New Solar Tech Captures CO₂ from air and Turns It into Fuel
A new solar-powered direct air capture system not only removes CO₂ from the atmosphere but converts it into syngas, a key precursor for synthetic fuels.
Most climate efforts focus on reducing carbon dioxide (CO₂) emissions. However, the challenge remains: we’ve already released vast amounts of CO₂ into the atmosphere. While direct air capture (DAC) technologies exist, they are expensive and difficult to scale. But what if we could transform that CO₂ into something useful?
A new study presents a solar-powered direct air capture system that not only extracts CO₂ from the atmosphere but also converts it into renewable syngas — a key precursor for synthetic fuels. This system operates solely on sunlight, removing the need for high temperatures, pressure, or purified CO₂ feeds.
Image credits: University of Cambridge.
Carbon Capture and Storage (CCS) is often proposed as a solution to the climate crisis. However, CCS is energy-intensive and expensive, with costs ranging from $125 to $335 per ton of CO₂. For perspective, the U.S. alone emits approximately 13 million tons of CO₂ daily. Additionally, long-term underground CO₂ storage remains controversial, as its long-term effects are uncertain.
Instead of sequestering captured CO₂ underground, this new system offers an alternative: converting the extracted CO₂ into syngas, which can be used to produce synthetic fuels.
“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,” said Professor Erwin Reisner, who led the research. “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.”
“What if instead of pumping the carbon dioxide underground, we made something useful from it?” said first author Dr. Sayan Kar from Cambridge’s Yusuf Hamied Department of Chemistry. “CO2 is a harmful greenhouse gas, but it can also be turned into useful chemicals without contributing to global warming.”
Depiction of traditional CCS. Image credits: CSIRO.
The newly developed system took inspiration from photosynthesis. It uses a solid silica-based absorbent material to trap CO₂ during the night. This process basically produces CO₂-free air, leaving all the other gases (like nitrogen or oxygen) to pass through. Then, during the daytime, a catalyst converts the CO₂ into syngas, using only sunlight as a source of heat. A mirror concentrates the sunlight, making the process more efficient.
Syngas, short for synthesis gas, is a mixture of carbon monoxide (CO) and hydrogen (H₂) that serves as a crucial intermediate in industrial chemistry. It is primarily used to produce synthetic fuels, methanol, ammonia, and various other chemicals. This could offset some of the costs associated with CCS and perhaps even make the technology scalable.
“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,” said Kar. “CO₂ is seen as a harmful waste product, but it is also an opportunity.”
Can this actually be scaled up?
Developing a proof-of-concept is one thing — scaling it up is another. Currently, the system produces up to 260 µmol of CO per gram of TiO₂ catalyst over 12 hours under concentrated sunlight at 25°C. While promising, further optimization is needed for commercial viability. Long-term stability and durability of the catalyst are also key concerns.
If scaled up, however, this technology could dramatically lower the net cost of DAC by creating a self-sustaining carbon economy, where carbon dioxide removal is financially viable through the sale of synthetic fuels. Instead of paying for storage, industries could profit from captured CO₂, making carbon capture more economically attractive and scalable. Since it operates on solar energy, the technology could complement solar power plants by capturing and utilizing CO₂.
The prospects are there. But at the end of the day, investments will decide whether this technology takes off or not.
“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 Reisner. “We can build a circular, sustainable economy – if we have the political will to do it.”
