ACTIVE SOLAR ENERGY: Solar radiation used by special equipment to provide space heating, hot water or electricity.

BIOMASS: Energy resources derived from organic matter. These include wood, agricultural waste and other living-cell material that can be burned to produce heat energy. They also include algae, sewage and other organic substances that may be used to make energy through chemical processes.

COAL CONVERSION: Changing coal into synthetic gas or liquid fuels.

DAYLIGHTING CONTROL: A control system that varies the light output of an electric lighting system in response to variations in available daylight.

ESCO: (Efficiency Service Company). A company that offers to reduce a client”s electricity consumption with the cost savings being split with the client.

FUEL CELL: A device or an electrochemical engine with no moving parts that converts the chemical energy of a fuel, such as hydrogen, and an oxidant, such as oxygen, directly into electricity. The principal components of a fuel cell are catalytically activated electrodes for the fuel (anode) and the oxidant (cathode) and an electrolyte to conduct ions between the two electrodes, thus producing electricity.

GEOTHERMAL ENERGY: Natural heat from within the earth, captured for production of electric power, space heating or industrial steam.

HEAT GAIN: An increase in the amount of heat contained in a space, resulting from direct solar radiation, heat flow through walls, windows, and other building surfaces, and the heat given off by people, lights, equipment, and other sources.

LIQUEFACTION: The process of making synthetic liquid fuel from coal. The term is also used to mean a method for making large amounts of gasoline and heating oil from petroleum.

NATURAL GAS: Hydrocarbon gas found in the earth, composed of methane, ethane, butane, propane and other gases.

NUCLEAR ENERGY: Power obtained by splitting heavy atoms (fission) or joining light atoms (fusion). A nuclear energy plant uses a controlled atomic chain reaction to produce heat. The heat is used to make steam run conventional turbine generators.

PHOTOVOLTAIC CELL: A semiconductor that converts light directly into electricity.

RADIANT ENERGY: Energy transferred by the exchange of electromagnetic waves from a hot or warm object to one that is cold or cooler. Direct contact with the object is not necessary for the heat transfer to occur.

SOLAR COLLECTOR: A component of an active or passive solar system that absorbs solar radiation to heat a transfer medium which, in turn, supplies heat energy to the space or water heating system.

SYNFUEL: Synthetic gas or synthetic oil. Fuel that is artificially made as contrasted to that which is found in nature. Synthetic gas made from coal is considered to be more economical and easier to produce than synthetic oil. When natural gas supplies in the earth are being depleted, it is expected that synthetic gas will be able to be used widely as a substitute fuel.

THERMODYNAMICS: A study of the transformation of energy into other manifested forms and of their practical applications.

This glossary of terms and definitions was abstracted from a resource compiled by the California Energy Commission (