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Combined Heat and Power (CHP), or cogeneration, provides both an on-site source of electric power and useful energy from a single fuel source. These systems capture thermal energy that would normally be lost in traditional power generation and use it to serve on-site heating and cooling needs.
A form of distributed generation, CHP systems typically are located at or near the energy-consuming facility. Recovering the heat normally lost in power generation or transmission processes to provide on-site heating or cooling results in increased energy-efficiency and reduced greenhouse gas emissions.
CHP systems are configured with either a topping or bottoming cycle. In a typical topping cycle system, fuel is combusted in a prime mover -- such as a gas turbine or reciprocating engine -- to generate electricity. Most energy lost from the prime mover’s hot exhaust and cooling systems is recovered and provides valuable and usable heated air or water. The heated air is generally used for industrial processes such as petroleum refining or food processing, and the hot water is typically used for laundry, dishwashing, space heating, cooling, and dehumidification. In a bottoming cycle system, also referred to as “waste heat recovery,” fuel is combusted to provide thermal input to a furnace or other industrial process. Any heat rejected from this process is then used for electricity production.
In Maryland, the energy generated by CHP systems must be consumed by the facility and no excess generation can be fed back onto the grid. Thus, no DC-to-AC inverter is required and Pepco does not install a net-capable meter. Based on the standard Maryland Level 2, 3, & 4 Interconnection Application and Agreement, the Maryland Combined Heat and Power Interconnection Application and Agreement facilitates these special circumstances and provides CHP-specific directions for completing the application form and review process.
CHP systems in Maryland may be eligible for rebates under the EmPOWER Maryland Energy Savings Program for Commercial & Industrial customers. This requires a separate application. For more information, see the EmPOWER Maryland CHP Program website.