基础设施规划，为绿氢项目的落地提供便利。
实际扶持效果： 政策激励已使得全球范围内绿氢制备项目数量大幅增加，规划总产能呈现爆发式增长。根据S&P Global的数据，全球绿氢项目投资额已达到3200亿美元。然而，在欧洲，由于缺乏像IRA那样直接且高额的生产补贴，绿氢生产成本（LCOH）仍然较高，这限制了其商业化进程。在中国，虽然有规划引导和部分地方补贴，但全国性的绿氢生产补贴尚未全面落地，使得绿氢在与灰氢的竞争中仍面临挑战。
6.2.3 政策对工业应用示范的扶持效果
工业应用是绿氢实现大规模商业化的关键突破口。政策对工业应用示范的扶持主要体现在：
- 强制性配额与碳定价： 欧盟通过其排放交易体系（EU ETS）和碳边境调节机制（CBAM），提高了工业碳排放的成本，从而间接激励高耗能行业转向绿氢等清洁能源。REPowerEU计划也明确了工业领域对绿氢的需求目标。
- 示范项目资金： 各国政府通过提供专项资金支持、低息贷款、税收优惠等方式，鼓励企业开展绿氢在钢铁、化工、炼化、交通等领域的应用示范项目。例如，德国、瑞典等国在绿氢炼钢领域投入大量资金进行示范。中国也在京津冀、长三角等地区开展燃料电池汽车示范应用，以及绿氢在化工领域的应用。
- 行业标准与认证： 制定绿氢在工业应用中的技术标准、安全规范和产品认证体系，为绿氢的推广应用提供可靠依据。
实际扶持效果： 政策推动了多个具有里程碑意义的工业级绿氢应用示范项目落地，验证了绿氢在脱碳方面的巨大潜力。例如，瑞典HYBRIT项目成功生产出绿氢还原钢，欧洲多家炼化企业开始尝试使用绿氢。然而，由于绿氢成本仍然较高，且现有工业流程改造需要巨额投资，目前这些应用仍主要依赖于政府补贴和试点项目。在缺乏强有力市场激励的情况下，企业大规模转向绿氢的动力不足。
6.2.4 未来绿氢政策的优化方向与支持重点
鉴于当前绿氢产业发展面临的挑战，未来政策的优化方向将主要围绕以下几点：
- 统一且可预测的长期政策框架： 建立稳定、清晰的长期政策框架，提供可预测的投资环境，降低不确定性，鼓励私人资本投入绿氢项目。这包括明确的绿氢生产目标、应用路径和财政激励机制。
- 强化财政激励的精准性和有效性：
- 生产侧补贴： 考虑在全球范围内推广类似美国IRA的生产税收抵免政策，或通过合同差价（CfD）等机制，锁定绿氢价格，降低生产商的风险，加速绿氢成本下降。
- 需求侧激励： 除了工业碳定价外，可探索对使用绿氢的终端产品提供绿色溢价补贴或采购配额制，以刺激市场需求。例如，制定强制性绿氢使用比例，推动企业主动采用绿氢。
- 基础设施建设资金： 持续投入氢气管道、加氢站、储运设施等基础设施建设，特别是公共基础设施部分，降低绿氢的储运成本。
- 加速技术创新与标准化：
- 研发投入： 继续加大对电解槽核心材料、储运技术（如液态有机氢载体LOHC、氨储运）以及燃料电池技术的研发支持，突破技术瓶颈，降低全产业链成本。
- 国际标准： 推动国际合作，统一绿氢生产、储运、应用的技术标准和安全规范，消除贸易壁垒，促进全球绿氢产业链协同发展。
- 优化监管环境与市场机制：
- 简化审批： 进一步简化绿氢项目的审批流程，提高效率。
- 绿氢认证： 建立健全可靠的绿氢认证体系，明确绿氢的来源、生产过程和碳足迹，确保绿氢的“绿色”属性，并与碳市场有效衔接。
- 电力市场改革： 改革电力市场机制，为电解槽作为柔性负荷提供辅助服务提供清晰的补偿机制，使其在电网调峰中发挥更大作用。
- 关注公平转型与社会接受度： 在推动绿氢产业发展的同时，要关注对传统化石能源从业人员的培训和转岗支持，确保能源转型过程中的社会公平性。同时，加强公众对氢能安全和环保优势的认知，提高社会接受度。
总而言之，现有政策对绿氢产业链各环节的扶持已初显成效，但在经济性、规模化和市场机制方面仍有提升空间。未来政策将更侧重于构建一个稳定、激励性强且全链条协同发展的生态系统，以加速绿氢从示范走向大规模商业化，最终实现其在能源转型中的战略目标。
7. 绿氢商业化推广的瓶颈与破局方向
7.1 当前绿氢商业化落地的核心瓶颈
尽管绿氢在全球能源转型中被寄予厚望，但其大规模商业化推广仍面临多重瓶颈。这些瓶颈涵盖技术、经济、基础设施、政策法规以及社会认知等多个维度，彼此交织，共同构成了绿氢产业发展的深层障碍。
7.1.1 技术成熟度与效率限制
- 电解水技术： 虽然碱性电解槽（AEC）技术成熟，但其响应速度慢，与波动性可再生能源的耦合效率不高。质子交换膜电解槽（PEMEC）响应速度快，但仍依赖昂贵的贵金属催化剂（如铂和铱），导致成本高昂，且长期运行稳定性有待提高。固体氧化物电解槽（SOEC）虽然电解效率高，但其高温操作条件对材料和系统集成的要求极高，技术成熟度相对较低，仍处于研发和示范阶段。这些技术在能效、耐久性和成本之间仍需寻找最佳平衡点。
- 储运技术：
- 应用端技术： 燃料电池、氢燃气轮机等应用端技术在效率、寿命、成本和可靠性方面仍有提升空间，尤其是在应对高纯度氢气需求和复杂工况适应性方面。
7.1.2 经济性与高成本障碍
- 高生产成本： 当前绿氢的生产成本远高于灰氢，这是其商业化推广的最大障碍 8990。主要原因包括：
- 高储运成本： 无论是高压气态、低温液态还是新型储氢技术，目前的储运成本仍然显著。尤其是长距离、大规模运输，需要建设昂贵的基础设施或承担高昂的能耗和损耗 89。
- 应用端成本： 燃料电池系统、氢气加注设施、工业设备改造等方面的初期投资成本高，使得绿氢在终端应用中的竞争力受限。例如，加氢站建设成本高昂，是燃料电池汽车推广的重要瓶颈。
7.1.3 基础设施建设滞后
- 氢气管网不足： 全球缺乏大规模的氢气专用管道网络，现有天然气管道的掺氢运输比例有限，难以满足大规模绿氢运输需求 8993。新建专用管道的投资巨大，且建设周期长。
- 加氢站稀缺： 加氢站数量少、分布不均且建设成本高昂，严重制约了燃料电池汽车的普及和应用 89。
- 储氢设施短缺： 大规模、低成本的储氢设施（如大型液氢储存罐、地下储氢库）仍处于建设初期或示范阶段，无法满足绿氢产业发展的需求。
- 供应链不完善： 缺乏完善的绿氢供应链，从生产、运输到终端应用的各个环节尚未形成高效协同的体系，导致绿氢流通成本高、效率低。
7.1.4 政策法规与标准体系不健全
- 政策协同性不足： 尽管各国政府纷纷出台了氢能发展规划，但不同部门、不同区域之间的政策协同性有时不足，缺乏统一的国家层面战略和激励机制，导致产业发展方向不明确，市场主体观望情绪浓厚 9495。
- 补贴机制不明确或不足： 缺乏长期稳定、可预测的财政支持政策，特别是在一些国家，绿氢生产补贴远不及美国《通胀削减法案》的力度，难以有效刺激市场需求和投资热情。
- 标准和认证体系缺失： 全球范围内，绿氢的定义、生产过程、碳排放核算、安全规范、产品质量标准等仍存在空白或不统一，阻碍了国际贸易和产业链的互联互通 8996。例如，对“绿色”属性的认定不清晰，可能导致“漂绿”行为。
- 安全法规滞后： 氢气的易燃易爆特性对安全管理提出高要求。然而，针对大规模氢气生产、储运和应用的法规、标准和规范仍需完善，尤其是在人员培训、应急响应、设备检测等方面 89。
7.1.5 市场认知与社会接受度
- 公众认知不足： 许多公众对氢能的认识仍停留在“易燃易爆”的刻板印象，对其作为清洁能源的潜力和安全性缺乏了解。对绿氢与灰氢、蓝氢的区别认知度低，可能引发环保方面的争议和抵触情绪 979899。
- 环保争议： 尽管绿氢被视为清洁能源，但其生产过程仍可能面临水资源消耗、可再生能源项目占地、以及基础设施建设对生态环境的影响等争议。
- “先有鸡还是先有蛋”困境： 由于成本高昂和基础设施不完善，市场需求难以启动；而缺乏足够的需求，又难以形成规模效应，进一步降低成本，形成了恶性循环。投资者在不确定性面前往往持谨慎态度。
这些瓶颈相互影响，使得绿氢的商业化进程充满挑战。要实现绿氢的快速发展和大规模应用，必须系统性地解决这些核心障碍，通过技术创新、政策支持和市场机制的协同作用，逐步构建一个成熟、高效的绿氢生态系统。
7.2 不同场景下的商业化破局路径建议
绿氢商业化落地的瓶颈错综复杂，需要针对不同的区域资源禀赋、应用场景和市场特性，采取差异化、系统性的破局策略。以下是针对性建议：
7.2.1 优先布局低成本可再生能源基地，打造区域绿氢枢纽
建议： 集中力量在风能、太阳能等可再生能源资源丰富且电力成本低的地区，规划建设大型“绿氢产业园”或“绿氢枢纽”。这些地区通常具备大规模、低成本生产绿氢的潜力。
- 资源禀赋优势： 利用西北部内陆地区（如中国新疆、甘肃、内蒙古）、中东和北非地区、澳大利亚以及南美洲等地的优质风光资源，确保绿氢生产的电力来源成本最低。这些地区的可再生能源发电成本已降至极低水平，为绿氢生产提供了坚实的基础。
- 一体化开发： 鼓励将风电场、光伏电站与电解水制氢装置进行直接耦合，形成“风光制氢一体化”项目。这种模式可以最大化利用弃风弃光电力，避免电网输配电损耗和成本，从而显著降低绿氢生产的度电成本。
- 集中式生产与分布式应用结合： 在绿氢枢纽内实现大规模、集中的绿氢生产，并通过管道、船运或有机氢载体等方式，将绿氢输送至周边工业园区或远距离用氢负荷中心，实现集中生产与分布式应用的有效结合。
- 产业集群效应： 鼓励绿氢生产、电解槽制造、氢气储运设备生产以及下游用氢企业在这些枢纽内形成产业集群，通过产业链协同降低综合成本，并吸引更多投资。
7.2.2 开展“制储运用”一体化示范，验证全链条经济性
建议： 从点到面，在具备条件的区域和场景率先开展“制储运用”一体化示范项目，通过真实运行数据验证全产业链的技术可行性和经济性，并积累宝贵的工程经验。
- 工业园区率先突破： 选择钢铁、炼化、合成氨/甲醇等大型工业园区作为突破口。这些园区氢气需求量大且稳定，现有基础设施便于改造，且对碳排放敏感。通过在园区内建设绿氢生产设施，配套储氢和输氢系统，并直接用于替代现有灰氢或化石燃料，形成封闭高效的绿氢供应链。例如，在化工园区，可以直接将绿氢用于合成氨或合成甲醇，实现从原料到产品的全绿色流程。
- 交通运输与能源领域融合： 在港口、物流枢纽等交通密集区域，结合可再生能源发电，建设绿氢生产、加氢站和燃料电池车辆（重卡、船舶、叉车）的应用示范。同时，探索绿氢在电网调峰、备用电源等能源领域的示范应用，如将可再生能源电力转化为绿氢储存，在电网负荷高峰期通过燃料电池发电反哺电网。
- 多元技术路线并举： 在一体化示范项目中，可以尝试不同的电解水技术（AEC、PEMEC、SOEC）和储运技术（高压气态、液态有机氢载体等），对比其在不同应用场景下的性能、成本和适用性，为后续大规模推广提供数据支撑。
7.2.3 政策持续发力，构建稳定可预测的市场环境
建议： 政府层面应出台长期稳定、可预测且具竞争力的支持政策，以降低绿氢投资风险，刺激市场需求。
- 财政激励精准化：
- 生产侧补贴： 借鉴美国《通胀削减法案》的经验，提供具有全球竞争力的绿氢生产税收抵免或直接补贴，有效缩小绿氢与灰氢的成本差距，加速绿氢平价进程。
- 投资补贴： 继续对电解槽制造、氢气储运基础设施建设等关键环节提供投资补贴或贷款优惠，降低初期投资门槛。
- 运营补贴： 对绿氢在特定“难脱碳”行业的初期应用给予运营补贴，帮助企业承担转型成本。
- 碳定价机制强化： 提高碳排放权交易价格，并扩大碳市场覆盖范围，同时逐步完善碳边境调节机制，使绿氢的碳减排价值得到充分体现，提升其经济竞争力。
- 完善标准法规： 加快制定和完善绿氢的生产、储运、应用标准体系，包括氢气纯度、安全规范、设备检测、绿氢认证溯源机制等，为市场提供清晰的规则和依据，保障产业健康有序发展。
- 公共采购与强制配额： 政府可以率先在公共交通、市政供热等领域推广绿氢应用，并通过公共采购引导市场需求。同时，可考虑在特定工业领域设定绿氢使用比例或碳排放上限，强制企业使用一定比例的绿氢。
7.2.4 加速技术创新，降低全链条成本
建议： 持续加大对绿氢全产业链关键核心技术的研发投入，特别是在催化材料、储运技术和系统集成方面，以从根本上降低成本。
- 电解水技术： 重点研发非贵金属催化剂、高性能电极材料和新型隔膜，降低PEMEC和SOEC的设备成本和运行能耗。同时，优化电解槽设计，提高单台设备的产氢能力和运行寿命。
- 储运技术： 突破高密度、低成本、高安全性的储氢技术。例如，开发更轻量化、高压的复合材料储罐；优化液化工艺，降低液化能耗；研发更高效的固态储氢材料和经济的氢化/脱氢催化剂。
- 系统集成与智能化： 运用人工智能、大数据等技术，优化绿氢生产、储运和应用的系统集成和运行控制，提高系统效率，降低运维成本。例如，开发预测性维护系统，提高设备利用率。
7.2.5 提升公众认知，推动国际合作
建议： 加强科普宣传，提高公众对绿氢的认知和接受度。同时，深化国际合作，共享技术经验，共同应对全球绿氢产业发展挑战。
- 公众教育： 通过媒体宣传、示范项目开放日等多种形式，普及绿氢的环保优势和安全性，消除公众疑虑，提升社会接受度。
- 人才培养： 加强绿氢领域专业人才的培养，包括研发、工程、运维等各个环节，为产业发展提供智力支持。
- 国际合作： 积极参与全球绿氢标准制定，推动绿氢国际贸易。与拥有丰富可再生能源资源的国家建立绿氢供应链合作，实现全球范围内的资源优化配置。
通过上述多维度、协同性的破局路径，绿氢有望逐步克服当前面临的瓶颈，实现从示范应用到大规模商业化的跨越，最终在全球能源转型中扮演核心角色。
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参考文献
1Current Development Status, Policy Support and Promotion Path of China’s Green Hydrogen Industries under the Target of Carbon Emission Peaking and Carbon NeutralityOpenAlex
Lei Yang, Shuning Wang, Zhihu Zhang, et al.
The green hydrogen industry, highly efficient and safe, is endowed with flexible production and low carbon emissions. It is conducive to building a low-carbon, efficient and clean energy structure, optimizing the energy industry system and promoting the strategic transformation of energy development and enhancing energy security. In order to achieve carbon emission peaking by 2030 and neutrality by 2060 (dual carbon goals), China is vigorously promoting the green hydrogen industry. Based on an analysis of the green hydrogen industry policies of the U.S., the EU and Japan, this paper explores supporting policies issued by Chinese central and local authorities and examines the inherent advantages of China’s green hydrogen industry. After investigating and analyzing the basis for the development of the green hydrogen industry in China, we conclude that China has enormous potential, including abundant renewable energy resources as well as commercialization experience with renewable energy, robust infrastructure and technological innovation capacity, demand for large-scale applications of green hydrogen in traditional industries, etc. Despite this, China’s green hydrogen industry is still in its early stage and has encountered bottlenecks in its development, including a lack of clarity on the strategic role and position of the green hydrogen industry, low competitiveness of green hydrogen production, heavy reliance on imports of PEMs, perfluorosulfonic acid resins (PFSR) and other core components, the development dilemma of the industry chain, lack of installed capacity for green hydrogen production and complicated administrative permission, etc. This article therefore proposes that an appropriate development road-map and integrated administration supervision systems, including safety supervision, will systematically promote the green hydrogen industry. Enhancing the core technology and equipment of green hydrogen and improving the green hydrogen industry chain will be an adequate way to reduce dependence on foreign technologies, lowering the price of green hydrogen products through the scale effect and, thus, expanding the scope of application of green hydrogen. Financial support mechanisms such as providing tax breaks and project subsidies will encourage enterprises to carry out innovative technological research on and invest in the green hydrogen industry.
2Connotation, innovation and vision of “carbon neutrality”OpenAlex
Caineng Zou, Huaqing Xue, Bo Xiong, et al.
Global climate change caused by geological processes is one of the main causes of the 5 global mass extinctions in geological history. Human industrialization activities have caused serious damage to the ecosystem, the greenhouse effect of atmospheric CO2 has intensified, and the living environment is facing threats and challenges. Carbon neutrality is the active action and common goal of mankind in the face of the climate change crisis, therefore, probing into its theoretical and technological connotation, scientific and technological innovation system has far-reaching significance and broad prospects. Studies indicate that (1) Carbon neutrality reflects the theoretical connotations of “energy science” and “carbon neutrality science”, including technical connotations of carbon emission reduction, zero carbon emission, negative carbon emission, and carbon trading. (2) Carbon neutrality spawns new industries such as carbon industry centering on CO2 capture, utilization, and storage (CCUS, or CO2 capture and storage CCS), and hydrogen industry centering on green hydrogen. “Gray carbon” and “black carbon” are the two application attributes of CO2. “Carbon+”, “Carbon−”, and “Carbon=” are three carbon-neutral products and technologies. (3) China faces three major challenges in achieving the goal of carbon neutrality: first, energy transition is large in scale and the cycle is short; Second, there are many problems in the process of energy transition, such as security uncertainties, economic utilization, and unpredictable disruptive technologies; Third, after transition, we may face new key techno-logical “bottlenecks” and “broken chain” of key mineral resources. (4) Based on current knowledge to predict the top 10 disruptive technologies and industries in the energy field: underground coal gasification, in-situ conversion process of medium and low-mature shale oil, CCUS/CCS, hydrogen energy and fuel cells, bio-photovoltaic power generation, space-based solar power generation, optical storage smart micro-grid, super energy storage, controllable nuclear fusion, wisdom energy Internet. Five strategic projects will be implemented, including energy conservation and efficiency improvement, carbon reduction and sequestration, scientific and technological innovation, emergency reserve and policy support. (5) In the future, different types of energy will have different orientations. Coal will play the role of ensuring the national energy strategy “reserve” and “guarantee the bottom line”. Petroleum will play the role of ensuring national energy security “urgent need” and the “cornerstone” of raw materials in people's livelihood. Natural gas will play the role in ensuring national energy “safety” and “best partner” of new energy. New energy will play the role in ensuring the “replacement” and “main force” of the national energy strategy. (6) Carbon neutrality is a major practice of the green industrial revolution, carbon reduction energy revolution, and ecological technology revolution, which will bring new and profound changes to human society, the environment and the economy. (7) Carbon neutrality needs to follow the four principles of “disruptive breakthroughs in technology, guarantee of energy security, realization of economic feasibility, and controllable social stability”. We should rely on technological innovation and management changes to ensure the realization of national energy “independence” and carbon neutrality goal, and make China's contribution to the construction of a livable earth, green development, and ecological civilization.
3Green hydrogen in the iron and steel industry increases resilience against shocks in energy pricesOpenAlex
Nicola Leuratti, Giacomo Marangoni, Laurent Drouet, et al.
Abstract Geopolitical tensions and conflicts can disrupt energy markets, threatening international energy supply security and imposing financial stress on energy-intensive industries reliant on imported fossil fuels. Exploring the challenges and opportunities associated with supply diversification is crucial for understanding the potential for hard-to-abate industry decarbonization under the risk of future energy price shocks. In this context, we investigate the role of green hydrogen as a viable and sustainable alternative to natural gas applications in iron and steel manufacturing. We first quantify how the integration of green hydrogen into the existing infrastructure can complement stringent climate action ambitions in reducing CO 2 emissions over the next five decades. We find that green hydrogen acts as a transitional technology, enabling a gradual shift towards electrification of heat supply while bridging the gap until low-carbon steel technologies become commercially feasible. Furthermore, we assess the benefits of timely green hydrogen investments in mitigating the economic repercussions of unforeseen natural gas price surges. Overall, this study underscores the potential of green hydrogen in decarbonizing the iron and steel industry while promoting energy independence, but it also highlights its contingency on sufficiently ambitious climate policies and adequate technological advancements.
4Critical perspective on green hydrogen-based seasonal operation of energy-intensive industry sectors with solid productsOpenAlex
Jure Voglar, Blaž Likozar
In the light of a future decarbonized power grid based primarily on non-dispatchable renewable energy sources, the operation of industrial plants should be decarbonized and flexible. An innovative, novel concept combining industrial plants with (i) a water electrolysis unit, (ii) a hydrogen storage unit and (iii) a fuel cell unit would enable seasonal supply-demand balancing in the local power grid and storage of surplus energy in the form of stable solid products. The feasibility of this concept was demonstrated in a case study, taking into account the overall energy balance and economics. The characteristics of the local power grid and the hydrogen round-trip efficiency must be carefully considered when dimensioning the hydrogen units. It was found that industries producing iron and steel, cement, ceramics, glass, aluminum, paper and other metals have the potential for seasonal operation. Future research efforts in the fields of technology, economics and social sciences should support the sustainable flexibility transition of energy-intensive industries with solid products. • Sustainable development will bring seasonal fluctuations in electricity supply. • An innovative method for balancing power supply and demand is proposed. • Energy-intensive industry sectors could adapt to utilize seasonal fluctuations. • Green hydrogen will serve as a short-term energy buffer. • Solid commodities will ensure stable storage of the seasonal energy surplus.
5Assessment of paper industry decarbonization potential via hydrogen in a multi-energy system scenario: A case studyOpenAlex
Alessandro Mati, Andrea Ademollo, Carlo Carcasci
Green hydrogen is currently regarded as a key catalyst for the decarbonization of energy-intensive industries. In this context, the pulp and paper industry stands out as one of the most demanding, given the simultaneous need for large amounts of heat and electricity usually satisfied via cogeneration systems. Given the urgent need for cost-effective solutions in response to the climate crisis, it is crucial to analyze the feasibility of retrofitting existing power plants to operate carbon-neutral. The aim of this work is to provide a techno-economic analysis for the conversion of a conventional cogeneration system to run on locally produced hydrogen. Building on the energy consumption of the paper mill, the operation of a hydrogen-fuelled gas turbine is modelled in detail. Based on these results, a multi-energy system model for the production of green fuel is presented, considering production via solar-powered PEM electrolyzers, storage in tanks and final use in the gas turbine. An optimal configuration for the system is defined, leading to the definition of a solution that ensures a cost of €6.41/kg for the production of green hydrogen. Finally, a sensitivity analysis highlights the close dependence of the economic profitability of the Power-to-X system on the natural gas price. The results indicate that although positive performance is achieved, the cost of investment remains still prohibitive for systems of this size, and the high initial capital expenditure needs to be supported by incentive policies that facilitate the adoption of hydrogen in industrial applications making it competitive in the short term.
6The Role of Green and Blue Hydrogen in the Energy Transition—A Technological and Geopolitical PerspectiveOpenAlex
Michel Noussan, Pier Paolo Raimondi, Rossana Scita, et al.
