EPA Proposes SCR Controls for NOx, PM Reduction at Four Corners Coal Plant

The Environmental Protection Agency (EPA) last week proposed requiring the Four Corners Power Plant near Farmington, N.M., to install and operate selective catalytic reduction (SCR) controls on all five of the 2,040-MW coal-fired facility’s units. The measure would cut the plant’s nitrogen oxide (NOx) and particulate matter emissions by nearly 80%, the agency said.

The requirement would be implemented under the Clean Air Act’s Regional Haze Rule, which requires the use of Best Available Retrofit Technology at older coal-fired power plants to reduce haze and improve visibility. If the proposal is finalized, the facility operated by the Arizona Public Service Co. will have five years to add the controls.

The proposed controls would reduce emissions of nitrogen oxides from about 45,000 tons per year to 9,000 tons per year, requiring the facility to meet an emission limit of 0.11 lb/MMBtu—one of the strictest in the nation. For particulate matter, the EPA is proposing to require the plant meet an emission limit of 0.012 lb/MMBtu for Units 1 through 3 and 0.015 lb/MMBtu for Units 4 and 5.

“These emissions limits are achievable by installing and operating any of several equivalent controls on Units 1 – 3, and through proper operation of the existing baghouse on Units 4 and 5,” the EPA said.

The proposal seeks to “improve visibility and human health,” particularly in the 16 national parks and wilderness areas in the vicinity of the 45-year-old plant, the agency said. It added that the controls are estimated to reduce the visibility impact by an average of 57% at these areas.

“The installation and operation of SCR is estimated to increase the electricity bill for the average Arizona Public Service residential customer by about 70 cents per week,” the EPA said. Though it did not release a concrete figure, the agency estimated the cost to install and operate the controls at the five units “would not exceed $100 million (in 1996 dollars) in a year.”

According to the New Mexico Business Weekly, the New Mexico Environment Department in June proposed that the nearby San Juan Generating Station install SCR controls, but Public Service Co. of New Mexico, which owns a majority of the plant, refused, saying the technology could cost between $750 million and $1 billion.

The agency is expected to continue to consult with the Navajo Nation and other affected tribes, and the federal land managers, before taking any final action. There will be a 60-day public comment period on the proposed action as well as two public hearings in the Four Corners area. 

Sources: EPA, POWERnews, New Mexico Business Weekly

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