Carbon-neutral fuel made from sunlight and air
Researchers from ETH Zurich have developed a novel technology that produces liquid hydrocarbon fuels exclusively from sunlight and air. For the first time worldwide they demonstrate the entire thermochemical process chain under real field conditions. The new solar mini-refinery is located on the roof of ETH’s Machine Laboratory building in Zurich.
Carbon-neutral fuels are crucial for making aviation and maritime transport sustainable. ETH researchers have developed a solar plant to produce synthetic liquid fuels that release as much CO2 during their combustion as previously extracted from the air for their production. CO2 and water are extracted directly from ambient air and split using solar energy. This process yields syngas, a mixture of hydrogen and carbon monoxide, which is subsequently processed into kerosene, methanol or other hydrocarbons. These drop-in fuels are ready for use in the existing global transport infrastructure.
Aldo Steinfeld, Professor of Renewable Energy Carriers at ETH Zurich, and his research group developed the technology. “This plant proves that carbon-neutral hydrocarbon fuels can be made from sunlight and air under real field conditions,” he explained. “The thermochemical process utilises the entire solar spectrum and proceeds at high temperatures, enabling fast reactions and high efficiency.” The research plant at the heart of Zurich advances ETH’s research towards sustainable fuels.
A small demonstration unit with big potential
The solar mini-refinery on the roof of ETH Zurich proves that the technology is feasible, even under the climate conditions prevalent in Zurich. It produces around one decilitre of fuel per day. Steinfeld and his group are already working on a large-scale test of their solar reactor in a solar tower near Madrid, which is carried out within the scope of the EU project external page sun-to-liquid. The solar tower plant is presented to the public in Madrid at the same time today as the mini-refinery in Zurich.
The next project goal is to scale the technology for industrial implementation and make it economically competitive. “A solar plant spanning an area of one square kilometre could produce 20,000 litres of kerosene a day,” said Philipp Furler, Director (CTO) of Synhelion and a former doctoral student in Steinfeld’s group. “Theoretically, a plant the size of Switzerland – or a third of the Californian 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.”
Two spin-offs already
Two spin-offs already emerged from Aldo Steinfeld’s research group: external page Synhelion, founded in 2016, commercializes the solar fuel production technology. external page Climeworks, founded already in 2010, commercialises the technology for CO2 capture from air.
How the new solar mini-refinery works
The process chain of the new system combines three thermochemical conversion processes: Firstly, the extraction of CO2 and water from the air. Secondly, the solar-thermochemical splitting of CO2 and water. Thirdly, their subsequent liquefaction into hydrocarbons. CO2 and water are extracted directly from ambient air via an adsorption/desorption process. Both are then fed into the solar reactor at the focus of a parabolic reflector. Solar radiation is concentrated by a factor of 3,000, generating process heat at a temperature of 1,500 degrees Celsius inside the solar reactor. At the heart of the solar reactor is a ceramic structure made of cerium oxide, which enables a two-step reaction – the redox cycle – to split water and CO2 into syngas. This mixture of hydrogen and carbon monoxide can then be processed into liquid hydrocarbon fuels through conventional methanol or Fischer–Tropsch synthesis.
Comments
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Fantastic, I knew this was possible and necessary, and it was only a matter of time which has now come. Yipee, Thank you
ETHZ: Where the future begins!!!
nice job!!!
Exceptional science, engineering, and demonstration by the imaginitive and creative scientists and engineers at ETH Zurich of critically required environmentally friendly green technology. This development needs to be expanded to several larger demonstration units and a prototype production facility. European and governments around the World need to get involved and aggressively support with appropriate funding.
Congratulations. Am I right in estimating around 0,5L / day for H2 production out of this 1 particular setup? And how does this compare to using regular solar power and electrolysis on the same ground surface area ?
It's a good idea and congratulations. I am a researcher and university professor in Brazil, enthusiastic about concentrated solar applications. I fully agree that capturing CO2 can be a good alternative, especially in Brazil, due to industrial processes, car emissions, the increased use of natural gas-fired thermoelectric plants. I would suggest making a comparison of thermal and electrical energy, both generated by the same high temperature heliothermic plant, to generate the same "heating value" for CO and H2 (kJ / kg), using thermochemistry and electrolysis, respectively. The extraction of CO2 does not seem to have an impact on water vapor in the atmosphere. On the other hand, H2 may perhaps cause some climatic disturbances in rainfall cycles, atmospheric humidity, and levels of water reservoirs in hydroelectric plants. In addition, perhaps CO2 extraction should be more efficient near thermal power plants, industrial cities, and large metropolises. Congratulations and go ahead.
What is the technical term for this?
Wishing you every success in this ongoing research and development. All new entries into clean sustainable fuel and Energy are good news in the gradual journey away from fossil fuels.
This is a great job and a wonderful solution. ETH rocks! I hope the technology will be soon commercially available and massively installed in all the major cities so to reduce the pollution in a convenient and affordable way.
Congratulations, keep going until it is used for daily transportation. Not investing in this by major companies like Airbus and Boeing and investment funds will prove how shortsighted and greedy are too many people still.
If I calculate well you become a production of 0,2 kw /m2 a day 20000 l fuel at 0,5 € a day how can you rentabilise this project
All will and good but are you going to compete with the petrol companies or do they need to invest in this? No matter how good of an invention you have, if no one invest with you no one will know you. Someone has to transport this and sell it at the pump.
A french version of this article would be good.
Cool application of a solar concentrator. Like it. But, why doing this from the air, with CO2 concentrations in the ppm range? Do this capturing a combustion power plant exhaust for instance. More fuel output and avoids putting CO2 in the atmosphere in the first place, rather than trying to capture it.
Wow - ETH Zurich leading the way! Congratulations!
Excellent! ETH Zurich has shown again it's world class in innovation.
Congratulation! Good job