Definitions

Effective Electric Efficiency
Effective electric efficiency is the net electric output divided by the effective fuel input. Effective fuel input is the total fuel used by the combined heat and power (CHP) system minus the fuel that would be used by an 80 percent efficient boiler to generate the same amount of steam as produced by the CHP system. For a discussion of effective efficiencies and calculations, please review the introduction to the Catalog of CHP Technologies and/or the Methods for Calculating Efficiency Web page.

Fuel Source
In CHP systems, fuel sources can include natural gas, biomass, biogas, coal, waste heat, or oil.

Opportunity Fuels
Opportunity fuels are materials from agricultural or industrial processes that would otherwise be wasted but could power a CHP system and are available at or in close proximity to a CHP site.

Prime Movers
Prime movers are the devices that convert fuels to electrical or mechanical energy.

Reliable Power
Reliable power refers to the ability to provide electric power that meets stringent standards for minimal power interruptions.

Spark Spread
For a CHP system, spark spread is the difference between the delivered electricity price and the total cost to generate power with CHP.