A solar thermal sorption-enhanced steam methane reforming (SE-SMR) approach and its performance assessment

This paper proposes an integration of concentrating solar power (CSP) with a sorption-enhanced steam methane reforming (SE-SMR) process and assesses its overall solar-to-fuel conversion performance. A thermodynamic treatment of the SE-SMR process for H₂ production is presented and evaluated in an innovative two reactors system configuration using CSP as a heat input. Four metal carbonate/metal oxide pairs are considered, and the equilibrium thermodynamics reveals that CaCO₃/CaO pair is the most suitable candidate for this process. Additionally, a reactor-scale thermodynamic model is developed to determine the optimum operating conditions for the process. For the carbonation step, temperatures between 700 and 900 K and steam-to-methane ratio ≥4 are found to be the most favorable. Furthermore, an advanced process model, which utilizes operating conditions determined from the reactor-scale model, is developed to evaluate the process efficiency. The model predicts that the proposed process can achieve a solar-to-fuel efficiency ∼41% for calcination temperature of 1500 K and carbonation temperature of 800 K, without considering any solid heat recovery. An additional 2.5% increase in the process efficiency is feasible with the consideration of the solid heat recovery. This study shows the thermodynamic feasibility of integrating the SE-SMR process with CSP technologies.