Due to their scalability, Power-to-Liquid (PTL) fuels are a key technology for carbon-neutral aviation. Bauhaus Luftfahrt and Ludwig-Bölkow-Systemtechnik (LBST) summarised the great potential of PtL in terms of technical, economic, and environmental aspects within the background paper “Power-to-Liquids – A scalable and sustainable fuel supply perspective for aviation”. The document is available for download from the website of the German Environment Agency 1 .
The initial version of the background paper, which was issued in 2016 by Bauhaus Luftfahrt and LBST on behalf of the German Environment Agency 2 , anchored PtL fuels within discussions on the future sustainable fuel supply of aviation. Meanwhile, PtL fuels are commonly understood as an important option to achieve carbon-neutral aviation by mid-century. Furthermore, with a growing number of project developments, the initial production ramp-up of PtL jet fuels is now within reach.
The updated background paper reviews the basic principles of typical routes for PtL fuel production as well as resource and production potentials. To meet the required scale, PtL fuels need to be primarily produced from solar and wind energy. In that case, the technical production potential within Europe exceeds the European jet fuel demand by about one order of magnitude. While significant cost reductions are expected, long-term PtL fuel production costs remain comparably high, in a range of 1170 – 1740 €/t. On the other hand, PtL fuels are much more resource-efficient in terms of land and water demand than biofuel production from energy crops.
Production costs and greenhouse gas emissions of key aviation fuel options
Global warming potential versus production costs of key options for renewable aviation fuels, in relation to conventional jet fuel prices, ICAO default emissions, and threshold values from the European Renewable Energy Directive (EU-RED II). ICAO default emissions for most first-generation biofuel pathways (examples: AtJ from corn ethanol, HEFA from soybean oil) exceed European threshold values for minimum GHG emission reductions. HEFA fuels from waste fats, oils, and greases (FOG) usually meet GHG requirements, but their scalability is limited by feedstock availability. Biofuel conversion pathways for advanced feedstock (BtL, HTL, Pyr) unlock significant additional feedstock potentials, but further research and development is required to commercialise advanced biofuels. The projected production costs and GHG emissions of synthetic fuels from CO2 and H2O (PtL, StL) and LH2 depend critically on the renewable resource potential at the plant location. At a given location, costs and emissions for LH2 production (without transport) will be significantly lower compared to PtL and StL due to a higher conversion efficiency and the need of a carbon source for kerosene synthesis.
Feedstock: Corn = corn grain; EtOH = ethanol; FOG = fats, oils, and greases; LigC = lignocellulose; MSW = municipal solid waste; Soy = soybean oil; SwS = sewage sludge; Conversion: AtJ = alcohol-to-jet; BtL = biomass-to-liquid; HEFA = hydroprocessed esters and fatty acids; HTL = hydrothermal liquefaction; LH2 = renewable liquid hydrogen from electrolysis*; PtL = power-to-liquid; Pyr = pyrolysis; StL = sunlight-to-liquid; Data source: Emission data of conventional jet fuel and first-generation biofuels (AtJ/EtOH/Corn, HEFA/Soy) from ICAO document “CORSIA Default Life Cycle Emissions Values for CORSIA Eligible Fuels”, 2nd Edition, March 2021; Advanced biofuels data from Bauhaus Luftfahrt literature research compendium; Performance ranges of LH2, PtL, and StL from Bauhaus Luftfahrt research and publications. * LH2 volume in kerosene equivalent of lower heating value