Carbon-neutral fuels are crucial for making air and sea transport sustainable. Aldo Steinfeld, professor of renewable energy sources at Eidgenössische Technische Hochschule Zürich, and a team of researchers have been operating a mini solar refinery for two years. He says, “This plant successfully demonstrates the technical feasibility of ... converting sunlight and ambient air into drop-in fuels. The system operates stably under real-world solar conditions and provides a unique platform for further research and development.” The technology is now ready for industrial application. The plant will be used to produce synthetic liquid fuels that release CO2 extracted directly from ambient air during their combustion using solar energy. The process yields syngas, a mixture of hydrogen and carbon monoxide, that can be processed into kerosene, methanol or other hydrocarbons.

Johan Lilliestam, a research group leader at the Institute for Advanced Sustainability Studies and professor of energy policy at the University of Potsdam, explains, “Unlike with biofuels whose potential is limited due to the scarcity of agricultural land, this technology enables us to meet global demand for jet fuel by using less than 1 percent of the world’s arid land, and would not compete with the production of food or livestock feed.” Given the high initial investment cost, solar fuels will need political support while the price of solar kerosene is high and production capacities are low. This would have little impact on the cost of flying, but would promote the construction of production facilities and lead to lower prices.