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2.2 Power Generation <br />The most prevalent use for landfill gas is as a fuel for power generation with the electricity sold to <br />a utility and /or a nearby power customer. Power generation is advantageous because it produces a <br />valuable end product — electricity — from the waste gas. Facilities that use landfill gas to generate <br />electricity can qualify as a "small power producer" under the Public Utilities Regulatory Policy <br />Act (PURPA), which requires electric utilities to purchase the output fi'om such facilities at the <br />utility's avoided cost The electricity can in some cases be used on site to displace purchased <br />electricity or be sold to a nearby electricity user (c g., municipality, industrial, etc.) Cogeneration <br />(electric power with waste gas heat recovery) is an alternative to the production of electricity only <br />Thermal energy cogenerated by landfill gas projects can be used on site for hearing, cooling and /or <br />process needs, or piped to a nearby industrial or commercial user to provide a second revenue <br />stream to the project. <br />2.3 Upgrade to High -Btu (Pipeline Grade) Natural Gas <br />Another option is to upgrade the landfill gas to a high -Btu product for compression and direct <br />introduction into a natural gas pipeline. This application requires extensive high technology <br />treatment of the gas to remove CO, and other impurities In addition, gas companies require that <br />gas injections into their pipeline systems conform to strict quality specifications, which can impose <br />additional quality control, cleanup, and compression requirements on the producer. However, this <br />can in some cases be an attractive option since it is possible to utilize all the gas that is recovered. <br />XM il] 11 �111�]O]fP__I <br />Determining the optimum size for a landfill gas recovery project requires a careful balance <br />between maximizing electricity In and /or direct landfill gas use while minimizing the risk <br />of insufficient gas supply in later years. The challenge arises because landfill gas production rates <br />change over time Gas generation may be increasing at an open landfill or decreasing at a closed <br />landfill. Other considerations such as existing and future electricity rates, equipment cost's, and <br />any penalties for shortfalls in electricity output must be factored into the system design. <br />The optimum design and operating scenario for a particular landfill gas project is likely to fall <br />somewhere between two general scenarios: (1) minimum gas flow design; and (2) maximum gas <br />flow design However, a third design scenario — a modular approach — may be used at landfills <br />where gas flow rates are expected to change substantially over time <br />For the purposes of this study, a minimum gas flow design was used in the evaluation of potential <br />landfill gas recovery alternatives The combined total production of gas from both the North and <br />South Eubanks Road landfill sites and the production from the South Eubanks site only were <br />respectively evaluated. <br />Orange County 2 March 2006 <br />Draft <br />