Thermo-economic optimisation of the integration of electrolysis in SNG production from wood

Converting wood to grid quality methane allows to distribute a CO 2 free, renewable energy resource in a conventional energy distribution system and use it in transportation applications. Applying a multi-objective optimisation algorithm to a previously developed thermo-economic process model for the thermochemical production of synthetic natural gas from wood, the present paper assesses the prospect of integrating an electrolyser in conversion systems based on directly and indirectly heated gasification. Due to an inherent lack of hydrogen for complete conversion of wood into methane and the possibility for rational use of oxygen, it is shown that electrolysis is an efficient and economically interesting option for increasing the gas output of the process while storing electricity and producing fuel that mitigates CO2 emissions.