Glossary of Energy Terms "G"

Gallon: A unit of volume. A U.S. gallon has 231 cubic inches or 3.785 liters.

Gas: Gaseous fuel (usually natural gas) that is burned to produce heat energy. The word also is used, colloquially, to refer to gasoline.

Gas Synthesis: A method producing synthetic gas from coal. Also called the Fischer–Tropsch Process.

Gasification: The process where biomass fuel is reacted with sub–stoichiometric quantities of air and oxygen usually under high pressure and temperature along with moisture to produce gas which contains hydrogen, methane, carbon monoxide, nitrogen, water and carbon dioxide. The gas can be burned directly in a boiler, or scrubbed and combusted in an engine–generator to produce electricity. The three types of gasification technologies available for biomass fuels are the fixed bed updraft, fixed bed downdraft and fluidized bed gasifiers. Gasification is also the production of synthetic gas from coal.

Gasohol: A blend of finished motor gasoline containing alcohol (generally ethanol but sometimes methanol) at a concentration between 5.7 percent and 10 percent by volume. The term, gasohol, was used in the late 1970s and early 1980s, but has been replaced in some areas of the country by terms such as E10, Super Unleaded With Ethanol, or Unleaded Plus. Also see Oxygenate.

Gasoline: A complex mixture of relatively volatile hydrocarbons, with or without small quantities of additives, which have been blended to form a fuel suitable for use in spark–ignition engines. Motor gasoline, as defined in ASTM Specification D 4814 or Federal Specification VV–G–1690C, is characterized as having a boiling range of 122 to 158 degrees Fahrenheit at the 10 percent recovery point to 365 to 374 degrees Fahrenheit at the 90 percent recovery point. Motor gasoline includes conventional gasoline; all types of oxygenated gasoline, including gasohol; and reformulated gasoline, but excludes aviation gasoline. Note: Volumetric data on blending components, such as oxygenates, are not counted in data on finished motor gasoline until the blending components are blended into the gasoline.

Gasoline (Leaded): Contains more than 0.05 grams of lead per gallon or more than 0.005 grams of phosphorus per gallon. The actual lead content of any given gallon may vary. Premium and regular grades are included, depending on the octane rating. Includes leaded gasohol. Blendstock is excluded until blending has been completed. Alcohol that is to be used in the blending of gasohol is also excluded.

Gasoline (Unleaded): Contains no more than 0.05 grams of lead per gallon and no more than 0.005 grams of phosphorus per gallon. Premium and regular grades are included, depending on the octane rating. Includes unleaded gasohol. Blendstock is excluded until blending has been completed. Alcohol that is to be used in the blending of gasohol is also excluded.

Gasoline Blending: The mechanical mixing of motor gasoline blending components, and oxygenates when required, to produce finished motor gasoline. Finished motor gasoline may be further mixed with other motor gasoline blending components or oxygenates, resulting in increased volumes of finished motor gasoline and/or changes in the formulation of finished motor gasoline (e.g., conventional motor gasoline mixed with MTBE to produce oxygenated motor gasoline).

Gasoline Blending Components: Naphthas (e.g., straight–run gasoline, alkylate, reformate, benzene, toluene, xylene) used for blending or compounding into finished motor gasoline. These components include reformulated gasoline blendstock for oxygenate blending (RBOB) but exclude oxygenates (alcohols, ethers), butane, and pentanes plus. Note: Oxygenates are reported as individual components and are included in the total for other hydrocarbons, hydrogens, and oxygenates.

Gasoline Grades: The classification of gasoline by octane ratings. Each type of gasoline (conventional, oxygenated, and reformulated) is classified by three grades: regular, midgrade, and premium. Note: Gasoline sales are reported by grade in accordance with their classification at the time of sale. In general, automotive octane requirements are lower at high altitudes. Therefore, in some areas of the United States, such as the Rocky Mountain States, the octane ratings for the gasoline grades may be two or more octane points lower.

• Regular gasoline: Gasoline having an antiknock index, i.e., octane rating, greater than or equal to 85 and less than 88. Note: Octane requirements may vary by altitude.
• Midgrade gasoline: Gasoline having an antiknock index, i.e., octane rating, greater than or equal to 88 and less than or equal to 90. Note: Octane requirements may vary by altitude.
• Premium gasoline: Gasoline having an antiknock index, i.e., octane rating, greater than 90. Note: Octane requirements may vary by altitude.

