Capturing carbon out of thin air?


Prof. David Keith, a well-respected climate-change scientist from the University of Calgary, believes it’s possible to design a machine that can snatch carbon dioxide out of ambient air. In fact, he knows it can be done — he has built the machine to do it. Now the challenge is to scale it up and make it more economical.

Keith and a team at the university announced this past week what he admits comes across as “absurd,” but after years of study and experimentation his efforts are paying off. The team has demonstrated the capture of CO2 directly from the air using less than 100 kilowatt-hours of electricity per ton of carbon dioxide. It means the electricity from a coal-fired plant could be used to capture 10 times as much CO2 as the power plant itself emitted.

What they’ve built so far is capable of capturing the equivalent of 20 tons per year of CO2 on a single square metre of scrubbing material. That’s about the average emissions that a single person generates each year in North America. The potential is huge, says Keith, to build such machines and place them anywhere in the world, as opposed to just the flue stacks of fossil-fuel power plants. This is important, because it means we can potentially remove CO2 from the atmosphere that is the result of transportation emissions, which current carbon capture and sequestration schemes (designed for new power plants) can’t address.

“A company could, in principle, contract with an oilsands plant near Fort McMurray (Alberta) 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,” explains Keith, who is director of the Institute for Sustainable Energy, Environment and Economy’s environmental systems group at the university, where he is a professor of chemical and petroleum engineering.

According to one report, the patented process extracts CO2 from the air using sodium hydroxide. For more technical details check out this presentation from Keith. Taking CO2 out of the atmosphere is considered a huge challenge because the greenhouse gas only represents .04 per cent of the air, whereas emissions from a power plant have concentrations closer to 10 per cent or higher, depending on the technology used.

And think about it — if we could actually do it, and do it economically, it could mean there’s a way to not just minimize how much CO2 we dump into the atmosphere, but also to remove more from the air than we actually put in. In other words, we can proactively lower CO2 concentrations. Keith acknowledges there are others pursuing this path, including researchers at Columbia University and Lawrence Livermore National Laboratory. The question now is who can get it┬áto the point of deploying a commercial-scale plant that can be economically replicated in a world where a value is placed on carbon?

Keith, to his credit, doesn’t oversell the idea. He emphasizes it’s a complement to existing approaches, and shouldn’t take attention away from other approaches — we’ll need them all. At the same time, such a radical, fabulous approach to dealing with the carbon problem can’t be ignored and must be pursued with vigour.

I’ve got a few questions. Like, what happens with the CO2 once it’s captured? What form is it in? Can it be safely stored? Is the chemical process, reportedly borrowed from the pulp and paper industry, something that can be scaled up enough to make a difference, or are there limitations? I hope soon to have a chat with Keith to clear these issues up.

If it wasn’t for the fact that Keith is a high-profile Canadian scientist with top credentials, I’d be a little more skeptical. But this appears to be a serious pursuit, and as such, it’s an area I’m encouraged by and hope to learn more about.

NOTE: Keith’s project was profiled on Discovery Channel. Click here for a tour of the “carbon scrubber.”

4 thoughts on “Capturing carbon out of thin air?”

  1. Other questions to ask include the total lifecycle GHG emissions including production of the capital equipment and production and disposal of the chemicals used, and whether there would be any added efficiency to the system if it were used on the more concentrated CO2 stream from a power plant.

  2. Sounds amazing, but how does the cost/benefit for this stack up against planting fast growing plants and lots of them? This sounds like an amazing technology if it works, and coupled to something like carbon nano-tube synthesis, or some other really good use for pure carbon, it could be world changing, but…

    Bamboo and certain vines can grow amazingly fast, get their mass from carbon in the atmosphere, how would this this stack up?

  3. So, doesn’t Richard Branson owe him some money?

    It’s hard to imagine this process being cheaper than avoiding emissions in most cases, but I suppose it could be tied to the harder-to-reduce emissions from aviation, or if China ever gets roped into a cap-n-trade system, they could use this technology to offset while they’re waiting for all those shiny new coal plants to finish their lifecycles. It’d have to be pretty cheap, though.

    Anyway, regardless of the expectations, we need all the silver buckshot we can get. And sooner or later, we’ll have to start considering carbon-negative schemes.

  4. I saw the Discovery show on this a couple of weeks ago. It was pretty amazing. They set it up in a football stadium and ran it all night. I wasn’t 100% clear on the results. They had a readout on the scoreboard and said if it was over 20 then the test was successful, it read like 50. I don’t know if that means it captured 25 times the CO2 or only 2.5 times the CO2.

Comments are closed.