RES-2010-054 Resolution Regarding the Use of Coal As An Energy Source for the Co-Generation Facility of UNC at Chapel Hill

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ORANGE COUNTY COMMISS[ON FOR THE ENVIRONMENT MEMORANDUM To: Board of County Commissioners From: Commission for the Environment Date: June 14, 2010 Subject: Petition submitted by Citizens for aCoal-Free Community On April 20, 2010 the Board of Commissioners received a petition from the Citizens for aCoal-Free Community, requesting the Board join others in asking the University of North Carolina at Chapel Hill to eliminate the burning of coal through a mix of energy conservation, energy efficiency, and using clean renewable energy sources. Subsequently, the Board asked the Commission for the Environment (CFE) to consider the petition and report back to the Board. The following is the CFE's response. The coal-fired plant referred to in the petition is UNC's cogeneration plant that has been operating since 1991. Cogeneration means that the plant generates both electricity and steam as well as steam heat (for use in both building heating and cooling), thereby operating at high efficiency because it uses the energy in the steam to turn a turbine generator and to run the various heating and cooling operations on campus. In most standard coal-fired electric generating plants the steam is used only for turbine operations and the heat content of phase change from liquid water to gaseous steam is discarded (unused). UNC's plant uses circulating fluidized bed (CFB) technology for cogeneration, which requires the use of at least 50% solid fuel though there is some flexibility in the nature of the solid fuel. Currently the plant burns coal (100,000 tons/year) and natural gas to annually generate 32 megawatts of electricity. The plant has won awards from the U.S. Environmental Protection Agency and U.S. Department of Energy for its efficiency and reduction of greenhouse gases (GHG's) compared to other fossil fuel fired alternatives, and the plant could operate for an additional 30 to 40 years. The CFE agrees that coal combustion is harmful to the environment and that costs of using coal are externalized as they are for all fossil fuels. Petitioners rightfully point out that coal combustion is a primary source of GHG's. UNC's plant is the largest stationary emitter of C02 in Orange County (~ 340,000 tons/yr), although the amount of C02 attributed to the burning of coal and natural gas has not been reported on an individual basis. Nitrous oxides (NOx) and sulfur dioxide (S02) emissions from the plant are relatively low, 500 tons and 150 tons/yr, respectively. Combustion temperatures of approximately 1,800° F versus 2,800° F in apulverized-fired boiler keep NOx emissions low. Limestone is added to the fluidized bed to reduce S02. Calcium sulfate (CaSO4) is precipitated as a by-product. It should be noted that the reaction between limestone and the S02 in the gas is, itself, a generator of C02 gas.