Making Fuels with Carbon Dioxide Pulled From Air Could be Affordable

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Carbon Engineering shows direct air capture could cost $100 a ton

In the fight to slow down climate change, few ideas generate more hype, scorn, and desperate hope than capturing carbon dioxide from the air. Critics point to its massive expense, as much as US $1000 to extract a metric ton of carbon dioxide.

Now Harvard geoengineer David Keith has proven that direct air capture is doable on an industrial scale for $100 a ton.

Carbon Engineering, the company Keith founded in 2009 and that has Bill Gates’ support, has been capturing a ton of carbon dioxide every day since 2015 at its pilot plant north of Vancouver. Keith and his team have now come up with the first-ever detailed engineering design and cost analysis of a plant that would capture 1 million tons of carbon dioxide a year. They describe their results today in the journal Joule.

“There has been a lot of talk about direct air capture technology,” Keith says. “We help to bring it down to reality. This is not some kind of narrow scientific innovation. It’s not something we did in the lab. It’s the product of a tested engineering process.”

Carbon Engineering uses a bank of giant fans to draw ambient air and push it through an aqueous solution that reacts with carbon dioxide. Heat and known chemical reactions separate the CO2 molecules. The company combines it with hydrogen produced from water electrolysis to create liquid fuels that can be used in today’s trucks and aircraft engines. They started making these fuels at the plant in December.

Keith acknowledges that making carbon dioxide an ingredient in fuel doesn’t help to reduce the overall amount of carbon dioxide in the atmosphere. But because the carbon-neutral fuel replaces fossil fuels that would add more planet-warming gas to the atmosphere, it would make a large dent in transportation-related CO2 emissions.