Exergetic analysis of renewable Fischer-Tropsch fuels production from biomass, CO2 and electricity

Kurzfassung

Greenhouse gas emissions in the transport sector could significantly be reduced when fossil fuels are replaced by green alternatives. Though, natural non-fossil resources are finite and resource efficient production processes have to be developed to limit both the ecological footprint and economic costs of future fuels. Exergy analysis is a powerful tool to analyze and optimize thermochemical and biological fuel production processes. In this study, green Fischer-Tropsch fuel production from biomass, CO2 and green electricity is analyzed from an exergetic point of view. Flow-sheeting models of various fuel concepts were developed in Aspen Plus® software and a detailed exergy analysis was carried out with the in-house software tool TEPET (Techno-Economic Process Evaluation Tool). Exergy flow diagrams were created to visualize exergy flows within the processes. Results show that syngas production is responsible for most of the exergy destruction within the fuel production system. Exergetic efficiencies in the range between 37.8 % and 63.5 % were calculated depending on the concept design and product definition. Technology options are discussed to further increase the overall energetic performance. Results can be used as starting point for an exergoeconomic process evaluation to identify optimal process designs characterized by lowest fuel production costs.