A CO2 pipeline is a steel pipeline built specifically to transport carbon dioxide, usually from industrial facilities to underground storage sites or oil fields. These pipelines move CO2 in a dense, compressed state similar to a liquid, and they operate under much higher pressure than a typical natural gas line. The United States currently has roughly 5,000 miles of dedicated CO2 pipelines, though proposed projects in the Midwest have pushed the topic into public debate over land rights and safety.
Why CO2 Needs Its Own Pipeline
Carbon dioxide doesn’t flow through a pipeline the way natural gas does. To move it efficiently, operators compress CO2 to pressures between 1,500 and 2,200 psi, which forces the gas into what’s called a supercritical state. In this form, CO2 behaves like a dense fluid: it fills space like a gas but has the density of a liquid, making it far more efficient to push through long distances. Reaching and maintaining this state requires multi-stage compression, where the gas is squeezed in steps with cooling between each stage. In the final stages, liquid pumps replace gas compressors, which cuts the energy needed to keep things moving.
That compression process is expensive. Compressor stations are the single largest operating cost in a CO2 pipeline system, and in one study, the compression equipment alone consumed about 7.5 percent of the total power output of a coal-fired plant. Along the route, metering stations periodically measure flow rate, pressure, and temperature to make sure conditions stay within the right range.
What CO2 Pipelines Are Used For
Most existing CO2 pipelines in the U.S. were built for enhanced oil recovery, or EOR. The idea is straightforward: injecting CO2 into aging oil fields pushes out crude that conventional pumping can no longer reach. This has been standard practice for decades, particularly in West Texas and the Permian Basin, where natural underground CO2 deposits have supplied pipelines since the 1970s.
More recently, the same infrastructure concept is being applied to climate goals. Carbon capture, utilization, and storage (CCUS) projects capture CO2 from power plants, ethanol refineries, or industrial facilities and pipe it to deep geological formations for permanent storage. Geological sequestration is considered the most viable large-scale option because of its storage capacity, long-term security, and existing regulatory frameworks. When paired with EOR, the economics improve: operators get revenue from additional oil production while keeping CO2 locked underground. This dual benefit is a major reason governments and companies are investing in new pipeline networks.
How the Pipelines Are Built
CO2 pipelines are typically made from carbon steel, the same general material used for oil and gas lines. But CO2 introduces a specific engineering challenge: moisture. When water mixes with carbon dioxide, it forms carbonic acid, which corrodes steel from the inside. Dry CO2 does not corrode carbon steel as long as the relative humidity inside the pipe stays below 60 percent. The industry standard in the U.S. caps water content at 650 parts per million.
Research shows that threshold matters. In lab tests, carbon steel exposed to supercritical CO2 with about 610 ppm of water showed no corrosion after 42 days. But at roughly 1,000 ppm, corrosion products formed on the steel within 21 days under the same conditions, with a corrosion rate of about 1 millimeter per year. That’s fast enough to eat through a pipe wall in a matter of years. So before CO2 enters the pipeline, it goes through dehydration using vapor-liquid separators and chemical absorption columns that strip water content down to below 50 ppm in conservative designs.
Safety Risks During a Leak
CO2 pipelines don’t carry the explosion risk that natural gas lines do. Carbon dioxide is neither toxic nor flammable. But it is an asphyxiant, meaning it displaces oxygen, and that creates a different kind of danger. At concentrations of 1 percent in the air, CO2 causes drowsiness. Above 2 percent, it produces a mildly narcotic effect. Concentrations above 20 percent can cause immediate death.
What makes a CO2 pipeline rupture particularly hazardous is the behavior of the gas after release. Because CO2 is denser than air, it doesn’t rise and disperse the way natural gas does. Instead, it settles into low-lying areas like ditches, basements, and valleys, where it can accumulate to dangerous concentrations. A rupture releasing large volumes of supercritical CO2 creates a cold, heavy plume that can linger near ground level. This is precisely what happened during a 2020 pipeline rupture in Satartia, Mississippi, where dozens of residents were hospitalized after a CO2 cloud settled over the town.
Regulation and Federal Oversight
In the United States, CO2 pipelines fall under the same federal safety framework as oil pipelines. The Pipeline and Hazardous Materials Safety Administration (PHMSA), part of the Department of Transportation, enforces the rules. The specific regulations are in Title 49, Part 195 of the Code of Federal Regulations, which covers the transportation of hazardous liquids and carbon dioxide. Under these rules, “carbon dioxide” is defined as a fluid consisting of more than 90 percent CO2 molecules compressed to a supercritical state.
Critics have argued that these regulations were written primarily for oil pipelines and haven’t been fully updated to address the unique risks of CO2 transport, particularly the asphyxiation hazard and the behavior of dense CO2 plumes. PHMSA has been reviewing its CO2 pipeline safety rules, but as of now, the same basic regulatory framework applies.
Land Rights and Public Opposition
Siting new CO2 pipelines has become one of the most contentious infrastructure issues in the Midwest. Several large projects proposed in Iowa, South Dakota, and surrounding states would capture CO2 from ethanol plants and pipe it hundreds of miles to underground storage. These projects have run into strong opposition from landowners and local communities.
The core dispute involves two connected issues: safety and eminent domain. Pipeline developers often need to cross private land, and when they can’t reach voluntary agreements with landowners, some seek eminent domain authority to force access. Whether a CO2 pipeline company can use eminent domain depends on state law, and the rules vary significantly. Some states grant it, others don’t, and the legal landscape for interstate projects is even murkier. Several proposed pipelines have been denied state siting permits, and the combination of property rights concerns and safety fears has stalled projects that were expected to break ground years ago.
Scale of Existing Infrastructure
The current U.S. CO2 pipeline network is small compared to the country’s oil and gas systems. PHMSA’s 2024 data lists about 5,000 to 6,000 miles of CO2 pipelines in operation, concentrated mainly in the Permian Basin region of Texas and New Mexico. For context, the U.S. has over 190,000 miles of oil pipelines and more than 300,000 miles of natural gas transmission lines. If carbon capture and storage scales up as projected in national climate plans, the CO2 pipeline network would need to expand dramatically, potentially by tens of thousands of miles over the next two decades.