Swiss concentrated solar

Switzerland is a centre for cutting edge research into solar energy. Photovoltaics is the main application of solar energy, generating electricity at around 20% efficiency. However, using the sun’s heat more directly can improve efficiency.

Solar Refinery

At ETH Zurich, a team of researchers are running small-scale application, which uses a room-sized parabolic mirror to focus sunlight to heat a small area to 1,500°C. In a ceramic structure made of cerium oxide, a two-step reaction occurs:

1. Redox cycle: water and CO2 are split into syngas, a mixture of hydrogen and CO. 2. The H and CO are processed through the Fischer-Tropsch synthesis or other conventional methods to make liquid hydrocarbon fuels, such as methanol or kerosene.

Applications: these hydrocarbons are created by extracting carbon from the air. Combustion in aviation and maritime transport, sectors which do not have electrical alternative drives, will release CO2 and water. The use of the solar refinery ensures carbon-neutral fuel cycles, and enables the elimination of fossil fuels. The fuels can be inserted directly into the existing infrastruture and machinery, so this decarbonisation route is much more cost-effective than conversion to electrical drives or hydrogen fuel cells.

The thermochemical process utilises the entire solar spectrum.

The 3m trial mirror in Zurich can generate one decilitre of fuel per day. A larger scale project is being planned in a solar tower near Madrid, as part of the EU project Sun-to-Liquid.

Economic potential: one square km of solar plant could produce 20k litres of kerosene per day. The entire aviation industry could be fuelled by 40k km2, the size of Switzerland, or a third of the Mojave Desert. [Philipp Furler, Director of Synhelion]

Two spin-offs: Synhelion, founded i 2016, commercialises the solar fuel production technology. Climeworks, founded in 2010, commercialises CO2 capture technology.