Contact Us | Privacy Policy
  Home About the Alliance Publications Press Resources

Jump to:  a b c d e f g h i k l m n o p r s t u v w

Aggregator: Any marketer, broker, public agency, city, county, or special district that combines the loads of multiple end-use customers in facilitating the sale and purchase of electric energy, transmission, and other services on behalf of these customers.

Ancillary Services: Needed services to support the transmission of energy from resources to loads while maintaining reliable operation of the transmission system. They are defined by the Federal Energy Regulatory Commission.

Barrel (oil): A volumetric unit of measurement equivalent to 42 U.S. gallons commonly used to measure oil production and oil reserves within the U.S.

Baseload: The minimum amount of electric power delivered or required over a given period of time at a steady rate. Baseload capacity is the generating equipment normally operated to serve loads on an around-the-clock basis. A baseload plant produces electricity at an essentially constant rate and runs continuously to maximize system mechanical and thermal efficiency and minimize system operating costs. Applied to natural gas, this term denotes a given consumption of gas remaining fairly constant over a period of time, usually not temperature sensitive.

Bilateral Contract: A direct contract between a power producer and an end-user or broker.

Biomass: A type of renewable fuel that includes trees and other crops and residues, solid waste, sewage and liquid fuels delivered from agricultural products. Some common energy sources derived from biomass are landfill gas, anaerobic digester gas, methane and biofuels including biodiesel, bio-oil and ethanol.

Blackouts (Rolling Blackouts): A controlled and temporary interruption of electrical service necessary when the electricity grid is unable to meet the heavy peak demands because of an extreme deficiency of power supply.

Boiling Water Reactor (BWR): A nuclear power unit in which water used as a coolant is allowed to boil at the core. The resulting steam may be used to drive electric turbines.

British Thermal Unit (Btu): A unit of heat measurement equal to the quantity of heat necessary to raise the temperature of one pound of water one degree Fahrenheit.

Broker: An entity that arranges the sale and purchase of electric energy, transmission, and other services between buyers and sellers, but does not take title to any of the power sold. A natural gas broker is one who sells or assigns firm transportation (or storage) capacity rights on an interstate pipeline to another entity.

Brownout: A reduction in voltage and/or power when demand for electricity exceeds generating capacity. Customers generally do not notice the reduction, except when using sensitive electronic equipment.

Bulk Power Supply: Refers to the aggregate of electric generating plants, transmission lines and other related equipment.

Capability: The maximum load that an electricity generating unit, generating station, or other electrical apparatus can carry under specified conditions for a given period of time without exceeding approved limits of temperature and stress.

Capacity: The amount of electric power delivered or required for which a generator, turbine, transformer, transmission circuit, station, or system is rated by the manufacturer.

Capacity Charge: An element in a two-part pricing method used in capacity transactions (energy charge is the other element). The capacity charge, sometimes called Demand Charge, is assessed on the amount of capacity being purchased.

Coal: A black or brownish-black solid combustible substance formed by the partial decomposition of vegetable matter without access to air. The rank of coal, which includes anthracite, bituminous coal, subbituminous coal, and lignite, is based on fixed carbon, volatile matter, and heating value.

Coal Gasification: A controlled process of reacting coal, steam and oxygen under pressure and elevated temperature. The crude gas is purified and has a low heating value. Subsequent catalytic upgrading can be employed to produce high-Btu pipeline grade gas.

Cogenerator: A generating facility that produces electricity and another form of useful thermal energy (such as heat or steam) used for industrial, commercial, heating, or cooling purposes.

Combined Cycle: A high-efficiency electric generating technology in which electricity is produced from otherwise lost waste heat exiting from one or more gas (combustion) turbines. The exiting heat is routed to a conventional boiler or to a heat recovery steam generator for utilization by a steam turbine in the production of electricity.

Commodity Charge: A charge per unit volume or heat content (therm) of natural gas delivered to the buyer.

Compressed Natural Gas (CNG): Natural gas in high-pressure surface containers that is highly compressed and can be used as a transportation fuel.

Congestion: A condition that occurs when insufficient transfer capacity is available to implement all of the preferred schedules for electricity transmission simultaneously.

Conservation Program: A program that attempts to reduce a customer's energy consumption over most or all hours of the day.

Cubic Foot: The most common unit of measurement of natural gas volume.

Curtailment: Curtailment of natural gas service is a method to balance a utility's natural gas requirements with its natural gas supply. Usually there is a hierarchy of customers for the curtailment plan. A customer may be required to partially cut back or totally eliminate his take of gas depending on the severity of the shortfall between gas supply and demand and the customer's position in the hierarchy.

Customer Choice: Allowing customers to purchase electricity from any of a number of companies that compete with each other.

