As interest grows in trapping carbon dioxide, the planet's primary human-created greenhouse gas, Minnesota is considering whether to regulate pipelines that would carry the liquified gas to underground storage areas.

Such pipelines have been proposed for Minnesota, including one in neighboring Otter Tail County.

The state does not now treat carbon dioxide as a hazardous substance when it comes to transporting the substance, unlike petroleum, petroleum products or anhydrous ammonia. Carbon dioxide helps create the bubbles in carbonated beverages; it's also used in fire extinguishers, life jackets and greenhouses. However, it can also be harmful. Carbon dioxide has no odor or color, making exposure difficult to detect. Mild exposure can cause headache or drowsiness, while high levels can be lethal.

A 2020 rupture in a Mississippi carbon dioxide pipeline created a green fog that sent 45 people to the hospital, caused some to foam at the mouth and bogged down vehicle engines, first responders told the Clarion-Ledger newspaper at the time. The incident has been cited by those wanting the state to get more involved in a carbon dioxide project that has been proposed for Minnesota, including Otter Tail County.

Two legs of a massive carbon dioxide pipeline are being proposed for nine counties in Minnesota by Iowa-based Summit Carbon Solutions. The company proposes to capture carbon dioxide from ethanol plants, including the Green Plains Partnership plant in Fergus Falls, and send it in liquified form underground about 250 miles to Bismarck, North Dakota.

Piping liquid carbon dioxide is new for Minnesota. On Dec. 21, the Minnesota Public Utilities Commission began soliciting public opinion on whether the state should include carbon dioxide on its list of hazardous.

Summit Carbon Solutions told the Echo Press that it welcomes state oversight, but that it prefers to work with counties, which is the current approach.

“We believe the county leadership is qualified in governing the routing of our project and managing the Environmental Assessment Worksheet process," said Jake Ketzner, vice president of public affairs for Summit Carbon Solutions. "Additionally, this project will significantly enhance ethanol and agricultural industries that are so critical to our local farmers, our regional economy, support hundreds of thousands of jobs, and provide millions of Americans with access to clean, renewable energy options.”

Ketzner said public safety is his company's highest priority. He called the Mississippi leak "an unfortunate event," and said the Mississippi pipeline carried hydrogen sulfide and carbon dioxide, which he said was much more dangerous than carbon dioxide alone.

"Our project only carries carbon dioxide," he said. "Nonetheless, the circumstances associated with the incident were investigated and the lessons learned will be factored in the design, construction, and operations of the Summit Carbon Solutions pipeline."

Summit provided the Echo Press with its answers to questions from the Iowa Utilities Commission, including a question about the impact of leaks and how it would respond.

Summit said the impact and response would depend on each leak, including the cause and rate, the location, weather conditions and other details.

A small and gradual leak would be unlikely to have much impact, it said. It did not provide answers about the impact of and response to a larger leak, but said it is workving to figure that out in accordance with federal regulations.

It said it plans to install more valves than federal requirements call for and place them in key locations.

Carbon dioxide isn't explosive or flammable, it said, pointing out that it is used as a fire suppressant. Any release would disperse as a gas and not flow over land, it said.

Enough exposure can lead to asphyxiation, but Summit argued that CO2 pipelines has not proved fatal in the nearly 20 years they have been used in the United States.

Nobody died in the Mississippi leak, however 300 people were evacuated from their homes and 45 people were hospitalized. Terry Gann, an investigator with the Yazoo County Sheriff's Department, told the Clarion Ledger that he found "two people, wandering around like zombies, just walking around" and "grabbed them and put them in my truck."

He rescued another woman, then was himself overtaken by the gas and had to be treated for carbon dioxide exposure.

"Starting out, it was real hard to breathe, like I'd run wide open up and down some stairs," he told the paper. "I was really, really winded, like I'd run a mile. Then it was headaches, my ears were popping, I was sick to my stomach and I kind of started getting disoriented. ... I didn't know I was saying stuff on the (fire channel) radio."

Jack Willingham, emergency management agency director for Yazoo County, told the Clarion-Ledger he could hear Gann and other first responders struggling over the radio. He said firefighters rescued three victims who were "foaming at the mouth."

The CO2 was so heavy in the air, he said, that it caused vehicles to stall.

Summit told the Iowa Utilities Board that it intends to assess the capabilities of first responders along the pipeline route and make sure local responders have relevant information, training and equipment to respond to any leaks.

"Further study may be required to determine the immediate and long term impacts," the company said.

The Public Utilities Commission will accept public comments through Jan. 31. To view the agency's documents pertaining to the issue, visit mn.gov/puc/edockets, select Go to eDockets Project Database, enter the year 21 and docket number 836, then hit search.

To submit a public comment online, visit mn.gov/puc/consumers/public-comments; email consumer.puc@state.mn.us; or mail to Consumer Affairs Office, Minnesota Public Utilities Commission, 121 7th Place East, Suite 350, St. Paul MN 55101.