The state Department of Environmental Quality (DEQ) has requested additional information from Southern Montana Electric Generation & Transmission Cooperative, Inc. (SME) on how it arrived at estimated pollution emissions from a natural gas-fired power station planned east of Great Falls. Brent Lignell, DEQ's Air Resources Management Bureau’s environmental engineer, stated that DEQ has to precisely account for power station emissions to ascertain the most suitable emissions-control technology.
SME is applying for approval from the DEQ to build a 120 megawatts (MW) gas-fired power station in place of the initially proposed coal-fired plant for the Highwood Generating Station site roughly eight miles east of Great Falls.
DEQ submitted a letter to SME on May 20, 2009 stating that building application was unfinished as inadequate analysis and/or lack of transparency in procedures and computations. The letter requests SME to supply explanatory narrative and formulas on emissions computations. The deadline for response by SME is July 20, 2009.
Jeff Chaffee, vice president of Bison Engineering, a consultant on the gas-fired project, said “They are asking for some additional explanation, i.e. a road map.”
As per SME’s application, the yearly emissions at the gas-fired power station would be a projected 171 tons of nitrogen oxides, 20 tons of volatile organic compounds, 380 tons of carbon monoxide, 6 tons of sulfur dioxide, 64 tons of particulate matter, and 250,000 tons of the greenhouse gas carbon dioxide.
Yearly emission estimations for the coal-fired plant were more. Carbon dioxide emissions from the power station would be 2.4 million tons. Emissions from particulate matter at the coal-fired station would be a projected 366 tons, as against 64 tons from the gas-fired station.
Lignell stated that DEQ wanted to know how SME arrived at its figures so that they can be replicated and comprehended by the public and the agency.
According to the DEQ, under permitting regulations, both the gas- and coal-fired plants are regarded as the same source of emissions, although the coal-fired power station is suspended.
Consequently, SME still should quantify the effects of the coal-fired facility, which could affect emissions restrictions for the gas-fired station.
The DEQ also is requesting SME for elucidation regarding the relationship between the two plants.
The application states the gas plant will not operate when the coal plant boiler is in operation, but fails to address specifics such as nonboiler emissions or lag time following boiler shutdown, the DEQ letter states.
SME affirms in its application that the two facilities would never run simultaneously.