Power-to-methane, coupling CO2 capture with fuel production: An overview

This paper provides a revision of the latest studies on the topic methanation, a multi-stage process where water is first converted into hydrogen in an electrolyzer, which subsequently reacts with carbon dioxide to produce methane. The present and future of the most common water electrolysis technologies is addressed. Critical issues to take into consideration when selecting a carbon dioxide source are evaluated. Chemical and biological approaches, together with photocatalytic configurations are discussed, analyzing pros and cons in all the cases. This paper also highlights the extensive work being done in the development of catalysts capable of selectively converting carbon dioxide into methane, as well as the different reactor configurations that can be used with this aim in any of the available methanation modalities. Relevant power-to-methane plants in Europe have been identified and assessed regarding their location, year of commissioning, capacity, technology for electrolysis and methanation type. Finally, cost issues are analyzed, highlighting economic perspectives of the power-to-methane technologies for the next decades. This document reviews all the key elements associated with the methanation process, revealing which aspects can pave the way for the large-scale implementation of this power generation model. In this sense, the gradual cost reduction of the equipment involved and the continuous increase in the efficiency of the processes are revealed as crucial aspects that can lead to a general implementation of the methanation concept on the way to a low carbon economy.