New Solar Device Removes Carbon Dioxide From the Atmosphere

If the experimental technology can be commercialized, it can become an important tool for reducing the impact of climate change. 

 

Researchers used simulated sunlight to power a solar cell that converts atmospheric carbon dioxide directly into syngas, a combination of hydrogen gas and carbon monoxide that can be burned for energy or converted into liquid fuels. (Photo: University of Illinois at Chicago/Jenny Fontaine)

A new type of solar-powered technology has the potential to play a big role in the fight against climate change if its inventors can take it from the laboratory to industrial-scale use.

On Thursday, a team of scientists announced in the journal Science that they have created a device that absorbs carbon dioxide from the atmosphere and uses sunlight to break it into a mix of carbon monoxide and hydrogen called synthesis gas or “syngas,” that can be used directly or turned into diesel or other liquid fuels, said Amin Salehi-Khojin, a mechanical engineer at the University of Illinois at Chicago who leads the lab that conducted the research.

The team aims to produce fuel at about $2 a gallon, he said, a price that would be cost-competitive with gasoline and, in his opinion, make drilling for oil or gas obsolete.

Although burning such a transportation fuel would release the carbon back into the atmosphere, it could be considered a carbon-neutral energy source. That’s because that carbon would have been removed from the atmosphere to make the syngas, thus producing no new emissions.

“This is a real artificial leaf, ” Salehi-Khojin said. Where plants use sunlight to power photosynthesis, absorbing CO2 and turning it into sugar for energy, “we use the energy from the sun, and by CO2 remediation, we store the energy of the sun in the chemical bonds” of the syngas.

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“The beauty of this work is it directly uses the energy of the sun. This doesn’t need any electricity or external energy,” said Mohammad Asadi, the study’s lead author and a researcher in Salehi-Khojin’s lab.

So far the team has created a working prototype of the device on a small scale, using artificial sunlight and a direct source of CO2 to study and optimize the chemical process, said Salehi-Khojin, who said a provisional patent has been filed for the technology. The Department of Energy and the National Science Foundation funded the research.

“In terms of the size of the setup, we have used 100 square centimeters of the catalyst,” Asadi said. “We need to make it bigger than this to take it to the industrial scale.” He envisions a “solar park” that would draw CO2 out of the atmosphere, as well as smaller installations attached to power plants and industrial facilities to capture their CO2 emissions.

The Intergovernmental Panel on Climate Change considers this sort of innovation—sometimes called “negative emissions” or carbon capture and storage technology—crucial to averting extreme climate change. Under the Paris agreement signed this year, nations pledged to keep global temperature increases below 2 degrees Celsius (3.6 degrees Fahrenheit). But the amount of carbon dioxide already in the atmosphere all but guarantees that temperatures will rise at least 1.5 degrees above historic norms in the coming century.

Global temperatures are already about 0.9 degrees Celsius above those of preindustrial times.

There are many efforts underway to expand carbon-neutral or negative emissions technologies, such as an Icelandic pilot project that is converting power plant emissions into stone. There’s even a Carbon X Prize competition under way, with a $20 million payoff for the winning team. But most of these projects focus on storing emissions from smokestacks rather than dealing with the carbon already in the atmosphere