EPA Tells Wisconsin Officials to Consider More Efficient Turbines in BACT Analysis

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By Andrew Childers  

The Environmental Protection Agency has ordered Wisconsin officials to consider requiring more efficient turbines as part of a greenhouse gas permit for a Milwaukee sewage treatment plant.

The Wisconsin Department of Natural Resources did not evaluate either combined cycle turbines or combined heat and power systems as part of its best available control technology (BACT) evaluation for a proposed permit for the Jones Island Water Reclamation Facility, EPA said.

Instead, Wisconsin's proposed greenhouse gas prevention of significant deterioration permit only considered less-efficient simple cycle turbines for the facility, which is operated by the Milwaukee Metropolitan Sewerage District (MMSD).

“Combined cycle turbines are generally more efficient than simple cycle turbines, and [combined heat and power] systems can be even more energy efficient,” Genevieve Damico, chief of the Air Permits Section in EPA's Region 5, said in her March 15 letter to Wisconsin.

The letter also asks Wisconsin officials to consider simple cycle turbines “with higher efficiency than the units selected.”

EPA asked Wisconsin to detail its reasons why the more efficient models would not be considered the best available control technology at the Jones Island site.

Representatives of the Wisconsin DNR could not be reached for comment.

According to EPA, the Jones Island facility plans to replace two existing turbines for generating electricity with five new units powered by landfill gas with a heat input capacity of 42.6 million Btu per hour each. The facility also plans to install a 1,500 kilowatt emergency diesel generator.

The Jones Island facility will burn landfill gas and requires a specific turbine to meet Wisconsin's stringent nitrogen oxides emissions limits, said a source familiar with the project, who requested anonymity because the permit talks are ongoing.

“We looked hard at all the turbines that were available for this project,” the source said.

EPA Seeks Numeric Limits

Margaret Peloso, an attorney at Vinson & Elkins LLP who works on permits for industry clients, told BNA that EPA's request seems to continue a trend of the agency asking state regulators for more specificity from their permits as they become more comfortable with the greenhouse gas determinations.

EPA's letter also asks Wisconsin permitting officials to set a single numeric greenhouse gas emissions limit for the sewage facility. The proposed permit had set varying emissions limits for the turbines based on ambient air temperature and turbine load, which EPA said “is difficult to practically enforce.”

“EPA is pushing people more in the direction of emissions limits,” Peloso said.

However, EPA's letter only asks Wisconsin to consider more efficient turbines during the first step of its best available control technology analysis. The state could still determine the combined cycle turbines or combined heat and power systems would be infeasible at the Jones Island site later in the evaluation, Peloso said.

Regulators and industry have reported few problems with the first wave of greenhouse gas permitting (233 DEN BB-1, 12/5/11).

New industrial facilities that emit the equivalent of 100,000 tons of carbon dioxide per year and modified sources that increase their emissions by 75,000 tons annually were required to get prevention of significant deterioration or Title V operating permits for greenhouse gas emissions.

The prevention of significant deterioration program requires new and modified sources to obtain permits for emissions of regulated air pollutants and to control those emissions using BACT, determined individually for each source.

For More Information

EPA's letter to the Wisconsin DNR is available at http://epa.gov/nsr/ghgdocs/20120315Milwaukee.pdf.