Opportunities and Challenges for Power-to-Liquid Technologies towards Sustainable Aviation

Abstract

The aviation industry will continue to rely on liquid fuels due to the required high energy density and the significant investment costs of changing today’s engine technology and airport infrastructure. In order to restrict aviation related greenhouse gas (GHG) emissions in the context of a continuously growing air traffic, the international aviation sector has agreed on an offsetting scheme called CORSIA to directly fund carbon-reducing activities in October 2016. The mid-term target is a CO2 neutral growth from 2021. Conversion of CO2 and sustainable hydrogen to fuels via the Power-to-Liquid (PtL) process is one promising option to reduce dependency on fossil fuels and mitigate climate change. Our previous study has already assessed the PtL process by means of water electrolysis, reverse water-gas shift reaction and Fischer-Tropsch synthesis for the production of certified jet fuel. A detailed flow-sheeting model of a PtL plant was implemented and investigated in an extensive techno-economic assessment. It was shown that the net production costs of such synthetic fuels are much higher compared to conventional kerosene. Recently, the specific carbon footprint of power based jet fuels and GHG abatement costs for different plant locations and applied renewable power sources have been evaluated in order to estimate their contribution to the set GHG reduction targets in the aviation sector. Furthermore, the effect of the application of different technology options on the abatement cost has been evaluated in terms of CO2 separation, water and/or CO2 electrolysis, CO2 activation (autothermal versus allothermal) and FT synthesis within the PtL concept and will be presented. For this purpose, the production cost flows within the PtL concept were visualized using exergoeconomic methods. Based on the results, recommendations are given were financial support for technology development will result in highest fuel cost reduction. Precise technology research and development goals were derived in order to reach market readiness level of alternative fuels. A further support for the PtL concept might be the inclusion of aviation in the European Emission Trading Scheme.