Impact of Solar Thermal Energy and Calcium Looping Implementation on Biomass Gasification for Low-carbon Hydrogen Production

In the search of low-carbon hydrogen production routes, this study evaluates four biomass gasification processes: conventional steam gasification (CSG), sorption-enhanced gasification (SEG), and their solar-assisted variants (SSG and SSEG). The comparison focuses on three key aspects: hydrogen production, overall energy efficiency (to H2 and power), and carbon capture potential (generation of a pure CO2 process stream for storage or utilization). For a realistic comparison, a pseudo-equilibrium model of a double-bed gasifier was developed based on experimental correlations of char conversion under conventional and SEG conditions. The solar processes were designed for stable year-round operation, considering seasonal weather variations by appropriately dimensioning the heliostat field and the thermal and chemical energy storage systems, whose inventory dynamics were modelled. Both the gasifier and central solar tower models were rigorously validated with published data, enhancing the reliability of the results. Solar-assisted configurations significantly outperform non-solar ones in hydrogen production, with SSEG yielding 128 kg H2/ton biomassdaf compared to 90–95 kg for non-solar options. SEG demonstrates superior carbon capture potential (76 %), while solar-assisted systems achieve higher energy efficiency (67–73 % vs. 60–63 % for non-solar). These results underscore the potential of solar-assisted gasification for sustainable hydrogen production, offering enhanced yields, improved efficiency, and substantial carbon capture capabilities. Future work will involve economic and environmental analysis to determine the best overall configuration.