Backup fuel: In a central heat pump system, the fuel used in the furnace that takes over the space heating when the outdoor temperature drops below that which is feasible to operate a heat pump.
Backup power: Electric energy supplied by a utility to replace power and energy lost during an unscheduled equipment outage.
Balancing item: Represents differences between the sum of the components of natural gas supply and the sum of the components of natural gas disposition. These differences may be due to quantities lost or to the effects of data reporting problems. Reporting problems include differences due to the net result of conversions of flow data metered at varying temperature and pressure bases and converted to a standard temperature and pressure base; the effect of variations in company accounting and billing practices; differences between billing cycle and calendar period time frames; and imbalances resulting from the merger of data reporting systems that vary in scope, format, definitions, and type of respondents.
Barrel: A unit of volume equal to 42 U.S. gallons.
Barrels per Calendar day: The amount of input that a distillation facility can process under usual operating conditions. The amount is expressed in terms of capacity during a 24-hour period and reduces the maximum processing capability of all units at the facility under continuous operation (see Barrels per Stream Day) to account for the following limitations that may delay, interrupt, or slow down production.
- the capability of downstream processing units to absorb the output of crude oil processing facilities of a given refinery. No reduction is necessary for intermediate streams that are distributed to other than downstream facilities as part of a refinery's normal operation;
- the types and grades of inputs to be processed;
- the types and grades of products expected to be manufactured;
- the environmental constraints associated with refinery operations;
- the reduction of capacity for scheduled downtime due to such conditions as routine inspection, maintenance, repairs, and turnaround; and
- the reduction of capacity for unscheduled downtime due to such conditions as mechanical problems, repairs, and slowdowns.
Barrels per Stream day: The maximum number of barrels of input that a distillation facility can process within a 24-hour period when running at full capacity under optimal crude and product slate conditions with no allowance for downtime.
Base (cushion) gas: The volume of gas needed as a permanent inventory to maintain adequate reservoir pressures and deliverability rates throughout the withdrawal season. All native gas is included in the base gas volume.
Base bill: A charge calculated by taking the rate from the appropriate electric rate schedule and applying it to the level of consumption.
Base load: The minimum amount of electric power delivered or required over a given period of time at a steady rate.
Base load capacity: The generating equipment normally operated to serve loads on an around-the-clock basis.
Base load plant: A plant, usually housing high-efficiency steam-electric units, which is normally operated to take all or part of the minimum load of a system, and which consequently produces electricity at an essentially constant rate and runs continuously. These units are operated to maximize system mechanical and thermal efficiency and minimize system operating costs.
Base period: The period of time for which data used as the base of an index number, or other ratio, have been collected. This period is frequently one of a year but it may be as short as one day or as long as the average of a group of years. The length of the base period is governed by the nature of the material under review, the purpose for which the index number (or ratio) is being compiled, and the desire to use a period as free as possible from abnormal influences in order to avoid bias.
Base rate: A fixed kilowatthour charge for electricity consumed that is independent of other charges and/or adjustments.
Btu conversion factors: Btu conversion factors for site energy are as follows:
- Electricity: 3,412 Btu/kilowatthour
- Natural Gas: 1,031 Btu/cubic foot
- Fuel Oil No.1: 135,000 Btu/gallon
- Kerosene: 135,000 Btu/gallon
- Fuel Oil No.2: 138,690 Btu/gallon
- LPG (Propane): 91,330 Btu/gallon
- Wood: 20 million Btu/cord
British thermal unit: The quantity of heat required to raise the temperature of 1 pound of liquid water by 1 degree Fahrenheit at the temperature at which water has its greatest density (approximately 39 degrees Fahrenheit).
Btu: The abbreviation for British thermal unit(s).
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.
Capacity factor: The ratio of the electrical energy produced by a generating unit for the period of time considered to the electrical energy that could have been produced at continuous full power operation during the same period.
Capacity transaction: The acquisition of a specified quantity of generating capacity from another utility for a specified period of time. The utility selling the power is obligated to make available to the buyer a specified quantity of power.
