Glossary of Energy Terms

Here you will find definitions for many energy terms. The glossary is organized alphabetically, so if you are looking for "renewable energy", click on "R" and read down the list to find the term. You can also scroll the entire library to learn lots of new energy terms.
A | B | C | D | E | F | G | H | I | J | K | L | M |
N | O | P | Q | R | S | T | U | V | W | X | Y | Z |
Access ChargesA fee paid by a user to a utility for the ability to send or receive electricity or natural gas through its transmission or distribution systems.
AggregatorsAn organization that combines customers into a group to purchase natural gas or electricity services, hoping to achieve volume discounts.
Anthracite CoalAnthracite, or hard coal, is jet black with a high luster. The moisture content generally is less than 15 percent. It usually has a high fixed carbon and ash content and is low in volatile matter.
Barrel (Petroleum)A unit of volume equal to 42 U.S. gallons.
Biomass EnergyEnergy derived from wood, wood wastes, other organic wastes, landfill gas, and animal and human wastes.
Bituminous CoalBituminous coal is the most common coal. It is dense, black, often with well-defined bands of bright and dull materials. Its moisture content usually is less than 20 percent. It is used for generating electricity, making coke, and space heating.
British Thermal Unit (Btu)The quantity of heat needed to raise the temperature of 1 pound of water by 1 degree Fahrenheit at or near 39.2 degrees Fahrenheit.
ButaneA normally gaseous hydrocarbon which is extracted from natural gas or refinery gas streams. It is used as a household fuel, propellant and refrigerant.
CapacityAn amount of electricity that would be available from a generating unit, utility or system. Capacity is valued in units of energy such as megawatts for electrical power or cubic feet for natural gas.
CoalA black or brownish/black solid, combustible substance formed by the partial decomposition of vegetable matter without access to air. Types of coal are anthracite, subanthracite, bituminous, subbituminous, and lignite; the categories are based on fixed carbon, volatile matter, coking properties, and heating value.
CogenerationA source that generates electricity and also provides heat or thermal energy for industrial or commercial uses.
Coke (Coal)In general, coke is made from bituminous coal from which the volatile constituents are driven off by baking in an oven at temperatures as high as 2,000 degrees Fahrenheit, so that the fixed carbon and ash are fused together. Coke is hard and porous and is strong enough to support a load of iron ore in a blast furnace. It is used both as a fuel and a reducing agent in smelting iron ore in a blast furnace.
Compact Fluorescent Lighting (CFL)Compact fluorescents are an efficient form of lighting; CFL bulbs use one-quarter to one-third as much electricity to give the same light output as a standard incandescent bulb while creating much less heat, and last up to 10 times as long as a standard incandescent light (10,000 vs. 1,000 hours).
Condensing Furnace/BoilerCondensing furnaces and boilers are the most energy-efficient units on the market today. The combustion process produces gas by-products that include water vapor and carbon dioxide. In a conventional heating system, these by-products are vented out of the house. Condensing systems cool the combustion gases to the point that water condenses and the process releases additional heat that is captured and distributed to the home. Condensing gas furnaces are generally 10-15% more efficient than conventional units.
Conversion FactorA number that translates units of one system into corresponding values of another system. Conversion factors can be used to translate physical units of measure for various fuels into Btu equivalents.
Crude OilA mixture of hydrocarbons that exists in liquid phase in underground reservoirs and remains liquid at atmospheric pressure after passing through surface separating facilities. Included are lease condensate and liquid hydrocarbons produced from tar sands, gilsonite, and oil shale.
Customer ChoiceCustomer Choice is one of the terms, another being retail choice, to describe a competitive market where energy consumers are given a choice of energy supplier.
Delivery ChargeThe component of an energy bill covering the cost of delivering electricity or gas.
Demand (Or Load)The instantaneous electric energy use, either of a single customer or for all customers.
Demand Side Management (DSM)Utility activities designed to help customers use electricity more efficiently.
DeregulationThe process of removing regulations or other barriers that may restrict an industry.
Distillate Fuel OilA general classification for one of the petroleum products produced in conventional distillation operations. It is used primarily for space heating, diesel engine fuel, and electric power generation. Included are products known as No. 1, No. 2, and No. 4 fuel oils; No. 1, No. 2, and No. 4 diesel fuels.
DistributionThe delivery of electricity to an end-user through low-voltage lines or natural gas through pipeline systems.
Electricity Installed CapacityThe maximum load that a generating station can carry under specified conditions for a given period of time and not limited by existing service conditions.
Energy Guide LabelBy law, most new appliances have to carry EnergyGuide labels which provide an estimate of how much energy the appliance will use in one year - based on average household use patterns, or the energy efficiency rating of the appliance. Each label also has a bar scale, showing the range of efficiencies for all similar appliances and an arrow, indicating where in the range this model falls.
Energy MarketerAn organization that arranges deals to sell electricity or natural gas for a customer and may provide other services. In the electricity market they may be referred to as Power Marketers.