Hydrogen is currently enjoying a renewed and widespread momentum in many national and international climate strategies. This review paper is focused on analysing the challenges and opportunities that are related to green and blue hydrogen, which are at the basis of different perspectives of a potential hydrogen society. While many governments and private companies are putting significant resources on the development of hydrogen technologies, there still remains a high number of unsolved issues, including technical challenges, economic and geopolitical implications. The hydrogen supply chain includes a large number of steps, resulting in additional energy losses, and while much focus is put on hydrogen generation costs, its transport and storage should not be neglected. A low-carbon hydrogen economy offers promising opportunities not only to fight climate change, but also to enhance energy security and develop local industries in many countries. However, to face the huge challenges of a transition towards a zero-carbon energy system, all available technologies should be allowed to contribute based on measurable indicators, which require a strong international consensus based on transparent standards and targets.
7The Blue Hydrogen Economy: A Promising Option for the Near-to-Mid-Term Energy TransitionOpenAlex
Daniel Addokwei Tetteh, Saeed Salehi
Abstract Hydrogen is recently being promoted immensely as the primary energy carrier to replace fossil fuels for the envisioned environmentally friendly and sustainable future energy system, given its peculiar properties and advantages over conventional fuels and other alternative energy sources. Hydrogen is classified into various color categories based on the type of feedstock, technology, and CO2 emissions in its production pathway. This paper focuses on blue hydrogen, discussing its potential as the most promising hydrogen production pathway for the near-to-mid-term transition into a hydrogen economy. First, a comprehensive overview of the hydrogen economy is given with a detailed description of hydrogen's color-code categorization. Blue hydrogen production methods are explained, and blue and green hydrogen are compared on the subject of the grand energy transition. Furthermore, the arguments favoring blue hydrogen as the most promising alternative for the near-to-mid-term energy transition are explained. Finally, a comparative life cycle analysis (LCA) of environmental emissions and resource usage in blue hydrogen and other selected commonly used fuel production pathways is conducted using the greenhouse gases, regulated emissions, and energy use in technologies (GREET) model to analyze the potentials of the blue hydrogen production pathway. The LCA results showed that more efforts need to be committed to reducing nitrous and sulfur oxides in the blue hydrogen production pathway and improving energy and CO2 capturing efficiencies in carbon capture and storage (CCS) plants.
9Shaping the Future of Green Hydrogen Production: Overcoming Conventional Challenges with Molecular Catalysts, Immobilization, and Scalable ElectrolyzersOpenAlex
Suhana Karim, Niharika Tanwar, Srewashi Das, et al.
The energy crisis is a daunting global problem that calls for innovative and supportable solutions to ensure future energy security and environmental stability. To counter this energy uncertainty, accelerating renewable-driven hydrogen production stands as a vital option to foster carbon-neutral energy infrastructure. This review conveys an overview of worldwide hydrogen generation techniques (steam methane reformation, thermochemical, biological, and electrolytic), highlighting the key features, indicating the pros and cons, and unraveling the potential environmental consequences. Herein, the conventional gray and cutting-edge green hydrogen production technologies are compared, with a focus on sustainable water electrolysis utilizing renewable energy sources. The existing difficulties with conventional electrolysis, including the usage of expensive catalysts in both cathode and anode, are discussed along with the possible gateway with cost-effective and sustainable electrocatalysts. This review focuses on the potential of three types of 3d transition metal-based molecular catalysts─cobaloximes, iron porphyrins, and nickel bis-phosphines─for hydrogen evolution reactions (HER), stressing their strategic synthetic designs, mechanistic routes, and catalytic parameters. Despite their high activity and selectivity, these molecular systems confront stability and scalability issues, limiting their practical applicability. To address this, the immobilization of these catalysts into solid matrices is studied, simplifying their integration into membrane electrode assembly (MEA) water electrolyzers for industrial-scale renewable-driven hydrogen production. To bridge the gap between lab-scale investigations and commercial implementation, several design components of the MEA stack are examined, such as flow patterns and scaling methodologies. A comprehensive approach to catalyst development and deployment is ensured by highlighting the significance of Life Cycle Assessment (LCA) and Techno-Economic Analysis (TEA) in assessing environmental sustainability and economic viability. The review closes with a call for multidisciplinary research and innovation to improve electrochemical water-splitting technology and accelerate the transition to an enduring hydrogen economy.
10Palm trees, energy security and green hydrogen futures: Tourists' views on Mallorca's low carbon transitionOpenAlex
Noreen Brennan, Thomas M. van Rensburg
The development of green hydrogen can provide a welcome boost in energy security, particularly for island nations that may be reliant on energy imports or intermittent renewables as part of their energy transition. However, the expansion of a green hydrogen economy may have social, environmental and economic impacts on tourism-reliant islands, which may not be accounted for using typical market assessments. In this study, focus groups and an online choice experiment survey are conducted with recent international tourists to Mallorca, Spain, to elicit preferences for green hydrogen infrastructure, including the visual and biodiversity impacts, potential for export, and the value for the provision of additional local and tourism benefits. The results indicate generally positive attitudes to the development of green hydrogen in Mallorca, however respondents indicate significant disutility associated with high visual impact of green hydrogen infrastructure, with the exception of respondents that have previous experience with hydrogen transport. In general, respondents favour policies that do not negatively impact biodiversity, value restrictions on exports to enhance energy security on the island and are willing to pay to support green hydrogen development in Mallorca which provides benefits to tourism and local residents. • Tourists indicate generally positive attitudes to the development of green hydrogen in Mallorca. • Balancing the visual, biodiversity and social aspects of green hydrogen is crucial to tourist acceptance. • Tourists value energy security for the island, and prefer that any green hydrogen generated is used in Mallorca. • Tourists are willing to pay for green hydrogen development that provides financial benefits to local residents. • Prior experience with hydrogen transport plays a positive role in the social acceptance of green hydrogen.
11Study on the Multi Energy Integration Development in Offshore Energy IslandsOpenAlex
Jinmao Chen, Xudong Wang, Wanli Xu, et al.
Offshore energy islands are innovative carriers for the in-depth integration of marine space and clean energy. They integrate the production of offshore wind power, offshore photovoltaics (PV), and wave energy, while coupling seawater desalination, green hydrogen production and storage, and electrochemical energy storage and conversion. Relying on offshore step-up substations, submarine cables, and hydrogen transmission pipelines to build a transportation network, they form a clustered commercial model centered on power supply, hydrogen supply, and fishery. As a key fulcrum for energy transition and the achievement of the "dual carbon" (carbon peaking and carbon neutrality) goals, this paper systematically sorts out the energy production system, conversion technology, transportation channels, and benefit model of offshore energy islands. It analyzes the current progress in technological breakthroughs and engineering practices, points out challenges such as adaptability to extreme climates, high initial investment costs, and ecological impact assessment, and looks forward to directions including floating platform technology and nuclear-renewable hybrid systems. This study provides theoretical references and practical insights for the large-scale development and commercial application of offshore energy islands.
12Study on Energy Allocation Strategy of Multiple Electrolyzers for Renewable Energy-Based Hydrogen Production SystemOpenAlex
Jianqiang Xu, Jiangong Zhu, Hao Yuan, et al.
Abstract In the context of the Carbon Peaking and Carbon Neutrality Goals, the utilization of renewable energy to produce hydrogen by water electrolysis is of great significance as it can solve the problems of renewable energy consumption and large-scale green hydrogen production. However, the renewable energy-based hydrogen production system faces many problems such as large fluctuation of renewable energy and high cost of hydrogen production. Therefore, this study proposes an average power strategy to enhance the system economy without significant improvement in the performance and cost of the existing power system and electrolyzers. Firstly, the wind-hydrogen capacity ratio is caried out, and according to the real data of a wind fam in Qinghai, a reasonable number of 1,000 standard cubic meters of alkaline electrolyzers is configured. Subsequently, the objective function is developed with economy as the main goal and considering the lifetime of the electrolyzer. Finally, the average power strategy and the common rated power strategy are introduced in detail, and they are compared through example analysis. The results show that, compared with the rated power strategy, the average power strategy improves the economic efficiency, renewable energy consumption rate, and the consistency of the electrolyzer lifetime.
13Research on the Strategic Planning of New Power System Considering the Cooperative Optimization Operation of Source and Network Load and Storage Under the Dual Carbon TargetOpenAlex
Tong Wu, Zhanying Wang, Zongyuan Wang, et al.
This paper studies the strategic planning of the new power system under the background of dual-carbon target, with special attention to the cooperative optimization of the load and storage operation of the source network. This study simulates the development trend of China's energy and power system from 2020 to 2060 by constructing a medium - and long-term energy and power development forecast model, and analyzes the evolution trend of related core indicators. The study emphasizes the strategic importance of green electricity substitution and green hydrogen substitution in the construction of new energy systems and new power systems, and explores the key role of these alternative strategies in achieving low-carbon transition. In order to improve the flexibility and reliability of the system, this paper also studies the cooperative control methods in the new power system, including the construction of the source load and storage model, the construction of the control target model, the constraint setting and the optimization algorithm solving. Through improved genetic algorithm and ant colony algorithm, an optimized cooperative control scheme is proposed to minimize total operating cost and load fluctuation. The findings provide comprehensive analysis and strategic insights for policy development and energy system planning to support the achievement of carbon peaking and carbon neutrality goals
14Green hydrogen: A new flexibility source for security constrained scheduling of power systems with renewable energiesOpenAlex
Abbas Rabiee, Andrew Keane, Alireza Soroudi
Green hydrogen, i.e. the hydrogen generated from renewable energy sources (RES) will significantly contribute to a successful energy transition. Besides, to facilitate the integration and storage of RES, this promising energy carrier is well capable to efficiently link various energy sectors. By introduction of green hydrogen as a new flexibility source to power systems, it is necessary to investigate its possible impacts on the generation scheduling and power system security. In this paper, a security-constrained multi-period optimal power flow (SC-MPOPF) model is developed aiming to determine the optimal hourly dispatch of generators as well as power to hydrogen (P2H) units in the presence of large-scale renewable energy sources (RES). The proposed model characterizes the P2H demand flexibility in the proposed SC-MPOPF model, taking into account the electrolyzer behavior, reactive power support of P2H demands and hydrogen storage capability. The developed SC-MPOPF model is applied to IEEE 39-bus system and the obtained numerical results demonstrate the role of P2H flexibility on cost as well as RES's power curtailment reduction.
15Integration of Government Policies on the Global Level for Green Hydrogen ProductionOpenAlex
Shahrukh Nawaj Alam, Zaira Khalid, Bhaskar Singh, et al.
The majority of the hydrogen produced today is derived from fossil fuels, with natural gas accounting for almost half of the total hydrogen production worldwide in 2018. While coal remained a significant contributor to global hydrogen production in 2018, accounting for 18% primarily due to its prevalent use in China, cleaner sources like electricity and oil each contributed only 0.48%. The remaining fraction came from by-products of industrial processes. Recognizing its transformative potential as a clean energy carrier and key enabler of net-zero goals, the global community is embracing hydrogen with unprecedented enthusiasm. Projections point towards a significant expansion, with demand expected to surge tenfold or more in the foreseeable future. Hydrogen's trajectory has shown moderate growth with a 28% increase in global demand since 2010. However, studies predict a transformative leap fueled by strategic incentives and investments. By 2050, under optimal conditions, hydrogen is poised to account for 18% to 24% of global energy consumption, with individual countries potentially exceeding this range. The global landscape of climate action is witnessing a paradigm shift towards hydrogen and embracing this transformative potential, countries and regions worldwide are diligently formulating their own hydrogen development strategies. These country-specific roadmaps meticulously chart optimal supply pathways and end-use applications, aiming to fuel their transition to clean economies and carve out lucrative niches in the international hydrogen market. With net-zero ambitions taking center stage, these nations are actively crafting policies that directly incentivize investments in hydrogen technologies, recognizing its pivotal role in a clean energy future. Through this comprehensive examination of global policies on green hydrogen aims to inform policymakers, researchers, and industry stakeholders, contributing to the ongoing discourse on sustainable energy transition and fostering a deeper understanding of the multifaceted dimensions of green hydrogen policy development. This chapter discusses the status of governmental policies and their integration at the global level to achieve an effective framework for green hydrogen production.
16Current Status of Green Hydrogen Production Technology: A ReviewOpenAlex
Ayiguzhali Tuluhong, Qingpu Chang, Lirong Xie, et al.
As a clean energy source, hydrogen not only helps to reduce the use of fossil fuels but also promotes the transformation of energy structure and sustainable development. This paper firstly introduces the development status of green hydrogen at home and abroad and then focuses on several advanced green hydrogen production technologies. Then, the advantages and shortcomings of different green hydrogen production technologies are compared. Among them, the future source of hydrogen tends to be electrolysis water hydrogen production. Finally, the challenges and application prospects of the development process of green hydrogen technology are discussed, and green hydrogen is expected to become an important part of realizing sustainable global energy development.
17Prospects for the Development of Hydrogen Energy: Overview of Global Trends and the Russian Market StateOpenAlex
Elena Vechkinzova, Larisa P. Steblyakova, Natalia Roslyakova, et al.
This review is devoted to an overview of the prospects for the development of the global hydrogen market and the strategies of individual countries aimed at transforming energy systems in favor of decarbonization and greening through the use of hydrogen. Special attention is paid to the prospects for the development of the Russian hydrogen market. The authors of the review used the method of comparative analysis and analytical generalization of publications, programs and regulatory documents from different countries. The results of the comparative analysis led to the conclusion that most of the publications currently focus on the technical and technological aspects of hydrogen energy, solving the problem of increasing the efficiency of methods for the production, transportation, distribution and storage of hydrogen fuel. The results of the analytical generalization led to the conclusion that in all countries of the world, the technology for the production of highly environmentally friendly “green” hydrogen is at an early stage, which makes it highly dependent on government initiatives to develop hydrogen projects and government funding of both scientific research in this area and realizable projects. In addition, the peaks of interest in the field of hydrogen energy are associated with market changes in the fossil energy markets, which makes the development of this technology unstable and dependent on market conditions. Moreover, the focus of attention of a number of authors is the prospects for the development of the hydrogen market. It is concluded that many countries are ready to invest in the development of hydrogen energy and, given the growth in demand for hydrogen, are ready to export it at an affordable price. That is, in the future, the international hydrogen market, as technical, technological, and economic problems are solved, will grow. The results of the study also indicate the fundamental co-direction of the trends in the development of hydrogen energy in Russia with global trends. At the same time, it should be emphasized that the high resource and scientific and technological potential allows Russia to fully focus its strategy on its implementation, not only developing the domestic market but also acting as an exporter of hydrogen and expanding international cooperation in this area.
18A SWOT Analysis of the Green Hydrogen MarketOpenAlex
Francisco L. D. Simões, Diogo M.F. Santos
Since the Industrial Revolution, humanity has heavily depended on fossil fuels. Recognizing the negative environmental impacts of the unmoderated consumption of fossil fuels, including global warming and consequent climate change, new plans and initiatives have been established to implement renewable and sustainable energy sources worldwide. This has led to a rapid increase in the installed solar and wind energy capacity. However, considering the fluctuating nature of these renewable energy sources, green hydrogen has been proposed as a suitable energy carrier to improve the efficiency of energy production and storage. Thus, green hydrogen, produced by water electrolysis using renewable electricity, is a promising solution for the future energy market. Moreover, it has the potential to be used for the decarbonization of the heavy industry and transportation sectors. Research and development (R&D) on green hydrogen has grown considerably over the past few decades, aiming to maximize production and expand its market share. The present work uses a SWOT (strengths, weaknesses, opportunities, and threats) analysis to evaluate the current status of the green hydrogen market. The external and internal factors that affect its market position are assessed. The results show that green hydrogen is on the right track to becoming a competitive alternative to fossil fuels soon. Supported by environmental benefits, government incentives, and carbon taxes, roadmaps to position green hydrogen on the energy map have been outlined. Nevertheless, increased investments are required for further R&D, as costs must be reduced and policies enforced. These measures will gradually decrease global dependency on fossil fuels and ensure that roadmaps are followed through.
19The potential of hydrogen technologies for low-carbon mobility in the urban-industrial symbiosis approachOpenAlex
Maria Angela Butturi, Rita Gamberini
The use of green hydrogen to power vehicles is recognized as contributing to the mitigation of the greenhouse gas (GHG) emissions responsible for climate change. On the other hand, the need for reducing GHG emissions is even more urgent in densely industrialized areas, traditionally located nearby highly populated zones. In these areas, road transportation is a relevant source of environmental pressures affecting air quality and the nearby communities' health: in Europe, private vehicles, vans, trucks, and buses produce more than 70% of the overall greenhouse gas emissions from transport, as well as particulate matter and nitrogen oxide. The European Hydrogen Strategy considers using green hydrogen as an energy carrier to de-carbonize industry and the transport sector, highlighting the need for the infrastructure to produce, store, and distribute hydrogen. The spatial configuration of the industrial sites and the existing infrastructure can facilitate the creation of hydrogen hubs serving both the logistics needs of companies and the public and private mobility in an urban-industrial symbiosis approach. Thus, this study aims at investigating the opportunities offered by the creation of synergies between industrial clusters and the nearby urban areas to improve the local sustainability by supporting the deploying of low-carbon mobility using green hydrogen. The available literature is reviewed in order to schematise and discuss the sustainability-related basis of adopting such a strategy, presenting an updated analysis of the latest research and application results suitable for future research applications and for supporting decision-making processes.
20Industrial status, technological progress, challenges, and prospects of hydrogen energyOpenAlex
Caineng Zou, Jianming Li, Xi Zhang, et al.
Under the requirements of China's strategic goal of ''carbon peaking and carbon neutrality'', as a renewable, clean and efficient secondary energy source, hydrogen benefits from abundant resources, a wide variety of sources, a high combustion calorific value, clean and non-polluting, various forms of utilization, energy storage mediums and good security, etc. It will become a realistic way to help energy, transportation, petrochemical and other fields to achieve deep decarbonization, and will turn into an important replacement energy source for China to build a modern clean energy system. It is clear that accelerating the development of hydrogen energy has become a global consensus. In order to provide a theoretical support for the accelerated transformation of hydrogen-related industries and energy companies, and provide a basis and reference for the construction of ''Hydrogen Energy China'', this paper describes main key technological progresses in the hydrogen industry chain such as hydrogen production, storage, transportation, and application. The status and development trends of hydrogen industrialization are analyzed, and then the challenges faced by the development of the hydrogen industry are discussed. At last, the development and future of the hydrogen industry are prospected. The following conclusions are achieved. (1) Hydrogen technologies of our country will become mature and enter the road of industrialization. The whole industry chain system of the hydrogen industry is gradually being formed, and will realize the leap-forward development from gray hydrogen, blue hydrogen to green hydrogen. (2) The overall development of the entire hydrogen industry chain such as hydrogen production, storage and transportation, fuel cells, hydrogen refueling stations and other scenarios should be accelerated. Besides, in-depth integration and coordination with the oil and gas industry needs more attention, which will rapidly promote the high-quality development of the hydrogen industry system. (3) The promotion and implementation of major projects such as ''north-east hydrogen transmission'', ''west-east hydrogen transmission'', ''sea hydrogen landing'', and utilization of infrastructures such as gas filling stations, can give full play to the innate advantages of oil and gas companies in industrial chain nodes such as hydrogen production and refueling, etc., which can help to achieve the application of ''oil, gas, hydrogen, and electricity'' four-station joint construction, form a nationwide hydrogen resource guarantee system, and accelerate the planning and promotion of the ''Hydrogen Energy China'' strategy.
21A comprehensive review of production, applications, and the path to a sustainable energy future with hydrogenOpenAlex
Abdulrahman Bin Jumah
Green hydrogen, a versatile and sustainable energy carrier, has garnered increasing attention as a critical element in the global transition to a low-carbon economy. This review article comprehensively examines the production, applications, and potential of green hydrogen, accompanied by the challenges and future prospects associated with its widespread adoption. The production of green hydrogen is a central focus, due to its environmental benefits and distinctive characteristics. The article delves into the various techniques and technologies employed in green hydrogen production, emphasizing the need for cost reduction and increased scale for economic viability. Focusing particularly on applications, the review discusses the diverse sectors where green hydrogen demonstrates immense promise. Challenges and limitations are explored, including the intermittent nature of renewable energy sources, high production costs, and the need for extensive hydrogen infrastructure. The article also highlights the pressing need for innovation in electrolysis technology and materials, emphasizing the potential for cost reduction and increased efficiency. As industries gradually transition to green hydrogen as a cleaner feedstock, its demand and cost-competitiveness are projected to increase. This review article thoroughly evaluates the current status of green hydrogen and provides valuable insights into its potential role in the transition to a sustainable energy system.
22Next-Generation Green Hydrogen: Progress and Perspective from Electricity, Catalyst to Electrolyte in Electrocatalytic Water SplittingOpenAlex
Xueqing Gao, Yutong Chen, Yujun Wang, et al.
Green hydrogen from electrolysis of water has attracted widespread attention as a renewable power source. Among several hydrogen production methods, it has become the most promising technology. However, there is no large-scale renewable hydrogen production system currently that can compete with conventional fossil fuel hydrogen production. Renewable energy electrocatalytic water splitting is an ideal production technology with environmental cleanliness protection and good hydrogen purity, which meet the requirements of future development. This review summarizes and introduces the current status of hydrogen production by water splitting from three aspects: electricity, catalyst and electrolyte. In particular, the present situation and the latest progress of the key sources of power, catalytic materials and electrolyzers for electrocatalytic water splitting are introduced. Finally, the problems of hydrogen generation from electrolytic water splitting and directions of next-generation green hydrogen in the future are discussed and outlooked. It is expected that this review will have an important impact on the field of hydrogen production from water.
24Alkaline Water Electrolysis Powered by Renewable Energy: A ReviewOpenAlex
Jörn Brauns, Thomas Turek
Alkaline water electrolysis is a key technology for large-scale hydrogen production powered by renewable energy. As conventional electrolyzers are designed for operation at fixed process conditions, the implementation of fluctuating and highly intermittent renewable energy is challenging. This contribution shows the recent state of system descriptions for alkaline water electrolysis and renewable energies, such as solar and wind power. Each component of a hydrogen energy system needs to be optimized to increase the operation time and system efficiency. Only in this way can hydrogen produced by electrolysis processes be competitive with the conventional path based on fossil energy sources. Conventional alkaline water electrolyzers show a limited part-load range due to an increased gas impurity at low power availability. As explosive mixtures of hydrogen and oxygen must be prevented, a safety shutdown is performed when reaching specific gas contamination. Furthermore, the cell voltage should be optimized to maintain a high efficiency. While photovoltaic panels can be directly coupled to alkaline water electrolyzers, wind turbines require suitable converters with additional losses. By combining alkaline water electrolysis with hydrogen storage tanks and fuel cells, power grid stabilization can be performed. As a consequence, the conventional spinning reserve can be reduced, which additionally lowers the carbon dioxide emissions.
25Hydrogen Production From Water Electrolysis: Current Status and Future TrendsOpenAlex
Alfredo Ursúa, Luis M. Gandía, Pablo Sanchis
This paper reviews water electrolysis technologies for hydrogen production and also surveys the state of the art of water electrolysis integration with renewable energies. First, attention is paid to the thermodynamic and electrochemical processes to better understand how electrolysis cells work and how they can be combined to build big electrolysis modules. The electrolysis process and the characteristics, advantages, drawbacks, and challenges of the three main existing electrolysis technologies, namely alkaline, polymer electrolyte membrane, and solid oxide electrolyte, are then discussed. Current manufacturers and the main features of commercially available electrolyzers are extensively reviewed. Finally, the possible configurations allowing the integration of water electrolysis units with renewable energy sources in both autonomous and grid-connected systems are presented and some relevant demonstration projects are commented.
26Hydrogen production by alkaline water electrolysisOpenAlex
Diogo M.F. Santos, C. A. C. Sequeira, José L. Figueiredo
Water electrolysis is one of the simplest methods used for hydrogen production. It has the advantage of being able to produce hydrogen using only renewable energy. To expand the use of water electrolysis, it is mandatory to reduce energy consumption, cost, and maintenance of current electrolyzers, and, on the other hand, to increase their efficiency, durability, and safety. In this study, modern technologies for hydrogen production by water electrolysis have been investigated. In this article, the electrochemical fundamentals of alkaline water electrolysis are explained and the main process constraints (e.g., electrical, reaction, and transport) are analyzed. The historical background of water electrolysis is described, different technologies are compared, and main research needs for the development of water electrolysis technologies are discussed.
27Influence of renewable energy power fluctuations on water electrolysis for green hydrogen productionOpenAlex
Hirokazu Kojima, Kensaku Nagasawa, Naoto Todoroki, et al.
