Electrochemical methane production from CO₂ for orbital and interplanetary refueling

Renewable CO₂ electrosynthesis is a potentially promising tool to utilize unwanted greenhouse gas. The greatest barrier to its adoption is rendering the production of CO₂-derived chemicals cost-competitive, such that they have higher net value than their fossil-derived equivalents. Among the commodities that have been made using CO₂, H₂O, and electricity, CH₄ is one of the simplest and most researched products. Technoeconomic studies of CO₂ methanation make it clear that its high-value applications are limited without significant subsidy on Earth, where it competes with low-cost natural gas. In space, however, CO₂ methanation via the Sabatier reaction is already used on the International Space Station to recycle atomic oxygen, and propulsion systems employing cryogenic liquid methane are in development for reusable rocket engines. Comparative analysis of power-to-gas using either CO₂ electrosynthesis or the Sabatier reaction from an aerospace perspective identifies research priorities and parameters for deployment. Given its atmospheric CO₂ concentration over 95%, Mars may present future opportunities for technology that could also help overcome our climate challenges on Earth.