Energy Service Company (ESCO)A business that installs energy efficient and other demand side management measures in facilities.
Energy StarENERGY STARŪ is a set of voluntary energy efficiency programs, sponsored by the US Environmental Protection Agency and the US Department of Energy. ENERGY STAR sets standards for, and labels, energy-efficient products and sets standards of energy efficiency for homes and businesses.
Federal Energy Regulation Commission (FERC)The federal agency that regulates the price, terms, and conditions of energy sold through interstate commerce and all transmission services.
Fossil FuelsFossil fuels, including coal, petroleum, etc., are derived from plants and animals buried for so long and under such heat and pressure that they became minerals. The energy from fossil fuels comes from the high energy bonds formed between one carbon atom and another, as well as those formed between carbon and hydrogen atoms. These fuels are limited in total quantity and are non-renewable.
GasoholA blend of finished motor gasoline (leaded or unleaded) and alcohol (generally ethanol but sometimes methanol) in which 10 percent or more of the product is alcohol.
GenerationThe process which produces electricity.
Generation ChargeThe component of an energy bill covering the cost of supplying the energy. For gas, this is typically referred to as the Gas Charge.
Geothermal PowerElectricity derived from heat found under the earth's surface. Within the earth, there are vast amounts of molten rock and metal, covered by succeeding layers of cooler material, up to the crust of the earth's surface. Underground rivers generate steam which is liberated in the form of geysers through fissures in the earth's surface.
Green eA voluntary labeling program established initially in California to indicate which competitive products use Green Power. The current requirement is that at least 50% of the energy sources be verified renewable, including solar, wind, ocean, biomass, geothermal and small hydroelectric, and that there be no more nuclear power than in the system-wide average for the region.
Green PowerGreen Power is a term used to describe electricity produced by sources that are less harmful to the environment than fossil fuels. While there is no strict definition of Green Power, generally renewable sources such as solar, wind power, geothermal, biomass, and some hydroelectric are considered Green Power sources.
H-axis Washing Machine (Tumble Washing Machine)A front-loading washing machine, long common in Europe but not in the US, that uses a tumble action washing method. These machines have been shown to use much less energy and water, and are reported to cause less wear and tear on clothes.
Heat PumpsHeat pumps extract heat from either the air (air source) or ground (ground source) and transfer that heat by circulating a refrigerant through a cycle of alternating evaporation and condensation. The cycle can be reversed for cooling. The efficiency of an air source heat pump varies tremendously with climate while ground source heat pumps take advantage of stable ground temperatures to deliver consistent performance. An air source heat pump is generally twice as efficient as a standard furnace, and a ground source heat pump can be twice as efficient still.
Hydroelectric PowerElectricity generated by an electric power plant whose turbines are driven by falling water.
Independent Power Producer (IPP)A company other than a utility that generates electricity. Also referred to as a non-utility generator or producer.
Independent System Operator (ISO)An organization created to control the operation of the power system, monitor reliability and coordinate the supply of electricity in a region.
KeroseneLight hydrocarbon distillate. Includes vaporizing oil for use in reciprocating engines (primarily tractors), lamp oil, and kerosene and heating oil.
Kilowatt (kW)One thousand watts, where a watt is a unit of electrical power calculated as the rate of energy transfer equivalent to one ampere flowing under a pressure of one volt.
Kilowatthour (kWh)The standard measure of electricity usage measured as one kilowatt of power supplied to, or taken from, an electric circuit steadily for l hour.
LigniteLignite is a young coal. It is brownish black in color and has a high moisture content, sometimes as high as 45 percent, and a high ash content. It tends to disintegrate when exposed to the weather.
Liquefied Natural Gas (LNG)Conventional natural gas which is liquefied by reducing its temperature to minus 260 degrees Fahrenheit at atmospheric pressure.
Liquefied Petroleum Gases (LPG)Ethane, ethylene, propane, propylene, normal butane, butylene, and isobutane produced at refineries or natural gas processing plants, including plants that fractionate raw natural gas plant liquids.
Load ManagementUtility activities designed to influence the timing and amount of electricity that customers may use.
Load ShiftingA type of load management that shifts use from peak to off-peak periods.
Local Distribution Company (LDC)The utility company that provides the distribution, customer and energy services for natural gas and electricity.
Municipal Electric Utilities (Munis) and CooperativesMunicipal Electric Utilities and Cooperatives are owned by the customers that they serve. Customer interests are represented by elected commissioners who oversee utility operations. Generally smaller than investor-owned utilities, Munis and Cooperatives account for roughly 4% of the electricity generated in the US.
Natural GasA mixture of hydrocarbon compounds, primarily methane and small quantities of various nonhydrocarbons existing in gaseous phase or in solution with crude oil in natural underground reservoirs at reservoir conditions.
Natural Gas Act (NGA)Federal law enacted in 1938 that established FERC's authority to regulate interstate pipelines.
