Carbon dioxide removal (CDR) and carbon, capture and storage (CCS) will both play a limited, yet critical role in helping meet climate goals. However, like most nascent technologies, there are important safety considerations that need to be understood and managed before there can be widespread deployment.
U.S. lawmakers have already begun developing policies that support responsible demonstration and deployment of both CCS and specific CDR approaches like direct air capture (DAC), but more data will be needed, and further actions can be taken by policymakers to better maximize safety and minimize the potential for negative impacts across the capture, transportation, and sequestration processes. Although inherently different technologies, DAC and CCS are often addressed within the same regulatory frameworks due to some similarities in their carbon capture technology and shared infrastructure.
This article reviews the existing U.S. regulations that apply to the capture, transportation and sequestration of carbon dioxide (CO2) that’s been captured at an emissions source by CCS, or from the ambient air through DAC, many of which build upon existing federal statutes to protect people and the environment. As understanding of these technologies evolves, subsequent policies and regulations, further research and development, as well as comprehensive emissions monitoring are needed to support their safe and responsible deployment.
Using CCS and CDR to meet climate goals
The Intergovernmental Panel on Climate Change (IPCC) has identified limited, yet critical, roles for both CCS and CDR in helping meet climate goals. CCS prevents CO2 from entering the atmosphere in the first place and CDR approaches remove CO2 that’s already accumulated in the atmosphere. Until around mid-century, CCS and CDR approaches might play complementary roles in addressing residual emissions. In the long-run, CDR approaches like DAC are the only way to achieve net-negative emissions, to lower accumulated or legacy emissions in the atmosphere in the case of overshoot.
Carbon capture and removal
The expected impacts and safety considerations of CCS and DAC facilities will vary greatly depending on facility type and design, capture technologies used and energy sources. Though the two types of projects are distinct from one another (the former captures carbon from polluting point sources of emissions while the latter removes ambient CO2 from the atmosphere) both facilities will likely be subject to similar permitting and regulatory requirements.
How are CO2 capture and removal installations regulated in the US?
Various federal statutes, along with state-level regulations, play key roles in determining how these technologies are permitted and monitored for compliance. Through the Clean Air Act, the Environmental Protection Agency (EPA) sets National Ambient Air Quality Standards and National Emission Standards for Hazardous Air Pollutants based on periodic scientific review. Major modifications (such as CCS retrofits) that emit pollutants covered by the Clean Air Act are subject to New Source Review permitting, which mandates emission standards and environmental impact analyses. Unexpected emissions of some of these chemicals are also required to be reported to the EPA under the Comprehensive Environmental Response, Compensation, and Liability Act.
While the EPA establishes minimum air quality standards through the Clean Air Act, states must develop State Implementation Plans (SIPs) to meet, maintain and enforce these national air pollution standards. States can also pass laws to regulate DAC or CCS installations. For example, Illinois enacted the SAFE CCS Act in April 2024 to prohibit CCS and DAC projects from increasing criteria air pollution. These state laws can provide safety assurances to communities and regulatory certainty to project developers.
What more can policymakers do?
While DAC and CCS have potential to help mitigate climate change and can be designed in ways that may improve overall health, policymakers have an opportunity to design regulations that push developers to maximize this potential. They include:
Incentivize dedicated renewable energy for CCS and DAC: Policymakers should explore incentives for the use of new renewable energy capacity to power CCS and DAC to maximize climate benefits and minimize negative health impacts.
DAC and CCS are expected to increase energy consumption. Post-combustion CCS retrofits on power plants increase energy consumption per net kilowatt hour (kWh) produced by about 13% to 44% while DAC plants currently use 2,000 kWh to 2,400 kWh per ton of carbon dioxide removed. The additional emissions from running the CCS unit may not always be captured and additional fossil fuel use would also create negative impacts further up the supply chain. DAC plants, on the other hand, will be new facilities that can be sited more flexibly, so they are better able to rely on dedicated renewables than CCS retrofits.
Conduct additional research, monitor and report co-pollutant emissions, and adjust regulations accordingly: Government agencies should require that operators regularly monitor and publicly report all potentially dangerous air pollutant emissions from capture units to receive permits. Also, national labs should conduct studies on the net health and environmental impacts of CCS and DAC technologies. The EPA should also consider updating the pollutants covered by air pollution regulations to ensure that any and all potentially harmful co-pollutants from CCS and DAC are regulated.