Capacity utilization: Capacity utilization is computed by dividing production by productive capacity and multiplying by 100.
Coal grade: This classification refers to coal quality and use.
- Briquettes are made from compressed coal dust, with or without a binding agent such as asphalt.
- Cleaned coal or prepared coal has been processed to reduce the amount of impurities present and improve the burning characteristics.
- Compliance coal is a coal, or a blend of coal, that meets sulfur dioxide emission standards for air quality without the need for flue-gas desulfurization.
- Culm and silt are waste materials from preparation plants. In the anthracite region, culm consists of coarse rock fragments containing as much as 30 percent small-sized coal. Silt is a mixture of very fine coal particles (approximately 40 percent) and rock dust that has settled out from waste water from the plants. The terms culm and silt are sometimes used interchangeably and are sometimes called refuse. Culm and silt have a heat value ranging from 8 to 17 million Btu per ton.
- Low-sulfur coal generally contains 1 percent or less sulfur by weight. For air quality standards, "low sulfur coal" contains 0.6 pounds or less sulfur per million Btu, which is equivalent to 1.2 pounds of sulfur dioxide per million Btu.
- Metallurgical coal (or coking coal) meets the requirements for making coke. It must have a low ash and sulfur content and form a coke that is capable of supporting the charge of iron ore and limestone in a blast furnace. A blend of two or more bituminous coals is usually required to make coke.
- Pulverized coal is a coal that has been crushed to a fine dust in a grinding mill. It is blown into the combustion zone of a furnace and burns very rapidly and efficiently.
- Slack coal usually refers to bituminous coal one-half inch or smaller in size.
- Steam coal refers to coal used in boilers to generate steam to produce electricity or for other purposes.
- Stoker coal refers to coal that has been crushed to specific sizes (but not powdered) for burning on a grate in automatic firing equipment.
Cogeneration: The production of electrical energy and another form of useful energy (such as heat or steam) through the sequential use of energy.
Coke (petroleum): A residue high in carbon content and low in hydrogen that is the final product of thermal decomposition in the condensation process in cracking. This product is reported as marketable coke or catalyst coke. The conversion is 5 barrels (of 42 U.S. gallons each) per short ton. Coke from petroleum has a heating value of 6.024 million Btu per barrel.
Cubic foot (cf), natural gas: The amount of natural gas contained at standard temperature and pressure (60 degrees Fahrenheit and 14.73 pounds standard per square inch) in a cube whose edges are one foot long.
Demand bid: A bid into the power exchange indicating a quantity of energy or an ancillary service that an eligible customer is willing to purchase and, if relevant, the maximum price that the customer is willing to pay.
Demand charge: That portion of the consumer's bill for electric service based on the consumer's maximum electric capacity usage and calculated based on the billing demand charges under the applicable rate schedule.
Demand charge credit: Compensation received by the buyer when the delivery terms of the contract cannot be met by the seller.
Demand indicator: A measure of the number of energy-consuming units, or the amount of service or output, for which energy inputs are required.
Demand interval: The time period during which flow of electricity is measured (usually in 15-, 30-, or 60-minute increments.)
Demand-metered: Having a meter to measure peak demand (in addition to total consumption) during a billing period. Demand is not usually metered for other energy sources.
Deregulation: The elimination of some or all regulations from a previously regulated industry or sector of an industry.
Energy service provider: An energy entity that provides service to a retail or end-use customer.
Interruptible or curtailable rate: A special electricity or natural gas arrangement under which, in return for lower rates, the customer must either reduce energy demand on short notice or allow the electric or natural gas utility to temporarily cut off the energy supply for the utility to maintain service for higher priority users. This interruption or reduction in demand typically occurs during periods of high demand for the energy (summer for electricity and winter for natural gas).
Interruptible power: Power and usually the associated energy made available by one utility to another. This transaction is subject to curtailment or cessation of delivery by the supplier in accordance with a prior agreement with the other party or under specified conditions.
Kilowatt (kW): One thousand watts.