The development of renewable energy technologies is essential to achieve carbon neutrality. Hydrogen can be stably stored and transported in large quantities to maximize power utilization. Detailed understanding of the characteristics and operating methods of water electrolysis technologies, in which naturally intermittent fluctuating power is used directly, is required for green hydrogen production, because fluctuating power-driven water electrolysis processes significantly differ from industrial water electrolysis processes driven by steady grid power. Thus, it is necessary to overcome several issues related to the direct use of fluctuating power. This article reviews the characteristics of fluctuating power and its generation as well as the current status and issues related to the operation conditions, water electrolyzer configuration, system requirements, stack/catalyst durability, and degradation mechanisms under the direct use of fluctuating power sources. It also provides an accelerated degradation test protocol method for fair catalyst performance comparison and share of effective design directions. Finally, it discusses potential challenges and recommendations for further improvements in water electrolyzer components and systems suitable for practical use, suggesting that a breakthrough could be realized toward the achievement of a sustainable hydrogen-based society.
28Dynamic energy and mass balance model for an industrial alkaline water electrolyzer plant processOpenAlex
Georgios Sakas, Alejandro Ibáñez-Rioja, Vesa Ruuskanen, et al.
This paper proposes a parameter adjustable dynamic mass and energy balance simulation model for an industrial alkaline water electrolyzer plant that enables cost and energy efficiency optimization by means of system dimensioning and control. Thus, the simulation model is based on mathematical models and white box coding, and it uses a practicable number of fixed parameters. Zero-dimensional energy and mass balances of each unit operation of a 3 MW, and 16 bar plant process were solved in MATLAB functions connected via a Simulink environment. Verification of the model was accomplished using an analogous industrial plant of the same power and pressure range having the same operational systems design. The electrochemical, mass flow and thermal behavior of the simulation and the industrial plant were compared to ascertain the accuracy of the model and to enable modification and detailed representation of real case scenarios so that the model is suitable for use in future plant optimization studies. The thermal model dynamically predicted the real case with 98.7 % accuracy. Shunt currents were the main contributor to relative low Faraday efficiency of 86 % at nominal load and steady-state operation and heat loss to ambient from stack was only 2.6 % of the total power loss.
29Effect of Converter Topology on the Specific Energy Consumption of Alkaline Water ElectrolyzersOpenAlex
Joonas Koponen, Vesa Ruuskanen, Antti Kosonen, et al.
Water electrolysis will be used to produce renewable hydrogen for energy storage and Power-to-X applications in the future renewable-energy-based energy systems. Therefore, the energy efficiency of hydrogen production will probably become a major issue. In this study, the effect of practical supply power converters on the specific energy consumption of megawatt (MW)-scale alkaline electrolyzers is studied and compared with an ideal dc power supply. The current quality and the stack specific energy consumption are studied in the case of traditional thyristor rectifiers and a transistor-based converter. The stack specific energy consumption is analyzed based on the simulated current waveforms and the electrical equivalent circuit of the electrolyzer stack. It is found that the transistor-based converter offers up to 14% lower electrolyzer stack specific energy consumption than the 6-pulse thyristor rectifier and up to 9.2% lower electrolyzer stack specific energy consumption than the 12-pulse thyristor rectifier as the current varies between 5000 and 1000 A. The simulated change in the stack specific energy consumption of the MW-scale alkaline water electrolyzer outweighs the losses occurring in the rectifiers. Further, selection of the ac voltage level may have a more adverse effect on the stack specific energy consumption with the thyristor rectifier topologies compared with the transistor-based topologies.
30Advancements in printed components for proton exchange membrane fuel cells: A comprehensive reviewOpenAlex
G. Costa, Diogo Miguel Esperança Garcia, Thi Hai Van Nguyen, et al.
Proton Exchange Membranes (PEM) are a promising technology for fuel cells and electrolyzer cells, in line with societal goals for clean and sustainable fuel conversion and generation, respectively, in a vast field of applications. PEM fuel cell (PEMFC) technology has an important advantage for energy conversion applications, because it requires a lower operating temperature and is lighter and more compact than other technologies, which makes it ideal for portable and transportation applications. However, open issues remain to be addressed for PEMFC that hinder their widespread adoption, both on the technical side, such as too high operational temperature range, cell efficiency, and long-term stability, as well as on the industrial side with implementation issues, material and device component availability, and cost. PEM technology research usually focuses on the synthesis of novel materials such as non-noble metal catalysts and non-halogenated membranes. In parallel, developing high-throughput and cost-effective manufacturing methods for components, in particular Membrane Electrode Assembly (MEA), can also lift an important barrier to their mass production, thus contributing to the same goals and securing industrial provision. From this perspective, printing technologies such as spray coating, inkjet printing, and screen printing have emerged as promising approaches with the required precision and scalability. This review covers recent advancements and developments in advanced PEMFC technology manufacturing, with a focus on 2D printing methodologies to fabricate some or all of the MEA components. Leveraging these techniques as simplified large-area manufacturing methods for PEM technology can become a more viable and industrially attractive solution. This work presents a comparison study addressing the key progress indicators both in process and in characterization to build a working framework in which both scientists, engineers and manufacturers can collaborate toward the industrial implementation of this emergent field.
32Recent Developments in Single‐Atom Engineering Ir/Ru‐Based Catalysts for the Oxygen Evolution Reaction in Acidic MediaOpenAlex
Qisheng Zeng, Jialin Tang, Yuan Ji, et al.
Abstract Proton exchange membrane water electrolysis (PEMWE) is a critical technology for sustainable green hydrogen production, yet its efficiency and cost are severely constrained by the kinetically sluggish kinetics and material instability of the anodic oxygen evolution reaction (OER) in acidic media. Iridium (Ir)‐ and ruthenium (Ru)‐based oxides remain the benchmark catalysts for this demanding reaction, but still face significant challenges such as the high cost and inadequate activity of Ir and the poor stability of Ru under harsh anodic conditions. In this review, recent breakthroughs in overcoming these limitations are comprehensively summarized through the strategic engineering of Ir‐ and Ru‐based electrocatalysts via single‐atom doping (SAD). Controllable synthetic methods for SAD Ir/Ru‐based catalyst design are summarized, and their underlying reaction mechanisms in the acidic OER are discussed. This single‐atom engineering method, as a promising strategy, shows exceptional potential and reliability for developing high‐performance and durable Ir/Ru‐based acidic OER catalysts, paving the way for more efficient and economically viable PEMWE systems.
33Membrane Electrode Assembly Design for High-Efficiency Anion Exchange Membrane Water ElectrolysisOpenAlex
Liming Yang, Shengbing Dong, Tao Yang, et al.
Growing interest in low-cost clean hydrogen production has positioned anion exchange membrane water electrolysis (AEMWE) as a leading sustainable technology. Its appeal lies in compatibility with platinum-group metal-free catalysts, inexpensive anode flow fields, and cost-effective bipolar plates. Recent advances in AEMWE focus critically on optimizing membrane electrode assembly (MEA) design to achieve industrially viable efficiency and durability. Key progress includes component-level innovations, such as developing nonprecious metal catalysts, fabricating anion exchange membranes (AEMs) with high ionic conductivity and alkaline stability, and engineering gas diffusion layers (GDLs) with hierarchical porosity for effective mass transport. Central to improving performance is interfacial engineering within the MEA, which combines catalyst layers (CLs), AEM, and GDLs to reduce ionic/charge transfer resistance and prevent mechanical delamination. A transformative breakthrough involves ordered, gap-free electrode assembly. This approach utilizes strategies such as ionomer-bonded architectures to establish continuous ion-conducting pathways or in situ catalyst deposition directly onto AEM surfaces, creating vertically aligned triple-phase boundaries. These ordered structures maximize catalyst utilization, markedly reduce voltage losses at industrially relevant current densities, and mitigate interfacial degradation during differential-pressure operation. Future advancements require scalable manufacturing of these ordered architectures to bridge material innovations with industrial deployment.
34Materials of solid oxide electrolysis cells for H <sub>2</sub>O and CO <sub>2</sub> electrolysis: A reviewOpenAlex
Peng Qiu, Cheng Li, Bo Liu, et al.
Reliable and economic energy storage technologies are urgently required to ensure a sustainable energy supply. H<sub>2</sub> is an energy carrier that can be produced environment-friendly by using renewable power to split H<sub>2</sub>O via electrochemical cells. This way, electric energy is stored as the chemical energy of H<sub>2</sub>, and the storage can be large-scale and economical. Among the electrochemical technologies for H<sub>2</sub>O electrolysis, solid oxide electrolysis cells (SOECs) operated at temperatures above 500 ℃ have the benefits of high energy conversion efficiency and economic feasibility. In addition to H<sub>2</sub>O electrolysis, SOECs can also be employed for CO<sub>2</sub> electrolysis and H<sub>2</sub>O-CO<sub>2</sub> co-electrolysis to produce value-added chemicals of great economic and environmental significance. However, SOEC technology is not yet fully ready for commercial deployment because of the material limitations of the key components, such as electrolytes, air electrodes, and fuel electrodes. As is well known, reactions in SOEC are, in principle, inverse to reactions in solid oxide fuel cells (SOFCs). The component materials of SOECs are currently adopted from SOFC materials. However, their performance stability issues are evident, and need to be overcome by materials development in line with the unique requirements of SOEC materials. Key topics discussed in this review include SOEC critical materials and their optimization, material degradation and its safeguards, future research directions, and commercialization challenges, from both traditional O<sup>2-</sup>-conducting SOEC and H<sup>+</sup>-conducting SOEC perspectives. It is worthy to believe that H<sub>2</sub>O or/and CO<sub>2</sub> electrolysis by SOECs provides a viable solution for future energy storage and conversion.
35Electrocatalysts for the generation of hydrogen, oxygen and synthesis gasOpenAlex
F.M. Sapountzi, José Gracia, C. J. Weststrate, et al.
Water electrolysis is the most promising method for efficient production of high purity hydrogen (and oxygen), while the required power input for the electrolysis process can be provided by renewable sources (e.g. solar or wind). The thus produced hydrogen can be used either directly as a fuel or as a reducing agent in chemical processes, such as in Fischer–Tropsch synthesis. Water splitting can be realized both at low temperatures (typically below 100 °C) and at high temperatures (steam water electrolysis at 500–1000 °C), while different ionic agents can be electrochemically transferred during the electrolysis process (OH−, H+, O2−). Singular requirements apply in each of the electrolysis technologies (alkaline, polymer electrolyte membrane and solid oxide electrolysis) for ensuring high electrocatalytic activity and long-term stability. The aim of the present article is to provide a brief overview on the effect of the nature and structure of the catalyst–electrode materials on the electrolyzer's performance. Past findings and recent progress in the development of efficient anode and cathode materials appropriate for large-scale water electrolysis are presented. The current trends, limitations and perspectives for future developments are summarized for the diverse electrolysis technologies of water splitting, while the case of CO2/H2O co-electrolysis (for synthesis gas production) is also discussed.
36High Performance Anion Exchange Membrane Electrolysis Using Plasma-Sprayed, Non-Precious-Metal ElectrodesOpenAlex
Li Wang, Thomas Weissbach, Regine Reißner, et al.
The production of green hydrogen by a cost-effective electrolysis technology is of paramount importance for future energy supply systems. In this regard, proton exchange membrane (PEM) electrolysis is the technology of choice due to its compactness and high efficiency; however, its dependence on the scarce iridium catalyst jeopardizes the deployment at large scale. Here, we present a low-cost electrolyzer consisting of an assembly of an anion exchange membrane (AEM) and plasma-sprayed electrodes without any precious metals. Several electrode materials are developed and tested in this configuration at 60 °C and feeding 1 M KOH electrolyte. The AEM electrolyzer with NiAlMo electrodes can achieve a potential of 2.086 V at a current density of 2 A cm–2, which is comparable to the performances of industrial MW-size PEM electrolyzers. The cell potential with NiAl anode and NiAlMo cathode is 0.4 V higher at the same current density, but it keeps a stable operation for more than 150 h. Through different post-mortem analyses on the aged electrodes, the degradation mechanism of NiAlMo anode is elucidated. The efficiencies of the developed AEM electrolyzer concept reported herein are close to those of the commercial PEM systems, and thus a cost-effective alternative to this technology is provided based on our results.
37Pathways to Low-Iridium Loading in Proton Exchange Membrane Water Electrolyzer Anodes: From Catalyst Design to Catalyst Layer IntegrationOpenAlex
Chanho Pak, Song Gyun Kim, Heena Yang, et al.
Proton exchange membrane water electrolyzers (PEMWEs) are a promising technology for large-scale green hydrogen production; however, the high cost and scarcity of iridium (Ir) remain major obstacles to commercialization. Reducing Ir loading while maintaining catalytic activity and durability is therefore essential to achieving cost-effective hydrogen production. Among various strategies, the development of supported oxygen evolution reaction catalysts has emerged as a particularly effective approach. By anchoring Ir nanostructures onto acid-stable, high-surface-area metal oxide supports, such as TiO2, SnO2, and Ta2O5, researchers have demonstrated enhanced catalyst utilization, improved stability, and significantly reduced precious metal content. These supports not only disperse active sites more effectively but also promote strong metal−support interactions, enabling robust performance under harsh PEMWE operating conditions. This perspective highlights recent advances in structure engineering, oxidation state modulation, and support material design that collectively enable the fabrication of low-Ir anodes with high efficiency. This work further focuses on the integration of these supported catalysts into membrane electrode assemblies (MEAs) and proposes future research directions aimed at achieving the Ir loading target (0.125 mgIr cm−2) suggested by the U.S. Department of Energy. Together, these innovations offer a path forward toward scalable and economically viable PEMWE systems for a sustainable hydrogen economy.
38Mixed iridium-nickel oxides supported on antimony-doped tin oxide as highly efficient and stable acidic oxygen evolution catalystsOpenAlex
Jonathan Ruiz Esquius, Alec P. LaGrow, Haiyan Jin, et al.
Abstract Proton exchange membrane (PEM) water electrolysis represents a promising technology for green hydrogen production, but its widespread deployment is greatly hindered by the indispensable usage of platinum group metal catalysts, especially iridium (Ir) based materials for the energy-demanding oxygen evolution reaction (OER). Herein, we report a new sequential precipitation approach to the synthesis of mixed Ir-nickel (Ni) oxy-hydroxide supported on antimony-doped tin oxide (ATO) nanoparticles (IrNi y O x /ATO, 20 wt.% (Ir + Ni), y = 0, 1, 2, and 3), aiming to reduce the utilisation of scarce and precious Ir while maintaining its good acidic OER performance. When tested in strongly acidic electrolyte (0.1 M HClO 4 ), the optimised IrNi 1 O x /ATO shows a mass activity of 1.0 mA µ g Ir −1 and a large turnover frequency of 123 s −1 at an overpotential of 350 mV, as well as a comparatively small Tafel slope of 50 mV dec −1 , better than the IrO x /ATO control, particularly with a markedly reduced Ir loading of only 19.7 µ g Ir cm −2 . Importantly, IrNi 1 O x /ATO also exhibits substantially better catalytic stability than other reference catalysts, able to continuously catalyse acidic OER at 10 mA cm −2 for 15 h without obvious degradation. Our in-situ synchrotron-based x-ray absorption spectroscopy confirmed that the Ir 3+ /Ir 4+ species are the active sites for the acidic OER. Furthermore, the performance of IrNi 1 O x /ATO was also preliminarily evaluated in a membrane electrode assembly, which shows better activity and stability than other reference catalysts. The IrNi 1 O x /ATO reported in this work is a promising alternative to commercial IrO 2 based catalysts for PEM electrolysis.
39Earth‐Abundant Transition‐Metal‐Based Bifunctional Electrocatalysts for Overall Water Splitting in Alkaline MediaOpenAlex
Jianmin Yu, Thi Anh Le, Ngoc Quang Tran, et al.
The depletion of fossil fuels has accelerated the search for clean, sustainable, scalable, and environmentally friendly alternative energy sources. Hydrogen is a potential energy carrier because of its advantageous properties, and the electrolysis of water is considered as an efficient method for its industrial production. However, the high-energy conversion efficiency of electrochemical water splitting requires cost-effective and highly active electrocatalysts. Therefore, researchers have aimed to develop high-performance electrode materials based on non-precious and abundant transition metals for conversion devices. Moreover, to further reduce the cost and complexity in real-world applications, bifunctional catalysts that can be simultaneously active on both the anodic (i.e., oxygen evolution reaction, OER) and cathodic (i.e., hydrogen evolution reaction, HER) sides are economically and technically desirable. This Minireview focuses on the recent progress in transition-metal-based materials as bifunctional electrocatalysts, including several promising strategies to promote electrocatalytic activities for overall water splitting in alkaline media, such as chemical doping, defect (vacancy) engineering, phase engineering, facet engineering, and structure engineering. Finally, the potential for further developments in rational electrode materials design is also discussed.
40Recent Advances in Electrocatalytic Hydrogen Evolution Using NanoparticlesOpenAlex
Jing Zhu, Liangsheng Hu, Pengxiang Zhao, et al.
production, has been the subject of extensive study over the past decades. In this comprehensive review, we first summarize the fundamentals of HER and review the recent state-of-the-art advances in the low-cost and high-performance catalysts based on noble and non-noble metals, as well as metal-free HER electrocatalysts. We systemically discuss the insights into the relationship among the catalytic activity, morphology, structure, composition, and synthetic method. Strategies for developing an effective catalyst, including increasing the intrinsic activity of active sites and/or increasing the number of active sites, are summarized and highlighted. Finally, the challenges, perspectives, and research directions of HER electrocatalysis are featured.
41Review of Water Splitting Electrolysis over Cobalt Oxide NanomaterialsOpenAlex
Khang Nhat Nguyen, Long Bao Hoang Nguyen, Thach Khac Bui, et al.
Given the recognition of hydrogen fuel as a future energy source, the demand for green hydrogen production necessitates rational electrode designs. Achieving stable durability and high efficiency in electrode fabrication requires a logical combination of substrate and catalyst materials. Cobalt oxide has emerged as a promising catalyst that has garnered significant attention due to its potential to enhance catalytic activity and robustness. In this study, we present a systematic approach to improve the water splitting activity of Co3O4 through morphology control, defect engineering, doping, and heterostructure integration. This study investigates the intrinsic properties of Co3O4, from the atomic to the crystal level, that govern its interfacial activity and synergistic behavior with other materials. These properties significantly influence the surface reaction dynamics of Co3O4, ultimately impacting the kinetics of water splitting. Furthermore, various synthesis routes have been developed to provide a comprehensive perspective on the direct deposition of Co3O4 nanostructures on different conductive substrates. This review encompasses diverse electrode fabrication strategies aimed at optimizing Co3O4 activity. The connection between these strategies offers a complete electrode design pathway, thereby fostering the sustainable development of high-efficiency electrodes for hydrogen production.
42Principles of Water Electrolysis and Recent Progress in Cobalt‐, Nickel‐, and Iron‐Based Oxides for the Oxygen Evolution ReactionOpenAlex
Mingquan Yu, Eko Budiyanto, Harun Tüysüz
Water electrolysis that results in green hydrogen is the key process towards a circular economy. The supply of sustainable electricity and availability of oxygen evolution reaction (OER) electrocatalysts are the main bottlenecks of the process for large-scale production of green hydrogen. A broad range of OER electrocatalysts have been explored to decrease the overpotential and boost the kinetics of this sluggish half-reaction. Co-, Ni-, and Fe-based catalysts have been considered to be potential candidates to replace noble metals due to their tunable 3d electron configuration and spin state, versatility in terms of crystal and electronic structures, as well as abundance in nature. This Review provides some basic principles of water electrolysis, key aspects of OER, and significant criteria for the development of the catalysts. It provides also some insights on recent advances of Co-, Ni-, and Fe-based oxides and a brief perspective on green hydrogen production and the challenges of water electrolysis.
43Designing MOF Nanoarchitectures for Electrochemical Water SplittingOpenAlex
Ben Zhang, Yijuan Zheng, Tian Ma, et al.
Electrochemical water splitting has attracted significant attention as a key pathway for the development of renewable energy systems. Fabricating efficient electrocatalysts for these processes is intensely desired to reduce their overpotentials and facilitate practical applications. Recently, metal-organic framework (MOF) nanoarchitectures featuring ultrahigh surface areas, tunable nanostructures, and excellent porosities have emerged as promising materials for the development of highly active catalysts for electrochemical water splitting. Herein, the most pivotal advances in recent research on engineering MOF nanoarchitectures for efficient electrochemical water splitting are presented. First, the design of catalytic centers for MOF-based/derived electrocatalysts is summarized and compared from the aspects of chemical composition optimization and structural functionalization at the atomic and molecular levels. Subsequently, the fast-growing breakthroughs in catalytic activities, identification of highly active sites, and fundamental mechanisms are thoroughly discussed. Finally, a comprehensive commentary on the current primary challenges and future perspectives in water splitting and its commercialization for hydrogen production is provided. Hereby, new insights into the synthetic principles and electrocatalysis for designing MOF nanoarchitectures for the practical utilization of water splitting are offered, thus further promoting their future prosperity for a wide range of applications.
44The nature of active sites for carbon dioxide electroreduction over oxide-derived copper catalystsOpenAlex
Dongfang Cheng, Zhi‐Jian Zhao, Gong Zhang, et al.
R. Herein, we describe realistic OD-Cu surface models by simulating the oxide-derived process via the molecular dynamic simulation with neural network (NN) potential. After the analysis of over 150 surface sites through NN potential based high-throughput testing, coupled with density functional theory calculations, three square-like sites for C-C coupling are identified. Among them, Σ3 grain boundary like planar-square sites and convex-square sites are responsible for ethylene production while step-square sites, i.e. n(111) × (100), favor alcohols generation, due to the geometric effect for stabilizing acetaldehyde intermediates and destabilizing Cu-O interactions, which are quantitatively demonstrated by combined theoretical and experimental results. This finding provides fundamental insights into the origin of activity and selectivity over Cu-based catalysts and illustrates the value of our research framework in identifying active sites for complex heterogeneous catalysts.
45Advanced Porous Transport Electrode for High-Performance Proton Exchange Membrane Water ElectrolyzersOpenAlex
Zhiqiao Zeng, Stoyan Bliznakov, Leonard J. Bonville, et al.
Proton exchange membrane water electrolyzers (PEMWEs) hold great potential for supplying green hydrogen to support extensive energy storage and mobility in a future energy landscape centered on renewable energy sources. 1,2 However, their contribution to global hydrogen production is currently limited, mainly due to their comparatively high cost. 3 To improve the economic competitiveness of green hydrogen and foster broader market penetration, the Department of Energy (DOE) has launched the Hydrogen Earthshots, aiming for a substantial cost reduction to $2 per kilogram by 2025 and $1 per kilogram for green hydrogen by 2030. 4 The high efficiency and prolonged durability are pivotal for the overall performance and cost reduction of the PEMWEs. This requires careful consideration of the interfacial contact between the porous transport layer (PTL) and the anode catalyst layer. 5 One option for PEMWEs is to directly coat the anode catalyst layer onto the PTL, forming porous transport electrodes (PTEs). Recent literature suggests that it is feasible to manufacture PTEs with low precious metal loading, demonstrating both high performance and durability. 6,7 In this study, an innovative reactive spray deposition technology (RSDT) is used to fabricate PTEs with low PGM loading (0.2 - 0.3 mg PGM cm -2 ) in both catalyst layers. The RSDT is a flame-based method that combines the synthesis and deposition of the catalyst in a single step, significantly reducing the fabrication time and cost of the membrane electrode assembly (MEA). 8–11 The RSDT-fabricated PTEs are coupled with various membranes, and their performance has been assessed and compared to the state-of-the-art MEAs for PEMWEs. In addition, the performance loss in each cell has been studied and discussed in detail. Furthermore, a standard accelerated stress test (AST) protocol has been applied to assess the durability of the RSDT-fabricated MEAs, with one order of magnitude lower PGM loading in their catalyst layers in comparison to the commercial MEAs for PEMWEs. Reference 1. Pham, C. Van, Escalera-López, D., Mayrhofer, K., Cherevko, S. & Thiele, S. Essentials of High Performance Water Electrolyzers – From Catalyst Layer Materials to Electrode Engineering. Adv. Energy Mater. 11, (2021). 2. Carmo, M., Fritz, D. L., Mergel, J. & Stolten, D. A comprehensive review on PEM water electrolysis. Int. J. Hydrogen Energy 38, 4901–4934 (2013). 3. Buttler, A. & Spliethoff, H. Current status of water electrolysis for energy storage, grid balancing, and sector coupling via power-to-gas and power-to-liquids: A review. Renew. Sustain. Energy Rev. 82, 2440–2454 (2018). 4. Styapal, S. et al. DOE Update on Hydrogen Shot, RFI Results, and Summary of Hydrogen Provisions. (2021). 5. Peng, X. et al. Insights into Interfacial and Bulk Transport Phenomena Affecting Proton Exchange Membrane Water Electrolyzer Performance at Ultra-Low Iridium Loadings. Adv. Sci. 8, (2021). 6. Xie, Z. et al. Ionomer-free nanoporous iridium nanosheet electrodes with boosted performance and catalyst utilization for high-efficiency water electrolyzers. Appl. Catal. B Environ. 341, 123298 (2024). 7. Lee, J. K. et al. Ionomer-free and recyclable porous-transport electrode for high-performing proton-exchange-membrane water electrolysis. Nat. Commun. 14, 1–11 (2023). 8. Zeng, Z. et al. Advanced nickel-based catalysts for the hydrogen oxidation reaction in alkaline media synthesized by reactive spray deposition technology: Study of the effect of particle size. Int. J. Hydrogen Energy 1–12 (2023) doi:10.1016/j.ijhydene.2023.03.249. 9. Zeng, Z. et al. Degradation Mechanisms in Advanced MEAs for PEM Water Electrolyzers Fabricated by Reactive Spray Deposition Technology. J. Electrochem. Soc. 169, 054536 (2022). 10. Xing, J. et al. Long-term durability test of highly efficient membrane electrode assemblies for anion exchange membrane seawater electrolyzers. J. Power Sources 558, 232564 (2023). 11. Mirshekari, G. et al. High-performance and cost-effective membrane electrode assemblies for advanced proton exchange membrane water electrolyzers: Long-term durability assessment. Int. J. Hydrogen Energy 46, 1526–1539 (2021).
