The aviation sector is responsible for approximately 5% of current anthropogenic greenhouse gas emissions causing climate change. It strongly relies on kerosene, or jet fuel, which is a liquid hydrocarbon fuel typically derived from crude oil. Currently, no clean alternative is available to power long-haul commercial flights on a global scale.
Now, an international team of researchers has developed a tower that uses solar energy to produce a synthetic alternative to fossil-derived fuels like kerosene and diesel. The fuel production system uses water, carbon dioxide (CO2), and sunlight to produce aviation fuel. The team has implemented the system in the field, and the design could help the aviation industry become carbon neutral.
The solar-made kerosene is fully compatible with the existing aviation infrastructure for fuel storage, distribution, and end use in jet engines. It can also be blended with fossil-derived kerosene, says Aldo Steinfeld, a professor from ETH Zurich and the corresponding author of the paper.
The solar fuel production plant consists of 169 sun-tracking reflective panels that redirect and concentrate solar radiation into a solar reactor mounted on top of a tower. The concentrated solar energy then drives oxidation-reduction (redox) reaction cycles in the solar reactor, which contains a reticulated porous ceramic structure made of ceria. The ceria – which is not consumed but can be used over and over – convert water and CO2 injected into the reactor into syngas, a tailored mixture of hydrogen and carbon monoxide. Subsequently, syngas is sent into a gas-to-liquid converter, where it is finally processed into liquid hydrocarbon fuels that include kerosene and diesel.
“This solar tower fuel plant was operated with a setup relevant to industrial implementation, setting a technological milestone towards the production of sustainable aviation fuels,” Steinfeld says.
During the nine-day run of the plant reported in the paper, the solar reactor’s energy efficiency – the portion of solar energy input that is converted into the energy content of the syngas produced – was around 4%. The team says they are working intensively on improving the design to increase the efficiency to values over 15%.
They are also exploring ways to optimize the ceria structure for absorbing solar radiation and developing methods to recover the heat released during the redox cycles. According to researchers, the fuel that is produced is fully compatible with the existing aviation infrastructure for fuel storage, distribution, and use in jet engines.
“With our solar technology, we have shown that we can produce synthetic kerosene from water and CO2 instead of deriving it from fossil fuels. The amount of CO2 emitted during kerosene combustion in a jet engine equals that consumed during its production in the solar plant,” Steinfeld says. “That makes the fuel carbon neutral, especially if we use CO2 captured directly from the air as an ingredient, hopefully in the not-too-distant future.”
meta: Researchers developed a tower that uses solar energy to produce a synthetic alternative to fossil-derived fuels like kerosene and diesel.