CO2 and water are extracted from air and split into their constituent molecules by help of energy produced by solar panels
Air travel accounts for around 2% to 3% of global carbon emissions, but scientists are working on ways to reduce the industry’s reliance on fossil fuels. As part of that project researchers in Switzerland have built a plant in Zurich for producing carbon-neutral liquid fuels from — wait for it — sunlight and air.
During the process carbon dioxide and water are extracted from air and split into their constituent molecules by help of energy produced by solar panels. The result is a mixture of hydrogen and carbon monoxide, which can then be processed into kerosene, methanol, and other hydrocarbons for fueling airplanes and ships at sea.
The scientists, who have published their findings in a study, are now working on upscaling their technology for their so-called “solar kerosene” to industrial production levels in a cost-effective manner with a liter of fuel costing between €1.20 to €2.
“This plant successfully demonstrates the technical feasibility of the entire thermochemical process for converting sunlight and ambient air into drop-in fuels,” explains Aldo Steinfeld, professor of renewable energy sources at ETH Zurich, whose team built the pilot project on a roof at the university.
“The system operates stably under real-world solar conditions and provides a unique platform for further research and development,” the scientist adds.
The scientists say that deserts bathed in sunshine all year round would be ideal sites for producing their solar-derived fuel.
“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 one percent of the world’s arid land and would not compete with the production of food or livestock feed,” stresses Johan Lilliestam, professor of energy policy at the University of Potsdam who was a leader of the research team.
“If the materials used to build the production facilities, such as glass and steel, are manufactured using renewable energy and carbon-neutral methods, emissions can be further reduced to close to zero,” the scientists note in a statement.
On the downside, initial investment costs would be high, but policymakers within the European Union could enact legislation to support the adoption of solar fuels.
“The European Union’s existing support instruments — emissions trading and offsetting — are not sufficient to stimulate market demand for solar fuels,” Lilliestam says. “In view of this, we propose the adoption of a European technology-specific quota system for aviation fuel. This would require airlines to acquire a specific share of their fuel from solar sources.”
Initially, the airline industry would need to adopt a share of 0.1% of “solar kerosene” when the fuel’s price is still high as a result of low production capacities.
“This would have little impact on the cost of flying, but would promote the construction of production facilities and set in motion a learning curve that could lead to technological enhancements and lower prices,” the scientists explain.
“The quota could then be gradually increased until solar kerosene achieves a market breakthrough without further support measures.”