Environmental issues related to global warming are constantly pushing the fossil fuel-based energy sector toward an efficient and economically viable utilization of renewable energy. However, challenges related to renewable energy call for alternative routes of its conversion to fuels and chemicals by an emerging Power-to-X approach. Methane is one such high-valued fuel that can be produced through renewables-powered electrolytic routes. Such routes employ alkaline electrolyzers, proton exchange membrane electrolyzers, and solid oxide electrolyzers, commonly known as solid oxide electrolysis cells (SOECs). SOECs have the potential to utilize the waste heat generated from exothermic methanation reactions to reduce the expensive electrical energy input required for electrolysis. A further advantage of an SOEC lies in its capacity to co-electrolyze both steam and carbon dioxide as opposed to only water, and this inherent capability of an SOEC can be harnessed for in situ synthesis of methane within a single reactor. However, the concept of in situ methanation in SOECs is still at a nascent stage and requires significant advancements in SOEC materials, particularly in developing a cathode electrocatalyst that demonstrates activity toward both steam electrolysis and methanation reactions. Equally important is the appropriate reactor design along with optimization of cell operating conditions (temperature, pressure, and applied potential). This review elucidates those developments along with research and development opportunities in this space. Also presented here is an efficiency comparison of different routes of synthetic methane production using SOECs in various modes, that is, as a source of hydrogen, syngas, and hydrogen/carbon dioxide mixture, and for in situ methane synthesis.

与全球变暖有关的环境问题不断推动基于化石燃料的能源部门向可再生能源的高效和经济可行的利用。但是，与可再生能源相关的挑战要求通过新兴的Power-to-X方法将其转化为燃料和化学物质的替代途径。甲烷是一种可以通过可再生能源驱动的电解路线生产的高价值燃料。这样的路线使用碱性电解槽，质子交换膜电解槽和固体氧化物电解槽，通常称为固体氧化物电解槽（SOEC）。SOEC有潜力利用放热甲烷化反应产生的废热来减少电解所需的昂贵电能输入。原位在单个反应器中合成甲烷。但是，原位SOEC中的甲烷化仍处于起步阶段，需要SOEC材料取得重大进展，特别是在开发出对蒸汽电解和甲烷化反应均具有活性的阴极电催化剂方面。同样重要的是适当的反应器设计以及电池运行条件（温度，压力和施加电势）的优化。这篇评论阐明了在该领域的发展以及研发机会。本文还介绍了使用SOEC在各种模式下（即作为氢气，合成气和氢气/二氧化碳混合物的来源）用于合成甲烷的不同生​​产路线的效率比较。原位 甲烷合成。