Instituto de Tecnología Química, Universitat Politècnica de València-CSIC , Avenida Los Naranjos s/n , 46022 Valencia , Spain.
IMDEA Energy Institute , Avenida Ramón de la Sagra 3 , 28935 Móstoles , Madrid , Spain.
Chem Rev. 2019 Apr 10;119(7):4777-4816. doi: 10.1021/acs.chemrev.8b00315. Epub 2019 Mar 14.
Among renewable energies, wind and solar are inherently intermittent and therefore both require efficient energy storage systems to facilitate a round-the-clock electricity production at a global scale. In this context, concentrated solar power (CSP) stands out among other sustainable technologies because it offers the interesting possibility of storing energy collected from the sun as heat by sensible, latent, or thermochemical means. Accordingly, continuous electricity generation in the power block is possible even during off-sun periods, providing CSP plants with a remarkable dispatchability. Sensible heat storage has been already incorporated to commercial CSP plants. However, because of its potentially higher energy storage density, thermochemical heat storage (TCS) systems emerge as an attractive alternative for the design of next-generation power plants, which are expected to operate at higher temperatures. Through these systems, thermal energy is used to drive endothermic chemical reactions, which can subsequently release the stored energy when needed through a reversible exothermic step. This review analyzes the status of this prominent energy storage technology, its major challenges, and future perspectives, covering in detail the numerous strategies proposed for the improvement of materials and thermochemical reactors. Thermodynamic calculations allow selecting high energy density systems, but experimental findings indicate that sufficiently rapid kinetics and long-term stability trough continuous cycles of chemical transformation are also necessary for practical implementation. In addition, selecting easy-to-handle materials with reduced cost and limited toxicity is crucial for large-scale deployment of this technology. In this work, the possible utilization of materials as diverse as metal hydrides, hydroxides, or carbonates for thermochemical storage is discussed. Furthermore, special attention is paid to the development of redox metal oxides, such as CoO/CoO, MnO/MnO, and perovskites of different compositions, as an auspicious new class of TCS materials due to the advantage of working with atmospheric air as reactant, avoiding the need of gas storage tanks. Current knowledge about the structural, morphological, and chemical modifications of these solids, either caused during redox transformations or induced wittingly as a way to improve their properties, is revised in detail. In addition, the design of new reactor concepts proposed for the most efficient use of TCS in concentrated solar facilities is also critically considered. Finally, strategies for the harmonic integration of these units in functioning solar power plants as well as the economic aspects are also briefly assessed.
在可再生能源中，风能和太阳能本质上是间歇性的，因此都需要高效的储能系统，以便在全球范围内实现全天候的电力生产。在这方面，太阳能聚光发电（CSP）在其他可持续技术中脱颖而出，因为它提供了一种有趣的可能性，可以通过显热、潜热或热化学手段将从太阳收集的能量存储为热能。因此，即使在没有阳光的时期，也可以在动力装置中连续发电，这为 CSP 工厂提供了显著的调度能力。显热存储已经被纳入商业 CSP 工厂。然而，由于其潜在的更高的能量存储密度，热化学储能（TCS）系统作为设计新一代发电厂的有吸引力的替代方案出现，预计这些发电厂将在更高的温度下运行。通过这些系统，热能被用于驱动吸热化学反应，随后可以通过可逆的放热步骤在需要时释放存储的能量。本综述分析了这种突出的储能技术的现状、主要挑战和未来展望，详细涵盖了为提高材料和热化学反应器性能而提出的许多策略。热力学计算允许选择高能量密度系统，但实验结果表明，为了实际应用，还需要足够快速的动力学和通过连续的化学转化循环的长期稳定性。此外，选择易于处理、成本低且毒性有限的材料对于该技术的大规模部署至关重要。在这项工作中，讨论了各种材料如金属氢化物、氢氧化物或碳酸盐用于热化学存储的可能性。此外，特别关注氧化还原金属氧化物的开发，如 CoO/CoO、MnO/MnO 和不同组成的钙钛矿，作为一种有前途的新类 TCS 材料，因为它们可以使用大气空气作为反应物工作，避免了对气体储罐的需求。详细审查了这些固体在氧化还原转化过程中或故意诱导时引起的结构、形态和化学改性的当前知识，以改善它们的性能。此外，还批判性地考虑了为在集中太阳能设施中最有效地使用 TCS 而提出的新反应器概念的设计。最后，还简要评估了这些单元在功能太阳能发电厂中的和谐集成策略以及经济方面。