46Hydrogen Storage for Mobility: A ReviewOpenAlex
Etienne Rivard, Michel L. Trudeau, Karim Zaghib
Numerous reviews on hydrogen storage have previously been published. However, most of these reviews deal either exclusively with storage materials or the global hydrogen economy. This paper presents a review of hydrogen storage systems that are relevant for mobility applications. The ideal storage medium should allow high volumetric and gravimetric energy densities, quick uptake and release of fuel, operation at room temperatures and atmospheric pressure, safe use, and balanced cost-effectiveness. All current hydrogen storage technologies have significant drawbacks, including complex thermal management systems, boil-off, poor efficiency, expensive catalysts, stability issues, slow response rates, high operating pressures, low energy densities, and risks of violent and uncontrolled spontaneous reactions. While not perfect, the current leading industry standard of compressed hydrogen offers a functional solution and demonstrates a storage option for mobility compared to other technologies.
47Research on Storage and Transportation Cost Control and Technological Breakthroughs from the Perspective of Global Hydrogen Energy DevelopmentOpenAlex
Yongxiang Gu, Depeng Pan, Ning Yang, et al.
As the world accelerates towards the "carbon neutrality" goal, the green transformation of the energy system has become an inevitable choice in addressing climate change. Hydrogen energy, with its unique characteristics, is regarded as the "fourth-generation energy" following coal, oil and electricity, and plays a crucial role in addressing energy and environmental challenges. Germany, Japan, China, the European Union and other countries have all elevated it to a national strategy. This article focuses on the high cost issue of hydrogen storage and transportation, clarifies the cost differences among various storage and transportation technologies (high-pressure gaseous, cryogenic liquid, magnesium-based solid-state hydrogen storage, and ammonia/methanol carrier transportation), determines the optimal applicable scenarios for each technology, and provides solutions to reduce storage and transportation costs. This study employs a technical and economic comparison analysis method. Based on the cost data of hydrogen storage and transportation technologies (such as magnesium-based hydrogen storage costs and transportation costs over different distances) and technical parameters, it comparatively analyzes the economic performance of various technologies under different transportation distances and scales. Suggestions such as giving priority to hydrogen blending in existing pipelines and developing 35MPa road transportation can effectively reduce the cost of hydrogen storage and transportation, facilitate the large-scale application of hydrogen in transportation, industry and other fields, and provide support for the integration of hydrogen into the global sustainable energy system.
48Advancements in hydrogen production, storage, distribution and refuelling for a sustainable transport sector: Hydrogen fuel cell vehiclesOpenAlex
Pobitra Halder, Meisam Babaie, Farhad Salek, et al.
Hydrogen is considered as a promising fuel in the 21st century due to zero tailpipe CO2 emissions from hydrogen-powered vehicles. The use of hydrogen as fuel in vehicles can play an important role in decarbonising the transport sector and achieving net-zero emissions targets. However, there exist several issues related to hydrogen production, efficient hydrogen storage system and transport and refuelling infrastructure, where the current research is focussing on. This study critically reviews and analyses the recent technological advancements of hydrogen production, storage and distribution technologies along with their cost and associated greenhouse gas emissions. This paper also comprehensively discusses the hydrogen refuelling methods, identifies issues associated with fast refuelling and explores the control strategies. Additionally, it explains various standard protocols in relation to safe and efficient refuelling, analyses economic aspects and presents the recent technological advancements related to refuelling infrastructure. This study suggests that the production cost of hydrogen significantly varies from one technology to others. The current hydrogen production cost from fossil sources using the most established technologies were estimated at about $0.8–$3.5/kg H2, depending on the country of production. The underground storage technology exhibited the lowest storage cost, followed by compressed hydrogen and liquid hydrogen storage. The levelised cost of the refuelling station was reported to be about $1.5–$8/kg H2, depending on the station's capacity and country. Using portable refuelling stations were identified as a promising option in many countries for small fleet size low-to-medium duty vehicles. Following the current research progresses, this paper in the end identifies knowledge gaps and thereby presents future research directions.
50Nanoscale engineering of solid-state materials for boosting hydrogen storageOpenAlex
Yunting Wang, Yudong Xue, Andreas Züttel
nanoscale tuning and designing strategies on both physisorbents and chemisorbents have been devoted to improvements in their thermodynamic and kinetic aspects. Increasing the hydrogen storage capacity/density for physisorbents and chemisorbents and improving the dehydrogenation kinetics of hydrides are still considered a challenge. The extensive and fast development of advanced nanotechnologies has fueled a surge in research that presents huge potential in designing solid-state materials to meet the ultimate U.S. Department of Energy capacity targets for onboard light-duty vehicles, material-handling equipments, and portable power applications. Different from the existing literature, in this review, particular attention is paid to the recent advances in nanoscale engineering of solid-state materials for boosting hydrogen storage, especially the nanoscale tuning and designing strategies. We first present a short overview of hydrogen storage mechanisms of nanoscale engineering for boosted hydrogen storage performance on solid-state materials, for example, hydrogen spillover, nanopump effect, nanosize effect, nanocatalysis, and other non-classical hydrogen storage mechanisms. Then, the focus is on recent advancements in nanoscale engineering strategies aimed at enhancing the gravimetric hydrogen storage capacity of porous materials, reducing dehydrogenation temperature and improving reaction kinetics and reversibility of hydrogen desorption/absorption for metal hydrides. Effective nanoscale tuning strategies for enhancing the hydrogen storage performance of porous materials include optimizing surface area and pore volume, fine-tuning nanopore sizes, introducing nanostructure doping, and crafting nanoarchitecture and nanohybrid materials. For metal hydrides, successful strategies involve nanoconfinement, nanosizing, and the incorporation of nanocatalysts. This review further addresses the points to future research directions in the hope of ushering in the practical applications of hydrogen storage materials.
51Application of hydrides in hydrogen storage and compression: Achievements, outlook and perspectivesOpenAlex
José M. Bellosta von Colbe, J.R. Ares, Jussara Barale, et al.
Metal hydrides are known as a potential efficient, low-risk option for high-density hydrogen storage since the late 1970s. In this paper, the present status and the future perspectives of the use of metal hydrides for hydrogen storage are discussed. Since the early 1990s, interstitial metal hydrides are known as base materials for Ni – metal hydride rechargeable batteries. For hydrogen storage, metal hydride systems have been developed in the 2010s [1] for use in emergency or backup power units, i. e. for stationary applications. With the development and completion of the first submarines of the U212 A series by HDW (now Thyssen Krupp Marine Systems) in 2003 and its export class U214 in 2004, the use of metal hydrides for hydrogen storage in mobile applications has been established, with new application fields coming into focus. In the last decades, a huge number of new intermetallic and partially covalent hydrogen absorbing compounds has been identified and partly more, partly less extensively characterized. In addition, based on the thermodynamic properties of metal hydrides, this class of materials gives the opportunity to develop a new hydrogen compression technology. They allow the direct conversion from thermal energy into the compression of hydrogen gas without the need of any moving parts. Such compressors have been developed and are nowadays commercially available for pressures up to 200 bar. Metal hydride based compressors for higher pressures are under development. Moreover, storage systems consisting of the combination of metal hydrides and high-pressure vessels have been proposed as a realistic solution for on-board hydrogen storage on fuel cell vehicles. In the frame of the “Hydrogen Storage Systems for Mobile and Stationary Applications” Group in the International Energy Agency (IEA) Hydrogen Task 32 “Hydrogen-based energy storage”, different compounds have been and will be scaled-up in the near future and tested in the range of 500 g to several hundred kg for use in hydrogen storage applications.
52Strategies for Hydrogen Storage in Metal–Organic FrameworksOpenAlex
Jesse L. C. Rowsell, Omar M. Yaghi
Increased attention is being focused on metal-organic frameworks as candidates for hydrogen storage materials. This is a result of their many favorable attributes, such as high porosity, reproducible and facile syntheses, amenability to scale-up, and chemical modification for targeting desired properties. A discussion of several strategies aimed at improving hydrogen uptake in these materials is presented. These strategies include the optimization of pore size and adsorption energy by linker modification, impregnation, catenation, and the inclusion of open metal sites and lighter metals.
53Large-scale compressed hydrogen storage as part of renewable electricity storage systemsOpenAlex
Ahmed M. Elberry, Jagruti Thakur, Annukka Santasalo-Aarnio, et al.
Storing energy in the form of hydrogen is a promising green alternative. Thus, there is a high interest to analyze the status quo of the different storage options. This paper focuses on the large-scale compressed hydrogen storage options with respect to three categories: storage vessels, geological storage, and other underground storage alternatives. In this study, we investigated a wide variety of compressed hydrogen storage technologies, discussing in fair detail their theory of operation, potential, and challenges. The analysis confirms that a techno-economic chain analysis is required to evaluate the viability of one storage option over another for a case by case. Some of the discussed technologies are immature; however, this does not rule out these technologies; rather, it portrays the research opportunities in the field and the foreseen potential of these technologies. Furthermore, we see that hydrogen would have a significant role in balancing intermittent renewable electricity production.
54A comprehensive comparison of green ammonia and green methanol from a full chain: production, transportation, storage and utilizationOpenAlex
Cheng Cao, Bin Wen, Yanli Fang, et al.
Abstract The global transition to renewable energy and hydrogen development has brought increasing attention to green ammonia and green methanol which can be produced from green hydrogen. Developing these green chemicals not only promotes their respective industries but also supports the development of hydrogen. A thorough investigation and comparison are essential to determine the priority and specific scenarios for developing energy sources aimed at supporting hydrogen or other sectors. However, previous reviews have typically focused either on specific aspects, such as production or utilization, or have conducted comprehensive analyses limited to only one energy carrier, lacking an integrated comparative approach. This study offers a comprehensive assessment of ammonia and methanol across six dimensions: technology readiness level, energy efficiency, safety, logistical convenience, economic viability, and environmental impact. The analysis shows that each carrier has a distinct development trajectory. Ammonia can be transported through established supply chains and cracked to hydrogen at the point of use, a capability that supports large-scale hydrogen deployment. In contrast, the greater technological maturity of methanol as a fuel positions it for near-term decarbonization of the transport sector rather than immediate integration into hydrogen infrastructure.
55Comparing green hydrogen and green ammonia as energy carriers in utility-scale transport and subsurface storageOpenAlex
Anne H. Menefee, Brandon Schwartz
• Ammonia has thermodynamic advantages over hydrogen under relevant transport and storage conditions, but comes with greater uncertainties and more limited options in underground storage . • Ammonia benefits from a greater network of existing pipelines, standards, and regulations that could accelerate deployment of large-scale hydrogen transport and storage. • Round-trip efficiencies are still lower for ammonia when hydrogen is the intended end product, as advantages in energy density are offset by efficiency penalties in ammonia synthesis and decomposition, but can be comparable when considering ammonia-to-power systems. Many of the challenges associated with utility-scale hydrogen transport and storage relate to its low density, high diffusivity, and the risk of hydrogen embrittlement, motivating consideration to integrating ammonia as an energy carrier. Compared to hydrogen, ammonia is more compatible with pipeline materials and delivers energy at higher density. Ammonia is also a mature industry with a greater extent of established pipeline networks and regulations that may accelerate hydrogen transitions and penetration in energy grids. However, converting hydrogen produced by renewable-driven electrolysis into ammonia (and back to hydrogen, depending on end use) complicates logistics, and associated energy and resource demands may offset the green hydrogen's carbon neutrality. This work outlines core considerations for the use of hydrogen vs. ammonia during transport and storage operations, with an emphasis on green hydrogen or green ammonia pathways coupled to pipeline transport and underground storage. We compare tradeoffs in pipeline infrastructure and operations; subsurface storage options; and project economics. We also evaluate round-trip efficiencies (RTE) for both pathways, which indicate that hydrogen is more attractive from an energy efficiency perspective for hydrogen end-use applications due to the efficiency penalties of initial ammonia synthesis and subsequent cracking, but RTE's for ammonia transport and storage are comparable to hydrogen for direct use or ammonia-to-power systems. The tradeoffs presented in this work would need to be considered on a case-by-case basis, but indicate that selective use of ammonia as an energy-dense hydrogen carrier could support decarbonization goals in industry and hydrogen economies.
56Review on Ammonia as a Potential Fuel: From Synthesis to EconomicsOpenAlex
Agustín Valera-Medina, F. Amer-Hatem, A. K. Azad, et al.
<p>Ammonia, a molecule that is gaining more interest as a fueling vector, has been considered as a candidate to power transport, produce energy, and support heating applications for decades. However, the particular characteristics of the molecule always made it a chemical with low, if any, benefit once compared to conventional fossil fuels. Still, the current need to decarbonize our economy makes the search of new methods crucial to use chemicals, such as ammonia, that can be produced and employed without incurring in the emission of carbon oxides. Therefore, current efforts in this field are leading scientists, industries, and governments to seriously invest efforts in the development of holistic solutions capable of making ammonia a viable fuel for the transition toward a clean future. On that basis, this review has approached the subject gathering inputs from scientists actively working on the topic. The review starts from the importance of ammonia as an energy vector, moving through all of the steps in the production, distribution, utilization, safety, legal considerations, and economic aspects of the use of such a molecule to support the future energy mix. Fundamentals of combustion and practical cases for the recovery of energy of ammonia are also addressed, thus providing a complete view of what potentially could become a vector of crucial importance to the mitigation of carbon emissions. Different from other works, this review seeks to provide a holistic perspective of ammonia as a chemical that presents benefits and constraints for storing energy from sustainable sources. State-of-the-art knowledge provided by academics actively engaged with the topic at various fronts also enables a clear vision of the progress in each of the branches of ammonia as an energy carrier. Further, the fundamental boundaries of the use of the molecule are expanded to real technical issues for all potential technologies capable of using it for energy purposes, legal barriers that will be faced to achieve its deployment, safety and environmental considerations that impose a critical aspect for acceptance and wellbeing, and economic implications for the use of ammonia across all aspects approached for the production and implementation of this chemical as a fueling source. Herein, this work sets the principles, research, practicalities, and future views of a transition toward a future where ammonia will be a major energy player. </p>
57Safety Assessment of the Ammonia Bunkering Process in the Maritime Sector: A ReviewOpenAlex
Phan Anh Duong, Bo Rim Ryu, Mi kyoung Song, et al.
One of the main goals of the shipping industry is to decarbonize the fuels used in maritime transportation. Ammonia is thought to be a potential alternative for hydrogen storage in the future, allowing for CO2-free energy systems. Ammonia’s beneficial characteristics with regard to hydrogen storage include its high volumetric hydrogen density, low storage pressure, and long-term stability. However, ammonia is characterized by toxicity, flammability, and corrosiveness, making safety a challenge compared to other alternative fuels. In specific circumstances, leakage from ammonia bunkering can cause risks, dispersion, and unsafe areas due to its flammability and toxicity. Based on an analysis of 118 research papers and 50 regulations and guidelines, this review report evaluates various aspects of the hazards associated with the ammonia bunkering processes, considering both current and future implications. This report also includes the latest advancements and potential developments related to the safety of ammonia as a marine fuel. Several related regulations and standards for ammonia supply systems are discussed. This paper examines experiments and numerical investigations conducted using different methods of ammonia bunkering, such as terminal-to-ship, ship-to-ship, and truck-to-ship transfers. This review shows that the toxicity of ammonia is more relevant to the topics of vapor cloud dispersion and ammonia bunkering than its flammability. Finally, the main challenges and recommendations for the implementation of ammonia bunkering and further development of ammonia as a marine fuel are proposed. This review suggests new directions to overcome the disadvantages and research gaps associated with the leakage of ammonia during bunkering periods.
58Techno-economic assessment of long-term methanol production from natural gas and renewablesOpenAlex
Carlos Arnaiz del Pozo, Schalk Cloete, Ángel Jiménez Álvaro
Growing climate change concerns are driving interest in alternative energy carriers to fossil fuels. Methanol (MeOH) is a promising candidate to alleviate the challenges faced by hydrogen regarding transportation and storage, with a developed pre-existing infrastructure and a well-known and scalable synthesis process. This study presents a techno-economic assessment of the different avenues for producing MeOH from 1) natural gas and 2) renewable energy with direct air capture (DAC), for effective CO2 removal from the atmosphere. Under European natural gas prices (6.5 €/GJ), state-of-the-art MeOH production from natural gas reach levelized costs as low as 268.5 €/ton, while an advanced plant using gas switching reforming attains a cost of 252.2 €/ton and approximately 60% lower CO2 emissions. Middle Eastern costs can drop as low as 135.2 €/ton thanks to low natural gas costs (2 €/GJ). In comparison, renewable MeOH with DAC reach 471.6–784.9 €/ton using technology assumptions representative of the year 2050, with Saudi Arabia achieving the lowest cost thanks to its outstanding solar resource. Overall, renewable MeOH with DAC required CO2 prices of 121.4–146.7 €/ton to break even with renewable plants using pipeline CO2, while CO2 prices in the range of 300 €/ton are required for competitiveness against natural gas routes. Furthermore, a consistent comparison to NH3 as a carbon-free energy carrier showed that blue and green NH3 require CO2 taxes of 49.8 and 274.3 €/ton to break even with natural gas-based MeOH, respectively. However, NH3 is 14% cheaper than MeOH for renewable pathways, as it avoids the need for DAC. Thus, strong policy support will be required to deploy green MeOH at scale, even in the long-term future.
