Retrofitted production of bio-hydrogen. Large-scale biowaste valorization via solar-based gasification

• A solar gasifier is analyzed with a two-phase model and industrial validation. • Syngas rich in H 2 is obtained, but without reduction of tars due to low temperature. • The industrial scale showed energy losses, suggesting segmented heating. • Modular design and segmented heating are key due to scaling limits and heat losses. • It would operate only in summer in Spain; Cádiz and Tenerife have the highest output. Hydrogen production from gasification of biowaste generates large volumes of CO 2 due to endothermic biowaste decomposition. Alternatively, the Sun can provide that energy. To evaluate the yield and performance of solar-based gasifiers at country scale, a multi-scale approach is required. First, the operation of a solar gasifier is analyzed by developing a two-phase model, validated and scaled to industrial level. Next, the performance and yield of such technology as a function of the radiation received is studied, taking Spain as a case study. The results were promising obtaining a syngas rich in H 2 . However, tar and char were not reduced due to insufficient temperature. Scale-up studies revealed energy losses to the environment in the industrial-scale gasifier, which suggested the use of segmented heating. In turn, diameters no larger than 0.8 m and biomass feeding rates below 0.85 kg/s, highlight the deployment of a modular design due to particle size limitations. Finally, the large-scale waste valorization showed that the gasifier can only operate in Spain in the summer months. It can run over 180 h/month and more than 250 days/year only in Cádiz and Santa Cruz de Tenerife, which also showed the highest yearly production capacities.