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This chapter characterizes the prime mover technologies typically used in CHP applications. The characterizations include reciprocating engines, microturbines, gas turbines, steam turbines, and fuel cells. Historically the primary industrial technologies are gas turbines, reciprocating engines and steam turbines. Conventional large industrial systems are relatively widely deployed and utilize readily available thermal technologies.
Even though the commercial sector is about 75% as large as the industrial sector in terms of electricity demand, the existing applications of CHP are nine times larger in the industrial sector. There are viable CHP opportunities in the commercial sector, but technology and application matching in the commercial sector is more difficult:
• On average, commercial sites are much smaller than industrial sites. Technologies for smaller applications have been more expensive and less efficient than larger CHP.
• Commercial establishments generally operate fewer hours per year and have lower load factors, providing fewer hours of operation per year in which to payback their higher first costs.
Unlike the majority of industrial projects that can absorb the entire thermal output of a CHP system onsite, many commercial sites have either an inadequate thermal load or a highly seasonal load such as space heating. The best overall efficiency and economics come from a steady thermal load. These loads are concentrated in relatively few types of commercial applications. These have been the focus of the traditional commercial/institutional CHP market (e.g., education, hospitals, and hotels).
4.1 Recip Engines
4.2 Microturbines
4.3 Gas Combustion Turbines
4.4 Fuel Cells
4.5 Steam Turbines
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