59Ultra-long-duration energy storage anywhere: Methanol with carbon cyclingOpenAlex
Tom Brown, Johannes Hampp
Tom Brown leads a group of energy system modelers at the Technische Universität Berlin, where he holds the professorship for digital transformation in energy systems. His group researches future pathways for the energy system, with a particular focus on revealing the trade-offs between energy resources, network expansion, flexibility, and public acceptance of new infrastructure. He is a strong supporter of openness and transparency in research and is one of the lead developers of the widely used open-source software Python for Power System Analysis (PyPSA).Graphical AbstractView Large Image Figure ViewerDownload Hi-res image Download (PPT)Johannes Hampp is a researcher at the Potsdam Institute for Climate Impact Research and is finishing a doctorate at the University of Gieβen in energy system modeling. His research focuses on the production of hydrogen and hydrogen derivatives and on the effects of regional differences in renewable endowments around the world on energy and feedstock supply chains. Tom Brown leads a group of energy system modelers at the Technische Universität Berlin, where he holds the professorship for digital transformation in energy systems. His group researches future pathways for the energy system, with a particular focus on revealing the trade-offs between energy resources, network expansion, flexibility, and public acceptance of new infrastructure. He is a strong supporter of openness and transparency in research and is one of the lead developers of the widely used open-source software Python for Power System Analysis (PyPSA). Johannes Hampp is a researcher at the Potsdam Institute for Climate Impact Research and is finishing a doctorate at the University of Gieβen in energy system modeling. His research focuses on the production of hydrogen and hydrogen derivatives and on the effects of regional differences in renewable endowments around the world on energy and feedstock supply chains. Wind and solar generation are rapidly expanding around the globe as their costs come down and societal pressure to reduce greenhouse gas emissions rises. To supply a high fraction of electricity demand with variable sources, different types of storage are needed to balance daily, weekly, seasonal, and interannual weather fluctuations. Battery storage can bridge several hours of low solar and wind feed-in. However, if wind and solar penetration rises to cover all demand in the absence of other generation technologies, longer duration energy storage becomes necessary to supply multiple days or weeks of dark wind lulls and seasonal variations in supply and demand, as well as to bridge years of low renewable production. While the term long-duration energy storage (LDES) is often used for storage technologies with a power-to-energy ratio between 10 and 100 h,1Denholm P. Cole W. Frazier A.W. Podkaminer K. Blair N. The challenge of defining long-duration energy storage. NREL, 2021https://www.nrel.gov/docs/fy22osti/80583.pdfCrossref Google Scholar we introduce the term ultra-long-duration energy storage (ULDES) for storage that can cover durations longer than 100 h (4 days) and thus act like a firm resource. Battery storage with current energy capacity investment costs of 100–200 €/kWh would be too costly for these long periods. Simulations show that for renewable systems to be competitive with dispatchable low-carbon technologies, ULDES would need to cost at most around 10 €/kWh.2Sepulveda N.A. Jenkins J.D. Edington A. Mallapragada D.S. Lester R.K. The design space for long-duration energy storage in decarbonized power systems.Nat. Energy. 2021; 6: 506-516https://doi.org/10.1038/s41560-021-00796-8Crossref Scopus (208) Google Scholar (Note that all costs are given in 2020 euros, while all fuel energy units and efficiencies refer to the lower heating value.) Hydrogen storage is a promising candidate for ULDES, whereby hydrogen is produced by electrolysis of water, stored and then used to generated electricity in a gas turbine or fuel cell.3Blanco H. Faaij A. A review at the role of storage in energy systems with a focus on power to gas and long-term storage.Renew. Sustain. Energy Rev. 2018; 81: 1049-1086https://doi.org/10.1016/j.rser.2017.07.062Crossref Scopus (428) Google Scholar,4Dowling J.A. Rinaldi K.Z. Ruggles T.H. Davis S.J. Yuan M. Tong F. Lewis N.S. Caldeira K. Role of long-duration energy storage in variable renewable electricity systems.Joule. 2020; 4: 1907-1928https://doi.org/10.1016/j.joule.2020.07.007Abstract Full Text Full Text PDF Scopus (195) Google Scholar,5Llewellyn-Smith C. Large-scale Electricity Storage. The Royal Society, 2023https://royalsociety.org/electricity-storageGoogle Scholar While aboveground pressure vessels can cost 10–40 €/kWh, depending on their rated pressure, storing hydrogen underground in solution-mined salt caverns has much lower costs in the range 0.1–0.5 €/kWh. Several salt caverns with sizes up to 274 GWh are already used for storing hydrogen at petrochemical facilities in the United Kingdom and in Texas in the United States. Despite the attractive cost, hydrogen salt caverns face several challenges. Many regions do not have salt deposits, such as large parts of Africa, southeast Europe and southeast Asia.3Blanco H. Faaij A. A review at the role of storage in energy systems with a focus on power to gas and long-term storage.Renew. Sustain. Energy Rev. 2018; 81: 1049-1086https://doi.org/10.1016/j.rser.2017.07.062Crossref Scopus (428) Google Scholar In those countries that do have suitable salt deposits for caverns, they are often highly localized: in the northeast of the island of Ireland, centrally in Great Britain, and in the north of the Netherlands and Germany, to name a few examples.3Blanco H. Faaij A. A review at the role of storage in energy systems with a focus on power to gas and long-term storage.Renew. Sustain. Energy Rev. 2018; 81: 1049-1086https://doi.org/10.1016/j.rser.2017.07.062Crossref Scopus (428) Google Scholar The distance of cavern sites from hydrogen supply and demand presents a transportation challenge: bringing electricity to electrolyzers at storage sites would mean a significant expansion of power transmission lines, while placing electrolyzers close to renewables sites and transporting the hydrogen would require a hydrogen pipeline network.6Neumann F. Zeyen E. Victoria M. Brown T. The potential role of a hydrogen network in Europe.Joule. 2023; 7: 1793-1817https://doi.org/10.1016/j.joule.2023.06.016Abstract Full Text Full Text PDF Scopus (1) Google Scholar Small-diameter hydrogen pipelines have been in service for decades, and existing fossil gas pipelines could be repurposed for hydrogen, but open challenges remain such as the embrittlement of pipeline steel and the global warming potential of hydrogen leaks.7Sand M. Skeie R.B. Sandstad M. Krishnan S. Myhre G. Bryant H. Derwent R. Hauglustaine D. Paulot F. Prather M. Stevenson D. A multi-model assessment of the global warming potential of hydrogen.Commun. Earth Environ. 2023; 4: 203https://doi.org/10.1038/s43247-023-00857-8Crossref Scopus (12) Google Scholar There may be delays when building new transmission lines or hydrogen networks or problems during the simultaneous scale up of hydrogen supply, transport, and storage. Proposals for new salt cavern storage have encountered public opposition, with concerns that range from ground shifting above caverns and the impacts of saline discharge from solution mining on marine wildlife to general concerns about hydrogen safety. On the generation side, the high combustion temperature of hydrogen leads to high nitrogen oxide emissions from gas turbines, which must be managed with strategies such as water injection. Methanol as ULDES could offer an alternative to hydrogen storage. A concept for methanol storage with carbon cycling from Baak et al.8Baak J. Pozarlik A. Arentsen M. Brem G. Techno-economic study of a zero-emission methanol based energy storage system.Energy Convers. Manag. 2019; 182: 530-545https://doi.org/10.1016/j.enconman.2018.12.015Crossref Scopus (39) Google Scholar is sketched in Figure 1 with all inputs and outputs. Methanol can be synthesized from electrolytic hydrogen and carbon oxides (so called “e-methanol”). E-methanol is already produced today at a scale of thousands of tons per year in Iceland, and a similar process is used for methanol at megaton scale using gasified coal in China, where the methanol is used in the chemical industry.9Bertau M. Offermanns H. Plass L. Schmidt F. Wernicke H.-J. Methanol: The Basic Chemical and Energy Feedstock of the Future: Asinger’s Vision Today. Springer, 2014https://doi.org/10.1007/978-3-642-39709-7Crossref Scopus (244) Google Scholar Methanol is liquid at ambient temperature and pressure, and can thus be stored in large aboveground tanks, just as oil products are today, at costs of around 0.01–0.05 €/kWh. A single 200,000 m3 cylindrical tank with diameter 80 m and height 40 m can store 880 GWh of methanol. When combusted with pure oxygen in a transcritical Allam cycle turbine using carbon dioxide as the working fluid, up to 98% of the carbon dioxide from combustion can be captured with minimal effort, producing power at efficiencies of up to 66%.10Mitchell P. Avagyan V. Chalmers H. Lucquiaud M. An initial assessment of the value of Allam Cycle power plants with liquid oxygen storage in future GB electricity system.Br. J. Neurosurg. 2019; 33: 1-2https://doi.org/10.1016/j.ijggc.2019.04.020Crossref PubMed Scopus (30) Google Scholar The oxygen for the turbine can be taken from the water electrolysis and stored cryogenically as a liquid in aboveground steel tanks or separated from the air. A 50 MWth plant using the Allam cycle is already operating in Texas11Martin S. Forrest B. Rafati N. Lu X. Fetvedt J. McGroddy M. Brown B. Allam R. Beauchamp D. Freed D. Progress Update on the Allam Cycle: Commercialization of Net Power and the Net Power Demonstration Facility.in: 14th Greenhouse Gas Control Technologies Conference Melbourne 21-26 October 2018 (GHGT-14). 2018https://doi.org/10.2139/ssrn.3366370Google Scholar and several commercial plants are planned in the United States and Europe in the 300 MW range. The captured carbon dioxide can then be stored as a liquid in aboveground pressure vessels to be used again for methanol synthesis, thus closing the carbon cycle. The Allam cycle is chosen for its high efficiency and high capture rates, which avoids having to source carbon dioxide from elsewhere. By combusting in pure oxygen rather than air, the system avoids both nitrogen oxide emissions and the thermodynamic cost of separating the carbon dioxide from the exhaust gases. Any carbon dioxide that leaks can be topped up either from biogenic sources or captured directly from the air. Ideas for a methanol economy, by which methanol could be used in transport, chemicals, power, and heat, go back at least to the 1980s, when Friedrich Asinger suggested using methanol as an alternative to imported hydrocarbons, first from coal gasification and later based on electrolysis using nuclear power.12Asinger F. Methanol — Chemie- und Energierohstoff. Springer, 1986https://doi.org/10.1007/978-3-642-70763-6Crossref Google Scholar More recently, methanol has been discussed using renewable power as the primary energy source.9Bertau M. Offermanns H. Plass L. Schmidt F. Wernicke H.-J. Methanol: The Basic Chemical and Energy Feedstock of the Future: Asinger’s Vision Today. Springer, 2014https://doi.org/10.1007/978-3-642-39709-7Crossref Scopus (244) Google Scholar,13Olah G.A. Goeppert A. Prakash G.K.S. Beyond Oil and Gas: The Methanol Economy.2nd Edition. Wiley, 2006Google Scholar,14Shih C.F. Zhang T. Li J. Bai C. Powering the future with liquid sunshine.Joule. 2018; 2: 1925-1949https://doi.org/10.1016/j.joule.2018.08.016Abstract Full Text Full Text PDF Scopus (456) Google Scholar While many studies see a role for methanol in industry as a precursor chemical for producing olefins and aromatics, for long-distance shipping, or as an intermediate for kerosene production for long-distance aviation, its potential role in long-duration storage is less explored. It has been favorably compared to methane for storage in terms of round-trip efficiency but without carbon cycling or economic analysis.15Räuchle K. Plass L. Wernicke H.-J. Bertau M. Methanol for renewable energy storage and utilization.Energy Tech. 2016; 4: 193-200https://doi.org/10.1002/ente.201500322Crossref Scopus (58) Google Scholar Cycling of carbon, oxygen, and hydrogen-derivatives has been suggested in the concept of “thermal hydrogen”16Moore J. Meeks N. Hourly modelling of Thermal Hydrogen electricity markets.Clean Energy. 2020; 4: 270-287https://doi.org/10.1093/ce/zkaa014Crossref Scopus (3) Google Scholar but not in the context of very high of renewable energy and storage. cycling with Allam has been for methanol storage J. Pozarlik A. Arentsen M. Brem G. Techno-economic study of a zero-emission methanol based energy storage system.Energy Convers. Manag. 2019; 182: 530-545https://doi.org/10.1016/j.enconman.2018.12.015Crossref Scopus (39) Google Scholar but the focus on the cost of storage based on about capacity rather than a in with variable renewables and other storage like has been is a for high of wind and solar in a power system many weather which we in In production facilities using fossil methanol is with these high with hydrogen supply from variable electricity would require hydrogen storage to the hydrogen, which may not be as discussed While hydrogen can be in pressure vessels for several of low wind and solar generation would a challenge for is from large research as well as initial from plants be to methanol to large hydrogen storage. can be by to V. A. A. H. S. of or a Environ. 2020; Google T. K. methanol and with the Energy. Scopus Google S. A. D. or intermediate 2023; Google Scholar down V. A. A. H. S. of or a Environ. 2020; Google J. J. T.H. S. R. R. A for pathways to renewable energy for J. Hydrogen Energy. 2023; Scopus (3) Google Scholar V. A. A. H. S. of or a Environ. 2020; Google Scholar and the T. K. methanol and with the Energy. Scopus Google J. M. and to in design and of chemical Tech. 2020; Scopus Google Scholar that the can be on and as long as of of capacity per are Simulations for methanol show that in the of and can reduce the cost of methanol by compared to C. A. The role of process in the of variable renewable energy chemical Convers. Manag. 2021; Scopus Google Scholar the to the in To methanol with hydrogen we the supply of a electricity demand with and storage in the United Germany, and using a single of weather for the years M. D. Hourly and weather and for energy system Scopus Google Scholar The of and either hydrogen or methanol ULDES to supply the demand in of the years of a long taken in to both seasonal as well as wind in particular is to go of the years the large of years is used in the of different weather The years are by the storage of and for pressure hydrogen storage in aboveground steel pressure cycle gas turbine for electricity salt hydrogen storage in underground salt caverns, for electricity Allam methanol all storage in aboveground steel tanks or pressure for methanol synthesis, to Allam cycle carbon dioxide from Allam capture or biogenic for methanol all storage in aboveground steel tanks or pressure for methanol synthesis, to without capture of all for methanol from biogenic facilities taken for the year and are in A cost of of is It is that up to 98% of carbon dioxide can be captured from the Allam turbine and that carbon dioxide is with by electricity and from a fossil are the have carbon dioxide Methanol is synthesized directly from carbon dioxide and and are as in to the are in The system cost for electricity are in Figure on and can be in underground salt caverns pressure vessels for hydrogen storage costs by steel pressure vessels reduce the storage capacity and the system to wind and solar which is then While the United Kingdom with its wind solar is in less and and variations need less storage in pressure vessels than wind in the United methanol storage with aboveground tanks for all stored is than underground hydrogen storage. using the methanol system is lower in cost than using aboveground pressure vessels for hydrogen, presents the most solution of those where salt deposits are not The round-trip efficiency for hydrogen storage at is than for methanol storage with carbon cycling at on the for Germany, the Allam cycle just of electricity The is either directly by wind and solar or by in Figure of the carbon dioxide used for the methanol is captured from the Allam turbine and while the from There is a between storing all of the from the Allam turbine with a very large storage and using at when electricity is for the oxygen supply for the Allam of the oxygen is stored from the while from the cost for methanol storage come from the Allam cycle et P. Avagyan V. Chalmers H. Lucquiaud M. An initial assessment of the value of Allam Cycle power plants with liquid oxygen storage in future GB electricity system.Br. J. Neurosurg. 2019; 33: 1-2https://doi.org/10.1016/j.ijggc.2019.04.020Crossref PubMed Scopus (30) Google Scholar we have that the Allam cycle cost as much as a if the cost to the methanol storage system would be just than cavern hydrogen storage the methanol in a without carbon the system to on to source the carbon is lower cost than the carbon cycle of methanol storage and than underground hydrogen storage. In costs are on the turbine as well as the storage of oxygen and carbon However, solution on up which has not been at large The cost of carbon dioxide with is around in the if biogenic is could reduce the cost carbon dioxide is a of the system A to the cost is in and a low the carbon is longer in the methanol could be imported from regions at lower J. M. Brown T. for chemical energy from renewable sources to 2023; Scopus Google Scholar of the energy demand of the the round-trip efficiency in is to The energy of the ULDES in the underground hydrogen and methanol is for in Figure underground hydrogen the storage is to cover 50 days of electricity demand and a seasonal in the and then in hydrogen is between while the of the is managed by building wind and solar large for years and in methanol on the other the storage is low cost to be used both for as well as seasonal storage. It is to cover days of electricity A study on methanol storage with carbon cycling that a a round-trip efficiency of and a of J. Pozarlik A. Arentsen M. Brem G. Techno-economic study of a zero-emission methanol based energy storage system.Energy Convers. Manag. 2019; 182: 530-545https://doi.org/10.1016/j.enconman.2018.12.015Crossref Scopus (39) Google Scholar round-trip efficiency is at we a efficiency for the Allam turbine and for the methanol However, is in the range we the cost of electricity for the storage and Allam cycle has a lower capacity of compared to the capacity of in Baak et al.8Baak J. Pozarlik A. Arentsen M. Brem G. Techno-economic study of a zero-emission methanol based energy storage system.Energy Convers. Manag. 2019; 182: 530-545https://doi.org/10.1016/j.enconman.2018.12.015Crossref Scopus (39) Google Scholar cost of methanol in the Allam from to is carbon cycling and is cost rises to The range to which is than fossil methanol of but in with for methanol in J. M. Brown T. for chemical energy from renewable sources to 2023; Scopus Google Scholar underground hydrogen the of storage is than that in a study at weather S. in a renewable electricity and Scopus Google Scholar with the by the cavern costs of €/kWh in that which the balance less storage and To the of the to the most are in with the less methanol synthesis, methanol and underground hydrogen fossil methane with carbon capture and costs for lower costs for the Allam a seasonal demand that the of space and the of wind The countries as a single which leads to of wind and solar and that transporting hydrogen is costly in and energy than a would methanol. There is around costs for for technologies like the Allam cycle and that are just in the process of and generation technologies, such as or and storage technologies, such as or energy could lead to system cost depending on the The above are to low wind and solar that have in the To the system other would be to the methanol storage for a of days of would the effects of that solar generation for several E. of on an study with to the 2016; Scopus Google Scholar to imported energy and of energy a methanol would be similar to the that for oil products and gas are An attractive of methanol storage is that can be down without costs too of the of scale are already from a of MW to the electrolysis J. Pozarlik A. Arentsen M. Brem G. Techno-economic study of a zero-emission methanol based energy storage system.Energy Convers. Manag. 2019; 182: 530-545https://doi.org/10.1016/j.enconman.2018.12.015Crossref Scopus (39) Google Scholar and methanol units are on the at sizes down to 10 at 10 MW MW Scholar could methanol for and other In hydrogen pipelines and underground storage are large that first from Methanol ULDES or parts of the storage system may have the electricity system In where capacity is renewable can be with ULDES to their of the While not carbon Allam could be used in the with fossil gas and the captured carbon dioxide could be used to methanol with hydrogen, which could then be used in or the most of its are widely the Allam cycle has been in a 50 MWth commercial plants at 300 MW scale are While is the than hydrogen turbines, may be problems that with the or up production In carbon capture to which have already been with M. Offermanns H. Plass L. Schmidt F. Wernicke H.-J. Methanol: The Basic Chemical and Energy Feedstock of the Future: Asinger’s Vision Today. Springer, 2014https://doi.org/10.1007/978-3-642-39709-7Crossref Scopus (244) Google Scholar or the without capture and from the or like the for either using methanol directly or with a to hydrogen, are a turbine may be attractive given its The from a turbine can be used when is not power by the from the turbine that the as a storage with the energy methanol to liquid hydrogen, and other liquid hydrogen The methane is similar to methanol in that carbon must be in the system, both can existing fossil fuel for storage and transport, the round-trip efficiencies are and the costs of and methanol are On the the costs of building new methane storage are than underground storage is than methane to be for and and gas pipelines require for of methane may existing for fossil of methane must be and is a greenhouse can be stored cryogenically or pressure as a liquid and not require carbon nitrogen can be separated from the air. On the is highly its and storage is highly pure have a low when is combusted in a leads to nitrogen oxide emissions that need to be hydrogen significant and power, which for such as have similar to methanol storage but have lower and the costs of the In to methanol as a long-duration energy storage are several research The effects of methanol on and be More is needed on methanol with carbon dioxide rather than carbon It would be if on the Allam cycle in the public The trade-offs for storage of carbon dioxide and oxygen capture be explored. The to the methanol from its could be explored. methanol and carbon dioxide could be to and from the by or could be to methanol and carbon dioxide given that their are While storing hydrogen underground in salt caverns is an attractive for long duration methanol storage can offer several flexibility, and is by the need to cycle carbon in to carbon but we that can be using Allam cycle on methanol and promising facilities for the Allam cycle have given new to research firm up the for ultra-long-duration methanol storage.
60Hydrogen Production from the LOHC Perhydro-Dibenzyl-Toluene and Purification Using a 5 µm PdAg-Membrane in a Coupled Microstructured System.PubMed
Alexander Wunsch, Tatjana Berg, Peter Pfeifer
Materials (Basel). 2020 Jan 8;13(2):277. doi: 10.3390/ma13020277.
Hydrogen bound in organic liquid hydrogen carriers (LOHC) such as dibenzyl-toluene enables simple and safe handling as well as long-term storage. This idea is particularly interesting in the context of the energy transition, where hydrogen is considered a key energy carrier. The LOHC technology serves as a storage between volatile energy and locally and timely independent consumption. Depending on the type of application, decisive specifications are placed on the hydrogen purity. In the product gas from dehydrogenation, however, concentrations of 100 to a few 1000 ppm can be found from low boiling substances, which partly originate from the production of the LOHC material, but also from the decomposition and evaporation of the LOHC molecules in the course of the enormous volume expansion due to hydrogen release. For the removal of undesired traces in the LOHC material, a pre-treatment and storage under protective gas is necessary. For purification, the use of Pd-based membranes might be useful, which makes these steps less important or even redundant. Heat supply and phase contacting of the liquid LOHC and catalyst is also crucial for the process. Within the contribution, the first results from a coupled microstructured system-consisting of a radial flow reactor unit and membrane separation unit-are shown. In a first step, the 5 µm thick PdAg-membrane was characterized and a high Sieverts exponent of 0.9 was determined, indicating adsorption/desorption driven permeation. It can be demonstrated that hydrogen is first released with high catalyst-related productivity in the reactor system and afterwards separated and purified. Within the framework of limited analytics, we found that by using a Pd-based membrane, a quality of 5.0 (99.999% purity) or higher can be achieved. Furthermore, it was found that after only 8 h, the membrane can lose up to 30% of its performance when exposed to the slightly contaminated product gas from the dehydrogenation process. However, the separation efficiency can almost completely be restored by the treatment with pure hydrogen.
61Carbon Dioxide-Free Hydrogen Production with Integrated Hydrogen Separation and Storage.PubMed
Stefan Dürr, Michael Müller, Holger Jorschick, et al.
ChemSusChem. 2017 Jan 10;10(1):42-47. doi: 10.1002/cssc.201600435. Epub 2016 Jun 23.
An integration of CO -free hydrogen generation through methane decomposition coupled with hydrogen/methane separation and chemical hydrogen storage through liquid organic hydrogen carrier (LOHC) systems is demonstrated. A potential, very interesting application is the upgrading of stranded gas, for example, gas from a remote gas field or associated gas from off-shore oil drilling. Stranded gas can be effectively converted in a catalytic process by methane decomposition into solid carbon and a hydrogen/methane mixture that can be directly fed to a hydrogenation unit to load a LOHC with hydrogen. This allows for a straight-forward separation of hydrogen from CH and conversion of hydrogen to a hydrogen-rich LOHC material. Both, the hydrogen-rich LOHC material and the generated carbon on metal can easily be transported to destinations of further industrial use by established transport systems, like ships or trucks.
62Large-scale stationary hydrogen storage via liquid organic hydrogen carriers.PubMed
Zainul Abdin, Chunguang Tang, Yun Liu, et al.
iScience. 2021 Aug 9;24(9):102966. doi: 10.1016/j.isci.2021.102966. eCollection 2021 Sep 24.
Large-scale stationary hydrogen storage is critical if hydrogen is to fulfill its promise as a global energy carrier. While densified storage via compressed gas and liquid hydrogen is currently the dominant approach, liquid organic molecules have emerged as a favorable storage medium because of their desirable properties, such as low cost and compatibility with existing fuel transport infrastructure. This perspective article analytically investigates hydrogenation systems' technical and economic prospects using liquid organic hydrogen carriers (LOHCs) to store hydrogen at a large scale compared to densified storage technologies and circular hydrogen carriers (mainly ammonia and methanol). Our analysis of major system components indicates that the capital cost for liquid hydrogen storage is more than two times that for the gaseous approach and four times that for the LOHC approach. Ammonia and methanol could be attractive options as hydrogen carriers at a large scale because of their compatibility with existing liquid fuel infrastructure. However, their synthesis and decomposition are energy and capital intensive compared to LOHCs. Together with other properties such as safety, these factors make LOHCs a possible option for large-scale stationary hydrogen storage. In addition, hydrogen transportation via various approaches is briefly discussed. We end our discussions by identifying important directions for future research on LOHCs.
63Dehydrogenation mechanism of liquid organic hydrogen carriers: dodecahydro-N-ethylcarbazole on Pd(111).PubMed
Max Amende, Stefan Schernich, Marek Sobota, et al.
Chemistry. 2013 Aug 12;19(33):10854-65. doi: 10.1002/chem.201301323. Epub 2013 Jul 15.
Dodecahydro-N-ethylcarbazole (H12-NEC) has been proposed as a potential liquid organic hydrogen carrier (LOHC) for chemical energy storage, as it combines both favourable physicochemical and thermodynamic properties. The design of optimised dehydrogenation catalysts for LOHC technology requires a detailed understanding of the reaction pathways and the microkinetics. Here, we investigate the dehydrogenation mechanism of H12-NEC on Pd(111) by using a surface-science approach under ultrahigh vacuum conditions. By combining infrared reflection-absorption spectroscopy, density functional theory calculations and X-ray photoelectron spectroscopy, surface intermediates and their stability are identified. We show that H12-NEC adsorbs molecularly up to 173 K. Above this temperature (223 K), activation of C-H bonds is observed within the five-membered ring. Rapid dehydrogenation occurs to octahydro-N-ethylcarbazole (H8-NEC), which is identified as a stable surface intermediate at 223 K. Above 273 K, further dehydrogenation of H8-NEC proceeds within the six-membered rings. Starting from clean Pd(111), C-N bond scission, an undesired side reaction, is observed above 350 K. By complementing surface spectroscopy, we present a temperature-programmed molecular beam experiment, which permits direct observation of dehydrogenation products in the gas phase during continuous dosing of the LOHC. We identify H8-NEC as the main product desorbing from Pd(111). The onset temperature for H8-NEC desorption is 330 K, the maximum reaction rate is reached around 550 K. The fact that preferential desorption of H8-NEC is observed even above the temperature threshold for H8-NEC dehydrogenation on the clean surface is attributed to the presence of surface dehydrogenation and decomposition products during continuous reactant exposure.
64Industrial decarbonization via hydrogen: A critical and systematic review of developments, socio-technical systems and policy optionsOpenAlex
Steve Griffiths, Benjamin K. Sovacool, Jinsoo Kim, et al.
Industrial decarbonization is a daunting challenge given the relative lack of low-carbon options available for “hard to decarbonize” industries such as iron and steel, cement, and chemicals. Hydrogen, however, offers one potential solution to this dilemma given that is an abundant and energy dense fuel capable of not just meeting industrial energy requirements, but also providing long-duration energy storage. Despite the abundance and potential of hydrogen, isolating it and utilizing it for industrial decarbonization remains logistically challenging and is, in many cases, expensive. Industrial utilization of hydrogen is currently dominated by oil refining and chemical production with nearly all of the hydrogen used in these applications coming from fossil fuels. The generation of low-carbon or zero-carbon hydrogen for industrial applications requires new modes of hydrogen production that either intrinsically produce no carbon emissions or are combined with carbon capture technologies. This review takes a sociotechnical perspective to examine the full range of industries and industrial processes for which hydrogen can support decarbonization and the technical, economic, social and political factors that will impact hydrogen adoption.
65Optimum investment strategy for hydrogen-based steelmaking project coupled with multiple uncertainties.PubMed
Shuo Xu, Xiaoyang Wang, Yingqi Jiang, et al.
J Environ Manage. 2024 Apr;356:120484. doi: 10.1016/j.jenvman.2024.120484. Epub 2024 Mar 23.
The large-scale application of hydrogen steelmaking technology is expected to substantially accelerate the decarbonization process of the iron and steel industry. However, hydrogen steelmaking projects are still in the experimental or demonstration stage, and scientific investment decision-making methods are urgently needed to support the large-scale development of the technology. When assessing the investment value, existing studies usually only consider the intrinsic project value under a specific pathway, while ignoring the option value under realistic multiple uncertainties in terms of technology, market, and policy, leading to an underestimation of the investment value. To address this issue, this study constructs a real options model to explore the optimal investment timing and revenue of the hydrogen steelmaking project, by taking into account multi-dimensional uncertainties stemming from price fluctuations in the steel market, the development of the carbon market, and technological advances. Additionally, the impacts of various subsidy policies on the investment strategy are also investigated. Least Squares Monte Carlo method is applied to overcome computational challenges posed by dynamic programming under multi-dimensional uncertainties. The results show that: (i) Investment is not recommended based on current crude steel price and hydrogen price. (ii) When the annual reduction rate of hydrogen price reaches 5%, the optimal investment timing would advance to 2036. (iii) On this basis, with the introduction of a 20% green hydrogen subsidy policy, the optimal investment timing would be further brought forward to 2033. The implementation of tax incentives would significantly increase the investment value. The investment value would surge from 170 million CNY to 262 million CNY as the tax rate decreases from 20% to zero. The findings could provide reasonable suggestions for investment decisions under realistic volatile environments, as well as scientific references for policy design, thus facilitating the large-scale and high-level development of hydrogen-based steelmaking technology.
