Environmental groups are asking Minnesota regulators to reconsider a decision to back Minnesota Power's proposed $700 million natural gas plant in Superior.

In a petition filed Wednesday, the groups continued to argue the Minnesota Public Utilities Commission's October approval of Duluth-based Minnesota Power's proposed Nemadji Trail Energy Center was wrong because the PUC denied an environmental review of the project, the state should give preference to emission-free power plants and the company did not show the plant was needed, which an administrative law judge also said in 2018.

"The choice to build a new fossil fuel power plant would lock in decades of greenhouse gas pollution," said Kevin Lee, climate and energy program director at the Minnesota Center for Environmental Advocacy, one of the groups filing the petition. "Consumers don't want the added expense, and studies show Minnesota's electricity needs can be met with clean, renewable energy."

The Sierra Club, Clean Grid Alliance, Fresh Energy and Union of Concerned Scientists also joined in on the petition.

Minnesota Power, which is planning to build the 550-megawatt plant with La Crosse-based Dairyland Power Cooperative on a plot of land between Enbridge Energy's Superior terminal and the Nemadji River, maintains that the plant would supplement its push for more renewable energy sources "when the wind isn't blowing and sun isn't shining" and lessen the company's dependence on coal.

Minnesota Power spokesperson Amy Rutledge pointed out that during last month's polar vortex, wind energy only accounted for 5 percent of the system's energy.

"Natural gas provides a reliable, efficient, affordable and cleaner back up to fill in the gaps when renewable energy is not there," Rutledge said.

The project is now being considered by the Public Service Commission of Wisconsin, which is weighing whether the plant "satisfies the reasonable needs of the public for an adequate supply of electric energy," its "design and location or route is in the public interest" and "will not have undue adverse impact on other environmental values."

A final decision is expected in 2020, officials with Allete, Minnesota Power's parent company, said in its fourth quarter call Thursday morning.

The company hopes to have the plant operational by 2025.

If built, Nemadji would be Minnesota Power's first natural gas plant.

The PUC has 60 days to respond to the petition.