Direct Air Capture

Direct air capture (DAC) is a method of capturing CO2 from the atmosphere. The two technologies in this space are Solid sorbents and liquid solvents. The major challenge with this approach is cost. Estimates range from ~$100/ton to $1000/ton. At the scale needed to have an impact this is hundreds of billions of dollars of investment. Additionally, the carbon still needs to be sequestered somewhere, geological sequestration being the currently viable route. DAC is challenged by the relatively (vs. flume gases) concentrations of CO2 in the atmosphere. Therefore, DAC has high energy requirements. This energy requirement is key to sustainability of DAC since energy source can be a driver of cost and CO2 emissions1.

Alternatively, the CO2 can be sold as a gas, but the market is small (e.g. soda beverages, algae farms, green houses). Serving this market imposes its own costs on already expensive model2. Additionally, it will likely produce CO2 further reducing the net efficiency of the process. Some CO2 can also be sold off to oil companies to be used to release stored oil3. This can lead to problematic incentives.

Companies in this space

References

1.
of Sciences, N. A., Engineering & Medicine. Negative emissions technologies and reliable sequestration: A research agenda. (The National Academies Press, 2019). doi:10.17226/25259.
2.
Fasihi, M., Efimova, O. & Breyer, C. Techno-economic assessment of CO2 direct air capture plants. Journal of cleaner production 224, 957–980 (2019).
3.
Olick, D. These companies are sucking carbon out of the atmosphere and investors are piling in. Cnbc at https://www.cnbc.com/2021/07/23/these-companies-are-sucking-carbon-from-the-atmosphere.html (2021).
4.
Keith, D. W., Holmes, G., St. Angelo, D. & Heidel, K. A Process for Capturing CO2 from the Atmosphere. Joule 2, 1573–1594 (2018).

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