66Techno-Economic Assessment of Hydrogen Integration for Decarbonizing the Steel Industry: A Case StudyOpenAlex
Farhan Haider Joyo, Daniele Groppi, Lorenzo Villani, et al.
The iron and steel industry is one of the largest industrial sources of greenhouse gas emissions. This paper examines the potential of green hydrogen as a reducing agent for decarbonizing primary steel production, focusing on the Taranto integrated steelworks in southern Italy. Producing about 3.5 Mt of crude steel annually, the plant is also among the country’s biggest emitters, with CO2 emissions of roughly 8 Mt per year at typical blast furnace intensity (2.2 tCO2/t steel). The analysis quantifies the hydrogen demand required to replace fossil fuels in iron ore reduction and evaluates the techno-economic feasibility of meeting it with green hydrogen. Using DWSIM (open-source chemical process simulation software, v9.0.2) for water electrolysis powered by renewables, the study estimates both the CO2 emission reductions and cost impacts of hydrogen-based steelmaking. Results show that integrating green hydrogen at Taranto could achieve deep decarbonization by cutting emissions by over 90%, with a base-case levelized hydrogen cost (LCOH) of 3.6 EUR/kg and green steel production cost 653 EUR/t. With optimistic assumptions (renewable electricity at 40 EUR/MWh and electrolyzer CAPEX halved to 500 EUR/kW), hydrogen cost could be reduced to 2.3 EUR/kg, making green steel cost-competitive with conventional steel and implying a breakeven carbon price of under 60 EUR/t. Sensitivity analyses highlight that falling renewable electricity prices, supportive carbon policies, and successful demonstration projects are key enablers for economic viability. The findings underscore that renewable hydrogen can be a viable decarbonization pathway for steel when coupled with continued technological improvements and policy support.
67Green ammonia as a spatial energy vector: a reviewOpenAlex
Nicholas Salmon, René Bañares‐Alcántara
This review examines the cost of green ammonia production and intercontinental transport to assess the complete supply chain for energy in a global, decarbonised ammonia economy. It further identifies the major constraints on supply and demand.
68Energy Storage Systems for Photovoltaic and Wind Systems: A ReviewOpenAlex
Djamila Rekioua
The study provides a study on energy storage technologies for photovoltaic and wind systems in response to the growing demand for low-carbon transportation. Energy storage systems (ESSs) have become an emerging area of renewed interest as a critical factor in renewable energy systems. The technology choice depends essentially on system requirements, cost, and performance characteristics. Common types of ESSs for renewable energy sources include electrochemical energy storage (batteries, fuel cells for hydrogen storage, and flow batteries), mechanical energy storage (including pumped hydroelectric energy storage (PHES), gravity energy storage (GES), compressed air energy storage (CAES), and flywheel energy storage), electrical energy storage (such as supercapacitor energy storage (SES), superconducting magnetic energy storage (SMES), and thermal energy storage (TES)), and hybrid or multi-storage systems that combine two or more technologies, such as integrating batteries with pumped hydroelectric storage or using supercapacitors and thermal energy storage. These different categories of ESS enable the storage and release of excess energy from renewable sources to ensure a reliable and stable supply of renewable energy. The optimal storage technology for a specific application in photovoltaic and wind systems will depend on the specific requirements of the system. It is important to carefully evaluate these needs and consider factors, such as power and energy requirements, efficiency, cost, scalability, and durability when selecting an ESS technology.
69Comprehensive Review Based on the Impact of Integrating Electric Vehicle and Renewable Energy Sources to the GridOpenAlex
Pampa Sinha, Kaushik Paul, Sanchari Deb, et al.
Global warming, pollution, and the depletion of fossil fuels have compelled human beings to explore alternate sources of energy and cleaner modes of transport. In recent years, renewable energy sources (RES) have been massively introduced to the grid. Furthermore, Electric Vehicles (EVs) are becoming popular as a cleaner mode of transport. However, the introduction of RESs and EVs to the grid has imposed additional challenges on the grid operators because of their random nature. This review aims to focus on the integration of RES and EVs to the grid, thereby presenting the global status of RESs and EVs, the impact of integrating RESs and EVs to the grid, the challenges of integrating RES and EV to the grid, optimization techniques for EV and RES integration to the grid, and mitigation techniques. A total of 153 research papers are meticulously reviewed, and the findings are put forward in this review. Thus, this review will put forward the latest developments in the area of EV and RES integration into the grid and will enlighten the researchers with the unsolved questions in the area that need investigation.
70A Survey of Commercial and Industrial Demand Response Flexibility with Energy Storage Systems and Renewable EnergyOpenAlex
Roksana Yasmin, B M Ruhul Amin, Rakibuzzaman Shah, et al.
The transition from traditional fuel-dependent energy systems to renewable energy-based systems has been extensively embraced worldwide. Demand-side flexibility is essential to support the power grid with carbon-free generation (e.g., solar, wind.) in an intermittent nature. As extensive energy consumers, commercial and industrial (C&I) consumers can play a key role by extending their flexibility and participating in demand response. Onsite renewable generation by consumers can reduce the consumption from the grid, while energy storage systems (ESSs) can support variable generation and shift demand by storing energy for later use. Both technologies can increase the flexibility and benefit by integrating with the demand response. However, a lack of knowledge about the applicability of increasing flexibility hinders the active participation of C&I consumers in demand response programs. This survey paper provides an overview of demand response and energy storage systems in this context following a methodology of a step-by-step literature review covering the period from 2013 to 2023. The literature review focuses on the application of energy storage systems and onsite renewable generation integrated with demand response for C&I consumers and is presented with an extensive analysis. This survey also examines the demand response participation and potential of wastewater treatment plants. The extended research on the wastewater treatment plant identifies the potential opportunities of coupling biogas with PV, extracting the thermal energy and onsite hydrogen production. Finally, the survey analysis is summarised, followed by critical recommendations for future research.
71Renewable Energy and Energy Storage SystemsOpenAlex
Enas Taha Sayed, A.G. Olabi, Abdul Hai Alami, et al.
The use of fossil fuels has contributed to climate change and global warming, which has led to a growing need for renewable and ecologically friendly alternatives to these. It is accepted that renewable energy sources are the ideal option to substitute fossil fuels in the near future. Significant progress has been made to produce renewable energy sources with acceptable prices at a commercial scale, such as solar, wind, and biomass energies. This success has been due to technological advances that can use renewable energy sources effectively at lower prices. More work is needed to maximize the capacity of renewable energy sources with a focus on their dispatchability, where the function of storage is considered crucial. Furthermore, hybrid renewable energy systems are needed with good energy management to balance the various renewable energy sources’ production/consumption/storage. This work covers the progress done in the main renewable energy sources at a commercial scale, including solar, wind, biomass, and hybrid renewable energy sources. Moreover, energy management between the various renewable energy sources and storage systems is discussed. Finally, this work discusses the recent progress in green hydrogen production and fuel cells that could pave the way for commercial usage of renewable energy in a wide range of applications.
72Integration of Renewable-Energy-Based Green Hydrogen into the Energy FutureOpenAlex
Ismail Marouani, Tawfik Guesmi, Badr M. Alshammari, et al.
There is a growing interest in green hydrogen, with researchers, institutions, and countries focusing on its development, efficiency improvement, and cost reduction. This paper explores the concept of green hydrogen and its production process using renewable energy sources in several leading countries, including Australia, the European Union, India, Canada, China, Russia, the United States, South Korea, South Africa, Japan, and other nations in North Africa. These regions possess significant potential for “green” hydrogen production, supporting the transition from fossil fuels to clean energy and promoting environmental sustainability through the electrolysis process, a common method of production. The paper also examines the benefits of green hydrogen as a future alternative to fossil fuels, highlighting its superior environmental properties with zero net greenhouse gas emissions. Moreover, it explores the potential advantages of green hydrogen utilization across various industrial, commercial, and transportation sectors. The research suggests that green hydrogen can be the fuel of the future when applied correctly in suitable applications, with improvements in production and storage techniques, as well as enhanced efficiency across multiple domains. Optimization strategies can be employed to maximize efficiency, minimize costs, and reduce environmental impact in the design and operation of green hydrogen production systems. International cooperation and collaborative efforts are crucial for the development of this technology and the realization of its full benefits.
74Energy Storage Technologies for Modern Power Systems: A Detailed Analysis of Functionalities, Potentials, and ImpactsOpenAlex
Subrat Sahoo, Pascal Timmann
Power systems are undergoing a significant transformation around the globe. Renewable energy sources (RES) are replacing their conventional counterparts, leading to a variable, unpredictable, and distributed energy supply mix. The predominant forms of RES, wind, and solar photovoltaic (PV) require inverter-based resources (IBRs) that lack inherent synchronous inertia desired for the grid and thereby warrant additional interventions for maintaining grid stability by organizing various contingency planning. Such scenarios become more pertinent in the wake of rapid decarbonization objectives adopted by different countries, stringent grid code compliance, and improved grid resilience milestones. Energy storage technologies can potentially address these concerns viably at different levels. This paper reviews different forms of storage technology available for grid application and classifies them on a series of merits relevant to a particular category. The varied maturity level of these solutions is discussed, depending on their adaptability and their notion towards pragmatic implementations. Some specific technologies that require particular mention are - hydrogen ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$H_{2}$ </tex-math></inline-formula> ) storage with fuel cells (FC) as the reconversion medium, molten metal, and gravity batteries due to their highly scalable and siteable characteristics participating in load shifting; batteries and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$ H_{2}$ </tex-math></inline-formula> FC due to their high flexibility for peak shaving; and flywheels and supercapacitors for quick response applications, such as frequency regulation and voltage support. Various performance metrics are critically evaluated by comparing them on their usability scale, thus helping readers make a subjective judgment on a particular technology while being aware of the forthcoming limitations. Finally, the paper delves into some emerging trends that decide the selection of a particular technology based on life cycle assessment, economic viability, and commercial and environmental considerations that are presented under the given circumstances. The paper is believed to offer a broad overview of possible directions for the electric grid business, eventually emphasizing the need for more hybrid solutions with opportunities for short and long-term storage options.
75Grid-Connected Energy Storage Systems: State-of-the-Art and Emerging TechnologiesOpenAlex
Glen G. Farivar, William Manalastas, Hossein Dehghani Tafti, et al.
High penetration of renewable energy resources in the power system results in various new challenges for power system operators. One of the promising solutions to sustain the quality and reliability of the power system is the integration of energy storage systems (ESSs). This article investigates the current and emerging trends and technologies for grid-connected ESSs. Different technologies of ESSs categorized as mechanical, electrical, electrochemical, chemical, and thermal are briefly explained. Especially, a detailed review of battery ESSs (BESSs) is provided as they are attracting much attention owing, in part, to the ongoing electrification of transportation. Then, the services that grid-connected ESSs provide to the grid are discussed. Grid connection of the BESSs requires power electronic converters. Therefore, a survey of popular power converter topologies, including transformer-based, transformerless with distributed or common dc-link, and hybrid systems, along with some discussions for implementing advanced grid support functionalities in the BESS control, is presented. Furthermore, the requirements of new standards and grid codes for grid-connected BESSs are reviewed for several countries around the globe. Finally, emerging technologies, including flexible power control of photovoltaic systems, hydrogen, and second-life batteries from electric vehicles, are discussed in this article.
76Hydrogen production, storage, utilisation and environmental impacts: a reviewOpenAlex
Ahmed I. Osman, Neha Mehta, Ahmed M. Elgarahy, et al.
Abstract Dihydrogen (H 2 ), commonly named ‘hydrogen’, is increasingly recognised as a clean and reliable energy vector for decarbonisation and defossilisation by various sectors. The global hydrogen demand is projected to increase from 70 million tonnes in 2019 to 120 million tonnes by 2024. Hydrogen development should also meet the seventh goal of ‘affordable and clean energy’ of the United Nations. Here we review hydrogen production and life cycle analysis, hydrogen geological storage and hydrogen utilisation. Hydrogen is produced by water electrolysis, steam methane reforming, methane pyrolysis and coal gasification. We compare the environmental impact of hydrogen production routes by life cycle analysis. Hydrogen is used in power systems, transportation, hydrocarbon and ammonia production, and metallugical industries. Overall, combining electrolysis-generated hydrogen with hydrogen storage in underground porous media such as geological reservoirs and salt caverns is well suited for shifting excess off-peak energy to meet dispatchable on-peak demand.
77Underground hydrogen storage: a reviewOpenAlex
Johannes Miocic, Niklas Heinemann, Katriona Edlmann, et al.
Abstract Large-scale underground storage of hydrogen gas is expected to play a key role in the energy transition and in near future renewable energy systems. Despite this potential, experience in underground hydrogen storage remains limited. This work critically reviews the most important elements of this crucial technology, including hydrogen properties and their significance for subsurface operations, sources for hydrogen and historical hydrogen storage operations, to set the state of the art. The cyclical nature of hydrogen storage operations will produce pressure and stress changes within the reservoir that could affect the integrity of the well, the reservoir, the caprock and the entire subsurface storage complex. To minimize geomechanical leakage risks and optimize the storage operation it is crucial to understand the pressure and stress history of the storage site, to optimize well locations to manage pressure and to identify the reservoir-specific cushion gas to working gas ratio. Finally, we outline the major scientific and operational challenges required to ensure the safe and efficient deployment of underground hydrogen storage at a large scale.
78MACHINE LEARNING FOR GREEN HYDROGEN PRODUCTIONOpenAlex
Kelvin Edem Bassey, Chinedu Ibegbulam
Green hydrogen production, achieved through the electrolysis of water using renewable energy sources, represents a promising pathway towards sustainable energy systems. However, optimizing the electrolysis process to enhance efficiency and reduce costs remains a significant challenge. This study explores the application of machine learning (ML) techniques to develop AI-driven models that optimize the electrolysis process, thereby improving the efficiency and cost-effectiveness of green hydrogen production. Machine learning models can analyze complex datasets generated during the electrolysis process, including variables such as electricity input, water quality, temperature, pressure, and electrochemical properties. By identifying patterns and relationships within these datasets, ML algorithms can predict optimal operational conditions and provide real-time adjustments to maximize hydrogen output while minimizing energy consumption. The research focuses on the development and validation of various ML models, including regression analysis, neural networks, and reinforcement learning, to enhance the performance of the electrolysis process. These models are trained on historical data from industrial-scale electrolysis operations and laboratory experiments, ensuring robustness and reliability. Feature selection and engineering techniques are employed to isolate the most significant factors influencing efficiency and cost. Key findings demonstrate that AI-driven optimization can significantly improve the energy efficiency of hydrogen production, with potential energy savings of up to 20%. Additionally, predictive maintenance algorithms developed through machine learning can anticipate equipment failures and schedule timely maintenance, further reducing operational costs and downtime. The study also explores the integration of machine learning models with renewable energy management systems, enabling dynamic adjustments based on the availability of renewable power sources such as solar and wind. This integration ensures that the electrolysis process operates during periods of peak renewable energy generation, thereby maximizing the use of green electricity and reducing reliance on fossil fuels. Application of machine learning to green hydrogen production offers a transformative approach to optimizing the electrolysis process. AI-driven models enhance efficiency, reduce costs, and facilitate the integration of renewable energy sources, supporting the broader transition to a sustainable energy future. This research advocates for continued exploration and implementation of advanced machine-learning techniques to drive innovation in green hydrogen production. Keywords: ML, Green Hydrogen Production, AI-driven Models, Electrolysis Process, Renewable Energy Sources.
79AI-DRIVEN OPTIMIZATION IN RENEWABLE HYDROGEN PRODUCTION: A REVIEWOpenAlex
Sharif Md Yousuf Bhuiyan, A. K. M. Alauddin Chowdhury, Md Shahadat Hossain, et al.
This paper presents a comprehensive systematic review of artificial intelligence (AI)-driven optimization in renewable hydrogen production, emphasizing its pivotal role over the past decade in enabling the transition toward a sustainable, low-carbon energy future. As green hydrogen gains prominence as a clean energy carrier—particularly in hard-to-decarbonize sectors such as transportation, heavy industry, and grid balancing—the demand for efficient, scalable, and economically viable production methods has intensified. AI has emerged as a transformative enabler, offering innovative solutions to technical and economic barriers across various production pathways, including electrolysis (proton exchange membrane, alkaline, and solid oxide), biomass gasification, solar-to-hydrogen, and wind-to-hydrogen systems. This study employs a structured methodology based on a systematic literature review (SLR), drawing from over 150 peer-reviewed journal articles, patents, industry reports, and conference proceedings published between 2014 and 2024. Data were sourced from academic databases, leading energy organizations, and international technology forums. The review categorizes AI techniques—machine learning, deep learning, reinforcement learning, and optimization algorithms—and examines their applications in process control, predictive maintenance, energy forecasting, material discovery, cost reduction, and hybrid renewable system integration. Emerging trends include AI-powered digital twins, AI-quantum hybrid frameworks, and intelligent supply chain management. However, the widespread deployment of AI in hydrogen systems faces challenges, such as limited access to high-quality real-time datasets, lack of standardization, regulatory hurdles, and high computational demands. The paper concludes by identifying key research gaps and outlining future directions, including the development of lightweight, explainable AI models, cross-sectoral collaborations, and supportive policy frameworks. Ultimately, this review underscores the transformative potential of AI in accelerating the commercialization, optimization, and global adoption of renewable hydrogen technologies, laying the groundwork for a robust, intelligent, and decarbonized energy infrastructure.
80Techno-economic analysis and process simulation of alkoxylated surfactant production in a circular carbon economy frameworkOpenAlex
Oliver J. Fisher, Jhuma Sadhukhan, Thorin Daniel, et al.
• Novel TEA of AE7 surfactant production using CO2 from steel industry flue gas • CO2 conversion rates around 3% in different processing capacities • Green hydrogen costs are the biggest factor influencing minimum selling price (MSP) • Lowest MSP of $8.77/kg exceeds the forecasted $3.75/kg for fossil-based AE7 • Monte Carlo simulation shows a 21% chance of positive NPV vs. bio-based surfactants Successfully transitioning to a net-zero and circular carbon economy requires adopting innovative technologies and business models to capture CO 2 and convert it into valuable chemicals and materials. Given the high economic costs and limited funding available for this transition, robust economic modelling of potential circular carbon pathways is essential to identify economically viable routes. This study introduces a novel techno-economic analysis (TEA) of producing alcohol ethoxylate (AE7), a valuable surfactant, from industrial flue gas. Traditionally, AE7 is produced by reacting fatty alcohols with ethylene oxide derived from fossil or bio-based sources. This research explores a method using CO 2 captured from steel industry flue gas to produce AE7, addressing a notable gap in the literature. It evaluates a thermo-catalytic pathway involving Fischer-Tropsch (FT) synthesis with syngas generated by the reverse-water gas-shift reaction, where CO 2 reacts with H 2 . CO 2 conversion rates range around 3% across processing capacities of 25 kt/a, 100 kt/a, and 1000 kt/a. The study finds that the CO 2 mass fraction concentration in the process emission is 2.47 × 10 –5 , compared to 0.13 in the incoming flue gas, highlighting the system's positive environmental impact. A radial basis function neural network was built to forecast the long-term average price of fossil-based and bio-based surfactants to benchmark the results against. Economic analysis reveals that the cost of green hydrogen significantly impacts the minimum selling price (MSP), making cost parity with existing fossil-based surfactants challenging. The lowest MSP of $8.77/kg remains above the long-term forecasted price of $3.75/kg for fossil-based C 12–14 AE7. However, Monte Carlo simulations show a 21% probability of achieving a positive net present value (NPV) compared to leading bio-based surfactant alternatives. Sensitivity analyses identify capital costs, the price of low-carbon hydrogen (LCOH), and diesel prices as the most influential factors affecting the MSP. Continued advancements in Fischer-Tropsch catalyst technologies, reductions in green hydrogen costs and growing consumer demand for environmentally friendly products could significantly enhance the economic feasibility of this sustainable approach, paving the way for broader adoption and contributing to a circular carbon economy.
81Techno-economic analysis of wind-powered green hydrogen production to facilitate the decarbonization of hard-to-abate sectors: A case study on steelmakingOpenAlex
Francesco Superchi, Alessandro Mati, Carlo Carcasci, et al.
Green hydrogen is among the most promising energy vectors that may enable the decarbonization of our society. The present study addresses the decarbonization of hard-to-abate sectors via the deployment of sustainable alternatives to current technologies and processes where the complete replacement of fossil fuels is deemed not nearly immediate. In particular, the investigated case study tackles the emission reduction potential of steelmaking in the Italian industrial framework via the implementation of dedicated green hydrogen production systems to feed Hydrogen Direct Reduction process, the main alternative to the traditional polluting routes towards emissions abatement. Green hydrogen is produced via the coupling of an onshore wind farm with lithium-ion batteries, alkaline type electrolyzers and the interaction with the electricity grid. Building on a power generation dataset from a real utility-scale wind farm, techno-economic analyses are carried out for a large number of system configurations, varying components size and layout to assess its performance on the basis of two main key parameters, the levelized cost of hydrogen (LCOH) and the Green Index (GI), the latter presented for the first time in this study. The optimal system design and operation logics are investigated accounting for the necessity of providing a constant mass flow rate of H2 and thus considering the interaction with the electricity network instead of relying solely on RES surplus. In-house-developed models that account for performances degradation over time of different technologies are adapted and used for the case study. The effect of different storage technologies is evaluated via a sensitivity analysis on different components and electricity pricing strategy to understand how to favour green hydrogen penetration in the heavy industry. Furthermore, for a better comprehension and contextualization of the proposed solutions, their emission-reduction potential is quantified and presented in comparison with the current scenario of EU-27 countries. In the optimal case, the emission intensity related to the steelmaking process can be lowered to 235 kg of CO2 per ton of output steel, 88 % less than the traditional route. A higher cost of the process must be accounted, resulting in an LCOH of such solutions around 6.5 €/kg.
83Hydrogen liquefaction and storage: Recent progress and perspectivesOpenAlex
Tongtong Zhang, Joao M. Uratani, Yixuan Huang, et al.
The global energy sector accounts for ∼75% of total greenhouse gas (GHG) emissions. Low-carbon energy carriers, such as hydrogen, are seen as necessary to enable an energy transition away from the current fossil-derived energy paradigm. Thus, the hydrogen economy concept is a key part of decarbonizing the global energy system. Hydrogen storage and transport are two of key elements of hydrogen economy. Hydrogen can be stored in various forms, including its gaseous, liquid, and solid states, as well as derived chemical molecules. Among these, liquid hydrogen, due to its high energy density, ambient storage pressure, high hydrogen purity (no contamination risks), and mature technology (stationary liquid hydrogen storage), is suitable for the transport of large-volumes of hydrogen over long distances and has gained increased attention in recent years. However, there are critical obstacles to the development of liquid hydrogen systems, namely an energy intensive liquefaction process (∼13.8 kWh/kgLH2) and high hydrogen boil-off losses (liquid hydrogen evaporation during storage, 1–5% per day). This review focuses on the current state of technology development related to the liquid hydrogen supply chain. Hydrogen liquefaction, cryogenic storage technologies, liquid hydrogen transmission methods and liquid hydrogen regasification processes are discussed in terms of current industrial applications and underlying technologies to understand the drivers and barriers for liquid hydrogen to become a commercially viable part of the emerging global hydrogen economy. A key finding of this technical review is that liquid hydrogen can play an important role in the hydrogen economy - as long as necessary technological transport and storage innovations are achieved in parallel to technology demonstrations and market development efforts by countries committed liquid hydrogen as part of their hydrogen strategies.
