Glossary (A through M)

Adequacy (electric):  The ability of the electric system to supply the electrical demand and energy requirements of the end-use customers at all times, taking into account scheduled and reasonably expected unscheduled outages of system elements.

Ampere:  The unit of measurement of electrical current produced in a circuit by 1 volt acting through a resistance of 1 Ohm.

Ancillary services:  Services that ensure reliability and support the transmission of electricity from generation sites to customer loads. Such services may include load regulation, spinning reserve, non-spinning reserve, replacement reserve, and voltage support.

Apparent power:  The product of the voltage (in volts) and the current (in amperes). It comprises both active and reactive power. It is measured in "volt-amperes" and often expressed in "kilovolt-amperes" (kVA) or "megavolt-amperes" (MVA). See Power, Reactive Power, Real Power.

Base load:  The minimum amount of electric power delivered or required over a given period of time at a steady rate.

Bundled utility service (electric):  A means of operation whereby energy, transmission, and distribution services are provided by one entity.

Circuit:  A conductor or a system of conductors through which electric current flows.

Commercial sector:  An energy-consuming sector that consists of service-providing facilities and equipment of businesses; Federal, State, and local governments; and other private and public organizations, such as religious, social, or fraternal groups. The commercial sector includes institutional living quarters. It also includes sewage treatment facilities. Common uses of energy associated with this sector include space heating, water heating, air conditioning, lighting, refrigeration, cooking, and running a wide variety of other equipment.

Cost-of-service regulation:  A traditional electric utility regulation under which a utility is allowed to set rates based on the cost of providing service to customers and the right to earn a limited profit.

Current (electric):  A flow of electrons in an electrical conductor. The strength or rate of movement of the electricity is measured in amperes.

Customer choice:  The right of customers to purchase energy from a supplier other than their traditional supplier or from more than one seller in the retail market.

Demand:  See Energy demand.

Demand-side management (DSM):  The utility activities designed to encourage consumers to modify patterns of electricity usage, including the timing and level of electricity demand. It does not refer to energy and load-shaped changes arising from the normal operation of the marketplace or from government-mandated energy-efficiency standards.

Deregulation:  The elimination of some or all regulations from a previously regulated industry or sector of an industry.

Direct access:  The ability of a retail customer to purchase electricity or other energy sources directly from a supplier other than their traditional supplier.

Distribution:  The delivery of energy to retail customers.

Distribution provider (electric):  Provides and operates the wires between the transmission system and the end-use customer. For those end-use customers who are served at transmission voltages, the transmission owner also serves as the distribution provider.

Distribution system:  The portion of the transmission and facilities of an electric system that is dedicated to delivering electric energy to an end-user.

Electric industry restructuring:  The process of replacing a monopolistic system of electric utility suppliers with competing sellers, allowing individual retail customers to choose their supplier but still receive delivery over the power lines of the local utility.

Electric plant (physical):  A facility containing electric generators and auxiliary equipment for converting mechanical, chemical, and/or fission energy into electric energy.

Electric rate schedule:  A statement of the electric rate and the terms and conditions governing its application, including contract terms and conditions that have been accepted by a regulatory body with appropriate oversight authority.

Electricity:  A form of energy characterized by the presence and motion of elementary charged particles generated by friction, induction, or chemical change.

Electricity broker:  An entity that arranges the sale and purchase of electric energy, the transmission of electricity, and/or other related services between buyers and sellers but does not take title to any of the power sold.

Electricity congestion:  A condition that occurs when insufficient transmission capacity is available to carry all of the desired power simultaneously.

Electricity demand:  The rate at which energy is delivered to loads and scheduling points by generation, transmission, and distribution facilities.

Electricity generation:  The process of producing electric energy or the amount of electric energy produced by transforming other forms of energy, commonly expressed in kilowatthours(kWh) or megawatthours (MWh).

Electricity sales:  The amount of kilowatthours sold in a given period of time; usually grouped by classes of service, such as residential, commercial, industrial, and other. "Other" sales include sales for public street and highway lighting and other sales to public authorities, sales to railroads and railways, and interdepartmental sales.

Energy charge:  That portion of the charge for electric service based upon the electric energy (kWh) consumed or billed.

Energy conservation features:  This includes building shell conservation features, HVAC conservation features, lighting conservation features, any conservation features, and other conservation features incorporated by the building. However, this category does not include any demand-side management (DSM) program participation by the building. Any DSM program participation is included in the DSM Programs.

Energy efficiency, Electricity:  Refers to programs that are aimed at reducing the energy used by specific end-use devices and systems, typically without affecting the services provided. These programs reduce overall electricity consumption. Such savings are generally achieved by substituting technologically more advanced equipment to produce the same level of end-use services (e.g. lighting, heating, motor drive) with less electricity. Examples include high-efficiency appliances, efficient lighting programs, high-efficiency heating, ventilating and air conditioning (HVAC) systems or control modifications, efficient building design, advanced electric motor drives, and heat recovery systems.

Energy source:  Any substance or natural phenomenon that can be consumed or transformed to supply heat or power. Examples include petroleum, coal, natural gas, nuclear, biomass, electricity, wind, sunlight, geothermal, water movement, and hydrogen in fuel cells.

Fossil fuel:  An energy source formed in the EarthRSQUO;s crust from decayed organic material. The common fossil fuels are petroleum, coal, and natural gas.

Generating unit:  Any combination of physically connected generators, reactors, boilers, combustion turbines, and other prime movers operated together to produce electric power.

Generation:  The process of producing electric energy by transforming other forms of energy; also, the amount of electric energy produced, expressed in kilowatthours.

Generation company:  An entity that owns or operates generating plants.

Grid:  The layout of an electrical distribution system. See electric power grid.

Independent power producer:  A corporation, person, agency, authority, or other legal entity or instrumentality that owns or operates facilities for the generation of electricity for use primarily by the public, and that is not an electric utility.

Independent system operator (ISO):  An independent, Federally regulated entity established to coordinate regional transmission in a non-discriminatory manner and ensure the safety and reliability of the electric system.

Interruptible load:  This Demand-Side Management category represents the consumer load that, in accordance with contractual arrangements, can be interrupted at the time of annual peakload by the action of the consumer at the direct request of the system operator. This type of control usually involves large-volume commercial and industrial consumers. Interruptible Load does not include Direct Load Control.

Interruptible load or interruptible demand (electric):  Demand that the end-use customer makes available to its utility via contract or agreement for curtailment

Investor-owned utility (IOU):  A privately-owned electric utility whose stock is publicly traded. It is rate regulated and authorized to achieve an allowed rate of return.

Kilowatt (kW):  One thousand watts.

Kilowatthour (kWh):  A measure of electricity defined as a unit of work or energy, measured as 1 kilowatt (1,000watts) of power expended for 1 hour. One kWh is equivalent to 3,412 Btu.

Load (electric):  An end-use device or customer that receives power from the electric system.

Load-serving entity (electric):  Secures energy and transmission service (and related Interconnect Operations Services) to serve the electrical demand and energy requirements of its end-use customers.

Market-based pricing:  Prices of electric power or other forms of energy determined in an open market system of supply and demand under which prices are set solely by agreement as to what buyers will pay and sellers will accept. Such prices could recover less or more than full costs, depending upon what the buyers and sellers see as their relevant opportunities and risks.

Megawatt (MW):  One million watts of electricity.

Megawatthour (MWh):  One thousand kilowatt-hours or 1million watt-hours.





Source:  U.S. Energy Information Administration (www.eia.doe.gov).