Carbon capture and storage

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Carbon capture and storage (CCS) is a process in which a relatively pure stream of carbon dioxide (CO₂) from industrial sources is separated, treated and transported to a long-term storage location.^[1]: 2221 In CCS, the CO₂ is captured from a large point source, such as a chemical plant, coal power plant, cement kiln, or bioenergy plant, and typically is stored in a suitable geological formation.

CCS has been discussed as a strategy to reduce greenhouse gas emissions and mitigate climate change,^[2][3] though some critics claim that CCS projects have been shown to increase, not decrease overall emissions.^[4] For example, CCS retrofits for existing power plants can be one of the ways to limit emissions from the electricity sector and meet the Paris Agreement goals.^[5]: 16However, as of 2022, only about one thousandth of global CO₂ emissions are captured by CCS, and most of those CCS projects are for natural-gas processing.^[6]: 32 The effectiveness of CCS projects in reducing carbon emissions depends on the capture efficiency, the additional energy used for CCS itself, and business and technical issues that can keep facilities from operating as designed. Most of the largest CCS implementations have failed to meet their emission-reduction goals.^[7]

Storage of the captured CO₂ is in deep geological formations. As of 2022, around 73% of the CO₂ captured annually is used for enhanced oil recovery (EOR), a process in which CO₂ is injected into partially-depleted oil reservoirs in order to extract more oil and then is left underground.^[8] Since EOR utilizes the CO₂ in addition to storing it, CCS is also known as carbon capture, utilization, and storage (CCUS).^[9] Based on the limited field data available, the IPCC estimates that at appropriately-selected and well-managed storage sites, it is likely that over 99% of CO2 will remain in place for more than 1000 years.^[2]: 14

CCS is a relatively expensive process.^[10] Carbon capture becomes more economically viable when the carbon price is high, which is the case in much of Europe.^[6] Some environmental activists and politicians have criticized CCS as a false solution to the climate crisis. They cite the role of the fossil fuel industry in origins of the technology and in lobbying for CCS focused legislation.^[11] Critics also argue that CCS is only a justification for indefinite fossil fuel usage and equate to further investments into the environmental and social harms related to the fossil fuel industry.^[12][13] With regards to public support, communities who have been negatively affected by an industrial activity in the past are less supportive of CCS.^[14] Communities that feel inadequately informed about or excluded from project decision-making may also resist CCS development.^[15]

Globally, a number of laws and rules have been issued that either support or mandate the implementation of CCS. In the US, the 2021 Infrastructure Investment and Jobs Act provides support for a variety of CCS projects, and the Inflation Reduction Act of 2022 updates tax credit law to encourage the use of CCS.^[16][17] Other countries are also developing programs to support CCS technologies, including Canada, Denmark, China, and the UK.^[18][19]