University of Calgary Scientist Captures CO2 from Air

• Oct 16, 2008

University of Calgary climate change scientist David Keith and his team are working to efficiently capture the greenhouse gas carbon dioxide (CO₂) directly from the air, using near-commercial technology, according to a recent press release. Keith and a team of researchers showed it is possible to reduce carbon dioxide using a relatively simple machine that can capture the trace amount of CO₂ present in the air at any place on the planet.

"At first thought, capturing CO₂ from the air where it's at a concentration of 0.04 percent seems absurd, when we are just starting to do cost-effective capture at power plants where CO₂ produced is at a concentration of more than 10 per cent," says Keith, Canada Research Chair in Energy and Environment. "But the thermodynamics suggests that air capture might only be a bit harder than capturing CO₂ from power plants. We are trying to turn that theory into engineering reality."

The research is significant because air capture technology is the only way to capture CO₂ emissions from transportation sources such as vehicles and airplanes. These so-called diffuse sources represent more than half of the greenhouse gases emitted on Earth.

"The climate problem is too big to solve easily with the tools we have," notes Keith, director of the Institute for Sustainable Energy, Environment and Economy's (ISEEE) Energy and Environmental Systems Group and a professor of chemical and petroleum engineering.

Energy-efficient and cost-effective air capture could play a valuable role in complementing other approaches for reducing emissions from the transportation sector, such as biofuels or electric vehicles, says David Layzell, ISEEE's executive director.

"David Keith and his team have developed a number of innovative ways to achieve the efficient capture of atmospheric carbon. That is a major step in advancing air capture as a solution to a very pressing problem," Layzell says.

Air capture is different than the carbon capture and storage (CCS) technology that is a key part of the Alberta and federal governments' strategies to reduce greenhouse gas emissions. CCS involves installing equipment at, for example, a coal-fired power plant to capture CO₂ produced during burning of the coal, and then sending it to permanent storage underground in a geological reservoir.

Air capture, on the other hand, uses technology that can capture -- no matter where the capture system is located -- the CO₂ that is present in ambient air everywhere. "A company could, in principle, contract with an oilsands plant near Fort McMurray to remove CO₂ from the air and could build its air capture plant wherever it's cheapest -- China, for example -- and the same amount of CO₂ would be removed," Keith says.

Keith and his team showed they could capture CO₂ directly from the air with less than 100 kilowatt-hours of electricity per ton of carbon dioxide. Their custom-built tower was able to capture the equivalent of about 20 tons per year of CO₂ on a single square meter of scrubbing material -- the average amount of emissions that one person produces each year in the North American-wide economy.

The U of C team has devised a new way to apply a chemical process derived from the pulp and paper industry to cut the energy cost of air capture in half, and has filed two provisional patents on their end-to-end air capture system.

The technology is still in its early stage, Keith stresses. "It now looks like we could capture CO₂ from the air with an energy demand comparable to that needed for CO₂ capture from conventional power plants, although costs will certainly be higher and there are many pitfalls along the path to commercialization." Nevertheless, the relatively simple, reliable and scalable technology that Keith and his team developed opens the door to building a commercial-scale plant.

For technical details of the air capture technology, visit www.ucalgary.ca/~keith/AirCapture.html.