As of January 23, 2025, the unofficial pre-publication rules are no longer available to view online and have not been published in the Federal Register. As the rules were not finalized prior to the administration change, it is yet to be determined whether they will be published as-is or revised.

The US Department of Transportation’s Pipeline and Hazardous Materials Safety Administration (PHMSA) has issued a notice of proposed rulemaking to enhance safety standards for carbon dioxide (CO2) pipelines. Given the important and complementary role that carbon management technologies will play in meeting net-zero emissions targets and the expected expansion of CO2 pipeline infrastructure, this notice is a welcome development for safe and responsible deployment.

Here are the key things to know:

  • If adopted as-is, the notice of proposed rulemaking will enhance the already strong safety standards for CO2 pipelines, as evidenced by the historical safety data from PHMSA.
  • The rulemaking would codify requirements developed in response to the 2020 accident in Satartia, Mississippi. This includes new requirements on emergency preparedness and first-responder training.
  • These new requirements could help build public confidence and increase trust among pipeline operators and the public.

What is the current safety record of CO2 pipelines?

A recent issue brief from GPI on the safety record of CO2 pipelines shows that CO2 pipeline accidents are rare. PHMSA’s data shows that CO2 pipelines have had an average of 4.1 accidents per year and have never had more than nine accidents in a single year. From 2004 to 2022, CO2 pipelines had an average accident rate of 0.001 per mile in operation per year. Additionally, CO2 pipeline accidents are typically smaller in scale and result in less property damage than pipeline accidents involving hazardous liquids.

While CO2 pipeline accidents are rare, it is important to be aware of the impacts they can have on surrounding communities. In 2020, a serious accident occurred involving natural force damage to a CO2 pipeline in Satartia, Mississippi. As a result of this accident, 200 residents near the rupture location were evacuated, and 45 people were taken to the hospital. PHMSA conducted a thorough investigation of this accident, which informed some of the newly proposed requirements.

What is in the notice of proposed rulemaking?

Although current regulations require robust safety checks and standards for CO2 pipelines, PHMSA recognized that the accident in Satartia necessitated enhanced standards to better protect communities. These new standards are reflected in the proposed regulations.

Some highlights:

  • Requiring all CO2 pipeline operators to provide training and necessary equipment to emergency responders addressing threats specific to CO2
  • Requiring all CO2 pipeline operators to develop more robust communications plans with the public in the event of an emergency.
  • Requiring CO2 pipeline operators to establish “emergency planning zones” extending two miles on either side of the pipeline to ensure members of the public have adequate emergency response information.
  • The inclusion of safety standards and reporting requirements for gas- and liquid-phase CO2 Current rules only cover supercritical CO2, which is the primary phase of CO2 transport via pipeline.
  • Requiring all CO2 pipeline operators to perform vapor dispersion analyses when determining whether their pipelines could affect high consequence areas as a part of their integrity management plans.
  • Requiring CO2 pipeline operators to do more rigorous monitoring and reporting on various impurities that may be present in a pipeline.
  • Enhanced right-of-way inspection requirements for CO2 pipeline operators, including programs to identify and take appropriate actions concerning geologic hazards and reduced depth of cover (the vertical distance between the top of an underground pipeline and the ground surface above it).
  • The introduction of a new agricultural area category regarding depth of cover requirements. While most areas have a required depth of cover ranging from 30 to 36 inches, pipelines constructed, replaced, or converted to service in agricultural areas must have a minimum depth of cover of 48 inches, helping prevent excavation-related damages to buried pipelines where farming activities exist.

Implications of the notice of proposed rulemaking

If adopted as-is, the new rules could help assure the public and policy makers that federal regulators and project developers are committed to preventing and responding to CO2 pipeline emergencies. Increased public confidence in the safety of this critical infrastructure could prevent deleterious and expensive project delays and allow projects to be built more efficiently.

The rulemaking also has implications for individual states. In response to public concerns about CO2 pipeline safety, two states–Illinois and California–implemented moratoria on CO2 pipeline construction until PHMSA had concluded their rulemaking. Once adopted, CO2 pipeline construction can commence in both states, barring additional legislative action.

Looking ahead

Once published to the Federal Register, interested parties have 60 days to comment on the notice of proposed rulemaking. PHMSA will consider all feedback received during this public comment period as they work to finalize the rulemaking.

Visit Carbon Capture Ready to learn more about CO2 pipeline infrastructure and explore more carbon management resources.

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