Opinion ID: 395148
Heading Depth: 1
Heading Rank: 2

Heading: PPG's Lake Charles Facility

Text: 9 Petitioner PPG owns and operates a chemical manufacturing plant located at Lake Charles, Louisiana, which requires large amounts of steam and electricity for its operations. To meet its energy requirements, PPG constructed a power plant designed to take advantage of new fuel-efficient cogeneration technology. The power plant is comprised of two parallel units. In each unit, a gas turbine burns fossil fuel to produce electricity. Waste heat gases thrown off by the turbine's exhaust, which would otherwise be discharged into the atmosphere, are funnelled as a heat source into a waste heat boiler. The total heat input of that boiler comes from a combination of waste heat and fossil fuel combustion. The waste heat contributes nearly 40% (approximately 371 million British thermal units per hour) of the total heat input to the boiler. A portion of the waste heat aids in the combustion of fossil fuel, either fuel oil or natural gas, which provides the other 60% of the heat input (approximately 598 million British thermal units) to the boiler. The highly pressurized steam thereby created in the boiler is used to turn a backpressure turbo-generator. This produces electricity which is then channelled back into PPG's main plan for use in the manufacturing process. 10 PPG's system is technically called a supplementary-fired, combined-cycle cogeneration system. The use of supplemental fossil fuel to heat the boiler distinguishes it from a standard combined-cycle cogeneration system, in which the boiler is heated solely by waste heat gases produced by the turbine. In such a standard system, the boiler produces only medium pressure steam which may nevertheless be useful in the manufacturing process. The addition of supplemental fossil fuel in PPG's cogeneration system, however, makes it more efficient by enabling the boiler to make high pressure steam that can be used to produce electricity. 11 The air pollutants from PPG's power plant are similar to those of any other boiler fired by fossil fuel. The pollutant of principal concern is sulfur dioxide, which is formed during combustion of sulfur-bearing fuels in the presence of oxygen. The higher the sulfur content of the fuel, the greater the amount of sulfur dioxide emitted upon combustion. Virtually all of the sulfur dioxide emissions from the power plant are directly attributable to the burning of fuel oil in the waste heat boiler and virtually none to the gas turbine exhausts. These emissions are, of course, considerably less than if the boiler were totally fired by fossil fuel. They may be reduced through the use of either flue gas desulfurization equipment (scrubbers) or fuel with a low sulfur content. 12 In addition to sulfur dioxide emissions, PPG's power plant emits particulate matter and nitrogen oxides. These pollutants, however, are not of great concern in this case, because nitrogen oxides are controlled primarily through boiler design, and combustion of fuel oil does not produce significant particulate emissions.