Carbon dioxide 'scrubber' captures greenhouse gases

University of Calgary climate change scientist David Keith and his team are working to efficiently capture the greenhouse gas carbon dioxide directly from the air, using near-commercial technology.

In research conducted at the U of C, Keith and a team of researchers showed it is possible to reduce carbon dioxide (CO2) – the main greenhouse gas that contributes to global warming – 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 per cent 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.

"While it's important to get started doing things we know how to do, like wind power nuclear power and 'regular' carbon capture and storage, it's also vital to start thinking about radical new ideas and approaches to solving this problem."

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.

"David Keith's vision and originality are key factors in our ranking this year as the top engineering school in Canada for sustainability initiatives, both in terms of research and curriculum," says Elizabeth Cannon, Dean of the Schulich School of Engineering. "Leaders like this are not commonplace, and we are proud to get behind this kind of leadership at the Schulich School."

Air capture is different than the carbon capture and storage (CCS) technology which 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 carbon dioxide produced during burning of the coal, and then pipelining this CO2 for 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 tonne of carbon dioxide. Their custom-built tower was able to capture the equivalent of about 20 tonnes per year of CO2 on a single square metre of scrubbing material – the average amount of emissions that one person produces each year in the North American-wide economy.

"This means that if you used electricity from a coal-fired power plant, for every unit of electricity you used to operate the capture machine, you'd be capturing 10 times as much CO2 as the power plant emitted making that much electricity," Keith says.

The U of C team has devised a new way to apply a chemical process derived from the pulp and paper industry 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.

Richard Branson, head of Virgin Group, has offered a $25-million prize for anyone who can devise a system to remove the equivalent of one billion tonnes of carbon dioxide or more every year from the atmosphere for at least a decade.

Keith and his team's research this summer, which included an outdoor test of their capture tower in McMahon Stadium in Calgary as a dramatic setting, is featured in an episode of Discovery Channel's new "Project Earth" series on television.

The series has the largest budget of any in Discovery Channel's history, and it may attract a global viewership of more than 100 million. The episode on Keith's research isn't scheduled to be broadcast in Canada until the second Friday of January 2009, but it has already aired in the U.S. and is available on Discovery Channel's website (> ); click on "Episodes."

Technical details of the air capture technology are available at:

Source: University of Calgary

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Sep 29, 2008
Sounds more like an engineer than a climate change scientist.

Sep 29, 2008
Lol I saw that episode and it did look like a very efficient machine. It very quickly removed carbon in the immediate area, from what i remember it dropped from 350 to 100 in a matter of 10 minutes...

Sep 29, 2008
So how do they do it?

Sep 29, 2008
Seems that they have a tower where they spray the air with NaOH. That gives Na2CO3 which they further process back to NaOH. The process is given here:
http://www.ucalga.../Misc/AC talk MIT Sept 2008.pdf

Sep 30, 2008
I wonder how they deal with the excess heat from the reaction as NaOH and CO2 creates a very strong exothermic response.

Maybe they could extract the heat energy from the exothermic response and convert that back to electricity...just a thought

Oct 01, 2008
This invention does not stand a chance of ever being implemented on a wide scale. Most people are more worried about their retirement than CO2 levels that measure in the PPMs. The people who ARE urging reductions in CO2 do NOT want a machine to do it with. They want you and me to drastically change our lifestyle. It's all about control over us. You are correct Graymouser, he's an engineer trying to help. Too bad no one really want's his machine.

Oct 07, 2008
MikeB, if you use less electricity, reuse more and trash less, and consume less fuel... how are you giving in to some secret conspiracy? What could anyone have to gain from you consuming LESS? Isn't MORE consumption how people transfer wealth in capitalism? Your thinking on this matter reminds me of conspiracies I have read about secret satanic cults or even 9-11... except at least in those situations the supposed conspirators have something to gain from their vast secret conspiracy. The only thing I can think of that could possibly resemble a conspiracy to make money is the carbon trading BS, which is just stupid anyways. Other then that, reducing your footprint on the environment is not a bad thing, and does not require a drastic change in lifestyle. You are just making excuses at this point.

Oct 08, 2008
"Isn't MORE consumption how people transfer wealth in capitalism?"
That's the point man, it AIN'T capitalism. It's not about money, it's all about control over you and me, as I stated above. Did you even read my comment?
Who made money when Castro took Cuba into socialism? Only Castro. But Cubans must be your heroes because they now use less electricity, reuse more and trash less, and consume less fuel.
Too bad they had to give up their freedom.
I guess I'm crazy but I've got this idea that the Cubans who came to America are much better off.

In short, mesa, I don't want the USA to become a Cuba.

Oct 17, 2008
I looked this guy up. He's a PhD in Physics so I wouldn't say he's a climatologist. Maybe that explains why he's doing an engineering project.

Nov 27, 2008
firstly ,freedom is relative . to be truly free one must own or control sufficient land and resources to be self sufficient and beholding to none. To release ourselves from the control of the oil and coal industries would be a move toward greater freedom , but only if we do not replace those industries with another that controls our energy resources. the ultimate aims should be to produce an efficient CO2 re-cycler
with as an end product a viable alternative fuel that can be readily used in currently available vehicles and power plants and adapted homes.

Sep 01, 2009
is this guy so brilliant? I remember back in 1988 when I was qualifying submarines I had to learn about the CO2 scrubber. This is really old technology where they mixed the air with a chemical called Amine and then it would use a process to make the Amine release the CO2 to a catch to pipe it off the boat. This guy must have had something to do with subs in some way and taking the technology to relabel it as a new product. The only question I have is once you scrubb the CO2, what are they going to do with it? There has to be some way to dispose of it. We just difussed it into the water since we did not want to keep it onboard. Maybe change it into something else that becomes solid and not dangerous, maybe even into straight carbon and the compress it into diamonds lol.

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