• Take-or-Pay Clause

    A contract provision obligating the buyer to pay for a certain minimum quantity of product, whether or not the buyer actually takes that quantity during the stated period.

  • Take-or-Pay Quantity

    Under a take-or-pay clause, the minimum amount of product that the buyer is obligated to pay for whether or not the buyer actually takes that amount of product, usually stated in terms of an absolute quantity, or a percentage of total contract quantity, over a specific period of time, usually a year.

  • Take-or-Pay Surcharge

    A surcharge to an interstate pipeline's sales and transportation rates permitted by FERC, designed to recover the pipeline's costs of settling its historic take-or-pay liabilities.

  • Tariff

    A document filed by a regulated entity with either a federal or state commission. It lists the rates the regulated entity will charge to provide service to its customers as well as the terms and conditions that it will follow in providing service.

  • Telemetering

    Process by which measurable electrical quantities from substations and generating stations are transmitted through telecommunication to a remote location.

  • Tenor

    The maturity of a swap transaction.

  • Terawatt hours (TWh)

    1 x 109 kilowatt hours; one thousand Gigawatt hours.

  • Term Swap

    Swaps often involve longer maturities than can generally be found on futures or option contracts traded on organized exchanges. Term swap usually involves maturities greater than three years.

  • Tertiary Recovery

    Enhanced methods for the recovery 'Of oil and natural gas that require a means for displacing the oil or natural gas from the reservoir rock, modifying the properties of the fluids in the reservoir, and/or the reservoir rock to cause movement of the oil or natural gas in an efficient manner and providing the energy and drive mechanism to force its flow to a production well.

  • Therm

    A unit of heating value equivalent to 100,000 British thermal units (Btu) (0.1 MMBtu).

  • Thermal Generation

    The production of electricity from plants that convert heat energy into electrical energy. The heat in thermal plants can be produced from a number of sources such as coal, oil, gas or nuclear fuel.

  • Tie Line

    Circuit which connects two or more control areas or systems of a power system.

  • Tiered Rates

    A rate design which divides customer use into different tiers, or blocks, with different prices charged for each.

  • Tight Pool

    A group of utilities who dedicate their generating and transmission resources for joint economic dispatch. Usually costs and revenues are divided after the fact and no individual pool member is responsible for the procurement of individual power supplies.

  • Time Error

    The integral of frequency error. Generally utilized as a measure of regulating performance for frequency regulation. Time error can be measured as the error between a clock synchronized to the electrical system and the astronomical time kept by the National Bureau of Standards.

  • Time Error Correction

    An offset to the interconnection's frequency to correct for the time error that accumulates on electric clocks.

  • Time-of-Use (TOU)

    Rates or Pricing A rate design imposing higher charges during periods of the day when relatively higher peak demands are experienced.

  • Time Value

    The dollar amount by which the premium of an option exceeds the intrinsic value of an option.

  • Tipple

    A surface processing structure for cleaning and sizing coal and automatically loading it onto railcars or trucks for movement to market.

  • Tolerable Zone

    The Tolerable Zone covers a band of voltage values above and below the Preferred Zone. In the Tolerable Zone, the customer's equipment may be expected to operate satisfactorily although the performance may perhaps be less than warranted by the manufacturer. (See Voltage Chart.)

  • Tolling Arrangement

    An arrangement whereby a party moves fuel to a power generator and receives kilowatt hours {kWh) in return for a pre-established fee.

  • Tolling Fee

    A fee paid for use of -electric generation assets used to convert fuel to power.

  • Transco

    The term for that portion of a functionally disaggregated electric utility's business that involves the bulk transmission of power that is operated separately from any other power functions the utility might own or operate.

  • Transformer

    An electrical device for changing the voltage of alternating current.

  • Transition Costs

    Costs associated with the change of an industry from a regulated, bundled service to a competitive open-access service, including "Stranded Costs."

  • Transmission

    The network of high voltage lines, transformers and switches used to move electrical power from generators to the distribution system. Also utilized to interconnect different utility systems and independent power producers together into a synchronized network: Transmission is considered to end when the energy is transformed for distribution to the consumer.

  • Transmission Company

    Company which obtains the major portion of its natural gas operating revenues from the operation of a natural gas transmission system and/or from mainline sales to industrial customers.

  • Transmission Dependent Utility

    A utility that relies on its neighboring utilities to transmit to it the power it buys from its suppliers. A utility without its own generation sources, dependent on another utility's transmission system to get its purchased power supplies.

  • Transmission Grid

    An interconnected system of electric transmission lines and associated equipment for the transfer of electric energy in bulk between points of supply and points of demand.

  • Transmission Loss

    The power lost in transmission between one point and another. It is measured as the difference between the net power passing the first point and the net power passing the second point.

  • Transmission System (Electric)

    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 is delivered to other electric systems.

  • Transmission (Trunk) Line

    Pipeline transporting natural gas from principal supply areas to distribution centers, large volume customers or other transmission lines. Transmission lines generally have a linear configuration, may be quite large in diameter, operate at relatively high pressure, and traverse long distances.

  • Transmission Voltage

    Voltage levels utilized for bulk transmission systems generally 69 KV - 750 KV AC or DC.

  • Transportation Contract

    A contract setting forth the terms and .conditions applicable togas or electric transportation service.

  • Transporter

    The pipeline company that transports natural gas for a shipper.

  • Treating Plant

    Facility that treats raw natural gas to remove undesirable impurities such as carbon dioxide, hydrogen sulfide, and water vapor. Treating plants may be owned by producers, independent treaters, or transmission pipeline companies.

  • Trunk Lines


  • Turbine

    The part of a generating unit usually consisting of a series of curved vanes or blades on a central spindle, which is spun by the force of water, steam or hot gas to drive an electric generator. Turbines convert the kinetic energy of such fluids to mechanical energy through the principles of impulse and reaction, or a measure of the two.

  • Two Part Rate

    A charge for energy consisting of a demand component and an energy or commodity component.