The direct methanation of biogas using hydrogen from electrolysis is a promising pathway for seasonal storage of renewables in the natural gas network. It offers particular advantages over the methanation of carbon dioxide separated from biogas, as it eliminates a costly and unnecessary carbon dioxide separation step. The key implementation challenges facing direct methanation of biogas are reviewed here: 1) treatment of biogas impurities; 2) competing reactor concepts for methanation; and 3) competing process concepts for final upgrading. For each of these three aspects, the state of the art is reviewed, focusing especially on results which have been validated at a high Technology Readiness Level (TRL) at recent long-duration demonstrations. The different technology solutions have advantages and disadvantages which may fit best to different technical and economic boundary conditions, which are discussed. As a final outlook, TRL 8 demo plants will be necessary to show the full potential of these systems, and to obtain consistent operation data to allow a cost comparison.

使用来自电解的氢气将沼气直接甲烷化是在天然气网络中季节性存储可再生能源的有前途的途径。与从沼气中分离出的二氧化碳甲烷化相比，它具有特别的优势，因为它省去了昂贵且不必要的二氧化碳分离步骤。这里回顾了沼气直接甲烷化面临的主要实施挑战：1）处理沼气杂质；2）竞争的甲烷化反应器概念；和3）竞争性的过程概念以进行最终升级。对于这三个方面中的每一个，都对现有技术进行了回顾，尤其关注在最近的长期演示中已在高技术准备水平（TRL）上得到验证的结果。不同的技术解决方案具有各自的优点和缺点，这些优点和缺点可能最适合于讨论的不同技术和经济边界条件。作为最终的展望，TRL 8演示工厂将有必要展示这些系统的全部潜力，并获得一致的运行数据以进行成本比较。