CO2 electroreduction: Sustainability analysis of the renewable synthetic natural gas
Javier Fernández-González, Marta Rumayor, Antonio Domínguez-Ramos, Ángel Irabien
Abstract
Capture and utilization of industrial CO 2 emissions into low-carbon fuels is a promising alternative to store renewable electricity into chemical vectors while decarbonizing the economy. This work evaluates the viability pathways of producing synthetic natural gas (SNG) by direct CO 2 electroreduction (ER) in Power-To-Synthetic Natural Gas electrolyzers (PtSNG). We perform an ex-ante techno-economic (TEA) and life cycle analysis (LCA) for a 2030 framework in Europe. ER performance is varied in defined scenarios and assessed using a built-in process model of the PtSNG system, revealing uncharted limitations and benchmarks to achieve. Results show that substitution of fossil natural gas with renewable SNG could avoid more than 1 kg CO 2e /kg SNG under moderate ER conditions when using low-carbon electricity (< 60 kg CO 2e /MWh). SNG profitability for 2030 would rely on: i) higher CH 4 current densities (800–1000 mA/cm 2 ), ii) improvements in energy efficiency (higher than 60%), and iii) valorization of the anodic product or additional carbon incentives. Our study proves that if market and technology evolve appropriately in the coming years, the SNG by CO 2 ER may be a mid-term climate change mitigation technology, among others.