A Federal Implementation Plan (FIP) proposed on Monday by the U.S. Environmental Protection Agency (EPA) asks three Oklahoma coal-fired power plant operators to install technology or switch to natural gas to control air emissions. The agency said the plants, built more than 30 years ago, did not meet regional haze requirements under the Clean Air Act.

Operators of the Oklahoma Gas and Electric (OG&E) plant near Muskogee, the OG&E Sooner plant in north central Oklahoma, and the American Electric Power (AEP) Northeastern plant northeast of Tulsa will be required under federal limits to reduce sulfur dioxide (SO2) emissions by about 95%. This could result in a reduction of about 61,000 tons of SO2 per year, the EPA said.

“These three power plants emit greater than one-third (36%) of all the SO2 pollution from the hundreds of industrial and utility sources in Oklahoma,” the agency said, adding that “federal law requires them to take practical steps to modernize their pollution controls.”

The EPA said that an evaluation of the state’s implementation plan found that all Oklahoma sources of air pollution except the three coal-fired plants met the level of control needed to address haze requirements. Under the FIP, the plants will have three years to add SO2 scrubbers, switch to natural gas, or do both.

OG&E Corp. will be required to modernize its 477-MW Unit 4 and the 517-MW Unit 5 at the Muskogee plant as well as the 522-MW Unit 1 and 524-MW Unit 2 at the Sooner plant. AEP will be forced clean up Units 3 and 4 at its Northeastern plant.

Installing scrubbers at its eastern coal plants could cost AEP about $700 million and take five years to design, engineer, permit, and install, spokesman Stan Whiteford told Reuters on Tuesday.

The EPA had in December asked PNM Resources to install—also within three years—selective catalytic reduction as the “best available retrofit technology,” to reduce nitrogen oxide emissions at its 1,640-MW San Juan coal plant in New Mexico. That would cost the utility up to $1 billion, PNM has said.

The EPA’s action was criticized by Sen. James Inhofe (R-Okla.), ranking member of the Senate Committee on Environment and Public Works. State officials worked with state utilities to ensure lower emissions while securing energy sources, he said, “but that was too much for the Obama EPA, which rejected the Oklahoma-led plan in favor of their preferred scheme to put Washington bureaucrats in charge and, ultimately, to make fossil-fuel-based electricity more expensive for consumers.”

Inhofe declared he would fight the “regulatory power grab,” saying, “through my leadership position on the Senate Committee on Environment and Public Works, I will do everything I can to work with Oklahoma officials to protect consumers from EPA’s attack on affordable electricity.”

A 60-day public comment period will begin after the agency publishes the proposal in the Federal Register. “Upon publication in the Federal Register, additional information on the proposed rulemaking and opportunities to provide input will be available at http://regulations.gov (docket number EPA-R06-OAR-2010-0190),” the EPA said in a release.

Sources: POWERnews, EPA, Reuters, PNM, Sen. James Inhofe