Deliverability: The volume of natural gas a well, field, pipeline or distribution system can supply in a given period of time.

Demand (Electric): The rate at which electric energy is delivered to or by a system, part of a system, or piece of equipment, at a given instant or averaged over any designated period of time.

Demand (Gas): The rate at which natural gas is delivered to or by a system expressed in cubic feet or therms for a designated period of time.

Demand Response: Programs and policies that provide both retail and wholesale electricity customers with a choice whereby they can respond to prices or other types of incentives by reducing and/or shifting electricity usage, with the result being that they become a resource for cost-effectively addressing pricing, reliability, emergency response and infrastructure planning, operations and deferral.

Demand-Side Management (DSM): Activities designed to encourage consumers to modify patterns of electricity usage, including the timing and level of electricity demand. It refers only to energy and load-shape modifying activities that are undertaken in response to utility-administered programs. It does not refer to energy and load-shape changes arising from the normal operation of the marketplace or from government-mandated energy-efficiency standards. DSM covers load-shape objectives, including strategic conservation and load management, as well as strategic load growth.

Deregulation: The elimination of regulation from a previously regulated industry or sector of an industry.

Direct Access: The ability of a retail customer to purchase electricity or natural gas directly from the wholesale market rather than through a local distribution utility.

Distributed Generation: A distributed generation system involves small amounts of generation located on a utility's distribution system for the purpose of meeting local (substation level) peak loads and/or displacing the need to build additional (or upgrade) local distribution lines.

Distribution: The delivery of electricity or natural gas to customers (including homes, businesses, etc.). The distribution system is the portion of an electric or gas system that is dedicated to delivering energy to an end user.

Divestiture: The stripping off of one utility function from the others by selling (spinning-off) or in some other way changing the ownership of the assets related to that function.

Dual Fuel: Ability of an energy-using facility to alternately use more than one kind of fuel (usually oil and natural gas).

Energy: Electrical energy is usually measured in kilowatthours. Energy charge is that portion of the charge for electric service based upon the electric energy (kWh) consumed.

Energy Efficiency: 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, often without explicit consideration for the timing of program-induced savings. Such savings are generally achieved by substituting technically 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: The primary source that provides the power that is converted to electricity through chemical, mechanical, or other means. Energy sources include coal, petroleum and petroleum products, gas, water, uranium, wind, sunlight, geothermal, and other sources.

Federal Energy Regulatory Commission (FERC): A quasi-independent regulatory agency having jurisdiction over interstate electricity sales, wholesale electric rates, hydroelectric licensing, natural gas pricing, oil pipeline rates, and gas pipeline certification.

Firm Gas: Gas sold on a continuous and generally long-term contract.

Firm Power: Power or power-producing capacity intended to be available at all times during the period covered by a guaranteed commitment to deliver, even under adverse conditions.

Fluidized Bed Combustion: Coal is burned in a bed of limestone that is suspended by an upward flow or air and gases and forms a dry calcium sulfate waste.

Forced Outage: The shutdown of a generating unit, transmission line or other facility, for emergency reasons or a condition in which the generating equipment is unavailable for load due to unanticipated breakdown.

Fossil Fuels: Oil, coal and natural gas come from the long-term decomposition of plant and animal matter from millions of years ago. These fuels are the main sources of energy used to generate electricity, heat and fuel for transportation.

Gasification: The process during which liquefied natural gas (LNG) is returned to its vapor or gaseous state through an increase in temperature and a decrease in pressure.

Generating Unit: Any combination of physically connected generator(s), reactor(s), boiler(s), combustion turbine(s), or other prime mover(s) operated together to produce electric power.

Generation (Electricity): The process of producing electric energy by transforming other forms of energy; also, the amount of electric energy produced, expressed in watthours (Wh).

Generation Company: An entity (non-regulated in restructured states) that operates and maintains electricity generating plants. Generation is the amount of electric energy produced by the generating units at a generating station or stations.

Generator Nameplate Capacity: The full-load continuous rating of a generator, prime mover, or other electric power production equipment under specific conditions as designated by the manufacturer. Installed generator nameplate rating is usually indicated on a nameplate physically attached to the generator.

Gigawatt (GW): One billion watts or one thousand megawatts (1,000MW).

Gigawatt-hour (GWh): One billion watt-hours or one million kilowatt-hours of electric power.

Grid: A system of interconnected power lines and generators that is managed so that the generators are dispatched as needed to meet the requirements of the customers connected to the grid.

Hub: A supply area pooling/delivery point where natural gas supply transactions occur that serve to facilitate the movement of gas between and among interstate pipelines.

