Glossary of electric industry, energy & cooperative terms

G

Gable
In house construction, the portion of the roof above the eave line of a double-sloped roof.

Gable-End Louver
Vent mounted on one of two gables. Can act as both air intake and exhaust system.

Gas
A fuel burned under boilers and by internal combustion engines for electric generation. These include natural, manufactured and waste gas.

Gas Turbine Plant
A plant in which the prime mover is a gas turbine. A gas turbine consists typically of an axial-flow air compressor, one or more combustion chambers, where liquid or gaseous fuel is burned and the hot gases are passed to the turbine and where the hot gases expand to drive the generator and are then used to run the compressor.

Generating Unit
Any combination of physically connected generator(s), reactor(s), boiler(s), combustion turbine(s), or other prime mover(s) operated together to produce electric power.

Generation (Electricity)
The process of producing electric energy by transforming other forms of energy; also, the amount of electric energy produced, expressed in watt-hours (Wh).

Generation Company
A regulated or non-regulated entity (depending upon the industry structure) that operates and maintains existing generating plants. The generation company may own the generation plants or interact with the short-term market on behalf of plant owners. In the context of restructuring the market for electricity, the generation company is sometimes used to describe a specialized "marketer" for the generating plants formerly owned by a vertically-integrated utility.

Generation and Transmission Cooperative (G&T)
A power-supply cooperative owned by a group of distribution cooperatives. G&Ts generate power and/or may purchase it from public, or investor-owned utilities, or from both.

Generator
A machine that converts mechanical energy into electrical energy.

Generator Nameplate Capacity
The full-load continuous rating of a generator, prime mover, or other electric power production equipment under specific conditions as designated by the manufacturer. Installed generator nameplate rating is usually indicated on a nameplate physically attached to the generator.

Geothermal
Energy from the internal heat of the earth. Hot water from geysers is one type of geothermal energy. It has potential for electric power production, but only in certain geographic regions.

Geothermal Power
Electricity made by a generator powered by steam or hot water trapped and warmed below Earth’s surface by Earth’s internal heat.

Geothermal Plant
A plant in which the prime mover is a steam turbine. The turbine is driven either by steam produced from hot water or by natural steam that derives its energy from heat found in rocks or fluids at various depths beneath the surface of the earth. The energy is extracted by drilling and/or pumping.

Geothermal System
An efficient electrical device for heating and cooling a home or other building by moving heat into or out of the structure. It uses an antifreeze solution or refrigerant in a pipe buried in the ground to collect or disperse heat.

GIF
Graphics Interchange Format. It is a graphics file format commonly used in HTML documents.

Gigawatt (gw)
A unit of power equal to 1,000 megawatts or one billion watts.

Gigawatt-hour (gwh)
A gigawatt-hour is a unit of energy equal to 1,00 megawatt-hours (mwh).

Grain
The direction, size, arrangement, appearance or quality of the fibers in wood.

Greenhouse Effect
The increasing mean global surface temperature of the earth caused by gases in the atmosphere (including carbon dioxide, methane, nitrous oxide, ozone, and chlorofluorocarbon). The greenhouse effect allows solar radiation to penetrate but absorbs the infrared radiation returning to space.

Grid
The entire interlocking system for delivering electricity from the generating station to the ultimate customer. It is a system of interconnected high-voltage transmission lines and power-generating facilities that allows bulk-power suppliers to share resources on a regional basis. This system provides emergency generation and transmission.

Gross Generation
The total amount of electric energy produced by the generating units at a generating station or stations, measured at the generator terminals. (See also net generation)

Ground-Fault Circuit Interrupter (GFCI)
A device that instantly breaks the circuit when a short develops. Required for outlets that are used in bathrooms, kitchens, outdoors or wherever electrical equipment might come into contact with water.

Grout
Mortar made of such consistency (by adding water) that it will flow into the joints and cavities of masonry work and fill them solid.

Page last updated: October 29, 2012