(In a previous version of this story we indicated the entire plant was closing while only Unit 3 is closing. We regret the error.)

Stricter federal emission rules for power plants are having an effect in Wyoming. Rocky Mountain Power says plans to convert one unit of a coal-powered plant to natural gas in western Wyoming fell through and instead they’ll shut it down at the end of 2017.

The Environmental Protection Agency recommended the Naughton Unit 3 to convert to natural gas to comply with new emission standards, but company spokesman Paul Murphy says they realized it was more cost effective to shut the unit down altogether.

“Sometimes we think we think we have an answer and then technology changes, federal laws change,” Murphy says. “And so we have to keep changing with those times and unfortunately this is the result of one of those changes.”

Murphy says they hope to re-open if and when clean coal technology advances.

“Right now coal provides about twice the amount the emissions of natural gas. And so we’re looking at ways to make coal burn cleaner. And so maybe some of that research will help in our decision about what to do with the Naughton 3 plant.”

Murphy says the decision was released in the company’s most recent report to the public utility commission.