Base Load Duke Power’s "24-hour-a-day" load, or the amount of electric power delivered or needed at the lowest point of demand during the day. At Duke Power, base load is met primarily by our nuclear-fueled generating plants.

British Thermal Unit (Btu) The amount of heat energy necessary to raise the temperature of one pound of water one degree Fahrenheit. A standard unit for measuring thermal energy or heat commonly used as a gauge for the energy content of natural gas and other fuels.

Cogeneration Facility A facility that produces electric energy and useful thermal energy for industrial, commercial, heating or cooling purposes.

Combined Cycle The combination of one or more gas turbines and steam turbines in an electric generation plant. An electric generating technology in which electricity is produced from otherwise lost waste heat exiting from one or more gas turbines.

Distribution The system of lines, transformers and switches that connect the electric transmission system to customers, such as homes and businesses, delivering electric energy at relatively low voltages.

Federal Energy Regulatory Commission (FERC) The agency that regulates the transportation of electricity and natural gas in interstate commerce and authorizes the buying and selling of energy commodities at market-based rates.

Gathering System Pipeline, processing and related facilities that access production and other sources of natural gas supplies for delivery to mainline transmission systems.

Generation The process of transforming other forms of energy, such as nuclear or fossil fuels, into electricity. Also, the amount of electric energy produced, expressed in megawatt-hours.

Independent System Operator (ISO) Ensures non-discriminatory access to a regional transmission system, providing all customers access to the power exchange and clearing all bilateral contract requests for use of the electric transmission system. Also responsible for maintaining bulk electric system reliability.

Jurisdictional Facilities and activities subject to the primary regulatory oversight of FERC, the North Carolina Utility Commission (NCUC) or The Public Service Commission of South Carolina (PSCSC).

Liquefied Natural Gas (LNG) Natural gas that has been converted to a liquid by cooling it to -260° F and reducing its volume by 600:1. This allows large quantities of natural gas to be transported by tanker.

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.

Natural Gas Liquids (NGLs) Liquid hydrocarbons extracted during the processing of natural gas. Principal commercial NGLs include butanes, propane, natural gasoline and ethane.

Natural Gas/Power Marketer An entity which buys and sells a commodity or commodities at either fixed or index prices. More sophisticated trader/marketing entities also provide comprehensive energy management services, such as capacity, supply, storage and price risk management.

Order 636 The FERC pipeline service restructuring rule that guided the natural gas industry’s transition to unbundled, open-access pipeline contract transportation and related services, creating a more market-responsive environment.

Order 888 The FERC electric utility rule requiring public utilities with interstate electric transmission facilities to offer open access service to others, thus opening wholesale power sales to competition.

Peak Load The amount of electricity required during periods of highest demand. Peak periods fluctuate by season, generally occurring in the morning hours in winter and in late afternoon during the summer. At Duke Power, peak demand is met by power generated by base load stations, coal-fired units, hydroelectric stations and combustion turbine units, and by purchased power.

Throughput The amount of natural gas transported through a pipeline system.

Transmission System (Electric) An interconnected group of electric transmission lines and related equipment for moving or transferring electric energy in bulk between points of supply and points at which it is transformed for delivery over a distribution system to customers, or for delivery to other electric transmission systems.