Sequestration

What you need to know

As discussed in our brief on decarbonization, most strategies for reducing CO2 levels in the atmosphere involve switching to power generation and transportation technologies that produce less CO2. An alternate strategy is to extract and store carbon dioxide from the atmosphere, referred to as sequestration. At first glance, sequestration could be an attractive option for achieving the “net zero” goal, where the total amount of CO2 in the atmosphere would remain constant instead of increasing. Instead of building costly new renewable energy sources, retrofitting buildings, and switching to electric vehicles, sequestration offers a way for society to continue producing and using energy largely as we do now. The primary difference is that we would have to implement enough sequestration measures to offset global CO2 emissions. The question is, is sequestration on the levels required to achieve this outcome even possible? What would it cost?

How does Sequestration work?

One sequestration technique, Carbon Capture and Storage (CCS), collects CO2 as it is produced by a power plant or factory. This method has the advantage of capturing CO2 before it is released into the atmosphere. The CO2 is pressurized into liquid form and then injected into rock formations within geological basins, deep enough that it will not leak back into the atmosphere. CO2 can also be injected into depleted oil and natural gas wells to increase production.

A second technique, Direct Air Capture (DAC), involves extracting CO2 from the atmosphere and injecting it underground. At present, this technique is only used in small-scale experimental facilities.

A third technique, Biological Carbon Sequestration (BCS), involves efforts to increase the biomass (plants and trees) in the environment, which removes carbon dioxide from the atmosphere through the natural process of photosynthesis. Conservation ensures that the carbon remains in solid form, or, the biomass can be harvested and burned to produce energy, with the resulting CO2 emissions captured and stored.

Can Sequestration make a difference?

At present, sequestration is a minor contributor to controlling atmospheric CO2 levels. The Rhodium Group, a leading, independent researcher on climate and energy policy, estimates that the United States emitted 5,100 MM tons in 2023 (MM = million metric tons, one metric ton equals about 2,200 pounds), a 1.9% drop in emissions from the prior year. Sequestration was a very minor component of this decline. The United States houses 15 CCS facilities as of September 2023. These facilities can capture about 22 MM tons of carbon emissions each year (or approximately 0.4% of the total emissions in the United States).

Cost estimates for a larger sequestration effort that would capture enough CO2 to offset continued emissions are unavailable. CCS systems have only been implemented for a narrow set of CO2-generating facilities such as power plants. It is unclear how to capture CO2 from other major producers such as automobiles and aircraft. DCS systems exist today only in experimental form.

As for biological methods, an estimate developed by a team of scientists led by Dr. Thomas Crowther and published in a leading journal (Science 365) found that meeting the goal of capturing enough CO2 to limit global temperature increases to 1.5 degrees Celsius would require doubling the size of the world’s forests – a dramatic change in land-use patterns and one that might require government expropriation of privately-held lands. For more details on the laws governing expropriation, see our brief on Eminent Domain in the further reading section. It is impossible to estimate the cost of this effort, but it is surely massive.

It is also possible that increased CO2 levels could cause increased plant growth, leading to some additional carbon capture without human intervention. However, studies of this mechanism also suggest that higher CO2 levels could lead to increased releases of CO2 from decayed plant matter in the soil. Thus, it is unclear whether the net effect of higher CO2 levels on sequestration is positive or negative.

The introduction of large-scale sequestration technologies would raise additional questions. The capture and transportation of compressed CO2 requires specially designed pipes and storage facilities that are expensive to build. Moreover, the Environmental Protection Agency’s underground injection control program mandates a 50-year post-injection period in which the site must be maintained and monitored. It is unclear whether existing techniques ensure that CO2 will not leak out during this time, or what could be done to stop a leak once it started.

Current federal programs offer grants to demonstration and pilot projects for development of new sequestration programs. However, the success of these efforts is far from guaranteed.

The Take-Away

If large-scale, cheap sequestration was possible, it could be an ideal choice for reducing global CO2 levels. At present, however, sequestration is expensive and can only deal with a small percentage of global CO2 emissions. Without significant technological breakthroughs, sequestration is currently not a viable option for addressing climate change.

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Sources

How Does Sequestration work?

United States Geological Survey. (n.d). What is carbon sequestration? https://tinyurl.com/yckmv7pv, accessed 3/14/24.
United States Geological Survey. (n.d). What’s the difference between geologic and biologic carbon sequestration? https://tinyurl.com/y9eck257, accessed 3/14/24.
Environmental Protection Agency. (2017). Carbon Dioxide Capture and Sequestration: Overview. https://tinyurl.com/rcf5ve2p, accessed 3/14/24.
Howard, H. (2023). Carbon Capture. MIT Climate Portal. https://tinyurl.com/3ber78s6, accessed 3/14/24.

Can Sequestration Make a Difference?

King, B., Gaffney, M., & Rivera, A. (2024). Preliminary US Greenhouse Gas Emissions Estimates for 2023. Rhodium Group. https://tinyurl.com/4a4trz7r, accessed 3/14/24.
Kearns, D., Liu, H., & Consoli, C. (2021). Technology Readiness and Cost of CCS. Global CCS Institute. https://tinyurl.com/ztawxyyv, accessed 3/14/24.
Musick, N., et al. (2023). Carbon Capture and Storage in the United States. Congressional Budget Office. https://tinyurl.com/3wbdf8dt, accessed 3/14/24.
Psarras, P., He, J., Pilorgé, H., McQueen, N., Jensen-Fellows, A., Kian, K., & Wilcox, J. (2020). Cost Analysis of Carbon Capture and Sequestration from U.S. Natural Gas-Fired Power Plants. Environmental Science & Technology, 54 (10), 6272-6280. https://tinyurl.com/bdd3dsy2, accessed 3/14/24.
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Bastin, Jean-Francois, Yelena Finegold, Claude Garcia, Danilo Mollicone, Marcelo Rezende, Devin Routh, Constantin M. Zohner, and Thomas W. Crowther. “The global tree restoration potential.” Science 365, no. 6448 (2019): 76-79.
Alonso-Serra, J. (2021). Carbon sequestration: counterintuitive feedback of plant growth. Quantitative Plant Biology, 2, e11.
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Contributors

Schuyler Bordeau (Intern) is a Political Science and Philosophy double major at Wake Forest University expected to graduate in May 2024. Upon graduation, she will join Capstone in Washington, D.C. as a Policy Associate.
Noah Martinez (Intern) is a Political Science major at the University of Illinois Chicago expected to graduate in 2024. In addition to his current role at Policy vs Politics, he is an intern at Joe Moore Strategies LLC, a government relations consulting firm.
Dr. Robert Holahan (Subject Matter Expert) is Associate Professor of Political Science and Faculty-in-Residence of the Dickinson Research Team (DiRT) at Binghamton University (SUNY). He holds a Ph.D in Political Science in 2013 from Indiana University-Bloomington, where his advisor was Elinor Ostrom.
Dr. Nick Clark (Content Lead) is Professor of Political Science at Susquehanna University, where he is also Department Head in Political Science and Director of the Public Policy Program and the Innovation Center. He received his Ph.D. from Indiana University and researches political institutions, European politics, and the politics of economic policy.
Dr. William Bianco (Research Director) received his Ph.D in Political Science from the University of Rochester. He is Professor of Political Science and Director of the Indiana Political Analytics Workshop at Indiana University. His current research is on representation, political identities, and the politics of scientific research.