Hydropower: An energy technology that uses moving water to produce electricity. In a hydroelectric system, water flows downstream through a turbine that spins and in turn rotates adjacent generators to transform the rotational energy into electricity.

Independent System Operator: An independent, Federally-regulated entity that coordinates regional electricity transmission in a non-discriminatory manner and ensures the safety and reliability of the electric system. ISO New England is the not-for-profit corporation responsible for the day-to-day reliable operation of New England's power generation and transmission system and oversees the region's wholesale electricity marketplace and manages the regional power planning system.

Interruptible Gas: Gas sold to customers with a provision that permits curtailment or cessation of service at the discretion of the distributing company under certain circumstances, as specified in the service contract.

Interruptible Load: Refers to program activities that, in accordance with contractual arrangements, can interrupt consumer load at times of seasonal peak load by direct control of the utility system operator or by action of the consumer at the direct request of the system operator. It usually involves commercial and industrial consumers.

Kilowatt (kW): One thousand watts.

Kilowatt-hour (kWh): The most commonly used unit of measure for the amount of electricity consumed over time representing one kilowatt supplied for one hour.

Landfill Gas: Gas produced by aerobic and anaerobic decomposition of a landfill generally composed of approximately 55% methane and 45% carbon dioxide.

Liquefied Natural Gas (LNG): Natural gas which has been liquefied by reducing its temperature to minus 260 degrees Fahrenheit at atmospheric pressure. It occupies 1/600 of the volume of gas vapor at standard conditions.

Liquefied Petroleum Gas (LPG): A gas containing certain specific hydrocarbons which are gaseous under normal atmospheric conditions but can be liquefied under moderate pressure at normal temperatures. Propane and butane are examples.

Load: The amount of electric power or natural gas delivered or required at any specific point or points on a system.

Marginal Cost: In the utility context, the cost to provide the next kilowatt-hour of electricity.

Market Clearing Price: The price at which supply equals demand in the competitive electricity wholesale marketplace.

Marketer: An agent for generation projects who markets power on behalf of the generator.

Mcf: One thousand cubic feet.

MMcf: One million cubic feet.

Megawatt (MW): One million watts or 1,000 kilowatts.

Megawatt-hour (MWh): One million watt-hours or one thousand kilowatt-hours.

Methane: The chief constituent of natural gas.

Natural Gas: A naturally occurring mixture of hydrocarbon and non-hydrocarbon gases found in porous geological formations beneath the earth's surface often in association with petroleum. The principal constituent is methane.

Non-Firm Power: Power or power-producing capacity supplied or available under a commitment having limited or no assured availability.

Nuclear Energy: Nuclear energy relies on the splitting of uranium atoms in a process called fission which generates heat for producing steam that then turns a turbine to produce electricity.

Off-Peak: The period during a day, week, month or year when the load being delivered by electricity or gas is not at or near the maximum amount delivered by that system for the corresponding period of time.

Outage: The period during which a generating unit, transmission line, or other facility is out of service.

Peak Demand: The maximum load during a specified period of time.

Peak Load Plant: A plant usually housing steam units; gas turbines; diesels; or pumped-storage hydroelectric equipment normally used during the peak-load periods.

Peaking Capacity: Capacity of generating equipment normally reserved for operation during the hours of highest daily, weekly, or seasonal loads.

Pipeline: A line of pipe with pumping machinery and apparatus (including valves, compressor units, metering stations, regulator stations, etc.) for conveying a liquid or gas.

Pipeline Capacity: The maximum quantity of gas than can be moved through a pipeline system at any given time.

Power: Electricity for use as energy.

Power Marketers: Business entities engaged in buying, selling, and marketing electricity. Power marketers do not usually own generating or transmission facilities. As opposed to brokers, they take ownership of the electricity and are involved in interstate trade and must file with the Federal Energy Regulatory Commission.

Power Pool: An association of two or more interconnected electric systems having an agreement to coordinate operations and planning for improved reliability and efficiencies. The New England Power Pool (NEPOOL) is a voluntary association of entities that are engaged in the electric power business in New England.

Pressurized Water Reactor (PWR): A nuclear power unit cooled by water that is pressurized to keep it from boiling when it reaches high temperatures.

Rate Base: The value of property upon which a utility is permitted to earn a specified rate of return as established by a regulatory authority. The rate base generally represents the value of property used by the utility in providing service and may be calculated by any one of several accounting methods.

Real-Time Pricing: The instantaneous pricing of electricity based on the cost of the electricity available for use at the time demanded by the customer.

Regional Transmission Group: A utility industry concept that the Federal Energy Regulatory Commission embraced for the certification of voluntary groups that would be responsible for transmission planning and use on a regional basis.