84The EU Energy Crisis and a New Geopolitics of Climate TransitionOpenAlex
Andreas Goldthau, Richard Youngs
In 2022, the Russian invasion of Ukraine had a profound effect on EU energy and climate policies. The EU redesigned its approach to the geopolitics of energy security as it sought alternatives to Russian supplies with accelerated urgency. It upgraded its commitments to energy transition internally and through external actions too, whilst member states balanced these with the domestic politics of a cost-of-living crisis triggered by the war. The new era of geopolitical power had repercussions for the conceptual contours of EU approaches to energy and climate security, which were elevated to hard security issues. The article reviews the key developments in EU energy and climate policies in 2022 and notes three emerging and inter-related conceptual shifts in these: the securitization of the green transition, a more realpolitik approach to external climate actions and a rebalancing towards state intervention. The energy crisis that shook European politics in 2022 started before Russia's war against Ukraine. A function of post-Covid recovery, European, North American and Asian economies had begun to revive in 2021, which brought back industrial demand for process heat and electricity. Strong economic recovery in Asia drove up liquefied natural gas (LNG) prices and meant that lower quantities were available for other consumers (IEA, 2022). Moreover, EU carbon prices picked up, which incentivized a fuel switch from coal to gas (Reuters, 2021). Other factors, such as a hot summer, brought about marginal additional demand. On the supply side, outages at LNG export facilities left global LNG markets strained even further. Russia had higher-than-usual domestic demand (TASS, 2021), whilst also deliberately going slow on filling up storage capacity in Europe over the summer (IEA, 2022). By the beginning of the heating season 2021, filling levels in European gas storage stood at 74.6%, 20% lower than the preceding year, and Gazprom-run storages were at a mere 22% (European Commission, 2022d). This brought Europe into direct competition with Asian consumer markets for alternative LNG supplies. Energy markets were tight as Europe went into 2022. Russia's invasion and the ensuing gradual reduction of gas exports to Europe dramatically aggravated this situation. From July to September 2022, Russian pipeline gas exports to Europe reduced by some 74% compared with 2021. Yamal Europe, the pipeline through Belarus and landing in Poland, was down almost entirely, whilst transit through the Ukrainian pipeline system landing in Slovakia and Romania was reduced by 63% (European Commission, 2023e). Russian gas supply to Europe through Nord Stream came to a halt at the end of September 2022 as the pipeline through the Baltic Sea was sabotaged. By the end of 2022, gas exports had dwindled to marginal volumes. After many years of sending around 150 billion cubic metres to European consumer markets every year or a third of overall EU consumption, Russia ended its role as a prime supplier. Against the backdrop of a strained market situation, this amounted to a perfect storm. Gas prices at the TTF, the European benchmark for LNG, saw all-time highs of 319.98 EUR/MWh in August 2022 – some 15 times the pre-war levels. Because the European power market is indirectly tied to gas – thanks to gas setting the price as the marginal fuel, the so-called merit order principle – electricity markets were in upheaval as well. As per estimates of the European Commission, power benchmark prices in the third quarter of 2022 averaged 339 EUR/MWh, an increase of 222% compared with 2021 (European Commission, 2023d). An already high Eurozone inflation picked up even further, reaching 10% by the end of 2022 (Eurostat, 2023). Clearly, skyrocketing TTF prices ensured LNG cargos found their way into Europe and drove imports of LNG to record levels. Yet, the macroeconomic impact was significant as energy-intensive sectors such as chemicals, paper and steel decreased production, making longer term European industrial competitiveness a key policy concern (Bloomberg, 2022; Reuters, 2022c). What is more, high energy prices became a social issue as they affected vulnerable households the most. European policy responses centred around replacing natural gas with alternative fuels and decarbonizing the European energy and production system. This, on the one hand, meant bringing back fossil fuels, notably coal. Though demand increments remained smaller than feared, power sector CO2 emissions alone went up by almost 4% in 2022 (Ember, 2023). It also meant enhancing the supply of renewable energy and increasing production capacity. In May 2022, the Commission presented a comprehensive policy package dubbed REPowerEU, aimed at phasing out Russian fossil fuels in Europe's imports ‘well before 2030’ and at speeding up the clean energy transition. The REPowerEU plan rested on enhancing clean energy sources by raising renewables targets, eventually agreed to be 42.5% by 2030, accelerating the permitting processes for major renewable projects and building up a (green) hydrogen economy. Aimed at helping the decarbonization of industry, the EU prepared a Green Deal Industrial Plan that member states eventually signed off in early 2023. This aimed to support a faster transition to climate neutrality, inter alia through a Net Zero Industry Act (European Commission, 2023a, 2023c) supporting the build-up of clean tech production within Europe. The Plan envisaged the loosening of state aid to support industrial transformation by at the same time encouraging national governments to consider tax breaks in support of green net-zero technologies investments. A ban of fossil-fuel-based combustion engines by 2035 agreed in late 2022 (Reuters, 2023a), coupled with efforts to revise the Energy Performance of Buildings Directive (Council of the EU, 2022) sought structurally to alter demand patterns in mobility and heating. On the national level, governments also rushed to enhance clean energy targets. For example, the Netherlands announced plans to double capacity in offshore wind by 2030 (Reuters, 2022b). Germany upped its goal for renewables in the power mix to 80% by 2030 (Cleanergywire, 2022), whilst Italy entered the offshore wind business with determination, aiming to install 5.5 GW of offshore wind capacity by 2030 (WindPower Monthly, 2022). Greece introduced the country's first Offshore Wind Law and set a target of 2 GW of offshore wind capacity by 2030 (IEA, 2023). Portugal raised targets for renewable energy in its power mix by 20%, now aiming for 80% by 2026 (Reuters, 2022). In a 2022 energy security strategy, the United Kingdom promised ‘self-sufficient’ energy supply as a way of decarbonizing the electricity system by 2035 (HM Department for Business, 2022). Even coal-heavy Poland made determined efforts to increase the share of renewables in the mix, with 2022 marking a year of significant growth of the industry (Reuters, 2023b). Belgium, Denmark, France, Germany, Ireland, Luxembourg, Norway, the United Kingdom and Sweden agreed on developing 300 GW of offshore wind capacity by 2050, thus effectively making the North Sea a ‘green power plant’ (De Croo et al., 2023). The European Union collectively and national governments individually mobilized significant funds in reaction to the energy crisis. Much of this funding was meant to buffer high energy costs. By October 2022, energy subsidies earmarked or spent in support of industry and households had surpassed EUR 700 billion (Goldthau and Tagliapietra, 2022). Spending was uneven across Europe and reflected European governments' differing abilities to spend their way out of the crisis. The European Commission allowed green state aid to the tune of EUR 51 billion during the year (European Commission, 2023a). Germany announced plans to invest more than EUR 200 billion into industrial decarbonization (Reuters, 2022a), whereas other large economies such as France pledged additional spending on decarbonizing its economy, on top of EUR 30 billion of green recovery money announced earlier (Euractiv, 2022a). Portugal announced more than EUR 25 billion of public and private finance over 10 years (Reuters, 2022). On the European level, REPowerEU is to add EUR 210 billion in investment for, mainly, renewables, hydrogen and energy efficiency (S&P Global, 2022). Taken together, these measures are argued to having brought forward the EU energy transition by a decade (The Economist, 2023). In parallel to these profound adjustments to domestic energy policies, European governments also introduced a battery of new external commitments in 2022. In reaction to a ‘return of geopolitical energy security’ (Kuzemko et al., 2022), European policy-makers were quick to put in place policy measures aimed at ensuring supplies, lowering demand and keeping prices in check. The EU and member states signed dozens of new energy accords to increase oil and gas imports in 2022. A flurry of energy diplomatic efforts aimed to contract additional gas from producer countries, including Norway, Qatar and the United States. The EU signed a deal with Azerbaijan to double gas supplies, whilst talks about East Mediterranean gas involved a new accord with Egypt and Israel. Several governments negotiated their own supply agreements with countries like Algeria, Angola and Libya (ECFR, 2022a). The EU invested significant time during the year in introducing a cap on the price of gas imports, a measure that would previously have been anathema to the logic of external energy policy. It also moved forward with a common purchasing vehicle, the EU Energy Platform, to help drive down the price of imported gas; this measure had been discussed on and off over many years but without gaining momentum and yet now advanced, to start operation in 2023 (European Commission, 2023a, 2023b). Significantly, most of the new gas deals included clean energy commitments. The EU was able to argue that notwithstanding the turn to alternative gas supplies to offset the loss of Russian supplies in the immediate short term, the priority in 2022 was to strengthen external co-operation on renewables. This co-operation was aimed both at supporting energy transition in third countries and more directly at increasing renewables imports into Europe. The EU's new accord with Azerbaijan included a focus on green hydrogen exports from the country. The EU signed a major new energy deal to bring renewables from Georgia and the South Caucasus across the Black Sea to Romania. It signed new co-operation with Arab Gulf states on solar and hydrogen especially (Council of the European Union, 2022b). An EU–Morocco Green Partnership also promised co-operation on hydrogen supplies. Franco-Spanish agreement was reached on a new H2MED pipeline between Barcelona and Marseilles to help transport hydrogen from North Africa to European markets. The EU increased funding under the African Green Energy Initiative and, after several years of debate, launched plans for a Global European Hydrogen Facility (European Commission, 2022c). In similar vein, the EU worked up text for a new Critical Materials Act – which would eventually be agreed in early 2023 – aimed at securing better access to minerals crucial for energy transitions. Several agreements on critical mineral supplies from countries like Kazakhstan and Namibia advanced. After years of going through the Brussels institutions, the Carbon Border Adjustment Mechanism moved into a new implementation phase at the end of 2022 when the European Parliament and the Council of the European Union reached a provisional agreement; this was eventually approved by the European Parliament in April 2023. European global climate funding also increased in 2022 and there were several highly notable developments in this area of EU external action. After many years resisting, at the COP27 summit in Egypt in November 2022, European countries backed a new ‘loss and damage’ fund – finally agreeing to the kind of de facto climate compensation for which developing countries had long pushed. The EU channelled funding into new Just Energy Transition Partnerships with Indonesia, India, Senegal and Vietnam, based on an earlier EU–South Africa accord. Its 1-billion-euro contribution to the 20-billion Indonesian partnership was its biggest funding climate-funding initiative ever (European Commission, 2022b). Alongside the increased renewables investments and supply agreements, there were more directly political elements to the climate agenda too. As extreme weather events in 2022 made the impacts of climate change ever more tangible, the EU also introduced several new commitments in the sphere of so-called climate security. The EU's 2022 Strategic Compass and the 2021 Climate Defence Roadmap promised to make security deployments more climate sensitive, and they committed to making Common Security and Defence Policy (CSDP) missions less resource intensive and to building better early warnings for climate stresses to trigger more effective action. New council conclusions on climate security were agreed upon under the Czech presidency in late 2022 with upgraded commitments to embed climate issues at the core of mainstream foreign and security policy (Council of the European Union, 2022a; see also European External Action Service, 2022). In similar vein, France introduced a new Climate and Defence Strategy in April 2022 (Ministère des Armes, 2022). After a summer of extreme weather events, the Commission made a pitch for more extensive crisis management powers to deal with climate disasters. A European Parliament resolution urged the EU to step up progress in moulding defence and security policy around climate factors, triggering far-reaching debate on this topic (European Parliament, 2022). In light of extreme weather experienced during 2022, this area of policy moved up several gears and was now set to become an increasingly important aspect of EU security deliberations in future years. In sum, the year 2022 saw an unprecedented urgency, intensity and breadth of policy change in the area of energy and climate action. Within this intense range of policy developments, it is possible to detect three incipient changes to the EU's overarching approaches to energy security and ecological challenges. These represent potentially significant changes that have a bearing on longstanding conceptual frameworks and interpretations of EU energy and climate-change strategies. The three changes are, first, a securitization of renewables; second, a bolder renewables extractivism; and third, a more state-interventionist energy policy. These shifts are separate from but to some extent inter-related. With regard to the first, the energy crisis of 2022 is likely to leave its mark as the moment when energy transition becomes more explicitly securitized. Whereas policy responses to past energy crises centred on making the fossil energy system more robust to external shocks, for example, by way of establishing strategic petroleum reserves at OECD level in the wake of the 1970s oil crises (Kohl, 2010), the 2022 crisis had a different outcome (Bazilian and Goldthau, 2023). This time – notwithstanding sometimes patchy emergency measures – the policy answer was to enhance resilience through energy system decarbonization. Renewables moved to the heart of European security policy. In terms of policy discourse, this coincided with a fundamental shift in the policy framing of renewables. The Commission attested ‘renewable energy […] an overriding public interest’ (European Commission, 2022a, p. 11), thus justifying the comprehensive REPowerEU policy package and its profound impact on the European energy system. Germany's finance minister renewables (Euractiv, their contribution to on foreign such as similar were made by the to the effect that of and renewable was key to enhancing energy security Germany, 2022). this shift to renewables. et energy securitization is in would as a of the 2022 that policy had on security before the war. Yet, it is highly significant that it was renewables that were and were made to crisis policy including as as industrial policy In its the shift towards renewables and clean as a of the 2022 energy crisis changes the of energy security in EU policy. Energy security was by the and patterns oil and and a function of its at prices be the accelerated decarbonization with the to – – of fossil fuel for years to Yet, the for and clean energy supply in the effective between public funds and private as to the mobilized by turn into capacity build-up at within a short of time and thus the system. The but from a and to a on and (Bazilian and Goldthau, 2023). In a second, and the EU moved towards policies centred on renewable energy from third countries for export to European markets. This be a of renewables – an ecological of the longstanding of powers oil and gas from This reflected an approach more directly centred on EU geopolitical and less on the balanced of the global energy order as and from other countries dramatically in 2022 against this ever more EU argue that new green hydrogen projects now in developing states are and increasingly to the European energy than in with the of 2021). Even the EU that its climate actions in other countries are of and (Council of the European Union, in European policy is increasingly with of the EU's own supplies – with help for developing states to in a way towards ecological a more The EU's for access to developing critical mineral own energy and in 2022 an incipient in critical mineral third countries during the year that the EU was the European Green Deal in a way that was towards its own energy crisis (ECFR, 2022). This reflected a more realpolitik approach to – on the EU's longstanding in a that is and The way in which the EU its own targets in 2022 with other energy and climate or the for more effective global ecological action. The third conceptual and change in the EU energy policy to the role of state intervention. of market sought to European energy markets and enhance their the 2022 events saw the to a deliberately with policy (Goldthau and 2022). of the policy measures were to the crisis situation, such as the of European gas under costs. Yet, the Ukraine war the more political – or security – of in for gas supply at costs. the going forward a of the approach EU energy rebalancing political and economic even through state in and energy The is significant in the of the EU Energy (European Commission, and gas price cap dubbed (Council of the European Union, 2022b). with the to in green enhance the resilience of supply and to competition in the emerging global clean tech the way forward is likely to be by state than the EU's economic more In 2022, energy and ecological issues a more place in EU state against Russia's invasion of Ukraine in to energy security and climate too. a moment of such the to energy and climate policy commitments in 2022 a core of the European remained on energy and climate-change the war brought European governments in agreed support for accelerated and more far-reaching ecological transition With on the to from Russian energy supplies, support for energy transition notably in 2022. the commitments made in 2022 were be a long and the large of new European climate and ecological made during the year by most of these had been on the energy transition to is to the ecological in economic or too, the longer the war into 2023 and a focus on security the less there been for effective through on the external 2023). Yet, the year was one of change in the sphere of energy and by the way that the invasion of Ukraine and issues with which the EU had been for many years. This place of climate transition in to the 2022 invasion with earlier in the EU's with This ecological commitments a more place in European in of the impact of energy prices but also green issues had by now become more to the EU's and 2023). Moreover, there were in 2022 of change in the way the EU and energy and climate policies. The policy commitments were highly significant in their own but also a more energy and climate policies are more that across other of European In 2022, energy and climate issues became a issue of domestic politics and also a core of EU security and geopolitical is this but that the policy changes introduced in 2022 trigger The shift between the different – and their and geopolitical – that have been to EU energy and climate policies. These adjustments extensive in the years to as the events of 2022 out over In 2022, climate and security to more into with Yet, as EU and between energy security and ecological in 2022 and as they forward in their and it is possible that some of the strategic and of the invasion this was a year for energy and climate policy and one that to the of the EU's to a new geopolitical The would like to and for to an earlier of this funding and by
85Revisiting the Energy Trilemma in the European UnionOpenAlex
Ernesto Bonafé
As a response to Russia's invasion of Ukraine, the heads of state or government of the EU member states met in the Palace of Versailles to consider a historic decision to end EU dependency on Russian gas, oil and coal imports. The United States, the United Kingdom, Canada and Australia had announced energy embargos on Russia, and many expected the EU to follow suit, but this was not possible due to the complex decision-making in the EU. Instead, what was agreed was the REPowerEU Plan, setting out the European Commission's strategy of diversifying gas supplies, switching to renewables and hydrogen, improving energy efficiency, and mitigating the impact of rising energy prices. The Plan attempts to fit into the broader context of the Paris Agreement, the EU Green Deal, the EU's ‘Fit for 55’ framework and the EU law for climate neutrality. The gravity of the current situation is illustrated by the arrangements being put in place to prepare for a complete cut-off of Russian gas exports and by restarting the burning of coal, an energy source that Europe had recently consigned to history. This paper reviews the REPowerEU Plan and recent key proposals in the electricity and gas sectors from a policy and legal perspective. It is structured in three parts corresponding to the familiar notion of the energy trilemma: affordability, security and sustainability. REPowerEU is about rapidly reducing dependency on Russian fossil fuels by fast forwarding the clean transition to deliver affordable, secure and sustainable energy. Its goals might initially suggest that a new energy theorem is being launched, but this paper will argue that, in the EU context at least, the classic energy trilemma persists, and indeed is more acute in its effects than ever before.
86A sustainability and governance index for assessing the EU’s green hydrogen import optionsOpenAlex
Almudena Nunez, Katherine Caro, Andreas Goldthau
Abstract The European Commission’s REPowerEU plan set the target of importing 10 million tonnes of ‘green’ hydrogen into the European Union (EU) by 2030. Against this backdrop, this paper sets out to assess a central question: which countries can be identified as suitable partners for European green hydrogen imports? Using Germany as a reference case, the article develops a quantitative sustainability and governance index (SGI), assessing five dimensions identified as central to ranking external partners: (i) the political will to scale up a green hydrogen sector; (ii) a country’s integration with the EU/Germany; (iii) its commitment to international engagement and climate targets and policies; (iv) environmental regulatory effectiveness; and, (v) its governance performance. With this, the SGI offers a novel way of thinking about potential EU green hydrogen partnerships. Rather than focusing on the geography of renewables or cost structures underpinning a country’s export potential, the present index captures the extent to which countries may be suitable for green hydrogen partnerships if judged by political and environmental factors. The empirical analysis suggests significant differences between a total of 113 assessed countries as per their overall index ranking, but also the individual dimensions composing the index. This allows drawing conclusions on the policy focus of potential partnerships, taking choices when facing trade-offs regarding individual dimensions, and prioritizing among the latter.
