• Gas

    That state of matter which has neither independent shape nor volume. Gas expands to fill the entire container in which it is held. Gas is one of the three forms of matter: solid, liquid and gas.

  • Gas-Flow

    A set of standard record formats supporting the electronic data interchange of files, established by a joint Task Force of the Interstate Natural Gas Association of America (INGAA), the Council of Petroleum Accountants Society (COPAS), and the American Gas Association (AGA).

  • Gas Inventory Charge (GIG)

    A charge paid by a buyer to its supplier for holding natural gas supplies ready to be delivered to the buyer.

  • Gas-Reserves

    Natural gas in natural underground formation in wells, fields or pools.

  • Gas Transported for Others

    Natural gas owned by another company received into and transported through any part of a pipeline transmission system under a transportation agreement.

  • Gas Turbine Plant

    A plant in which the prime mover is a gas turbine. A gas turbine typically consists of an axial-flow compressor which feeds compressed air into one or more combustion chambers where liquid or gaseous fuel is burned. The resulting hot gases are expanded through the turbine, causing it to rotate. The rotating turbine shaft drives the compressors as well as the generator, producing electricity.

  • Gasification

    Any of various processes by which coal is turned into natural gas.

  • Gathering Line

    Network-like pipeline that transports natural gas from individual wellheads to a compressor station, treating or processing plant, or main trunk transmission line. Gathering lines are generally relatively short in length, operate at a relatively low pressure, and are small in diameter.

  • Gathering Station

    A compressor station at which natural gas is gathered from wells by suction because wellhead pressure is not sufficient to produce the desired rate of flow into a transmission or distribution system.

  • Genco

    The term used for that portion of a functionally disaggregated electric utility's business that involves the production of power which is operated separately from any other power functions which the utility owns or operates.

  • 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

    The process of producing electric energy by transforming other forms of energy such as steam, heat or falling water. Also, the amount of electric energy produced, expressed in kilowatt-hours (kWh) or megawatt-hours (mWh).

  • Generation Company (Genco)

    A regulated or non-regulated entity (depending upon the industry structure) that operates and maintains existing generating plants. The Genco may own the generation plants or interact with the short-term market on behalf of plant owners.

  • Generator

    A machine that converts mechanical energy into electrical energy. Generally rated in terms of real power (megawatts) and reactive power (Megavars) output or in terms or real power output (megawatts) and power factor. Generators require a source of mechanical energy input (typically a turbine) and ancillary equipment to interface with the transmission network.

  • Geothermal

    Power generated from heat energy derived from hot rock, hot water, or steam below the earth's surface.

  • Geothermal Plant

    A plant in which the prime mover is a steam turbine, 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.

  • Giga-NOPR

    A slang term referring to the Notice of Proposed Rulemaking in the electric power industry that launched the FERC's efforts to implement full open access of the electric transmission system. Docket No. RM 95-8-000. It is parallel to "Mega-NOPR", which was used to describe Order No. 636, which substantially completed the move to open access of the natural gas pipeline industry.

  • Gigajoule

    A unit of energy equaling 943,213.3 Btu.

  • Gigawatt (GW)

    One billion watts.

  • Gigawatt-hour (GWh)

    One billion watt-hours.

  • Grade

    Gas Revenue Accounting Data Exchange: A system for the electronic communication of natural gas production and sales data between companies in the energy industry.

  • Graduated Rate


  • Grandfather Clause

    A clause in a contract which maintains the prior rule or policy where a new rule or policy would otherwise be applicable.

  • Graveyard

    Light load hours. The time of the day when an electric power system would experience its lightest load, usually in the middle of the night.

  • Greenfield Development

    Development of a new power generating facility.

  • Greenhouse Effect

    The increasing mean global surface temperature of the earth believed to be 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 layout of the electrical transmission system or a synchronized transmission network.

  • Gross Actual Generation

    Actual number of electrical megawatt-hours (MWH) generated by the unit during the period being considered.

  • Gross Available Capacity (GAC)

    Greatest capacity at which a unit can operate with a reduction imposed by a derating.

  • Gross Dependable Capacity (GDC)

    GMC modified for seasonal limitation over a specified period of time.

  • Gross Generation:

    The total amount of electric energy produced by the generating units at a generating station or stations, measured at the generator terminals.

  • Gross Maximum Capacity (GMC)

    Maximum capacity a unit can sustain over a specified period of time when not restricted by seasonal or other deratings.