Feasibility study of power-to-gas as simultaneous renewable energy storage and CO2 utilization: Direction toward economic viability of synthetic methane production

Abstract

According to an increase in concerns for environmental issues, the energy transition toward sustainable and alternative energy has received much attention. Synthetic methane, which is a fuel synthesized by the reaction of green hydrogen (H2) and carbon dioxide (CO2), is perceived as a promising alternative to fossil-fuel-based natural gas. A feasibility study of synthetic methane production focusing on green H2 production is conducted to investigate how to make the technology economically feasible. Cost estimation for methane production is performed by classifying various scenarios of H2 production based on water electrolysis technologies and renewable energy resources. The production costs of synthetic methane show diverse ranges following the considerations: 0.049-0.199, 0.059-0.215, and 0.154-0.273 $ kWh-1 for alkaline water electrolysis, polymer electrolyte membrane water electrolysis, and solid oxide water electrolysis, respectively. Moreover, sensitivity analysis discloses that parameters associated with green H2 production costs dominate the methane costs; therefore, predictive analysis demonstrates the economic outlook of synthetic methane production by applying learning-by-doing effects, future performance of electrolyzer, and renewable electricity costs. Consequently, we reveal the possibility of onshore wind electricity that can achieve economic feasibility with fully developed electrolysis systems for green H2 production at low electricity prices.