Exergy valorization of a water electrolyzer and CO 2 hydrogenation tandem system for hydrogen and methane production

Abstract

In this work, we introduce a water electrolysis and CO 2 hydrogenation tandem system which focuses on methane generation. The concept consists of a water electrolyzer thermally coupled to a CO 2 hydrogenation reactor, where the power required to generate hydrogen comes from renewable energy. A thermodynamic analysis of the tandem system was carried out. Our analysis exposes that it is possible to increase the exergy efficiency of the water electrolyzer and CO 2 hydrogenation system by thermal coupling, where the thermal energy required to split water into H 2 and O 2 during the electrolysis process is compensated by the heat generated during the CO 2 hydrogenation reaction. Here, the conditions at which high exergy efficiency can be achieved were identified.