Retrofitted Production of Bio-hydrogen. Large-scale Biowaste Valorization via Solar-based Gasification

Hydrogen production from gasification of biowaste generates large volumes of CO2 due to endothermic biowaste decomposition. Alternatively, the Sun can provide that energy. To evaluate the yield and performance of solarbased 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 H2. 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 C´ adiz and Santa Cruz de Tenerife, which also showed the highest yearly production capacities.