National Energy Technology Laboratory Support Contractor, U.S. Department of Energy, Pittsburgh, Pennsylvania 15236, United States.
National Energy Technology Laboratory, U.S. Department of Energy, Pittsburgh, Pennsylvania 15236, United States.
Environ Sci Technol. 2022 Jun 21;56(12):8581-8589. doi: 10.1021/acs.est.2c00093. Epub 2022 Jun 2.
Renewable natural gas (RNG) sources are being considered in future energy strategy discussions as potential replacements for fossil natural gas (FNG). While today's supply of RNG resources is insufficient to meet U.S. demands, there is significant interest in its viability to supplement and decarbonize the natural gas supply. However, the studies compare the life cycle global warming potential (GWP) of various RNG production pathways are lacking and focus mostly on a singular pathway. This effort is an attempt to close this gap and provide a comparison between the life cycle GWP of three major RNG pathways and the FNG pathway. The three RNG pathways evaluated are anaerobic digestion (AD), thermal gasification (TG), and power-to-gas (P2G) using various feedstocks. The functional unit is 1 MJ of compressed RNG ready for injection into the natural gas transmission network. The results show that RNG production is not always carbon neutral or negative. Depending on the pathway, the GWP impact of RNG production can range from -229 to 27 g COe/MJ compressed RNG, with AD of animal manure and AD of municipal solid waste being the least and the most impactful pathways, respectively, compared to the 10.1 g COe/MJ impact for compressed FNG.
可再生天然气（RNG）资源正被纳入未来能源战略讨论，作为化石天然气（FNG）的潜在替代品。尽管目前 RNG 资源的供应不足以满足美国的需求，但人们对其补充和减少天然气供应碳足迹的可行性仍有浓厚兴趣。然而，关于各种 RNG 生产途径的生命周期全球变暖潜能（GWP）的研究仍然缺乏，而且大多集中在单一途径上。本研究旨在填补这一空白，并比较三种主要 RNG 途径（厌氧消化（AD）、热气化（TG）和电转气（P2G））和 FNG 途径的生命周期 GWP。评估的三种 RNG 途径使用了不同的原料。功能单位为 1MJ 压缩 RNG，可注入天然气输送网络。结果表明，RNG 生产并非总是碳中和或负排放。具体取决于途径，RNG 生产的 GWP 影响范围从-229 到 27g COe/MJ 压缩 RNG，其中动物粪便的 AD 和城市固体废物的 AD 分别是影响最小和最大的途径，相比之下，压缩 FNG 的 GWP 影响为 10.1g COe/MJ。
