The PYSOLO Project: Biomass Pyrolysis by Concentrated Solar Power

Decarbonisation through electrification is not sufficient to reduce CO₂ emissions in the chemical industry, as fossil feedstocks remain a major emissions source. Defossilisation by switching to renewable carbon sources such as second-generation biomass should thus be pursued. Conventional biomass pyrolysis, converting wood residues into highvalue products such as bio-oil, biochar and pyrolysis gas, is typically sustained by burning char and pyrogas, an economically and ecologically inefficient step which also results in additional CO₂ emissions. The PYSOLO project aims at developing an indirectly heated solar-driven biomass pyrolysis system which, thanks to the use of solar heat in the pyrolysis process, maximizes the products yield and achieves negative emissions associated to biochar production. Introduction Methodology and Project Status System Description The PYSOLO project has started in July 2023. The particle receiver, based on a rotary kiln design, will be developed and tested by DLR. For the pyrolysis section, CSIC will design and test a fluidized bed reactor, while RE-CORD, supported by POLITO, will develop an Auger reactor. The project will also test particle/air and particle/char separators, along with a particle induction heating system. Various particle heat carriers (PHCs) will be assessed to identify the most effective option based on integrated system performance. POLIMI will carry out modelling at both component (receiver and pyrolyzer) and system levels to define the most cost-effective plant layout. NOVA and INERIS will evaluate the PYSOLO system through life cycle assessment (LCA) and risk analysis, respectively. CTFC will guide biomass selection for the experimental campaigns and identify the most suitable feedstocks for southern European applications. Finally, the biochar produced will be tested by CSIC for its potential as a fertilizer. PYSOLO is expected to successfully operate the TRL4 solar particle receiver in experimental campaigns at temperatures and with PHC relevant for solar pyrolysis for about 300h reaching peak thermal efficiencies in the 80-85% range. The TRL4 pyrolysis units will also be tested for about 300h with the selected PHC with expected limited variation (<10%) in the product composition for a selected set of operating conditions. The system’s techno-economic analysis is expected to demonstrate over 80% carbon efficiency and at least a 20% reduction in bio-oil production costs compared to conventional pyrolysis, with LCA indicating significant negative emissions of approximately –0.3 kg CO₂ per kg of biomass fed to the system. Expected Results The PY SOLO Project: Biomass Pyrolysis by Concentrated Solar Power Marco Binotti*, Marco Colombi, Tomás García, Neus Puy, Guy Marlair, Verena Kuhlmann, Clarisse Lorreyte, Giacomo Lombardi, Matteo Prussi, Martina Fantini *mail: [email protected], www.pysolo.eu This work is funded by the European Union under PYSOLO project (Grant Agreement n. 101118270). Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or CINEA. Neither the European Union nor the granting authority can be held responsible for them. Acknowledgements EUBCE 2025, 33rd European Biomass Conference & Exhibition, 9 -12 June 2025, Valencia Conference Center, Spain The particles heated in the solar receiver are directly used as heat carrier (PHC) in the pyrolyzer to sustain the endothermic pyrolysis process, thus avoiding the need of heat transfer surface in the reactor facilitating the system scale-up. Downstream, a particle separator allows the separation between the PHC and the biochar produced. Compared to directly irradiated biomass reactors, the decoupling between solar receiver and pyrolizer enhances flexibility and allows continuous operation with thermal energy storage integration or with hybrid operation. Project Objectives and Advantages The PYSOLO process aims at developing at TRL4 the two key unit operations of this novel solar pyrolysis system: the solar particle receiver and the pyrolysis reactor with the associated particle-char separator. The PYSOLO system can operate in different modes, offering several advantages: i) Solar mode: Produces bio-oil, pyrogas, and biochar using solar heat or stored high-temperature solids; ii) Self-sustained mode: Operates without solar input by using electric heating or combusting pyrogas/biochar when storage is depleted; iii) Grid balancing services: provides grid ancillary services by generating power from excess pyrogas or converting surplus PV/wind electricity to heat via induction heating.