Techno-economic analysis of integration possibilities for fluctuating renewable energy sources in the Power and Biomass to Liquid process

Abstract

Sustainable aviation fuels provide the opportunity to reduce the aviation industry’s climate impact while avoiding a complete replacement of the current aircraft fleet. The European Union directs its member states to a gradual uptake of sustainable aviation fuel from 2 %vol. in 2025 to 63 %vol. by 2050 with the ReFuelEU directive. Yet, biomass-based fuel production in Europe is limited by the availability of sustainable biomass. This limitation can be mitigated by the Power Biomass to Liquid process, which attains near full biogenic carbon conversion to fuel by the addition of electrolytic hydrogen. This work evaluates the economic feasibility and global warming impact of sustainable aviation fuel production via the Power Biomass to Liquid process. Different options to enhance process performance and reduce its footprint are analyzed. This includes a discussion of process configurations and integration options for fluctuating energy sources. Based on flowsheet simulations in Aspen Plus, production costs, emissions and fuel production volume are estimated under different economic and regional boundary conditions. The production cost for the Power Biomass to Liquid process is highly sensitive to the electricity price. In fact, the electricity cost is the largest cost contributor followed by the cost for the biomass and the electrolyzer investment. The electricity’s carbon footprint is also shown to be the determining factor for the fuel’s global warming potential. Therefore, regions with inexpensive and green electricity, either from their national grid mix or their renewable energy potential, are the ideal sites for the Power Biomass to Liquid process. In a region-specific analysis, Norway and Sweden present good production sites due to their suitable grid conditions. Ireland is a promising production site based on its onshore wind potential. High electricity prices and emissions can also be avoided by operating the Power Biomass to Liquid process dynamically. Yet, dynamically operated electrolysis units add substantial cost when over-dimensioned. Therefore, an optimum between reduced electricity costs and increased capital expenses has to be found. A cost reduction can also be achieved by identifying process configurations suited for the regionspecific boundary conditions. A higher CO2 recycle ratio, for example, leads to an enhanced product yield at the cost of a larger hydrogen demand. Due to the increased electricity demand for hydrogen production, this is only cost-effective at low electricity prices. When considering forest residues with an availability of 33 % as the feedstock for the Power Biomass to Liquid process, around 25 Mt/a sustainable aviation fuel can be produced within Europe. This output could be even higher when agricultural residues can also be utilized. Yet, this production volume of sustainable aviation fuel depends upon low-carbon electricity. When considering grid connected operation in Europe today, only around 5 Mt/a can be produced when adhering to the European sustainable aviation fuel definition of 70 % emission reduction compared to fossil fuel.