General Lighting: Lighting designed to provide a substantially uniform level of illumination throughout an area, exclusive of any provision for special visual tasks or decorative effects.

Generating Station: A power plant.

Generating Unit: An electric generator together with its prime mover.

Generator Nameplate Capacity: The full–load continuous rating of a generator, prime mover or other electrical equipment under specified conditions as designated by the manufacturer.

Generation: The process of producing electricity from other forms of energy.

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. In the context of restructuring the market for electricity, Genco is sometimes used to describe a specialized “marketer” for the generating plants formerly owned by a vertically–integrated utility.

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

Geothermal Energy 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 Gradient: The change in the earth's temperature with depth. As one goes deeper, the earth becomes hotter.

Geothermal Steam: Steam drawn from deep within the earth.

Gigawatt (GW): One thousand megawatts (1,000 MW) or one million kilowatts (1,000,000 kW) or one billion watts (1,000,000,000 watts) of electricity. One gigawatt is enough to supply the electric demand of about one million typical Nebraska homes.

Gigawatthour (GWh): One million kilowatthours of electric power.

Glazing: A covering of transparent or translucent material (typically glass or plastic) used for admitting light.

Global Climate Change: Gradual changing of global climates due to the buildup of carbon dioxide and other greenhouse gases in the earth's atmosphere. Carbon dioxide produced by burning fossil fuels has reached levels greater than what can be absorbed by green plants and the seas.

Greenhouse Effect: The presence of trace atmospheric gases make the earth warmer than would direct sunlight alone. These gases (carbon dioxide [CO2], methane [CH4], nitrous oxide [N2O], tropospheric ozone [O3], and water vapor [H2O]) allow visible light and ultraviolet light (shortwave radiation) to pass through the atmosphere and heat the earth's surface. This heat is re–radiated from the earth in form of infrared energy (longwave radiation). The greenhouse gases absorb part of that energy before it escapes into space. This process of trapping the longwave radiation is known as the greenhouse effect. Scientists estimate that without the greenhouse effect, the earth's surface would be roughly 54 degrees Fahrenheit colder than it is today: too cold to support life as we know it. See Global Climate Change (above).

Greenhouse Effect (relating to buildings): The characteristic tendency of some transparent materials (such as glass) to transmit radiation with relatively short wavelengths (such as sunlight) and block radiation of longer wavelengths (such as heat). This tendency leads to a heat build–up within the space enclosed by such a material.

Greenhouse Gases: Those gases, such as water vapor, carbon dioxide, tropospheric ozone, nitrous oxide, and methane that are transparent to solar radiation but opaque to long–wave radiation, thus preventing long–wave radiation energy from leaving the atmosphere. Greenhouse gases, found in trace quantities in the atmosphere, absorb infrared energy and prevent it from leaving the atmosphere. Increasing levels of greenhouse gases in the atmosphere may contribute to an increase in average global temperatures resulting in adverse climate changes. Although many gases found in the atmosphere exhibit these properties, Energy Information Administration's voluntary reporting program focuses on the gases most affected by human activity: carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), halogenated substances, and other radiatively enhancing gases [carbon monoxide (CO), nitrogen oxides (NOX), and nonmethane volatile organic compounds (NMVOCs)].

Grid: 1) A system of interconnected power lines and generators that is managed so that the generators are dispatched as needed to meet the requirements of the customers connected to the grid at various points. A Gridco is sometimes used to identify an independent company responsible for the operation of the grid. 2) The electric utility companies' transmission and distribution system that links power plants to customers through high power transmission line service [110 kilovolts (kV) to 765 kV]; high voltage primary service for industrial applications (23 kV–138 kV); medium voltage primary service for commercial and industrial applications (4 kV to 35 kV); and secondary service for commercial and residential customers (120 V to 480 V). 3) The layout of a gas distribution system of a city or town in which pipes are laid in both directions in the streets and connected at intersections.

Gross Area: The area of a surface including areas not belonging to that surface (such as windows and doors in a wall).

Gross National Product (GNP): The total market value of the goods and services produced by a nation before deduction or depreciation charges and other allowance for capital consumption and is widely used as a measure of economic activity.

Gross State Product (GSP): The total market value of the goods and services attributable to labor and property located in a state. It is the state counterpart of the nation's gross domestic product.

Group 3: Group 3, or the Group, is a spot market trading hub. It is primarily in the heartland: Oklahoma, Kansas, and Missouri. The Magellan and NuStar Pipelines would carry fuel from the Group 3 market to Nebraska.