A manufacturers group that has supported construction of coal-fired power plants said Friday that it objects to construction of a coal-fired plant in southwestern Wisconsin.

AdvertisementConstruction costs have been rising for the project, which Alliant Energy Corp. estimates at $1.2 billion to $1.3 billion.

That’s too costly for ratepayers, the Wisconsin Industrial Energy Group said.

The power plant “is not needed today (or tomorrow), and it is much, much too expensive,” the group said in a filing late Friday with state regulators.

But Alliant, in its filing, said the economic benefits — including construction jobs and the establishment of a biofuels market and economy in southwest Wisconsin — would bring value to the state.

“These are challenging economic times. So now, more than ever, this is the right plant for Wisconsin and WPL’s customers,” Alliant subsidiary Wisconsin Power & Light Co. said.

The Public Service Commission is expected to decide the fate of the plant in November.

Alliant was not surprised that the manufacturers group came out against the plant, given the questions it had posed, spokesman Rob Crain said.

“Obviously, we would rather have had their support,” Crain said, “but I don’t think that’s going to make or break the case.”

One key manufacturer that belongs to the group, Mercury Marine of Fond du Lac, has endorsed the Alliant plan, Crain said.

The plant is controversial because it represents a new coal-fired power plant and more emissions of carbon dioxide — the leading greenhouse gas — at a time of growing concern about global warming. The environmental group Clean Wisconsin and the ratepayer group Citizens Utility Board have opposed the plant since it was announced.

Alliant has won support from farm and some wildlife groups for its plan to use wood, switchgrass and other forms of biomass for up to 20% of the plant’s production.