Direct Air Capture, North America & Europe

Direct air capture (DAC)

Author: World Resource Institute

Direct air capture is a technology that uses chemical reactions to pull carbon dioxide out of the air. When air moves over these chemicals, they selectively react with and trap CO2, allowing the other components of air to pass through. Today’s leading systems use either liquid solvents or solid sorbents, which are composed of common chemicals that are already in use in other applications today, from soap to water filtration.

Once carbon dioxide is captured from the atmosphere, heat is typically applied to release it from the solvent or sorbent. Doing so regenerates the solvent or sorbent for another capture cycle. Other systems in development use electrochemical processes, which could reduce energy needs and costs.

The captured CO2 can then be injected deep underground for sequestration in certain geologic formations or used in various products and applications. The carbon benefit of use in products, or the net quantity of carbon that is durably stored, depends on the product. Use in products like concrete or plastic can provide long-term sequestration (decades or even centuries), whereas using carbon dioxide in products like beverages or synthetic fuel would quickly re-release carbon into the atmosphere. In some cases — jet fuel, for example — synthetic fuel produced with CO2 could still be a more favorable substitute for more emissions-intensive fossil fuel. 

However, to maximize climate benefit, most captured CO2 would need to go to vast and permanent underground sequestration rather than valuable but more limited utilization routes.

DAC has seen a surge in interest and investment over the past few years, and a growing number of companies are entering the space. This is due to the understanding that carbon removal will increasingly be needed to meet national and global climate goals, along with the benefits of DAC compared to other carbon removal approaches, which include few practical limits on scaling, relatively little land area use, and siting flexibility.

Companies with the most developed technologies today include Climeworks, Carbon Engineering, and Global Thermostat. Together, these companies have 18 plants of varying sizes (1 tCO2/yr up to 4,000 tCO2/yr capacity, the largest plant in operation today), capturing a total of just under 8,000 tCO2/yr. Around half of that is sequestered permanently — similar to the annual emissions from 870 cars — while the other half is sold for use in various products.

Despite the benefits and flexibility, direct air capture is more costly per tonne of CO2 removed compared to many mitigation approaches and natural climate solutions, as it is energy-intensive to separate carbon dioxide from ambient air. The range of costs for DAC varies between $250 and $600 today depending on the technology choice, low-carbon energy source, and the scale of their deployment; for comparison, most reforestation costs less than $50/tonne.

However, depending on the rate of deployment, which could accelerate through supportive policies and market development, costs for DAC could fall to around $150-$200 per tonne over the next 5-10 years. Going further than this, the U.S. Department of Energy (DOE) launched its Carbon Negative Shot initiative in late 2021, which aims to reduce the cost of carbon removal technologies and approaches that could reach a gigaton scale of $100/tCO2 over the next decade.

Climate models make it increasingly clear that carbon dioxide removal will likely need to happen on a multi-billion-tonne scale by mid-century, along with deep emissions reductions. And the slower we are to reduce emissions, the more we may need to rely on carbon removal — including DAC — to meet national and global climate goals.

 Achieving large-scale carbon removal will require a portfolio of different approaches, which will reduce cost and the risk of any one approach failing to provide the expected removal. Investing in DAC now will help reduce future costs, which can prove critical as carbon dioxide removal becomes even more necessary.

Source: https://www.wri.org/insights/direct-air-capture-resource-considerations-and-costs-carbon-removal