Solar Refinery Turns Light and Air into Liquid Fuel

Carbon-neutral fuels are an essential part of making aviation and maritime transportation sustainable.

Jul 17, 2019

Electric vehicles have come along way, and we now have electric cars, bikes, trains, and even small planes. But, the transportation industry depends on large airplanes and ships that can haul cargo across the globe. The batteries for electric vehicles do not have that capacity, so the only sustainable alternative to fossil fuels are synthetic fuels or biogas fuels made from natural substances.

Now, a research team of scientists and engineers from ETH Zurich in Switzerland announced that they had created a ground-breaking carbon-neutral solar refinery that can produce liquid fuels. It essentially turns light and air into fuel. And even more importantly, it releases as much CO2 during combustion as what was previously extracted from the air during production.

“This plant proves that carbon-neutral hydrocarbon fuels can be made from sunlight and air under real field conditions,” said Aldo Steinfeld, a professor of renewable energy carriers at ETH, in a news release. “The thermochemical process utilizes the entire solar spectrum and proceeds at high temperatures, enabling fast reactions and high efficiency.”

The system is not that complicated. The solar refinery extracts CO2 and water directly from ambient air and splits them using solar energy - then both go into the reactor. The solar radiation is concentrated by a factor of 3,000 generating heat of 1,500 degrees Celcius inside the reactor.

Next, during the redox cycle, the water and CO2 are split, and this yields syngas – a mixture of hydrogen and carbon monoxide – which is processed into liquid hydrocarbon fuels that can be used for global transportation.

The mini solar refinery built on the roof of the university shows that the technology works and produces around one deciliter (almost half a cup) of fuel per day. Now, the researchers are working on a large-scale test of a solar reactor in a tower near Madrid in Spain as part of the EU's sun-to-Liquid project.

The next goal is to scale the technology so that it can be used for industry and to make it economically competitive to use.

“A solar plant spanning an area of one square kilometer could produce 20,000 liters of kerosene a day,” said Philipp Furler, director of Synhelion, a spin-off that was founded in 2016 to make the technology commercial.

“Theoretically, a plant the size of Switzerland—or a third of the California Mojave Desert—could cover the kerosene needs of the entire aviation industry. Our goal for the future is to efficiently produce sustainable fuels with our technology and thereby mitigate global CO2 emissions,” Furler said.

Two spin-offs have already come out of Steinfeld’s research group: Synhelion and Climeworks (founded in 2010), both of which commercialized CO2 capture from air.

New solutions to eliminating fossil fuels and the threat they pose to the climate and our future are badly needed, and technological achievements like the solar refinery can help us save the earth.

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Bonnie Riva Ras has dedicated her life to promoting social justice. She loves to write about empowering women, helping children, educational innovations, and advocating for the environment & sustainability.