The Oklahama Department of Environmental Quality went out for comment on Sept. 15 on a draft air permit change that would allow Oklahoma Gas & Electric (OG&E) to repower its Mustang Generating Station.
“In this application, OG&E proposes to modernize the plant by retiring the four existing electric generating boilers and to construct seven (7) new gas-fired simple-cycle combustion turbines, as replacement generating capacity,” said a DEQ permitting document. “Each turbine will be a Siemens Trent Turbine with a higher heat value (HHV) rating of 552 MMBTUH capable of producing 58 megawatts (MW) at base load firing pipeline-quality natural gas.
“Each combustion turbine will utilize a wet low emitting (WLE) NOX burner, an Inlet Spray Inter-cooling (ISI) system, and an oxidative catalyst for the control of carbon monoxide (CO). The proposed modification also includes adding a 1,000 KW emergency diesel generator and a 350 hp emergency diesel fire pump will be installed in place of the previous 1,440 hp pump with associated 100 gallon diesel tank. Additionally, the project involves removing the house heat auxiliary boiler, emergency diesel fire water pump with associated 100 gallon diesel tank, and a 2,142 gallon diesel tank. The emergency propane generator will remain on site.”
The Mustang facility currently consists of four electric generating units. The boilers are natural circulation Babcock and Wilcox-type boilers capable of producing steam. The thermodynamic energy in the steam is converted to mechanical energy by the steam turbine/generator unit capable of producing electricity. The boiler units 1, 2, 3, and 4 use natural gas as their primary fuel. Other emission units at the facility include a gas-fired house-heat boiler and two storage tanks.
The new turbines will burn pipeline quality natural gas only. Generating boiler 2-B-01 will be permanently shut down, and retired no later than Dec. 31, 2015. Generating boilers 2-B-02, 2-B-03, and 2-B-04 will be shut down and retired no later than Dec. 31, 2017. The existing boilers need to be shut down prior to any of the proposed turbines becoming operational. A turbine will be considered operational only after a reasonable shakedown period, not to exceed 180 days.
Oklahoma Gas & Electric parent OGE Energy (NYSE: OGE) said in its Aug. 6 quarterly Form 10-Q statement about the need for this project: “On August 6, 2014, OG&E filed an application with the [Oklahoma Corporation Commission] for approval of its plan to comply with the EPA’s MATS and Regional Haze [Federal Implementation Plan] while serving the best long-term interests of customers in light of future environmental uncertainties. The application seeks approval of the environmental compliance plan and for a recovery mechanism for the associated costs. The environmental compliance plan includes installing dry scrubbers at Sooner Units 1 and 2 and the conversion of Muskogee Units 4 and 5 to natural gas.
“The application also asks the OCC to predetermine the prudence of replacing OG&E’s soon-to-be retired Mustang steam turbines in late 2017 (approximately 460 MW) with 400 MW of new, efficient combustion turbines at the Mustang site in 2018 and 2019 and approval for a recovery mechanism for the associated costs. OG&E estimates the total capital cost associated with its environmental compliance and Mustang Modernization Plan included in this application to be approximately $1.1 billion.”