A rush is on across the Midwest and Gulf Coast to build thousands of miles of new pipelines that would carry carbon dioxide, the main driver of global warming. The pipes would become a critical piece of a burgeoning industry that aims to remove the climate pollutant from industrial smokestacks before it reaches the atmosphere, and then store the gas deep underground.

But advocacy groups are warning that energy companies are moving faster than regulators and that some of the proposed pipelines could be up and running before there are any federal safety regulations to cover them.

At least two companies are planning to convert existing natural gas pipelines to carry carbon dioxide instead. But because of a regulatory loophole, there are currently no federal safety standards for this process.

“This is happening,” said Bill Caram, executive director of the Pipeline Safety Trust, an independent watchdog group. “These pipelines are getting converted, and in some cases, it’s very clear that they’re not regulated.”

The Pipeline and Hazardous Materials Safety Administration, or PHMSA, is in the process of updating its rules for carbon dioxide pipelines, but the proposed regulations are not expected until next year. 

In May, Pipeline Safety Trust and five major environmental groups wrote a letter to Transportation Secretary Pete Buttigieg, who oversees PHMSA, urging him to issue an immediate interim rule stating that all carbon dioxide pipelines are covered under existing regulations until the upcoming rules are in effect.

Caram and other experts say the regulatory gap could pose safety hazards for people living near the pipelines. Carbon dioxide has different chemical properties than natural gas that could, under certain conditions, corrode or embrittle the pipes that carry it. 

In the event of a rupture or leak, CO2 also sinks and can pool in low-lying areas, whereas natural gas rises and tends to disperse more quickly. Carbon dioxide is an asphyxiant that can cause health problems and even be fatal at high enough concentrations. It can also render vehicle engines inoperable. Advocates say that without proper regulations, there’s no guarantee that emergency responders would know what to do in the event of an accident.

“This stuff can kill,” said Richard Kuprewicz, an independent consultant and pipeline safety expert. “I don’t say that to scare anybody. I just say that to say, you have to think this through.”

Across the country, energy companies and other industries are racing to take advantage of a newly-expanded federal tax credit for capturing and storing carbon dioxide and billions of dollars in federal grants and loans for the practice that were approved with the 2021 bipartisan infrastructure bill. 

Some projects could reap hundreds of millions of dollars per year for 12 years from the tax credit, which was enhanced as part of the Biden administration’s signature climate legislation enacted last year.

There are currently more than 90 permits to inject CO2 underground awaiting approval from state and federal regulators, and dozens of proposals to build new pipelines and carbon capture operations across the country.

Many environmental advocates have warned that carbon capture and storage could prove to be an enormously expensive and ineffective way to cut the nation’s climate pollution. They have also raised concerns about new hazards and threats posed by the process, including leaks of carbon dioxide. 

Many of the projects would be built in communities that already suffer from the pollution and safety risks posed by industrial operations. These communities often are home to predominantly Black, Latino and Indigenous people.

But industry groups along with some academics and policy experts have argued that carbon capture could be a key means for reducing pollution from heavy industries like fertilizer production and cement and steel manufacturing. Ethanol plants across the Midwest and many heavy industries along the Gulf Coast are likely to be some of the first projects to move.

Pipeline proposals have become particularly controversial. PHMSA began updating its rules for carbon dioxide pipelines last year in response to a 2020 rupture of an existing line that sent dozens of people to the hospital. The existing rules only apply to pipelines that carry CO2 as a “supercritical liquid,” a form it takes under high pressure and temperatures.

Nearly all existing carbon dioxide pipelines, including the one that ruptured, carry the CO2 in a supercritical state because it is far more dense and efficient than piping it in gaseous form. As a result, that was all federal regulators focused on when they first enacted regulations decades ago. In 2012, Congress directed the Transportation Department to adopt minimum safety standards for gaseous CO2 pipelines, too, but it has yet to do so.

There are no major pipelines in operation that carry carbon dioxide as a gas, experts say, but there are now at least two conversions in the works. A company called Tallgrass is planning to convert a pipeline that runs through Nebraska, Colorado and Wyoming, and EnLink Midstream says it plans to convert some of its 4,000 miles of natural gas pipelines in Louisiana. EnLink has announced deals to carry millions of tons of carbon dioxide annually for ExxonMobil, Occidental Petroleum and others, who plan to capture the climate pollutant from fertilizer plants and other heavy industry.

Last month, Louisiana’s Department of Natural Resources updated its safety regulations to extend coverage to all carbon dioxide pipelines, including those carrying it in gaseous form, so the EnLink project would be covered by state regulations.

“CO2 is a whole different critter than it was 10 years ago,” said Patrick Courreges, a department spokesperson, who said the update came in response to plans by EnLink and other companies. “We need to start looking at what rule changes, what safety standards, what more specificity we’re going to need.”

Caram said the new rules from Louisiana are an improvement but still leave dangerous gaps. The rules do not set standards for what levels of water or impurities can be mixed into the carbon dioxide as a result of the capturing process, for example. When water mixes with carbon dioxide, it forms carbonic acid, which is highly corrosive to steel. There are also no requirements that operators add an odorant, to help residents know a leak has occurred.

Courreges said state regulators would handle those concerns on a case by case basis, and that the regulations set broad guidelines to ensure pipelines are carrying materials consistent with their design.

Megan Wright, an EnLink spokesperson, said that “transporting CO2 as a gas is very similar to transporting natural gas, so we can safely operate our gaseous phase CO2 pipelines at existing pressures where our current natural gas system runs.”

Tallgrass’ Trailblazer project in the Midwest would not currently be covered by any pipeline safety standards.

Rachel Carmichael, a company spokesperson, said that “we expect PHMSA guidance will be in place during the timeframe when Trailblazer is under construction. Currently, we are working with regulators to ensure we comply with their requirements.”

However, the PHMSA rules are still in progress and not yet complete, Caram noted, and will be subject to public review and changes even after the proposed rules are published.

“I have no reason to think Tallgrass is trying to dodge regulatory oversight,” Caram said in response to the company’s statement, “and I believe they would prefer this pipeline to be regulated. But the reality is that it is not.”

In the event that the new federal rules introduce more stringent construction standards, those would not apply to pipelines that have already been completed. In other words, while existing pipelines might have to change how they operate or are inspected, they likely would not be required to be retrofitted to meet the new construction standards.

In an email, a PHMSA spokesperson said that even though the agency has no regulations to cover gaseous carbon dioxide pipelines, it still has the authority to “investigate and address any safety issues, issue safety orders, and verify compliance with safety orders.”

For some residents and advocates, that is not enough. Scott Eustis, community science director for Healthy Gulf, a Louisiana-based advocacy group, has been tracking dozens of carbon dioxide pipeline proposals in that state, including many planned to cross fragile and degraded wetlands. Most of those would carry the gas in supercritical form, and therefore be covered under current federal regulations. But he said even existing state and federal standards have been inadequate to protect the Louisiana residents from the industries that surround them.

“CO2 is an asphyxiant, so it stops your car motor, it stops your boat motor,” Eustis said. “We’ve been evacuating thousands of people through oil vapor clouds, but I don’t want to think about what seems to be being contemplated, which is evacuating thousands of people through an asphyxiant cloud.”

Courreges, with the state Department of Natural Resources, said he understands the concerns about safety, but that the projects remain years away from completion. EnLink would need state approval to convert its natural gas pipelines, he said, but has yet to request it.