Researchers at the Paul Scherrer Institute PSI and partner institute Empa have started a joint research initiative called SynFuels. The goal is to develop a process for producing kerosene from carbond dioxide and green hydrogen. Over the next three years, the two Swiss research institutes will jointly search for practical ways of linking carbon dioxide and hydrogen to form longer-chain molecules and thus produce synthetic fuels. The Board of the Swiss Federal Institutes of Technology (ETH) is funding the SynFuels program with 6.2 million Swiss francs (US$6.9 million).

Aviation fuels are the fuels with the highest quality. If we can manage to produce them from renewable resources, then we will also be able to synthesise all other kinds of fuel.

—Thomas J. Schmidt, head of the Energy and Environment Division at PSI

For the foreseeable future, there’s no way around kerosene in aviation—be it fossil-based or synthetically produced. Kerosene is a mixture of hydrocarbons with very precisely specified chemical and physical properties that must be strictly maintained to ensure the economy and safety of flight operations. A synthetic fuel must have the same properties.

A synthesis process that produces such fuels from renewable resources is thus highly sought after.

—Brigitte Buchmann, head of the Mobility, Energy, and Environment Department at Empa

Carbon dioxide and green hydrogen are the starting materials for the manufacturing process to be developed. The carbon dioxide comes from various sources, such as from biomass, directly from ambient air, or from industrial manufacturing processes such as cement production. The hydrogen required, in turn, is generated from water with the help of renewable electric power.

The liquid fuel will not be synthesized in a single step, but via one or more intermediates such as methane, carbon monoxide, methanol, ethylene, or dimethyl ether. During the course of the SynFuels initiative, the researchers want to determine the advantages these different production methods offer as well as the challenges they pose.

A special focus is being placed on achieving better selectivity in the synthesis of both intermediates and products. Analyses to determine the synthesized fuel’s ecological footprint, its potential contribution to greenhouse gas reduction in Switzerland, and the economic viability of the manufacturing process are also important parts of the project.

PSI is mainly building on its experience with the test platform ESI: Energy System Integration. ESI tests renewable energy alternatives in their complex interaction. PSI has been investigating the synthesis of renewable methane for a long time.

Empa, too, has been engaged with using renewable energy to produce fuels for some time. Switzerland’s first hydrogen filling station was created as part of its mobility demonstrator, called move. In addition, the plant is currently being expanded to include a new methanation process.

The collaboration of our two institutions allows us to put more emphasis on liquid hydrocarbons. These are essential for mobility without fossil fuels – especially in the air or on the water.

—Brigitte Buchmann

Catalysts are the key to the success of the project. At Empa as well as at PSI, researchers are investigating various catalysts and processes that enable the stepwise conversion of carbon dioxide and hydrogen into liquid hydrocarbons on the molecular level. The catalysts are being used in chemical as well as electrochemical processes.

The Swiss Light Source SLS will be an important aid in the SynFuels programme, Thomas J. Schmidt explains.

With measurements at SLS, we will precisely characterise the catalysts and the reactions carried out to understand which can deliver the best results.

—Thomas J. Schmidt

With this large research facility, the collaborators can gain insights into the reaction mechanisms and investigate, for example, how the catalysts change during their operation and how these changes affect the range of products.