The HyFlexFuel project, aims to bring the green conversion technology known as hydrothermal liquefaction (HTL) to a higher technology readiness level. Hydrothermal liquefaction is emerging as innovative technology to produce renewable transportation fuels. The advantages of HTL are reflected in its high feedstock versatility, its ability to convert wet materials and its advantageous environmental and economic performance. The aim is to produce drop-in replacement fuels, particularly for transport sectors that are likely to depend on liquid hydrocarbon fuels for the short to medium-term future, such as aviation and maritime shipping.

The HTL technology is extremely versatile in its ability to use wet waste feedstocks such as wastewater sludges, manures, agricultural residues and other wastes. In the HyFlexFuel-project the core HTL production takes place at the Centre for Biorefining Technologies at the Foulum campus of Aarhus University. The pilot plant produces the raw product, bio-crude, which is similar to petroleum derived crude oil. The technology is indeed comparable to the natural production of fossil fuel where high heat and pressure produced crude oil under the earth surface over millions of years. The HTL process does the same, but in only 25 minutes by applying 350°C heat and 200 bar pressure in the presence of water. Analogous to crude oil, the bio-crude undergoes an upgrading and refining process.

Refining of bio-crude to final products ranging from aviation fuels to platform chemicals are investigated at Aalborg University (DK) and industrial partners from the petrochemical refining sector, Eni (IT) and Haldor Topsøe (DK). The complex reaction pathways, quality of bio-crudes and upgraded fuels are analysed using advanced analytical chemistry techniques at the iNANO/Department of Chemistry (AU) and the Paul-Scherrer Institut (PSI, CH). A deeper understanding of these chemical processes will aid in optimizing the process in terms of energy and carbon efficiency.

In the theme of the circular bioeconomy, a work package of HyFlexFuel is dedicated to the recovery of nutrients and valorization of carbon in all product phases which include a process water and a solid residue. The HTL pilot plant is able to recover most of the feedstock phosphorous in a concentrated solid residue using high temperature and pressure filtration. Scientists at the University of Hohenheim (DE) will combine the P with NH4 from the process water to produce a Magnesium-Ammonium-Phosphate fertilizer to close the nutrient cycle. The remaining carbon in the process water can be converted to methane using hydrothermal gasification (PSI, CH) or anaerobic digestion (Organic Waste Systems, BE). Using these technologies an overall carbon efficiency of ~80% can be achieved from feedstock to fuel.

HyFlexFuel is coordinated by Bauhaus Luftfahrt e.V. (DE), a non-profit research institution with focus on the future of mobility, especially of the aviation sector. Bauhaus Luftfahrt will assess the HyFlexFuel production pathway with respect to its potential environmental impact and economic performance. As an important task in HyFlexFuel, regional and local feedstock availability and supply chains will be analyzed by the German Biomass Research Centre (DBFZ).

HyFlexFuel has received funding from the European Union’s Horizon 2020 research and innovation programme. The project was awarded 5 million € of which 930,000€ are awarded to Aarhus University. Arttic (FR) is acting as the project management partner of HyflexFuel and follow the project on twitter for updates https://twitter.com/hyflexfuel