Minnesota utility regulators on Thursday ruled that a proposed carbon dioxide pipeline should undergo the most thorough environmental review available under state law.

Some sort of environmental review of Summit Carbon Solutions' pipeline is required. The Minnesota Public Utilities Commission voted 5-0 for an environmental impact statement (EIS), which was favored by environmental groups.

An EIS is commonly done on large controversial projects like mines and oil pipelines.

Christina Brusven, an attorney representing Summit, said at the PUC's Thursday meeting that an alternative to an EIS — a comparative environmental analysis (CEA) — would be just as "robust" and would take less time.

PUC Chair Katie Sieben questioned whether an EIS would take longer, and said that if it did: "Taking longer to make sure we get it right, isn't that in everybody's best interest? We have certainly heard a lot of concerns about CO2 pipelines."

Summit Carbon Solutions' pipeline would run for 234 miles in Minnesota, transporting carbon dioxide captured at six ethanol plants. The $4.5 billion pipeline also would ship CO2 from 25 other ethanol plants and also would run through Iowa, Nebraska and South Dakota, depositing the waste underground in North Dakota.

In September, Ames, Iowa-based Summit applied for a route permit for 28 miles of pipeline in Minnesota. The PUC on Thursday approved Summit's application for that stretch — a formality. The pipeline's merits will be debated in a PUC proceeding over the coming year.

Summit plans to file other route permit applications for sections of the pipeline in Minnesota, not for the project as whole. Its first application covers a 4.5-inch diameter pipe that would run from Green Plains' ethanol plant near Fergus Falls, Minn., to the North Dakota border south of Breckenridge, Minn.

Environmental reviews must be done on each section. "It would make more sense to do one EIS for all of the segments," said Amelia Vohs, an attorney representing the Minnesota Center for Environmental Advocacy and the Sierra Club in the Summit pipeline proceeding.

Still, she said in an interview that she hoped the PUC's decision Thursday would set a precedent for the other sections.

Ethanol plants are significant CO2 emitters, and carbon capture has become an increasingly popular — though often controversial — concept in recent years. It's aimed at reducing greenhouse gas emissions, the root of climate change.

But opponents of carbon capture say it promotes the continued use of fossil fuels, and if CO2 pipelines rupture. they pose threats to rivers, lakes and groundwater — as well as human health.

Summit Carbon Solutions argued that under state law, the PUC should order a CEA rather than an EIS. The Minnesota Department of Commerce, which advises the PUC, suggested modifications to the CEA process to ensure that it would address substantially the same issues as an EIS.

But Vohs, the environmental attorney, told the PUC that even with the Commerce Department's suggestions, a CEA would not be not as complete as an EIS.

Summit has faced fierce opposition in some other states over procuring land for its pipeline under eminent domain. The company does not have eminent domain power in Minnesota.

"I understand there is some pushback in neighboring states," PUC Commissioner John Tuma said to Summit representatives Thursday. "I see a lot of unhappy farmers in South Dakota [concerned] about eminent domain, and it's the same in Iowa."

Tuma asked Summit if the opposition would affect the company's pipeline timeline. The answer from Summit was "no": The company still expects to begin construction in the first quarter of 2024.

Correction: Earlier versions of this story had incorrect figures for the length of the pipeline proposed for Minnesota and the number of Minnesota ethanol plants that would be served.