Cogeneration

  The generation of electricity or shaft power by an energy conversion system and the concurrent use of rejected thermal energy from the conversion system as an auxiliary energy source.

  Production of heat energy and electrical or mechanical power from the same fuel in the same facility. A typical cogeneration facility produces electricity and steam for industrial process use.

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  The production of electrical energy and another form of useful energy (such as heat or steam) through the sequential use of energy.

  U.S. Dept. of Energy, Energy Information Administration's Energy Glossary

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  Cogeneration means the sequential use of energy for the production of electrical and useful thermal energy. The sequence can be thermal use followed by power production or the reverse, subject to the following standards:

  a) At least 5 percent of the cogeneration project's total annual energy output shall be in the form of useful thermal energy.

  b) Where useful thermal energy follows power production, the useful annual power output plus one-half the useful annual thermal energy output equals not less than 42.5 percent of any natural gas and oil energy input.

  California Energy Comission. Dictionary of Energy Terms