Integrated design of high temperature steam electrolysis and biomass to liquid fuel process

Abstract

Second generation biofuels offer a key for several energy issues, but feedstock is still limited. To improve the use of biogenic carbon, coupling Biomass to Liquid (BtL) process to a hydrogen supplier unit is studied. Water electrolysis enables to produce hydrogen and also required oxygen in line with energy issues; High Temperature Steam Electrolysis (HTSE) coupling is particularly promising: it allows to recover free heat from BtL process and to reuse coproduced water, offering therefore synergies. This work addresses the integrated design of the HTSE and BtL hybrid process for its optimization. The comprehensive gate-to-gate analysis includes BtL and hydrogen production on-site operations. Considering productivity, efficiency, cost and environmental issues, five criteria have been chosen: carbon matter yield; energy efficiency; greehouse gases emissions; water use; levelized biofuels production cost. Simulations are carried out using a commercial process simulation software - ProSimPlus® - to allow physical modeling and mass and energy balances; modeling is based on standard elementary and user modules and supported by various CEA previous works. The first concluding elements in studying integrated HTSE-BtL process verify that hydrogen input is almost doubling the productivity (biofuels/biomass). They bring out significant secondary energy saving for HTSE compared to standard process; and clear advantages over alkaline electrolysis considering technical and environmental criteria. The framework for design optimization is proposed.