SALT LAKE CITY — A group opposed to a new type of nuclear plant being developedsaid Thursday the price of power produced there would be more than other carbon-free energy sources, making it a bad investment for Utah's municipal utilities.

"We feel the numbers are independent and speak for themselves," Michael Shea, a senior policy associate for the Healthy Environmental Alliance of Utah, told reporters at a news conference discussing the findings in a new study.

The study, by Salt Lake City-based Energy Strategies, found power produced by the small modular nuclear reactors to be built in Idaho would cost more than $66 per megawatt hour, compared to as low as just over $38 for wind and solar power.

"It does not make economic sense from a market perspective for a group like (the Utah Associated Municipal Power Systems) to be investing in what is essentially a subsidized science project that has not ever been proven," Shea said.

A statement issued by the municipal power system disputed numbers in the study, including the cost of producing power by what's being called the Carbon Free Power Project, saying it is now at $55 and may drop further.

Longtime consumer protection watchdog Claire Geddes spoke at the news conference about her confidence in the study and her concerns about the impact of higher costs on the public.

Geddes, who said she has worked on utility issues since 1992, suggested the local governments supervising municipal utilities don't have the resources to adequately vet the project.

"It's really not fair to the public," she said. "I would stress that these cities understand, before they go into it, what the risks are to their citizens and their businesses."

Both the environmental alliance and Geddes called for further study by the municipal power system before local governments make a final decision next year on what would be a 40-year contract.

The statement from the municipal power system said the study authors should have consulted with them and that local government officials "have the expertise and sophistication needed to make informed decisions about the project."

In the end, the environmental alliance that in February labeled the plant as "the nuclear industry's latest attempt to convince the public that nuclear power is cheap and safe," wants to stop the project altogether.

"If UAMPS doesn't go forward with this project, there’s a large question of whether it goes forward at all," Scott Williams, the environmental alliance's executive director, said at the news conference. "We would like to see it not be built."

Besides the cost concerns, Williams said the new type of nuclear plant can't be presumed to be safe and would still produce at least as much nuclear waste as a traditional plant.

The intent is for the municipal power system to purchase all 12 modular reactors at the plant being built by an Oregon-based company, NuScale Power, system spokesman LaVarr Webb said.

The power generated would be used by the 46 members, mostly municipalities, in Utah and other states, Webb said, and would sold to other users including the federal government for use by the Idaho National Laboratory and the Department of Energy.

He said nuclear power still would "only be a small part of the portfolio" of energy sources used by members, which includes renewables but also requires the steady source of power the nuclear plant would supply.

"That's a big part of the reason for doing this," he said. "The reality is, renewable energy is intermittent. When the wind doesn't blow and the sun doesn't shine, you don't get the power."

At least 30 members of the municipal power system have signed on to the project and at least three have declined to participate. Webb said that's "normal. There's no project that every member belongs to."