The reduction in greenhouse gas emissions is an essential factor in addressing climate change. Today, April 22, 2021, the United States hosts the Leaders’ Summit on Climate, where President Biden will commit the U.S. to cut greenhouse gas emissions by 53% by 2030. This summit with international leaders will focus on efforts to reduce future greenhouse gas emissions and meet the goal of keeping global warming below 1.5c under the Paris Climate Agreement.
But what about all the greenhouse gases, specifically CO2, that have already been released? The concentration of CO2 in the atmosphere has been steadily rising since the Industrial Revolution during the 18th century. As of March 2021, the atmospheric CO2 concentration stands at 417.64 parts-per-million (ppm). For context, we only just crossed the 400-ppm mark in 2015, which is 100 ppm higher than the highest historical CO2 level reached 400,000 years ago. Considering CO2 can stay trapped in the atmosphere for 300 to 1,000 years, what can be done about the CO2 still lingering above our heads?
What is Direct Air Capture, and how does it work?
Direct air capture (DAC) is an emerging technology that works to remove CO2 directly from the atmosphere. DAC is different from Carbon Capture and Storage (CCS) because CCS is used at the point when emissions are released (think power plants, steel mills, and other industrial operations). In comparison, DAC technology removes atmospheric CO2 right out of the air from any location.
DAC can be done via two different systems: a liquid system and a solid direct system. Both systems use large fans to pull in atmospheric air and force it over a CO2 trapping liquid or solid substance, depending on the technique used. In a liquid system, that substance is a chemical solution that binds with the CO2 molecules, trapping it in the solution as a carbonate salt. Whereas in a solid direct system, the air is forced over a solid material called sorbent filters that then chemically bind with CO2.
What do we do with captured CO2?
Now that we have captured CO2, what can be done with it? First, in both processes, the CO2 trapping substance is heated to release the concentrated CO2, which can then be stored. This stored CO2 can be used to create synthetic fuels, and these fuels could be used as a carbon-neutral option compared to traditional fuel sources.
The other option is to turn the stored CO2 into stone. In Iceland, the company Carbfix is doing just that. To accomplish this, the stored CO2 from DAC is mixed with water. Through a proprietary process, it is then injected into reactive rock formations like basalt. Once the CO2-containing solutions interact with the rock formations, stable minerals begin to form in as little as two years, storing the CO2 indefinitely.
What is the future of DAC?
Is DAC the single technological solution to climate change that we have all been hoping for? Most likely not. But that doesn’t mean that it can’t play an essential role in tandem with other approaches and technologies to decarbonize the economy. Anthony Hobley, Executive Director of Mission Possible at the World Economic Forum, emphasizes the importance of decarbonization efforts:
“It is imperative given the urgency of the climate emergency that we are facing that we develop and deploy all of the tools at our disposal to achieve net-zero by 2050, including decarbonizing our economies in line with robust net-zero roadmaps and, where necessary, carbon capture technologies. Not as an alternative to net-zero driven emission reductions, but as well as – there is not enough time left for an either/or approach.”
The commercial use of DAC is still in the early stages, with one of the first commercial facilities being Orca, a DAC facility operated by the Swiss company Climeworks in partnership with the Icelandic company Carbfix, where they are working to sequester CO2 underground. Another use case is the Canadian online retailer Shopify that has recently struck a deal with the Canadian-based clean energy company Carbon Engineering and their DAC system to offset Shopify’s carbon footprint.
While DAC technology is still in its infancy, the ways in which DAC technology can be incorporated into local and global decarbonization plans are promising. DAC isn’t the magic technological bullet needed to fix climate change. Still, it can be one of many critical tools required to decarbonize the global economy and reign in the worst effects of climate change.
Climate Breakdown 