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APS Plans to Close One of the Four Generators at Cholla Power Plant

Arizona Public Service Co. is proposing to close at least one of the four units at the Cholla Power Plant in northern Arizona near Holbrook. Photo Credit: APS

Arizona Public Service Co. is proposing to close at
least one of the four units at the Cholla Power Plant
in northern Arizona near Holbrook. Photo Credit: APS

By Ryan Randazzo for The Arizona Republic

Arizona Public Service Co. plans to close one of the four generators at northern Arizona’s Cholla Power Plant, adding to a string of coal-plant closures in the West.

Under a proposal APS is discussing with the Environmental Protection Agency, the No. 2 unit at the plant would close in 2016, and the No. 1 and 3 units could convert to natural gas or close in 2025 when the plant’s coal contract expires.

While more coal closures are expected because of the recent EPA decision to reduce carbon emissions from them, Cholla’s closure is being spurred by rules regarding mercury and haze pollution.

In 2010, the EPA notified the utility that Cholla’s No. 2 unit would need new pollution controls to limit mercury, then in 2012 proposed additional pollution controls on the No. 2, 3 and 4 units to limit nitrogen-oxide emissions that contribute to haze.

“We believe we can comply with the EPA rules by closing Unit 2,” said Ann Becker, APS vice president of environmental and chief sustainability officer. “There will be no more emissions from that unit, and we can negotiate something with the EPA better than the environmental benefits by either closing or converting the others.”

It’s going to be cheaper to shut No. 2 and convert Nos. 1 and 3 to natural gas than spend an estimated $350 million on pollution controls, she said.

Switching the other units to natural gas would significantly reduce most forms of pollution associated with coal, should APS take that route. But it also would require a new gas pipeline to serve the plant, Hansen said.

Cholla could join a rapidly growing list of coal plants closing or converting to natural gas in the West.

Read more at The Arizona Republic