While there is still uncertainty around the amount and impact of co-pollutant emissions from CCS, post-combustion CCS retrofits are designed to scrub criteria pollutants from the flue stream to efficiently capture CO2, which significantly reduces air pollutants like nitrogen oxides, sulfur dioxide and particulate matter. This can counterbalance the potential increase of other co-pollutants like Volatile Organic Compounds (VOCs), nitrosamines and ammonia from the degradation of chemicals called amines which are commonly used to capture CO2.
Research so far has not linked amine-based capture to increased risk of cancer or cardiovascular disease for nearby workers or local communities, though more research is needed because some of these co-pollutants can be carcinogenic and toxic in other contexts. In addition, emissions of ammonia, some VOCs and nitrosamines are not yet regulated under the Clean Air Act. After future research on the health impacts of these possible co-pollutant emissions, these regulations may need to be updated. In the meantime, methods such as water washing and UV treatment can be employed to significantly reduce the risk of any co-pollutant emission increases from amine-based carbon capture.
As for DAC, preliminary research from WRI indicates DAC plants are unlikely to lead to negative air pollution impacts. This should continue to be studied as more DAC plants are deployed, since one of the leading DAC technology pathways also uses amines to capture CO2, albeit in a different form than in CCS.
Carbon dioxide transportation
While many carbon removal and capture facilities aim to co-locate with sequestration sites, such as the U.S. Department of Energy’s DAC Hubs, the captured CO2 often needs to be transported to where it will be sequestered or utilized. CO2 is primarily transported via pipelines, as this is the most cost-effective option for large volumes. Other modes like rail, trucking and barges are viable alternatives in some circumstances. While rail and truck are feasible for short distances or small quantities, their transport costs are significantly higher — up to 10 times more per metric ton — compared to pipelines.
How is CO2 transportation regulated in the US?
There are various ways to transport CO2, each of which is subject to different regulatory frameworks which govern their safety, environmental impact and operational requirements in the U.S.
The list below is not comprehensive, but provides an overview:
- Rail: Liquefied CO2 transported by rail is subject to regulation by the Federal Rail Administration and the Pipeline and Hazardous Materials Safety Administration (PHMSA), as it’s classified as a hazardous material.
- Truck: CO2 transported by truck is common for local shipments and is subject to hazardous-material regulations, such requirements for special licenses and endorsements.
- Barge: Barge transportation of liquefied natural gas in the United States is minimal due to restrictions imposed by the Jones Act. Similar constraints are likely to apply to CO2
- Pipelines: PHMSA regulates and enforces a pipeline project’s safety, overseeing inspection, maintenance and monitoring, whereas state regulators generally handle the siting and permitting. Both state and federal agencies review pipeline siting, construction and operation plans to determine project approval, with state regulations often building on federal standards. States can impose more stringent regulations. PHMSA reports on CO2 pipeline safety data and manages incident responses, including investigation, reporting and issuing fines. After a 2020 CO2 pipeline rupture in Satartia, Mississippi, caused over 40 people to seek medical care, PHMSA announced they would update their safety and emergency standards to include CO2 pipelines. In January 2024, PHMSA Deputy Administrator Tristan Brown testified that updating CO2 pipeline regulations is a top priority, with new rules addressing safety across all phases of transport, while also announcing a collaboration with the Department of Energy on projects to improve leak detection and assess potential impact zones.
Current U.S. regulations for CO2 pipelines may not fully address the unique transport risks. Experts have highlighted gaps in the regulatory framework, including unclear jurisdiction between federal and state authorities, a lack of clear guidance on the siting of these projects, and a need for safety and emergency-response improvements. As the CO2 pipeline network expands with the growth of carbon capture technologies, there is a need for updated safety and environmental protection policies.
What more can policymakers do?
Transporting CO2 is generally safer than transporting other substances such as oil and gas, but there are still some actions that policymakers can take:
Offer incentives to co-locate: Siting CO2 capture (CCS) and removal (CDR) facilities at the same place as the sequestration or utilization sites can help minimize transportation infrastructure and cost and help minimize the risk of transporting materials over longer distances.
