Glossary
A - F
A fee paid by an independent power producer or its customer to use a transmission company's system
An electric system's ability (maintenance, load following, planning for future needs, etc.) to supply the aggregate electrical demand and energy requirements of its customers at all times
An entity (for profit or non-profit) that assembles generators or customer loads to achieve economies of scale and diversity among the generators or loads being combined
A flow of electricity that is uncontrollable as to direction and amount
The services necessary to effect a transfer of electricity between purchasing and selling entities that transmission providers must include in their open access transmission tariffs; IOSs are the voluntary services that transmission providers may offer to their customers (FERC Order 888, April 24, 1996). Ancillary services include regulation and frequency response; reactive supply and voltage control from generating sources, economic dispatch, and the like
The measure of time that a generating unit, transmission line or other facility is capable of providing service, whether the unit, line or facility is in service (expressed as a percent available for the time under consideration)
The measure of the transfer capability remaining in the physical transmission network for commercial activity beyond already committed uses
Costs of new transmission or generation (sometimes both) that electric utilities can "avoid" by purchasing from other sources, managing demand, conservation
Power provided by contract to a customer when its normal sources are unavailable
The interconnected operations service that provides the needed capacity and energy to transmission customers to replace the loss of generation and to cover the portion of demand that exceeds generation supplies for more than a short period
G - K
An electric generation company
Conversion of nuclear, thermal, etc. energy into electricity
The interconnected power lines and generators that supply, transmit and distribute electric power to the customers connected to it
An independent company that operates an electric grid
A financial instrument that establishes the future prices and quantities of electricity independently of the short-term market, e.g., contracts for differences, forwards, futures, and option contracts
The market in which blocs of energy are traded on an hourly basis
The portion of a generator's load that is in addition to its existing load
Electric power or energy that flows from one entity to another
A system consisting of two or more individual electric systems that operates synchroniously and have connecting tielines
A facility that connects two transmission systems or control areas, or that connects a non-utility generator to a system or control area; (when capitalized, it refers to the North American Eastern, Western, ERCOT or Alaska electric systems)
L - P
Local distribution company
Pricing electricity to include the costs of transmission losses, congestion and the local costs of generation (also called location-based pricing)
Any consumer of electrical energy; also, the amount of power (demand) used by a utility system, electrical device or consumer. Load can be manually or automatically curtailed or shed temporarily during times of high usage (customers have agreed beforehand to such actions) or managed to ensure a reliable electricity supply
An area (city, etc.) that uses large amounts of electricity (also called a load pocket)
Planning by utilities to ensure that electric generators operate as scheduled, based upon load forecasts (also, operating a generator to balance short-term load fluctuations)
Planning by utilities to ensure a reliable electricity supply
Reducing electricity use from the grid during peak periods to increase reliability and moderate the energy-clearing price during system-wide peak demand; reducing electric load or using qualifying emergency generators on the customer side of the meter.
A transmission or distribution utility that has contractual or regulatory obligations to connect its load to the transmission grid
The difference between net capacity (a system's total capacity resources) and net internal demand, that is generally expressed in MW for operating reserves and as a percentage of either system load or installed generating capacity for planning reserves
The cost of providing additional electricity; "The competitive price of a MWh of electricity is equal to the additional amount it would cost to generate an additional MWh, once all current demand is met. This additional cost is commonly referred to as the marginal cost. The marginal cost of generating electricity rises as more electricity is produced, because different generators use different types and amounts of fuel_.under competition, the rising marginal cost of electricity leads to high prices when demand is high and low prices during low-demand periods." (GAO-02-828 Restructured Electricity Markets, page 13)
Q - U
Under PURPA, a non-utility generator of electric power that has received a certificate from FERC, enabling it to sell electricity only at wholesale avoided cost to a utility
Accumulated capital cost of a utility's purchased or installed facilities that serve customers
in economics, finding reduced economies of scale and applying them across all alternatives
Pricing electricity based on the actual cost at the time it is demanded by a customer
A for-profit or non-profit entity that coordinates transmission planning, operations and use on a regional and inter-regional basis and that is subject to FERC approval
An intangible (deferred debt cost, accelerated depreciation, etc.) that appears on a regulated utility's balance sheet and that can be recovered from ratepayers under regulation
The measure of performance of a bulk-power system that results in electricity being delivered to consumers within accepted standards and in the amount desired; measured by frequency, duration and magnitude of adverse impacts on the electric supply (also called system reliability). Reliability comprises both generation adequacy and system security.
Allowing a customer to buy electricity from a supplier of choice and transmit (wheel) it on the grid
An alternative regulation plan that caps a utility's allowed revenues with an external index
An agreed-upon transaction size (measured in MW), start and end times, start and end ramp times and rates required for delivery and receipt of power and energy between contracting parties and the control areas involved in the transaction
V - Z
The unit of measure of the power that maintains the constant variation of the electro-magnetic fields associated with alternating-current circuits
A utility that owns and controls generation, transmission and distribution components
The force that makes electricity flow; the unit of measure of electric potential
A fee for using the transmission or distribution system that is based on the volume of electricity that is transmitted
The bulk power market
Buying transmission services from a utility to transport (wheel) electricity to another utility, non-utility generator or a wholesale customer
Charging electric suppliers or their customers for the use of transmission or distribution wires