Process simulation of fuel production through integration of high-temperature co-electrolysis in a Biomass-to-Liquid process

To reduce greenhouse gas emissions in the aviation sector, the development of so-called sustainable aviation fuel (SAF) is indispensable. SAF can be produced via different synthesis routes and has identical properties to fossil-based conventional aviation fuel. Based on the results of previous research, a process pathway to produce SAF via a Biomass-to-Liquid (BtL) concept using entrained flow gasification and Fischer-Tropsch synthesis is simulatively investigated. To optimize overall process efficiency, high-temperature co-electrolysis can be integrated into the process chain resulting in a Power-and-Biomass-to-Liquid (PBtL) approach. Co-electrolysis makes it possible to split carbon dioxide as well as water electrochemically in a single apparatus and to produce synthesis gas with the required properties for Fischer-Tropsch synthesis. A detailed 0D Python model of a reversible solid oxide cell (rSOC) was developed at the Chair of Energy Systems to calculate the steady-state fuel cell and electrolysis operation based on a defined input parameter set. The validation using measured and literature data shows that the current density-cell voltage behaviour can be reproduced with an average relative error of less than 5%. Based on the existing BtL process, two concepts for the integration of co-electrolysis are identified and the 0D rSOC model is integrated into the Aspen Plus^® flowsheet simulation. The newly developed process options are compared with alternative PBtL process variants showing that an identical product yield and carbon efficiency is achieved in different configurations and that electrical power demand can be significantly reduced by integrating co-electrolysis.