A Virginia utility regulator says Appalachian Power must continue to study the early retirement of two West Virginia coal plants.

Appalachian Power, for now, intends to operate the John Amos and Mountaineer power plants through 2040.

Appalachian Power’s Virginia customers receive power from the Amos and Mountaineer plants.

It had asked Virginia regulators for permission to stop studying if early retirement of the plants could save electricity customers money.

A senior hearing examiner for Virginia’s State Corporation Commission last week said no.

Michael D. Thomas ruled Friday that the U.S. Environmental Protection Agency’s new rules on carbon dioxide emissions and wastewater treatment raise questions about the future operating costs of both plants.

The company, as well as the attorneys general of West Virginia and Virginia, have mounted a legal challenge to the EPA rules.

The mounting costs of operating the coal plants has come under scrutiny in both states. A third plant, Mitchell, supplies power to Kentucky and West Virginia customers.

The three plants operate less than half the time, and they lose money when they do, according to recent testimony to the West Virginia Public Service Commission.

The Sierra Club has sued the PSC over its 2021 directive for the plants to operate at least 69 percent of the time. They rarely come close, and few U.S. plants do.

Appalachian Power officials have told the PSC that they have too much coal on site at the three plants, and they’ve made the decision to burn it even when it was not economically justified.

Appalachian Power is asking its West Virginia customers for a 17 percent base rate increase. The PSC has put any potential rate increase on hold until next year.

Testimony in a federal court case challenging a more stringent wastewater treatment rule show that Appalachian Power has evaluated the cost of compliance.

Gary Spitznogle, vice president of environmental services for Appalachian Power parent American Electric Power, told the Eighth U.S. Circuit Court of Appeals that the rule would force the retirement of Amos and Mountaineer in 2034. If the rule stands, the company would have to make a decision by the end of next year to upgrade the plants at a cost of hundreds of millions of dollars or shut them down.

The rule’s opponents have asked the court to block it while it resolves the legal issues.