Centralize siting authority for CO2 pipelines: To ensure consistent safety and environmental protection, consider centralizing the siting authority at the federal level or through formalized state-level processes. This would provide a unified review of proposed pipelines, streamline permitting and reduce inconsistencies across different states.
Optimize pipeline routing for safety and environmental considerations: Pipeline routes should be strategically planned to avoid population centers and minimize environmental impact. This includes maximizing the use of already disturbed land, avoiding sensitive ecological areas and steering clear of topography that could worsen the consequences of potential ruptures or leaks.
CO2 pipelines have had a low accident rate, averaging 0.001 incidents per mile per year from 2004 to 2022 over the existing 5,000 miles in the U.S. In contrast, gas distribution lines, which extend over 2.7 million miles and run through populated areas, account for the majority of more severe consequences, including injuries, evacuations and fires, highlighting the increased risk associated with pipelines that go through densely populated regions.
Chemical impurities in CO2 streams, however, can increase the risk of pipeline rupture or leakage due to corrosion. If not adequately managed, CO2 transportation risks leaks, tank ruptures and other mechanical failures that pose health and environment risks.
Promote equity in project planning: Ensure that transportation routes do not disproportionately impact communities and minimize the need for eminent domain. Prioritizing public health, local hiring and decarbonizing the rail and trucking sectors are key steps for sustainable CO2 transportation.
Across all transportation modes, CO2 is often carried in a liquid or supercritical state, requiring high pressure and low temperatures. This may increase the potential for rapid gas expansion and hazardous conditions. The danger zone for a CO2 plume can extend many miles. Diligent monitoring at all project stages, transparency and established emergency response protocols are essential to safeguard human safety and build trust in the communities where these projects operate.
Carbon dioxide sequestration
Although geologic CO2 sequestration is well understood and has been demonstrated at scale, it will have to expand drastically to help meet climate goals. While the risks of negative impacts are very small, there are further policies that federal and state policymakers should consider to maximize safety.
How is CO2 sequestration regulated in the US?
CO2 sequestration is already comprehensively regulated. At the federal level, geologic sequestration sites are regulated by the EPA under the Underground Injection Control Program of the Safe Drinking Water Act . The program includes comprehensive permitting requirements for CO2 sequestration wells, also known as Class VI wells, although it is almost exclusively designed to prevent pollution of drinking water. This focus does not specifically address other potential risks of geologic sequestration such as induced seismicity, atmospheric CO2 leakage or human health risks from increased ground-level atmospheric CO2 concentration.
At the state level, North Dakota, Wyoming and Louisiana have been granted primacy, a process whereby the EPA delegates the regulatory and permitting authority over Class VI wells to state agencies to expedite permitting.
What more can policymakers do?
To help CO2 sequestration expand so that it can play a role in meeting climate goals, policymakers should focus on the following:
Commit to responsible primacy: EPA should prioritize states for primacy that demonstrate a robust permitting process and incorporate environmental justice values with proper transparency and community engagement processes. Although state regulations must be at least as stringent as the EPA’s rules to obtain primacy, environmental groups have argued that some states seeking primacy are known to have a poor track record upholding environmental protection and lack the capacity and expertise to effectively administer and enforce the permitting program.
Conduct further research to reduce remaining uncertainties: To scale the geologic sequestration of CO2, ongoing research will be needed to improve monitoring, site characterization and secondary trapping mechanisms.
CO2 is expected to remain permanently sequestered for thousands of years if sites are well-selected, managed and monitored. The risk of leakage is higher if wells are poorly abandoned or regulated, though modeling studies estimate a negligible leakage probability of 0.0008% per year over 10,000 years. However, the risk of leakage, particularly from injection or abandoned wells, is never fully eliminated, and uncertainties remain about the long-term behavior of CO2 in the subsurface over thousands of years.
These estimates are based on modeling, as we lack direct experience with CO2 sequestration over such long periods. Modeling is crucial for understanding injection risks, such as stress changes, fault reactivation, and caprock integrity, minimizing risks before field implementation. To scale geologic CO2 sequestration, ongoing research is required to improve the site characterization, diligent monitoring, and secondary trapping mechanisms.