Natural Gas Policy Act (NGPA)Federal law that updated the NGA and set guidelines for deregulation of new gas supplies and continued regulation of old supplies.
New GasGas produced from new formations and fields or drilling after April 1977.
New Renewable EnergyEnergy produced from a renewable generating source that was built more recently than a specified date.
Non-Utility SupplierA company other than a utility that provides natural gas or electricity. Also referred to as independent power producer.
Nuclear PowerElectricity generated by nuclear reactors of various types such as heavy water, light water, and boiling water.
Obligation To ServeCurrently, the obligation of a utility to provide natural gas or electric to any customer who requests it and is willing to pay the rates set for it.
Off-PeakA period of time when there is a low demand for electricity on a utility's generation system.
On-PeakA period of time when there is a high demand for electricity on a utility's generation system.
PetroleumA generic term applied to oil and oil products in all forms, such as crude oil, lease condensate, unfinished oils, refined petroleum products, natural gas plant liquids, and nonhydrocarbon compounds blended into finished petroleum products.
Power ExchangeAn organization established to facilitate the trading of and creation of a spot market for electricity. In some regions the Power Exchange has been incorporated in the ISO.
Power GridThe network of transmission lines that link all generating plants in a region with local distribution networks to help maximize service reliability.
PropaneA normally gaseous hydrocarbon. It is a colorless paraffinic gas that boils at a temperature of 143.67 degrees Fahrenheit. It is extracted from natural gas or refinery gas streams and used for home heating and cooking.
Proven ReservesProven reserves are the estimated quantities of fossil fuels, which analysis demonstrates with reasonable certainty to be recoverable in future years from known reservoirs under existing economic and operating conditions.
Public Utilities Regulatory Policy Act (PURPA)A 1978 federal law that requires utilities to buy power from eligible cogeneration sources, small hydro or waste-fueled facilities, under contracts at an avoided cost rate. The utilities also must provide a back up supply of electricity to customers who choose self-generation.
Renewable EnergyAn energy source for generating electricity that is not based on fuels with limited reserves. Included are solar power, hydro-power, wind power, geothermal power, biomass, and tidal power.
Residual Fuel OilThe topped crude of refinery operations which includes No. 5 and No. 6 fuel. Residual fuel oil is used for the production of electric power, space heating, vessel bunkering, and various industrial purposes.
Retail CompetitionA market that allows more than one energy provider to sell directly to customers and where customers have the choice of buying from more than one provider.
Spot MarketA market option that offers short-term contracts for set amounts of natural gas or electricity, thus establishing prices that vary in real time.
StorageThe placement of utility-owned gas in underground facilities during the summer, when demand is low, and withdrawn for the winter when gas consumption is higher.
Stranded CostsCosts that a utility has an obligation to pay for (e.g., long-term contracts or payments on a generation plant) but may not be able to recover in a competitive market where rates are no longer set by regulatory bodies.
ThermThe standard unit for measuring the amount of gas used, defined as the volume of gas needed to generate 100,000 Btu.
Time Of Use (TOU) PricingRates that are designed to reflect changes in a utility's cost of providing service that change by season or time of day.
Transition ChargeAn element of a utility bill designed to cover stranded costs as the industry transitions to a competitive market.
TransmissionThe transportation of electricity or natural gas from a generation plant or pipeline to another facility. Or, the transfer of energy between utility systems.
Transmission and Distribution LossNon-usable energy lost or required to deliver electricity or gas over their respective distribution systems. Much of the loss is thermal in nature due to the resistance/friction in the transmission medium. For example, electrical resistance in wires and friction in gas pipelines.
Transportation CustomerA customer who uses a utility's pipeline and distribution system but buys natural gas from a different supplier.
Types Of Electric ServiceFIRM -- The delivery of electricity by a company on a continuous basis. Residential and smaller commercial customers generally use this service. INTERRUPTIBLE -- The delivery of electricity to a customer that may be interrupted by the utility generally because of system supply or capacity limitations.
Types Of Natural GasFIRM -- The delivery of gas to a customer on a continuous basis. Residential and smaller commercial customers generally use this service. INTERRUPTIBLE -- The delivery of gas to a customer that may be interrupted by the utility generally because of system supply or capacity limitations. OFF-PEAK OR SEASONAL -- The delivery of gas, firm or interruptible, sold only during certain times of the year, generally when there are not high system demands.
UnbundlingThe separation and itemization of the prices or services offered by a local distribution company's rates.
Vented/Flared (Natural Gas)The release (venting) or burning (flaring) of associated gas as a means of disposal.
WheelingThe transmission of electricity to various companies by a company that does not own or directly use the power.
Wholesale CompetitionA market that allows a distribution company to buy energy from a variety of sources, and where the energy producers would be able to sell to distribution companies.
Wind PowerWind power has been used for many years to drive mills and water pumps. Although some of those uses continue, the most common commercial use of wind power today is for running turbines that generate electricity. Wind turbines are often set up in clusters, called wind farms, and the electricity generated is fed into the grid.
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