Learning Center

capability: The maximum generation that a machine, station or system can generate under specified conditions for a given interval without exceeding approved limits.

capacity: The maximum power that can be produced by a generating resource at specified times under specified conditions.

captive customers: Any customer that cannot readily purchase power from suppliers other than the local utility, even if they have the legal right to do so. Captive electricity customers are generally considered to be the residential and small commercial customers.

cogeneration: The production of heat and electricity from a common fuel source.

combined cycle: The combination of a gas turbine and steam turbine in an electric generating plant. The waste heat from the first turbine cycle provides the heat energy for the second turbine cycle.

combustion turbine: A fuel-fired turbine engine used to drive an electric generator.

comparability tariffs: In a restructured wholesale electrical market, according to FERC Order 888, there should be non-discriminatory, open access charges or tariffs for use of the transmission network by all generators of wholesale electricity on a comparable basis. These tariffs provide that the same prices, terms and conditions would apply to both the utility for its own transactions and to other generators.

competition transition charge: A mechanism to assure fairness and stability for existing utilities as we shift to a new market structure. The net effect of CTC will fall on customers who change suppliers during the Transition Phase. The purpose is to avoid cost-shifting, and to enable utilities to retire debt and compete fairly.

conductor: The wire cable strung between transmission towers or distribution poles through which current flows.

conservation: A resource produced by increasing the efficiency of energy use, production or distribution.

cooperative (co-op): A private non-profit utility owned by its members and essentially self-regulated by an elected board of directors.

coordinated operation: The operation of two or more interconnected electrical systems or a group of hydro plants to achieve greater reliability and economy.

cost-based ratemaking: Regulated rates based on costs expended, not on meeting performance objectives identified by management.

cost of service analysis: A study designed to determine the cost of providing service to various classes of customers; used as a basis for establishing power and transmission rates.

cost shifting: Shifting cost increases or decreases to classes of customers, e.g., to residential from industrial or to commercial from residential.

critical period: The portion of the historical 50-year streamflow record that would product the least amount of energy; that period is currently the 42 ½ months of water conditions from August 16, 1928 through February 1932. The critical period is used to determine the maximum firm load-carrying capability of the present system under "worst-case" conditions.

critical rule curve: A graphic representation of the storage level of a reservoir at various times of the year under critical streamflow conditions. The curve serves as a guide to the use of stored water by indicating the level at which storage would become insufficient to meet firm energy loads.

critical water: A sequence of streamflows under which the regional hydro system could produce an amount of power equal to that which could have been produced during the historical critical period given today's generating facilities and constraints.

cubic feet per second (cfs): A measurement of water flow representing one cubic foot of water moving past a given point in one second.

current diversion (or energy diversion): Theft of electric power in which current is diverted to bypass the meter. More generally, any type of tampering to obtain unmetered service.

curtailment: A temporary, mandatory load reduction under emergency conditions taken after all possible conservation and load management measures, and prompted by problems of meeting baseload rather than an upswing or peak.

customers: Industrial, agricultural, large retail, commercial and residential.

declining block rate: A rate structure that prices successive blocks of electricity use or kilowatt demand at a decreasing per-unit price. The more electricity a customer uses, the less the per-unit price.

demand: The rate at which electric energy is delivered to or by a system at a given instant or averaged over a designated period, usually expressed in kilowatts or megawatts.

demand forecast: An estimate of the level of energy that is likely to be needed at some time in the future.

demand-side management (DSM): Strategies for reducing consumption by influencing when and how customers use electricity. Demand-side management includes such things as conservation programs and incentives for switching electricity use from mid-day to evening.

deregulation: The loosening of federal and state laws and regulations that govern the generation, transmission and distribution of electricity.

direct access: Ability of a power producer to sell directly to the retail customer.

direct current (DC): An electric current that flows in one direction with a magnitude that does not vary or that varies only slightly.

Direct Service Industrial customers (DSIs): Industries that buy power directly from BPA rather than through retail utilities. The number of these customers is limited by law to those industries that were direct service customers on the date the Northwest Power Act was passed.

dispatch: The monitoring and regulation of an electrical system to provide coordinated operation; the sequence in which generating resources are called upon to generate power to serve fluctuating loads.

displacement: The substitution of less expensive energy generation for more expensive generation. Usually this means reducing or shutting down production at a thermal plant and using hydro power when it is available.

distribution: The transport of electricity to ultimate use points such as homes and businesses.

distribution utility (Disco): The regulated electric utility entity in a competitive world that would construct and maintain the distribution wires connecting the transmission grid to the final customer. This entity would make distribution service available to any qualified energy service company on comparable bases.

divestiture: The stripping off of one utility function from the others by selling or in some way changing the ownership of the assets related to that function. Most commonly associated with spinning off generation assets so that they are no longer owned by the shareholders that own the transmission and distribution assets. Divestiture, or legal separation, is distinguished from functional separation.

draft: Release of water from a reservoir, usually measured in feet of reservoir elevation.

drawdown: The distance the water surface of a reservoir is lowered from a given elevation as the result of releasing water. Drawdown can be expressed in terms of the acre-feet of stored water released.