87Climate and Energy Transitions in Times of Environmental Backlash? The European Union ‘Green Deal’ From Adoption to ImplementationOpenAlex
Pierre Bocquillon
The inception of the European Union's (EU's) ‘Green Deal’ – a flagship project of European Commission President Ursula von der Leyen launched to much acclaim in December 2019 – contrasts with its adoption in the final years of the Commission's term in office in 2023–2024. In 2019, unprecedented climate protests and mobilisations across Europe and the world – from the ‘Fridays for Future’ school strikes to climate marches and to more radical actions by groups like the Extinction Rebellion (XR) – pushed climate change and the energy transition to the top of the EU's political agenda. In this context, the 2019 European elections saw unprecedented successes for Green Parties across the continent, boosting the Greens/European Free Alliance (EFA) parliamentary group to a record 72 members (Pearson and Rüdig, 2020). With the main centre-left and centre-right groups together failing to command a majority in Parliament, the Greens were able to pressure Ursula von der Leyen to commit to ambitious policies. The EU ‘Green Deal’ stemmed directly from this context marked by ‘enabling politicisation’ of the climate issue (Dupont et al., 2024). The EU climate law (Regulation EU 2021/1119, 2021), formally adopted in July 2021, committed the block to reaching net-zero emissions by 2050 and reducing net emissions by 55% by 2030, whilst a large legislative package explicitly called ‘Fit for 55’ was proposed by the Commission that same month to achieve the headline targets. Although the Green Deal has been developed in times of crisis, the Commission and EU have held steady in their commitments (Eckert, 2021; Von Homeyer et al., 2022). Yet, the finalisation of the legislative proposals aimed at turning lofty goals into action in 2023–2024 – before the Commission's end of term and EU Parliament elections – has taken place in a starkly different context. Energy and cost of living crises, initially triggered by post-COVID-19 supply chain disruptions and dramatically heightened by the war in Ukraine leading to energy supply disruptions and commodity price hikes across Europe, have increasingly fuelled concerns about the costs of climate and energy transitions (Goldthau and Youngs, 2023; Kuzemko et al., 2022). Although energy prices have fallen since the end of 2023, cost of living and energy security issues have remained salient. Politically, this context has been instrumentalised by populist and radical right parties to mobilise against the climate and energy transitions (Yazar and Haarstad, 2023), whilst the centre has also become increasingly cautious, especially the centre right. At the European level, this is most evident for the European People's Party (EPP), which has increasingly contested Green Deal legislation, most notably the Nature Restoration Law (Regulation EU 2024/1991, 2024) (Tosun, 2023). This shift is in part a response to protests and contestations of energy and climate legislation across the continent, notably the highly covered farmer's protests starting in late 2023 and continuing throughout the spring of 2024 (Politico, 2024; Reuters, 2023). The June 2024 European Parliament elections reflect this new context, with a rise of far-right groups, whilst the Greens were the main losers along with the liberals (Hix et al., 2024). Against this background of ‘constraining politicisation’ of climate policy (Dupont et al., 2024), this article asks whether 2023–2024 represents a turning point for EU commitments to the climate and energy transitions. As a new European Commission and Parliament set in, it is a good time to assess progress and challenges for the EU ‘Green Deal’. Has it been faltering? What are the prospects for its implementation and for renewing the EU's green ambitions? I argue that, overall, the agenda for climate action and energy system decarbonisation has proved remarkably resilient. EU institutions and member states have remained committed to delivering the climate and energy dimensions of the Green Deal agenda by the end of the von der Leyen Commission's term and have mostly delivered. Yet, cost concerns, protests and their political use by right-wing populists also raise questions for implementation, possibly dampening ambitions going forward. This article first reviews the progress of the Green Deal legislation and whether the EU has delivered on its ambitions, focusing in particular on energy and climate change. It then assesses the seemingly waning momentum for climate action and the recent ‘green backlash’. Finally, it reflects on the prospects for Green Deal implementation and renewal, drawing insights from past crises and their effects on EU environmental and climate policies. It concludes that, whilst the energy and climate transition agenda is likely to prove resilient, its framing and focus may be changing in the context of domestic politicisation of the climate and energy transition and global geopolitical competition. In its initial communication launching the ‘Green Deal’, the European Commission (2019) presented a wide-ranging strategy to ‘make Europe the first climate-neutral continent by 2050’, protect biodiversity, create a circular economy, curb pollution and mobilise finance for the green transition, all whilst boosting the competitiveness of European industry and ensuring a just transition for the affected regions and workers. The implementation of this strategy has led to the proposal and subsequent adoption of a wide range of policy packages and individual laws across different sectors, from climate and energy to agriculture, transport and the environment. Since its launch as a core priority of the ‘geopolitical Commission’ and over the course of its evolution, the contours of the Green Deal as a political object have remained ill-defined. This is in part because it is a cross-cutting strategy reflecting the multisectoral, complex and evolving nature of the climate crisis, which requires climate policy integration across all areas (Dupont et al., 2024). This is also politically deliberate: to reframe and aggregate new and related initiatives as part of an all-encompassing, purposeful and popular narrative. The EU steamed ahead throughout 2023 and the first half of 2024 to finish off the negotiation and adoption of remaining Green Deal files ahead of the June 2024 EU elections, marking the end of the term of both the ninth legislature of the European Parliament and the first von der Leyen Commission. Uncertainty arose when the Commission Vice President and Green Deal chief, Frans Timmermans, known as a heavyweight skilled negotiator and vocal proponent of the Green Deal, left his post to compete in Dutch elections and lead a left-green alliance (Euractiv, 2023a). He was replaced by Commission Vice President Maroš Šefčovič and the new controversial Dutch appointee Wopke Hoekstra, criticised for his past employment at Shell and lacklustre record on climate (Taylor, 2023a). Yet, this did not derail work on finalising the Green Deal, which was successful overall with a majority of files adopted and a few blocked or withdrawn due to delays or intractable divisions.1 Looking specifically at the ‘Fit for 55’ package, which implements the headline emission reduction targets and energy transition objectives, it was originally composed of 13 legislative proposals, later extended to 19.2 As of July 2024, all proposals but one had been adopted by the co-legislators. Some of the legislation updates and strengthens pre-existing legislation, whilst new policies are also introduced. A significant step was the reform of the flagship EU Emission Trading System (EU ETS), adopted in April 2023, along with a raft of associated laws. It accelerates the reduction of emission allowances for energy-intensive industries and the power sector; progressively phases out free allowances; progressively includes shipping within the ETS; strengthens the rules for aviation emissions by phasing out free allowances for domestic flights and implementing the Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA) for extra-European flights; and revises the market stability reserve that aims to maintain stable and effective carbon prices. The reform aims to achieve an emission reduction of 62% in covered sectors by 2030, compared to 2005, a reduction slightly higher than initially proposed by the Commission. In addition, a new and distinct ETS is introduced for buildings, road transport and additional sectors – all considered hard to decarbonise – that apply to fuel distributors from 2027. A new Social Climate Fund, mostly supplied by revenues from the new ETS, aims to help vulnerable households, small companies and transport users cope with associated costs. This is a recognition of the concrete impacts and justice implications of this new scheme and an attempt at diffusing contestation to avoid a replay of protracted opposition, such as the ‘Yellow Vest’ protests that rocked France in 2018–2020 following an increase in fuel taxes. An innovative and internationally controversial piece of legislation is the Carbon Border Adjustment Mechanism (CBAM), which imposes a carbon tax on imports of products in carbon-intensive industries. CBAM is to be progressively phased in from 2026 in line with the phasing out of free allowances within the ETS, aiming to put EU and third-country industries on a level playing field and avoid carbon leakage – the outsourcing of industrial emissions to jurisdictions with lower emission standards and costs. In sectors not covered by the ETS (road and domestic maritime transport, buildings, agriculture, waste and small industries), emission reductions are defined by the Effort Sharing Regulation. The revision, adopted in March 2023, increases the 2030 EU-wide target from 29% to 40%, compared with 2005, and distributes the effort with binding national targets. Along with this, the revised Land Use, Land-Use Change and Forestry (LULUCF) regulation of March 2023 includes an increased EU-level target of at least 310 million tonnes of CO2 equivalent net removals of greenhouse gases for 2030, with associated and binding national targets. A new regulation on tracking and reducing methane emissions in the energy sector, adopted in November 2023, aims to implement the Global Methane Pledge signed along with over 100 countries at the UN Climate COP26. It requires the oil, gas and coal industries to measure, report and verify methane emissions and to put in place mitigation measures for leak detection and repair, as well as for closed wells and mines. For transport, a hard-to-decarbonise sector, a number of new laws were passed in addition to ETS provisions. The regulation on CO2 emission standards for cars and vans, updated and finally adopted in March 2023, introduces progressive emissions reduction targets, including a 100% emission reduction target for 2035, which effectively amounts to a complete phase-out of combustion car and van sales. In parallel, and to facilitate the growth of electric vehicles, the regulation on alternative fuel infrastructure finalised that same month mandates the installation of recharging stations for cars and vans every 60 km, as well as hydrogen refuelling stations for cars and lorries in all urban nodes from 2030 onwards. For shipping, a July 2023 agreement on the FuelEU maritime initiative mandates a reduction of greenhouse gas intensity for the energy used on-board ships by up to 80% by 2050, whilst promoting the use of renewable and low-carbon fuels. Concerning aviation, the ReFuelEU Aviation initiative adopted in October 2023 aims to promote sustainable aviation fuels (SAF) (e.g., advanced biofuels, renewable and low-carbon hydrogen and recycled fuels meeting sustainability and emissions-saving criteria). It sets obligations for fuel suppliers to ensure that aviation fuels contain minimum shares of SAF (from 2025) and synthetic fuels (from 2030), increasing progressively until 2050. The energy sector also saw key proposals updated. The revision of the flagship renewable energy directive, finally adopted in October 2023, sets a binding target of 42.5% renewable energy in EU final energy consumption by 2030 (up from a paltry 32.5%), with an extra 2.5% indicative top-up to reach the 45% supported by the most ambitious member states and European Parliament. The directive does not set binding national renewable energy targets but introduces a mix of binding and non-binding renewable sub-targets in transport, industry, buildings and district heating and cooling, whilst also mandating faster permitting procedures for renewable energy projects. Increased ambitions are in part the results of the REPowerEU plan of 18 May 2022, adopted in the context of the war in Ukraine and aiming at reducing EU dependence on Russian gas (Von Homeyer et al., 2023). It introduced to increase overall ambitions to As out by et the revised renewable energy directive also introduces a level of for member states the sub-targets as a of its have also been for energy The revised energy directive, in July 2023, sets a target to final EU energy consumption by in 2030 compared to This is than the proposed the REPowerEU plan in a the more ambitious Parliament and the more 2023). The directive also includes indicative national for member a increase of the energy target and a energy consumption reduction for the sector the of a set of The energy directive is by a revision of the energy of buildings directive, in 2024, which aims for all new buildings to be emission by 2030 and for buildings to be to have emissions by 2050, with mandates for energy in buildings and minimum energy standards and targets. Finally, a regulation and a directive adopted in December 2023 to facilitate the shift from gas to renewable and low-carbon gases by rules for hydrogen and the proposals associated with the ‘Fit for 55’ package, one The proposed revision of the directive on the of energy products and aims to from energy on to on energy fuels be at the and at the Energy is a and the of the member states the by the to which has proved a The directive sets minimum of on energy fuels and but energy on an of their carbon agreement that an is much a attempt in in the of member opposition, leading the Commission to the proposal in the from the in the of 2024, agreement be and its adoption has been to the legislature 2024). the challenges associated with post-COVID-19 and the war in from energy supply disruptions to energy the momentum for climate action and energy system decarbonisation has not EU institutions and member states have remained committed to delivering the climate and energy dimensions of the Green Deal agenda the term of the von der Leyen Commission and have mostly delivered. as have the crises have been into of for the Green Deal agenda (Eckert, 2021; Von Homeyer et al., 2022). The of and the associated and new in the of and With member states to at least of their and in of the green transition, this additional has to policies and than new initiatives et al., 2023). the EU's response to the war in in particular the REPowerEU plan to dependence on has mostly pre-existing Green Deal than a change of course 2023). It has led to a Commission's legislative proposal for an of the Green renewable and energy targets for 2030 to and additional of until to be defined in new REPowerEU to the of gas and to help (e.g., of a new EU Energy to energy and hydrogen of this has in the Green agenda. The is as to the overall of the energy in of national to up fuel with new and infrastructure (Goldthau and Youngs, 2023; Kuzemko et al., 2022). As most energy and climate legislation has been at least in this first of an implementation, which is to and Looking at the the for when the of and for ambitious and climate policies environmental policy and but in the of and also point out that is a of policy the in implementation, notably and implementing and 2020). As is evident from the adopted legislation is with such as indicative targets, and which may be in of national and to reach but also effective implementation This is the with the revised renewable energy directive, with its sub-targets and et al., 2023). policies also have and to in with increasing over 2030 (Von Homeyer et al., 2022). For targets for reducing and phasing out combustion cars reaching 100% in This is also the for which has obligations a with its tax into in 2026 in with the phasing out of free ETS The new ETS into from onwards. and phase-out create legislation for Some of the legislation, like the on new combustion in or the new directly impacts European for politicisation and contestation of the implementation which may be of legislation in the ‘Fit for 55’ package also have most notably It has been criticised and in For has a rules against a considered especially to countries (Euractiv, The EU's may implementation et al., 2024). In a context of geopolitical over the energy transition, the Green Deal has increasingly taken a new green industrial In response to the Reduction and as part of its Green Deal the Commission proposed in May 2023, and the adopted in March 2024, a new a non-binding target of to be within the as well as a European that sets for domestic of key all whilst aiming to up projects. The is to and dependence on key and from the and of for green to and electric This industrial and geopolitical framing is likely to become more in the Green Deal to achieve both growth and but it may also fuel The of the that, implementation and environmental with and EU ambitions et al., and may become to the costs of climate action or more about commit also an for against ambitious action to mobilise and Although the climate and energy dimensions of the Green Deal proved with the finalisation of most proposals, the years 2023–2024 also saw the of a of and protests against green including of the Green protests were covered in European and national presented as a ‘green or (e.g., 2024; Reuters, 2023; 2024). on the costs of green policies in a of and with the on place across Europe, the and and the and and covered were the protests that across the from to France to and to their were but to focus on notably as part of the of the and protests led to the Commission a proposal to use in the EU 2024). In the to pollution fuelled and the rise of a new The was not to and with on issues directly related to energy and such as the phasing out of and gas which the or the phasing out of combustion The has been by the right and right (Yazar and Haarstad, 2023). right populists to be to climate ambitions, on is as to their to EU policy when in power et al., Climate policy has become a and 2024) for which have it to and the and up from their climate At the EU level, the far-right of the European and and and as well as the centre-right which is part of the majority have the and of The target was the controversial Nature Restoration which sets a target of at least of the EU's and areas by on it to block it but was able to the (Taylor, in to domestic pressure or a change of President for a in the adoption of new green legislation to protect industries 2023), supported by such as as a The final of the on from car emissions to the energy of buildings, saw against the EU on combustion cars in (Politico, 2023). This to be not all of the Green Deal have been has to on and the of the and for climate action across member at to 2019, climate may have the of 2023). disruptions and energy prices due to the war in a majority of to the 2023 on climate change considered that the transition to a green be et on a across argue that the is and to the with for climate action and climate costs are green industrial policies and the June 2024 European elections challenges ahead for the Green The main were the far-right parties and for Europe and Europe of and the centre right with the main losers the Greens and the liberals Europe to 2019, when a key was a shift parties and 2024 a shift parties with an ambitious environmental the results were not by environmental As et and have the new majority not adopted legislation, but it for ambitious climate policies going the increasingly and the that the ambitious of the the liberals and the Greens a majority of In to the European Parliament ahead of the on which was successful on a against the Ursula von der Leyen to the climate objectives, including a reduction target for and to the Green Deal agenda. the a framing more on competitiveness and green industrial policy with the of a Deal’, whilst nature and the were in 2024). The EU Green Deal from its inception to its the and – or – of the politicisation of climate change (Dupont et al., 2024; et al., 2022). In 2019, climate pushed climate change – an and policy – on top of the EU's political agenda. In this context, the Commission proposed a cross-cutting and ambitious Green Deal, wide across member states and the political In this politicisation proved In the of the Green Deal ahead of EU elections has been marked by a different context, with a of the as well as the radical right and centre right the Green Deal agenda to it – a of ‘constraining politicisation’ (Dupont et al., 2024). The Green Deal has proved to the and the energy crisis, and implementing legislation has been mostly adopted in 2023 and the first half of 2024 – at least its energy and climate it be hard to and to Climate and energy policies are well from and are in the and of the Green Deal have been to Yet, implementation prove a for climate and with the policies that are due to be and be and most a of and forward. just as a new of is over the targets. The Green Deal a political object with than a likely than its one a change in its framing and focus – on competitiveness and green in particular – in the context of domestic politicisation of the climate and energy transition and global geopolitical competition. The like to the for their and in this
88Techno-Economic Analysis of Hydrogen Production: Costs, Policies, and Scalability in the Transition to Net-ZeroOpenAlex
Curcio, Eliseo
This study presents a comprehensive techno-economic analysis of gray, blue, and green hydrogen production pathways, evaluating their cost structures, investment feasibility, infrastructure challenges, and policy-driven cost reductions. The findings confirm that gray hydrogen (1.50-2.50/kg) remains the most cost-effective today but is increasingly constrained by carbon pricing. Blue hydrogen (2.00-3.50/kg) offers a transitional pathway but depends on CCS costs, natural gas price volatility, and regulatory support. Green hydrogen (3.50-6.00/kg) is currently the most expensive but benefits from declining renewable electricity costs, electrolyzer efficiency improvements, and government incentives such as the Inflation Reduction Act (IRA), which provides tax credits of up to 3.00/kg. The analysis shows that renewable electricity costs below 20-30/MWh are essential for green hydrogen to achieve cost parity with fossil-based hydrogen. The DOE's Hydrogen Shot Initiative aims to lower green hydrogen costs to 1.00/kg by 2031, emphasizing the need for CAPEX reductions, economies of scale, and improved electrolyzer efficiency. Infrastructure remains a critical challenge, with pipeline retrofitting reducing transport costs by 50-70%, though liquefied hydrogen and chemical carriers remain costly due to energy losses and reconversion expenses. Investment trends indicate a shift toward green hydrogen, with over 250 billion projected by 2035, surpassing blue hydrogen's expected 100 billion. Carbon pricing above $100/ton CO2 will likely make gray hydrogen uncompetitive by 2030, accelerating the shift to low-carbon hydrogen. Hydrogen's long-term viability depends on continued cost reductions, policy incentives, and infrastructure expansion, with green hydrogen positioned as a cornerstone of the net-zero energy transition by 2035.
89Hydrogen as an alternative fuel: A comprehensive review of challenges and opportunities in production, storage, and transportationOpenAlex
Md Monjur Hossain Bhuiyan, Zahed Siddique
The rapid growth of the global population and industrial activities has significantly increased greenhouse gases (GHGs) emissions, with projections indicating a temperature rise of 3–6 °C by 2050. Urgent action is needed to limit global warming to 1.5 °C above pre-industrial levels. Hydrogen, with its high energy density and compatibility with renewable energy systems, presents a promising clean energy solution to mitigate GHGs emissions. Yet, its widespread adoption faces challenges such as high production costs, limited infrastructure, and an underdeveloped value chain. At present, approximately 96% of global hydrogen production relies on fossil fuels, contributing to substantial emissions, while only 4% comes from water electrolysis. Green hydrogen, produced via electrolysis with 55–80% efficiency, remains expensive at $2.28–7.39/kg, compared to grey hydrogen at $0.67–1.31/kg, which generates 8.5 kg CO₂ per kg of hydrogen production. Hydrogen's low density poses challenges for storage, while transportation risks and insufficient infrastructure create further obstacles. The lack of global standards and investment uncertainties further impede the development of a comprehensive hydrogen economy. This review evaluates hydrogen's potential as a sustainable energy carrier, providing insights into advancements and ongoing challenges in production, storage, and transportation. Key findings highlight the necessity of coordinated efforts to enhance storage technologies, lower production costs, and establish supportive policies, highlighting hydrogen's critical role in achieving a sustainable energy transition. • Analyzed hydrogen's potential as a sustainable and clean energy carrier. • Reviewed global advancements and trends in hydrogen production and utilization. • Addressed key technical challenges in adopting hydrogen as an alternative fuel. • Evaluated opportunities in hydrogen production, storage, and transport systems. • Assessed barriers in hydrogen infrastructure, addressing technical challenges.
90Green hydrogen production and deployment: opportunities and challengesOpenAlex
Hussein A. Younus, Rashid Al‐Hajri, Nazir Ahmad, et al.
Green hydrogen is emerging as a pivotal energy carrier in the global transition toward decarbonization, offering a sustainable alternative to fossil fuels in sectors such as heavy industry, transportation, power generation, and long-duration energy storage. Despite its potential, large-scale deployment remains hindered by significant economic, technological, and infrastructure challenges. Current production costs for green hydrogen range from USD 3.8 to 11.9/kg H2, significantly higher than gray hydrogen at USD 1.5–6.4/kg H2, due to high electricity prices and electrolyzer capital costs exceeding USD 2000 per kW. This review critically examines the key bottlenecks in green hydrogen production, focusing on water electrolysis technologies, electrocatalyst limitations, and integration with renewable energy sources. The economic viability of green hydrogen is constrained by high electricity consumption, capital-intensive electrolyzer costs, and operational inefficiencies, making it uncompetitive with fossil fuel-based hydrogen. Infrastructure and supply chain challenges, including limited hydrogen storage, transport complexities, and critical material dependencies, further restrict market scalability. Additionally, policy and regulatory gaps, disparities in financial incentives, and the absence of a standardized certification framework hinder international trade and investment in green hydrogen projects. This review also highlights market trends and global initiatives, assessing the role of government incentives and cross-border collaborations in accelerating hydrogen adoption. While technological advancements and cost reductions are progressing, overcoming these challenges requires sustained innovation, stronger policy interventions, and coordinated efforts to develop a resilient, scalable, and cost-competitive green hydrogen sector.
91Niobium Interlayer Coating: Is it a Practical Approach to Tune the Protective Pt Loading in PEM Water Electrolyzers?OpenAlex
Hossein Kalhori, Mohammadhossein Johar, Leila Moradizadeh, et al.
Proton exchange membrane (PEM) water electrolysis is a pioneering and promising method for sustainable green hydrogen generation. However, the high cost of PEM water electrolyzer components poses a significant barrier to the commercialization and widespread application of this technology. In this research, a novel Niobium-Platinum coating is developed for the porous transport layer (PTL) to reduce the precious metal loading. Niobium (Nb)-based coating was applied as an interlayer between Pt and titanium (Ti) felt substrates to increase the adhesion of Pt. For this study, pulsed laser deposition (PLD) technique was applied for the first time to coat Nb and Pt multilayers onto Ti felt substrates. The results demonstrate that incorporating a Nb coating as an interlayer lead to reducing the Pt loading, which holds promise for the practical application of PTLs in PEM water electrolyzers.
93Challenges and Opportunities in Green Hydrogen Adoption for Decarbonizing Hard-to-Abate Industries: A Comprehensive ReviewOpenAlex
M. Jayachandran, Ranjith Kumar Gatla, Aymen Flah, et al.
The decarbonization of hard-to-abate industries is crucial for keeping global warming to below 2°C. Green or renewable hydrogen, synthesized through water electrolysis, has emerged as a sustainable alternative for fossil fuels in energy-intensive sectors such as aluminum, cement, chemicals, steel, and transportation. However, the scalability of green hydrogen production faces challenges including infrastructure gaps, energy losses, excessive power consumption, and high costs throughout the value chain. Therefore, this study analyzes the challenges within the green hydrogen value chain, focusing on the development of nascent technologies. Presenting a comprehensive synthesis of contemporary knowledge, this study assesses the potential impacts of green hydrogen on hard-to-abate sectors, emphasizing the expansion of clean energy infrastructure. Through an exploration of emerging renewable hydrogen technologies, the study investigates aspects such as economic feasibility, sustainability assessments, and the achievement of carbon neutrality. Additionally, considerations extend to the potential for large-scale renewable electricity storage and the realization of net-zero goals. The findings of this study suggest that emerging technologies have the potential to significantly increase green hydrogen production, offering affordable solutions for decarbonization. The study affirms that global-scale green hydrogen production could satisfy up to 24% of global energy needs by 2050, resulting in the abatement of 60 gigatons of greenhouse gas (GHG) emissions - equivalent to 6% of total cumulative <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CO</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> emission reductions. To comprehensively evaluate the impact of the hydrogen economy on ecosystem decarbonization, this article analyzes the feasibility of three business models that emphasize choices for green hydrogen production and delivery. Finally, the study proposes potential directions for future research on hydrogen valleys, aiming to foster interconnected hydrogen ecosystems.
94Economic, social, and regulatory challenges of green hydrogen production and utilization in the US: A reviewOpenAlex
Shree Om Bade, Olusegun Stanley Tomomewo, Ajan Meenakshisundaram, et al.
Green Hydrogen (GH) is increasingly recognized as a viable solution in the United States (US) for meeting energy demands, achieving net zero emissions by 2050, and mitigating the intermittent nature of renewable sources such as wind and solar. This review paper identifies and examines three crucial research areas concerning GH. Despite significant federal, state, and business investment in the development of hydrogen technology , numerous questions have remained unanswered including economic viability, social acceptance, and policies and regulations. In comparison to the US, Europe, and Asia have taken a lead role in studying the social and regulatory aspects of GH. The study shows limited focus on social acceptance, and the absence of dedicated policies and regulations for hydrogen. The US lacks coordinated policies for GH and is blended with natural gas. The literature shows that the relationship between economics, social sciences, and policies and regulations are intrinsic. The success of GH in the US will require massive investments, public and private collaboration, research on social sciences, and regulatory support. Hence, the GH rollout will bridge the energy transition, and climate and development targets which guide future industrial, government and public decisions. • Knowledge and experience play a major role in the acceptance of green hydrogen. • Green hydrogen technology lacks a value chain. • Lack of green hydrogen-specific regulatory agencies and standards in the US. • Economic, social, and regulatory challenges interlinked for green hydrogen.
95The green hydrogen role in the global energy transformationsOpenAlex
Sameer Algburi, Omer Al-Dulaimi, Hassan Falah Fakhruldeen, et al.
• Green hydrogen enhances energy storage and supports renewable grid integration. • High costs and infrastructure gaps hinder green hydrogen scalability. • AI offers potential to optimize hydrogen production and system efficiency. • Policy alignment and global cooperation are key to hydrogen deployment. Green hydrogen has the potential to significantly contribute to the global energy transition toward sustainable and decarbonized energy systems. Produced through renewable-powered electrolysis, green hydrogen provides a viable pathway for decarbonizing challenging sectors, such as heavy industry and transportation, while simultaneously addressing renewable intermittency by enabling large-scale energy storage and grid flexibility. This study evaluates the geopolitical and economic implications of developing robust green hydrogen supply chains, particularly in renewable resource-rich regions. Despite its promise, significant barriers persist, including high production costs, infrastructural inadequacies, and policy uncertainty. Emerging technological innovations, coupled with supportive financial strategies and comprehensive policy frameworks, can help overcome these barriers. The given outcomes recommended a strengthening international cooperation and implementing harmonized regulatory standards to accelerate green hydrogen adoption globally, positioning it as a core component of achieving net-zero emissions, driving economic growth, and advancing equitable energy transitions.
97Gauging public perceptions of blue and green hydrogen futures: Is the twin-track approach compatible with hydrogen acceptance?OpenAlex
Joel A. Gordon, Nazmiye Balta‐Ozkan, Seyed Ali Nabavi
National hydrogen strategies are emerging as a critical pillar of climate change policy. For homes connected to the gas grid, hydrogen may offer an alternative decarbonisation pathway to electrification. Hydrogen production pathways in countries such as the UK will involve both the gas network and the electricity grid, with related policy choices and investment decisions impacting the potential configuration of consumer acceptance for hydrogen homes. Despite the risk of public resistance, be it on environmental, economic, or social grounds, few studies have explored the emerging contours of domestic hydrogen acceptance. To date, there is scarce evidence on public perceptions of national hydrogen policy and the extent to which attitudes may be rooted in prior knowledge and awareness, or open to change following information provision and engagement. In response, this study evaluates consumer preferences for a low-carbon energy future, wherein parts of the UK housing stock may adopt low-carbon hydrogen boilers and hobs. Drawing on data from online focus groups, we examine consumer perceptions of the government's twin-track approach, which envisions important roles for both ‘blue’ and ‘green’ hydrogen to meet net zero ambitions. Through a mixed-methods, multigroup analysis, the underlying motivation is to explore whether the twin-track approach appears compatible with hydrogen acceptance. Moving forward, hydrogen policy should ensure greater transparency concerning the benefits, costs, and risks of the transition, with clearer communication about the justification for supporting respective hydrogen production pathways.
98In the green? Perceptions of hydrogen production methods among the Norwegian publicOpenAlex
Henrik Litleré Bentsen, Jon Kåre Skiple, Thea Gregersen, et al.
This article presents findings from a representative survey, fielded through the Norwegian Citizen Panel, examining public perceptions of hydrogen fuel and its different production methods. Although several countries, including Norway, have strategies to increase the production of hydrogen fuel, our results indicate that hydrogen as an energy carrier, and its different production methods, are still unknown to a large part of the public. A common misunderstanding seems to be confusing ‘hydrogen fuel’ in general with environmentally friendly ‘green hydrogen’. Results from a survey experiment (N = 1906) show that production method is important for public acceptance. On a five-point acceptance scale, respondents score on average 3.9 for ‘green’ hydrogen, which is produced from renewable energy sources. The level of acceptance is significantly lower for ‘blue’ (3.2) and ‘grey’ (2.3) hydrogen when respondents are informed that these are produced from coal, oil, or natural gas. Public support for hydrogen fuel in general, as well as the different production methods, is also related to their level of worry about climate change, gender, and political affiliation. Widespread misunderstandings regarding ‘green’ hydrogen production could potentially fuel public resistance as new ‘blue’ or ‘grey’ projects develop. Our results indicate a need for clearer communication from the government and developers regarding production methods to avoid distrust and potential public backfire.
99Green hydrogen powering sustainable festivals: Public perceptions of generators, production and ownershipOpenAlex
Connor Smith, Charlotte Bucke, Dan van der Horst
This paper is the first to explore public perceptions about a particular market niche for hydrogen; mobile generators. By utilising a combined research approach including in-situ surveys and online focus groups, this paper explores what festival audience members and residents who live near festival sites think about the displacement of incumbent diesel generator technology with hydrogen alternatives. We investigate if hydrogen production methods are important in informing perceptions and subsequent support, including the extent to which participants are influenced by the organisation or entity that produces the fuel and stands to profit from its sale. In addition to a primary focus on hydrogen energy, we reflect upon how sustainability might be better conceptualised in a festival context. Our findings reveal broad support for hydrogen generators, the use of green hydrogen as a fuel to generate electricity and community-led hydrogen production.