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Energy Currents
A Blog by Enerdynamics

Sucking Carbon out of Thin Air – Reality or Fantasy?

By Bob Shively, Enerdynamics President and Lead Facilitator

Scientists agree that to avoid the worst impacts of climate change caused by humans emitting greenhouse gases (GHG), we must dramatically reduce the amount of carbon in the atmosphere. Such efforts are currently focused on reducing future emissions through energy efficiency, shifting to low carbon fuels, and/or by carbon capture and storage from power plants and factory smokestacks.

But to really avoid dramatic climate impacts, reducing the carbon that has already been emitted as well as offsetting future emissions that can’t practically be avoided may also be necessary. Current efforts on this front include planting trees and preserving existing forests since trees absorb carbon from the atmosphere. An alternative approach is to utilize a machine that sucks carbon out of the air. This is called Direct Air Capture (DAC), an industrial process that removes carbon from the air and allows it to be stored in permanent underground storage or to be used in making synthetic fuels.

Simply sucking carbon out the air? Is this for real? It is already being done. But whether it can be done at a feasible cost on a large enough scale to be a meaningful contributor remains to be determined.

Let’s look at how DAC works. While details vary from project to project, the overall concept is the same. Atmospheric air is sucked into the DAC unit with large fans. The air is circulated through either liquid chemical solutions that absorb carbon or through solid sorbent filters that chemically bind with carbon. A process is applied to remove the carbon from the liquid or the filters and combine it with oxygen, resulting in CO2 collection. The CO2 can then be used for other industrial processes, or it more likely will be sequestered in permanent underground storage.

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The International Energy Agency (IEA) reports there are currently 19 direct energy projects in the world. But all are small, mostly research or demonstration projects. The first commercial project in operation is the Orca plant built by Climeworks in Iceland. Climeworks is operating using the liquid method. (See a video on how it works and you can also go to its website and subscribe for a specified amount of carbon to be removed on your behalf.) Much of the company’s investment comes from corporations who are using Climework’s services to help achieve corporate low-carbon goals including Microsoft, Audi, Shopify, and Stripe.

     The Orca DAC plant in Iceland (Photo courtesy of Climeworks)

Another company, Carbon Engineering, is currently engineering two larger DAC projects, one in west Texas and one in Scotland (their technology uses solid filters). Its investors include BHP, Chevron, Oxy Low Carbon Ventures, and the Bill Gates Foundation.

While the capability for DAC to work has been proven technologically, the biggest question is whether it can be made cost-effective. Climework’s current costs are believed to be in the range of $600 to $800/ton. But the current value of carbon reduction in today’s largest carbon trading markets is around $80/ton in Europe and $28/ton in California. Forecasts for future cost reductions, as DAC projects scale up and the technology is refined, suggest costs may be reduced to $200 to $300/ton in the next decade and ultimately to as low as $100/ton. This may be within the range of cost competitiveness.

Some environmentalists are lukewarm on DAC because the concept doesn’t discourage carbon emissions but rather leads to a “clean it up later” mentality. Others believe it may be an important tool among a larger toolset designed to combat climate change. Money for further development of the technology is available. The U.S. government has included $3.5 billion for four DAC hubs in the recently passed infrastructure bill; other governments around the world are also supporting development; and Elon Musk has offered a $100 million X-prize for carbon removal. While it will take some time to achieve meaningful levels of direct air carbon removal, it certainly seems that moving forward with commercializing the technology is an important insurance policy against failure of other decarbonization efforts.  

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