Glossary of electric industry, energy & cooperative terms

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ACES (Alliance for Cooperative Energy Services)
A cooperative created to address the new power markets. ACES purchases, schedules, and sells power for many co-ops across nation. Advises and purchases other forms of energy, gas, etc., used to generate electricity.

ACH (Automated Clearing House)
Method by which electronic transfers are made.

Acid Rain
Also called acid precipitation or acid deposition. Acid rain is precipitation containing harmful amounts of nitric and sulfuric acids formed primarily by nitrogen oxides and sulfur oxides released into the atmosphere when fossil fuels are burned. It can be wet precipitation (rain, snow, or fog) or dry precipitation (absorbed gaseous and particulate matter, aerosol particles or dust). Acid rain has a pH below 5.6. Normal rain has a pH of about 5.6, which is slightly acidic. The term pH is a measure of acidity or alkalinity and ranges from 0 to 14. A pH measurement of 7 is regarded as neutral. Measurements below 7 indicate increased acidity, while those above indicate increased alkalinity.

ACRE (Action Committee for Rural Electrification)
The grassroots political action committee of the National Rural Electric Cooperative Association. ACRE represents the interests of the nation’s nearly 1,000 not-for-profit electric cooperative systems and their 37 million consumers in rural, suburban, and urban areas of the country.
Aid to Construction – Money paid by members to offset electrical construction costs.

Active Solar Energy
Energy from the sun’s radiation, collected and transferred, then distributed or stored for use as needed.

Adjustment Bid
A bid that is used by the Independent System Operator to adjust supply or demand when congestion on the transmission system is anticipated.

Aggregator
An entity that puts together groups of customers into a buying group that purchases a commodity or service. The vertical-integrated investor owned utility, as well as municipal utilities and rural electric cooperatives, perform this function in today's power market. Other entities, such as buyer cooperatives or brokers, could perform this function in a restructured power market.

Airway
A space between roof insulation and roof boards for movement of air.

Air-To-Air Heat Pump
A heating and cooling device that uses electricity to move heat from the outside air into a building in winter, reversing the process for air conditioning in the summer. Also called air-source heat pump.

All-Requirements Power Contract
An agreement by which a distribution system agrees to purchase all its wholesale electric power from a single power supplier; primarily used by rural and municipal electric systems.

Alternating Current (AC)
An electric current that reverses its direction of flow periodically as contrasted to direct current (DC). The single period in which the alternating current changes from one direction to the other and returns to its original state is called a cycle. An alternating current consists of a succession of cycles, and the number of cycles per second is known as frequency. Electric utilities generate alternating current almost universally; in the U.S. a frequency of 60 Hertz (formerly 60 cycles pre second) is common.

Alternative Fuels
Sources of heat energy other than coal, nuclear power, natural gas or oil used to generate electricity; usually renewable materials such as wood chips, solar power or garbage.

American Public Power Association (APPA)
The American Public Power Association, established in 1940, represents more than 1,750 local publicly owned electric utilities in the United States, Puerto Rico, American Samoa, Guam, the Virgin Islands and Canada. Non-profit and non-partisan, APPA is a representative organization with policies established by an elected board of directors. The Association provides a wide range of services in government relations, engineering and operations, accounting and finance, consumer services, energy research and development, education, management and public communication. It also sponsors competitions among its members and bestows awards. The Florida affiliates are the Florida Municipal Utilities Association (FMUA) and the Florida Municipal Power Agency (FMPA).

Ampere (amp or a)
The unit of measurement of electrical current. It is proportional to the quantity of electrons flowing through a conductor pas a given point in one second. It is analogous to cubic feet of water flowing per second. An ampere equals the amount of current that is produced in a circuit by one volt acting through a resistance of one ohm. In simple terms, it is the measure of how much electricity is moving through a conductor. Amperes equal watts divided by volts; a 1,000-watt heater at 120 volts draws 8.33 amps. The term is commonly used to indicate the size of circuit breakers and fuses.

Anchor Bolts
Bolts used to secure a wooden sill plate to a concrete or masonry floor or wall.

Ancillary Services
Necessary services that must be provided in the generation and delivery of electricity. As defined by the Federal Energy Regulatory Commission, they include: coordination and scheduling services (load following, energy imbalance service, control of transmission congestion); automatic generation control (load frequency control and the economic dispatch of plants); contractual agreements (loss compensation service); and support of system integrity and security (reactive power, or spinning and operating reserves).

Anthracite
The highest rank of coal; used primarily for residential and commercial space heating. It is hard, brittle, and black lustrous coal, often referred to as hard coal, containing a high percentage of fixed carbon and a low percentage of volatile matter. The moisture content of fresh-mined anthracite generally is less than 15 percent. The heat content of anthracite ranges from 22 to 28 million Btu per ton on a moist, mineral-matter-free basis. The heat content of anthracite coal consumed in the United States averages 25 million Btu per ton, on the as-received basis (i.e., containing both inherent moisture and mineral matter). Note: Since the 1980's, anthracite refuse or mine waste has been used for steam electric power generation. This fuel typically has a heat content of 15 million Btu per ton or less.

AP
Accounts payable.

Appliance Saturation
A percentage reflecting the number of customers in a given customer class who use a particular type of energy-using equipment. The saturation for a particular appliance is calculated by dividing the number of customers in that customer class.

Apron
The flat member of the inside trim of a window placed against the wall immediately beneath the stool.

Areaway
An open subsurface space adjacent to a building used to admit light or air or as a means of access to a basement.

Ash
Impurities consisting of silica, iron, alumina, and other noncombustible matter that are contained in coal. Ash increases the weight of coal, adds to the cost of handling, and can affect its burning characteristics. Ash content is measured as a percent by weight of coal on a "received" or a "dry" (moisture-free, usually part of a laboratory analysis) basis.

Asphalt
Most native asphalt is a residue from evaporated petroleum. It is insoluble in water but soluble in gasoline and melts when heated.

Attic House Fan
A whole-house ventilating system that pulls outside air in through windows and doors and exhausts it through the attic, preventing heat in the attic from coming through the ceiling into the living area. It can reduce the cooling and energy consumption of air conditioning and in some instances eliminate the need for refrigerated air conditioning.

Attic Ventilators
In houses, screened openings provided to ventilate an attic space.

Available but not Needed Capability
Net capability of main generating units that are operable but not considered necessary to carry load, and cannot be connected to load within 30 minutes.

Average Revenue per Kilowatt-hour
The average revenue per kilowatt-hour of electricity sold by sector (residential, commercial, industrial, or other) and geographic area (State, Census division, and national), is calculated by dividing the total monthly revenue by the corresponding total monthly sales for each sector and geographic area.

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Page last updated: October 29, 2012