Solar-powered reactor created by University of Cambridge converts CO2 from the air into sustainable fuel

University of Cambridge researchers have developed a solar-powered reactor that takes carbon dioxide from the air and converts it into sustainable fuel.

It could be used to make fuel to power cars and planes, create chemicals and pharmaceutical products and used to generate fuel in remote or off-grid locations.

While carbon capture and storage (CCS) technology has been awarded £22bn funding by the UK government, there are concerns that it typically involves a fossil fuel-based power, and the transport and storage of carbon dioxide.

The new research, however, is inspired by photosynthesis and converts atmospheric CO2 using sunlight - with no batteries or cables required - into syngas, a key intermediate in the production of many chemicals and pharmaceuticals.

St John’s College fellow Prof Erwin Reisner, who led the research, said: “Aside from the expense and the energy intensity, CCS provides an excuse to carry on burning fossil fuels, which is what caused the climate crisis in the first place. CCS is also a non-circular process, since the pressurised CO2 is, at best, stored underground indefinitely, where it’s of no use to anyone.”

First author Dr Sayan Kar, from Cambridge’s Yusuf Hamied Department of Chemistry, said: “What if instead of pumping the carbon dioxide underground, we made something useful from it? CO2 is a harmful greenhouse gas, but it can also be turned into useful chemicals without contributing to global warming.”

With no transportation or storage required, the technology is much easier to scale up than earlier solar-powered devices.

The device is a solar-powered flow reactor that uses specialised filters to grab CO2 from the air at night, much like a sponge soaking up water.

When the sun comes out, the sunlight heats the captured CO2, absorbing infrared radiation and a semiconductor powder absorbs the ultraviolet radiation to start a chemical reaction that converts the captured CO2 into solar syngas. A mirror on the reactor concentrates the sunlight to make it more efficient.

The researchers are now working on converting the solar syngas into liquid fuels that could power cars, planes and more, without adding more CO2 to the atmosphere.

Dr Kar said: “If we made these devices at scale, they could solve two problems at once: removing CO2 from the atmosphere and creating a clean alternative to fossil fuels. CO2 is seen as a harmful waste product, but it is also an opportunity.”

The chemical and pharmaceutical sector could benefit, as syngas can be converted into many of the products we rely on every day, without contributing to climate change.

A larger scale version of the reactor is being built for testing this spring.

In theory, individuals could use the reactor to generate their own fuel, which would be useful in remote or off-grid locations.

“Instead of continuing to dig up and burn fossil fuels to produce the products we have come to rely on, we can get all the CO2 we need directly from the air and reuse it,” said Prof Reisner. “We can build a circular, sustainable economy – if we have the political will to do it.”

The technology is being commercialised with the support of Cambridge Enterprise, the university’s commercialisation arm. The research was supported in part by UK Research and Innovation (UKRI), the European Research Council, the Royal Academy of Engineering, and the Cambridge Trust.