Solar Fuels Via Methane Valorization: Thermochemical Pathways, Unified Metrics, and Techno-Economic Perspectives

Meeting global climate targets and sustainable energy demands requires carbon-neutral fuels and innovative conversion pathways. Solar fuels via methane valorization offer a promising approach by harnessing concentrated solar energy to convert abundant methane resources (e.g., natural gas or biogas) into clean hydrogen and synthetic fuels, effectively storing solar energy in chemical bonds while mitigating greenhouse gas emissions. This review article provides a comprehensive assessment of solar-driven thermochemical methane conversion pathways including solar reforming, methane pyrolysis, and chemical looping. It introduces a unified performance benchmarking framework, establishing consistent metrics for efficiency, conversion, and yield to enable fair cross-comparison of these diverse pathways. Furthermore, techno-economic analysis and life-cycle assessment are integrated, offering a holistic evaluation of each pathway's practical viability and environmental impact. By bridging fundamental solar-thermal reactor performance with economic and environmental perspectives, the review highlights key trade-offs and opportunities, guiding the development of scalable solar fuel technologies for a carbon-neutral future.