Thermodynamic performance of solar-driven methanol steam reforming system for carbon capture and high-purity hydrogen production

Solar energy storage via a thermochemical approach is a promising method to realize the efficient utilization of discontinuous sunlight. Traditional solar thermochemical conversion with the assistant of hydrocarbon requires the purification process of products, and a relatively high reaction temperature limits its thermodynamic efficiency. In this work, a thermodynamic study on solar-driven methanol steam reforming reaction in a Pd-Ag membrane reactor has been conducted. The partial pressure, conversion rate, and thermodynamic efficiency are studied and analyzed under different reaction temperatures (150-250 C) and permeate pressures (10-3-1 bar). Via the membrane reactor, the equilibrium of reaction shifts forward and the conversion rate of methanol can reach as high as above 99.9% in 150-250 C, and purified hydrogen and carbon dioxide can be collected separately. Under the optimized reaction temperature and pressure, the solar-to-fuel efficiency and exergy efficiency can reach as high as 55.2% and 74.79%, respectively. Due to the utilization of solar energy and membrane reactor, the annual coal saving rate and carbon dioxide reduction rate are predicted to be 0.63 t/m2 and 1.53 t/m2, respectively. This thermodynamic research provides an efficient approach for solar energy conversion and storage without CO2 emission.

Automated summary

In this study, a thermodynamic analysis of solar-driven methanol steam reforming reaction in a Pd-Ag membrane reactor was conducted. The results showed that, under optimized reaction conditions, the conversion rate of methanol reached high levels and purified hydrogen and carbon dioxide could be collected separately. Due to the use of solar energy and the membrane reactor, it is predicted that significant coal and carbon dioxide savings can be achieved.