Solar-Driven Biomass Pyrolysis Plant for Negative-Emission Biofuels Production

As part of the Horizon Europe Project PYSOLO, this study focuses on the integration of a 10 MWTH fast pyrolysis plant with a solar tower system equipped with a rotary kiln particle receiver. Heated particles act as a particle heat carrier (PHC) for the endothermic pyrolysis process, enhancing flexibility and allowing continuous operation compared to directly heated solar reactors. The system’s design, techno-economic analysis and storage capacity optimi-zation are performed considering two operation modes, solar-only and hybrid, in which biochar is combusted in absence of solar energy. Results indicate that, due to the rotary kiln flow re-gime constraints, its tilt angle has to be limited in a range between 0.5-2° to guarantee particles being in rolling mode, thus penalizing the achievable solar field optical efficiency. On the other hand solar-based pyrolysis can achieve carbon efficiencies close to 0.9 and, thanks to the carbon stored in biochar, net negative emissions equal to -27.05 and -19.45 kgCO2/GJOIL re-spectively in solar-only and hybrid mode. Moreover, as the pyrolysis section has the most rel-evant cost share, the system optimization pushes to maximise the pyrolysis plant operating hours (and thus the bio-oil production) to reduce the CAPEX impact on the Minimum Fuel Selling Price (MFSP). For this reason hybrid mode results in being the most convenient (i.e: MFSP of 25.71 vs 21.36 €/GJOIL).