The production of methane from CO2 was subject of intense research work over the last few years. Several different reaction technologies were applied, both using catalytic or biological reactors . The process efficiency observed in the cited references is relatively high, approaching the thermodynamic limit of ca. 60 % for the conversion from electricity to synthetic natural gas (SNG). The production of methanol from CO2 was demonstrated in some industrial applications, showing that the electricity-to-methanol efficiency is affected by the need of compression of the feed gas to overcome the thermodynamic limitations .