The Department of Energy’s CarbonSAFE initiative is already taking important steps by performing identification and characterization of geologic storage sites to reduce technical risk and uncertainties.
Transparency around permitting and monitoring procedures: Risks can be effectively reduced through proper risk mitigation and monitoring procedures, on-site characterization and selection, periodic re-evaluation of leakage pathways, effective well design and construction, limitations on injection pressure, risk assessment and management plans, and consistent monitoring during and post-injection.
Monitoring to detect leakage, track the CO2 plume and measure pressure is particularly crucial to ensure safe sequestration. If such procedures are followed, the risks and potential harms of leakage to health, safety, environment and the climate, are understood to peak during the injection phase and decrease at a steady rate in the post-closure period as a result of secondary trapping mechanisms and decreasing reservoir pressure.
Accidents and mismanagement however can occur, underscoring the importance of monitoring and reporting requirements. In those cases, it is crucial for policymakers to be transparent about the incident and notifying the public about whether it poses an environmental or health related risk. Overall, policymakers must increase transparency around CO2 sequestration permitting as well as compliance with the permit once granted. EPA has taken first steps towards increasing transparency around the Class VI permitting process by releasing an application permitting tracker.
Address more risks: At the federal level, the Class VI rule focuses on preventing the impacts of leakage on underground sources of drinking water. State-level frameworks for CCS and DAC should extend provisions to additional risks, including climate impacts of CO2 leakage, health and environmental risks due to elevated ground-level CO2 concentrations and induced seismicity.
Establish regulation for state-specific concerns: State legislation and more prescriptive regulations can address concerns such as state-specific natural hazards or geologic considerations to ensure the safe sequestration of CO2. Colorado, for example, has prohibited sequestration wells from being sited within 2,000 feet of residences, schools or commercial buildings as a cautious approach.
Address long-term liability considerations: The long timeframe associated with geologic CO2 sequestration raises unique regulatory challenges around who will be liable for remediating and financing potential damages hundreds of years after site closure. To date, there is no comprehensive long-term liability mechanism at the federal level. While the Safe Drinking Water Act determines that project operators are liable for post-injection site care, this only applies to a 50-year period, and impacts on underground sources of drinking water.
The discussion around liability has primarily focused on whether the liability should be transferred to the state after a given time period and once key requirements have been met, or whether it should remain with the operator in the long run. While determining who is liable in the long run is crucial to ensure safety and avoid moral hazard, determining what long-term financial mechanisms should be in place will be just as important to ensure that any potential risks to public health, environment and climate can be addressed in the long-run. For instance, a state-managed Post-Closure Stewardship Fund in Alberta, Canada, covers costs associated with long-term monitoring, managing orphan facilities and environmental regulation compliance and is based on a project-specific rate per ton of CO2 sequestered each year.
States could require projects to link to state-managed trust funds or risk-sharing pools, to cover the cost of remediating damage at sequestration sites, ideally extending beyond 100 years, even if the operator is no longer liable. This can help minimize moral hazard while also establishing financial mechanisms that can effectively cover the costs of potential long-term risks and ensure that remediation of damage doesn’t rely on future taxpayers. It is also crucial to define the covered liabilities and determine who will administer these financial mechanisms.
Future outlook for CDR and CCS regulatory frameworks
Regulations are already in place for the capture, removal, transportation and sequestration of CO2. However, further policy action, at the federal and state level will be required to continue setting a high bar for safety and to gain public trust.
It is imperative that policymakers establish robust safety and transparency provisions and requirements, alongside meaningful, two-way community engagement throughout the process to scale these technologies responsibly. Some states already have policy frameworks in place, establishing standards that build on existing federal regulations to help ensure responsible deployment. California for instance enacted the Carbon sequestration: Carbon Capture, Removal, Utilization and Storage Program, into law in 2022. It directs the California Air Resources Board to establish comprehensive regulations for safety, monitoring and long-term liability requirements (among others) for CDR and CCS projects requiring geologic sequestration.
Early adopters should develop and implement sound policies that not only align with federal regulations but also go further to protect host communities, particularly those historically and disproportionately affected, from experiencing additional harm.
This article first appeared on World Resources Institute on Oct. 15, 2024. It is republished here under a Creative Commons license.
