Stable methane dry reforming under fluctuating solar flux assisted by phase change thermal energy storage

Solar-driven dry reforming of methane (DRM) assisted by carbon dioxide offers a sustainable pathway to simultaneously reduce greenhouse gas emissions and supply valuable clean fuels. However, the inherent intermittency of solar irradiation presents significant challenges, including temperature overshoot or insufficiency, leading to catalyst deactivation and low light-to-fuel efficiency. Here, solar-driven DRM is integrated with phase change thermal energy storage to achieve efficient and stable solar-fuel conversion under fluctuating concentrated solar irradiation. A comprehensive multiphysics numerical model, incorporating solar light transfer, heat/mass transport, chemical reaction kinetics, and phase change processes, is developed and experimentally validated. Phase change modules surrounding DRM reactors not only absorb excess thermal energy during high solar irradiation periods, but also harvest otherwise underutilized peripheral low-intensity concentrated solar flux featured with a typical Gaussian-like distribution. The stored latent heat thermal energy is subsequently released during weak solar irradiation periods to maintain stable reaction temperature and continuous DRM operation. Experimental results demonstrate that the proposed integrated system simultaneously reduces temperature fluctuations by 40.57%, increases the CO2 conversion rate by 0.91%, raises the CH4 conversion rate by 1.46%, and achieves a high light-to-fuel efficiency of 38.2%. Meanwhile, carbon deposition on the catalyst is relieved with catalyst lifespan extended, thereby reducing the total annual cost by 7.89%. This work opens new routes for developing robust and efficient solar-driven DRM techniques under practical fluctuating solar irradiation conditions