Kilowatt-electric (kWe): One thousand watts of electric capacity.
Kilowatthour (kWh): A measure of electricity defined as a unit of work or energy, measured as 1 kilowatt (1,000 watts) of power expended for 1 hour. One kWh is equivalent to 3,412 Btu.
Load factor: The ratio of the average load to peak load during a specified time interval.
On peak: Periods of relatively high system demand. These periods often occur in daily, weekly, and seasonal patterns; these on-peak periods differ for each individual electric utility.
On-system: Any point on or directly interconnected with a transportation, storage, or distribution system operated by a natural gas company.
On-system sales: Sales to customers where the delivery point is a point on, or directly interconnected with, a transportation, storage, and/or distribution system operated by the reporting company.
Peak day withdrawal: The maximum daily withdrawal rate (Mcf/d) experienced during the reporting period.
Peak demand: The maximum load during a specified period of time.
Peak kilowatt: One thousand peak watts.
Peak load: The maximum load during a specified period of time.
Peak load month: The month of greatest plant electrical generation during the winter heating season (Oct-Mar) and summer cooling season (Apr-Sept), respectively.
Peak load plant: A plant usually housing old, low-efficiency steam units, gas turbines, diesels, or pumped-storage hydroelectric equipment normally used during the peak-load periods.
Peak megawatt: One million peak watts.
Peak watt: A manufacturer's unit indicating the amount of power a photovoltaic cell or module will produce at standard test conditions (normally 1,000 watts per square meter and 25 degrees Celsius).
Peaking capacity: Capacity of generating equipment normally reserved for operation during the hours of highest daily, weekly, or seasonal loads. Some generating equipment may be operated at certain times as peaking capacity and at other times to serve loads on an around-the-clock basis.
Power factor: The ratio of real power (kilowatt) to apparent power kilovolt-ampere for any given load and time.
Rate case: A proceeding, usually before a regulatory commission, involving the rates to be charged for a public utility service.
Rate features: Special rate schedules or tariffs offered to customers by electric and/or natural gas utilities.
Rate of return: The ratio of net operating income earned by a utility is calculated as a percentage of its rate base.
Rate of return on rate base: The ratio of net operating income earned by a utility, calculated as a percentage of its rate base.
Rate schedule (electric): A statement of the financial terms and conditions governing a class or classes of utility services provided to a customer. Approval of the schedule is given by the appropriate rate-making authority.
Regulation: The governmental function of controlling or directing economic entities through the process of rulemaking and adjudication.
Regulation, procedures, and practices: A utility commission carries out its regulatory functions through rulemaking and adjudication. Under rulemaking, the utility commission may propose a general rule of regulation change. By law, it must issue a notice of the proposed rule and a request for comments is also made; the Federal Energy Regulatory Commission publishes this in the Federal Register. The final decision must be published. A utility commission may also work on a case-by-case basis from submissions from regulated companies or others. Objections to a proposal may come from the commission or intervenors, in which case the proposal must be presented to a hearing presided over by an administrative law judge. The judge's decision may be adopted, modified, or reversed by the utility commissioners, in which case those involved can petition for a rehearing and may appeal a decision through the courts system to the U.S. Supreme Court.
Reregulation: The design and implementation of regulatory practices to be applied to the remaining regulated entities after restructuring of the vertically-integrated electric utility. The remaining regulated entities would be those that continue to exhibit characteristics of a natural monopoly, where imperfections in the market prevent the realization of more competitive results, and where, in light of other policy considerations, competitive results are unsatisfactory in one or more respects. Regulation could employ the same or different regulatory practices as those used before restructuring.
Substation: Facility equipment that switches, changes, or regulates electric voltage.
Subtransmission: A set of transmission lines of voltages between transmission voltages and distribution voltages. Generally, lines in the voltage range of 69 kV to 138 kV.
System Average Interruption Duration Index (SAIDI): Measures the average duration of interruptions for the average customer.
System Average Interruption Frequency Index (SAFI): Measures the average frequency of interruptions for the average customer.