Optimal year-round operation for methane production from CO2 and water using wind and/or solar energy

In this paper we present the optimal year round production of synthetic methane from water electrolysis and CO2 comparing the use of solar PV systems and wind turbines on a monthly basis. The process starts obtaining electricity in a wind farm or a solar field, which is then used to produce oxygen and hydrogen in a system of electrolyzers. The oxygen is purified and stored, and the hydrogen, after being purified using a deoxygenating reactor, reacts with CO2 to synthesize methane. We study the operation of the plant for a year considering the wind or solar availability. The use of wind or solar energy depends on the region and the area available for the installation of solar panels or wind turbines. Europe and the US have been screened for the use of both sources of energy, being solar preferable in most regions. We present a detailed case of study in the South of Europe, Gulf of Cádiz. Solar is cheaper than wind in terms of inversion (240 M€ vs. 363 M€) and production costs (0.33 €/m3 vs. 0.49 €/m3), while the monthly operation differs due to the availability of renewable energy.