Reliability: Electric system reliability has two components - adequacy and security. Adequacy is the ability of the electric system to supply electrical demand and energy requirements of the customers at all times, taking into account scheduled and unscheduled outages of system facilities. Security is the ability of the electric system to withstand sudden disturbances, such as electric short circuits or unanticipated loss of system facilities. The degree of reliability may be measured by the frequency, duration, and magnitude of adverse effects on consumer services.

Reliability Must-Run Generation: The operation of power plants that are needed to ensure system reliability (to meet reliability criteria, peak loads in constrained areas and to provide voltage support).

Renewable Portfolio Standards: Regulations that require electricity providers to utilize renewable energy sources for a percentage of power supply. Electricity suppliers demonstrate compliance through the purchase of renewable energy certificates (RECs).

Renewable Resources: Natural resources that can be replenished that include: biomass, hydro, geothermal, solar and wind. In the future, they could also include the use of ocean thermal, wave, and tidal action technologies.

Reserve Margin (Operating): The amount of unused available capability of an electric power system at peakload as a percentage of total capability.

Residual Fuel Oil: The topped crude of refinery operation including No. 5 and No. 6 fuel oils. Residual fuel oil is used for the production of electric power, space heating, vessel bunkering, and various industrial purposes.

Restructuring: The process of replacing a monopoly system of electric utilities with competing sellers, allowing individual retail customers to choose their electricity supplier but still receive delivery over the power lines of the local utility. It includes the reconfiguration of the vertically-integrated electric utility.

Retail Competition: The concept under which multiple sellers of electric power can sell directly to end-use customers and the process necessary to make it occur.

Retail Market: A market in which electricity, natural gas and other energy services are sold directly to the end-use customer.

Scheduled Outage: The shutdown of a generating unit, transmission line, or other facility, for inspection or maintenance, in accordance with an advance schedule.

Spot Purchases: A single shipment of fuel or volumes of fuel, purchased for delivery. Spot purchases are often made to fulfill a certain portion of energy requirements, to meet unanticipated energy needs, or to take advantage of low-fuel prices.

Stability: The stability of a power system is its ability to develop restoring forces equal to or greater than the disturbing forces so as to maintain a state of equilibrium.

Standby Facility: A facility that supports a utility system and is generally running under no-load. It is available to replace or supplement a facility normally in service.

Standby Service: Support services to supplement a consumer, a utility system, or to another utility if a schedule or an agreement authorizes the transaction.

Stranded Costs: Prudent costs incurred by a utility which may not be recoverable under market-based retail competition. Examples are underappreciated generating facilities, deferred costs, and long-term contract costs.

Solar Power: The sun's energy can be used to generate electricity, provide hot water and to heat, cool and light buildings using solar photovoltaic panels, concentrating solar power and passive solar designs.

Substation: Facility equipment that switches, changes, or regulates electric voltage.

Superconductor: A synthetic material that has very low or no electrical resistance.

Tariff: A natural gas company schedule detailing the terms, conditions and rate information applicable to various types of natural gas service.

Therm: One hundred thousand (100,000) British thermal units.

Transformer: An electrical device for changing the voltage of alternating current.

Transmission System: An interconnected group of electric transmission lines and associated equipment for moving or transferring electric energy in bulk between points of supply and points at which it is transformed for delivery over the distribution system lines to consumers or to other electric systems.

Uprate: An increase in the rating or stated measure of generation of transmission capability.

Utility Distribution Companies (Electric, Gas): The entities that provide regulated services for the distribution of electricity and natural gas to customers and serve customers who do not choose direct access. Regardless of where a consumer chooses to purchase power, the distribution company delivers the electricity or natural gas.

Vertical Integration: An arrangement whereby the same company owns all the different aspects of making, selling, and delivering a product or service. In the electric industry, it refers to the historically common arrangement whereby a utility would own its own generating plants, transmission system, and distribution lines to provide all aspects of electric service.

Voltage Reduction: Any intentional reduction of system voltage by 3 percent or greater for reasons of maintaining the reliability of the bulk electric power supply system.

Watt: The electrical unit of power. The rate of energy transfer equivalent to 1 ampere flowing under a pressure of 1 volt at unity power factor.

Watthour (Wh): An electrical energy unit of measure equal to 1 watt of power supplied to, or taken from, an electric circuit steadily for 1 hour.

Wholesale Competition: A system whereby a distributor of power would have the option to buy its power from a variety of power producers, and the power producers would be able to compete to sell their power to a variety of distribution companies.

Wholesale Power Market: The purchase and sale of electricity from generators to resellers (who sell to retail customers), along with the ancillary services needed to maintain reliability and power quality at the transmission level.

Wind Power: Wind power uses the kinetic energy flowing air to create mechanical energy in a wind turbine that can be transformed into electricity.