Capstone Energy Services

Energy Basics

Terms A-Z


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

A capacity charge, sometimes called Demand Charge, is assessed on the amount of capacity being purchased and may refer to generation, transmission or distribution capacity. This amount is fixed regardless of the amount of electricity purchased or delivered.

Capacity Release

A mechanism by which holders of firm interstate transportation capacity can relinquish their rights to utilize the firm capacity to other parties that are interested in obtaining the right to use that capacity for a specific price, for a given period of time and under a specifically identified set of conditions. The firm transportation rights may include transmission capacity and/or storage capacity.

Capacity Rights

Refers to the level of firm transportation service to which a customer has a contractual right.

Capacity, Peaking

The capacity of facilities or equipment normally used to supply incremental gas under extreme demand conditions; generally available for a limited number of days at maximum rate.


A feature in some curtailment plans or Balancing Agreements that allows volumes not used in one period to be used in the following period or periods.

Cashout Provisions

To the extent a shipper violates balancing provisions, any difference between receipts and deliveries will be "cashed out", with the pipeline purchasing excess receipts at below-market prices and selling receipt shortages at above-market prices.

Ceiling Price

The maximum lawful price which may be charged for regulated gas.

Check Meter

A device for measuring energy consumption within specific parts a large multifunctional facility or group of facilities where the utility service is supplied through a master meter.


An instrument used to analyze the make-up of various substances, and often used to determine the Btu content of natural gas.

City Gate Rate

The rate charged a distribution company or end-user by its supplier(s) which includes all costs and expenses delivered to the facilities of the distribution company.

City Gate Station

Point at which a distribution gas company receives gas from a pipeline company. See Gate Station.

Class of Service

Defines the type of customer. The common classes of service applied to ultimate consumers are: residential, which covers service to customers for domestic purposes (single, multifamily, or mobile homes, etc.); commercial, which includes service to customers engaged in wholesale or retail trade, agriculture, government, insurance and financial services and all other customers not classified by the other classes; and industrial, which covers service to customers engaged primarily in a process which either involves the extraction of raw materials from the earth or a change of raw unfinished materials into another form or product.

Clause, Adjustment

A provision in a utility tariff which provides for periodic changes in charges or credits to a customer due to increases or decreases in certain costs over or under those included in base rates and incurred by the seller such as purchased gas cost, transportation costs, or advance payments made for gas.


Federal Energy Regulatory Commission (FERC), or State public utility regulatory commission (PUC).

Commodity Charge

A charge per unit of a specific commodity delivered to the buyer.

Company Storage

Natural gas storage facilities owned and controlled by the LDC.

Compressor Station

Any permanent combination of facilities which supplies the energy to move gas at increased pressure from fields, in transmission lines, or into storage.

Confirmed Nomination

An agreement by a seller to deliver/cause delivery or a transporter to receive and deliver a specific quantity of gas for a specified period at various points under a Sales or Transportation Agreement or for all contracts at one specific point. The confirmed nomination is in response to a purchaser's or shipper's nomination.


The quantity of natural gas used by ultimate consumers.

Contract Balancing

A process of managing the difference between the quantities received and delivered at various points under a contract during a defined period of time (i.e., hourly, daily, monthly, etc.).

Contract Demand (CD)

The amount of the system's capacity to deliver gas which a natural gas pipeline or distributor agrees to reserve for a particular customer and for which the customer agrees to pay a demand charge as specified in the applicable tariff. Also, the daily quantity of gas which a supplier agrees to furnish and for which the buyer agrees to pay, under a specific contract.

Contract Price

Price established at the time a purchase contract was negotiated.

Cost Allocation

The rate design step that allocates the demand and commodity costs of the various functions to the customer classes. See Cost of Service.

Cost of Service

A term used in public utility regulation to mean the total number of dollars required to supply any total utility service (i.e., revenue requirements); it must include all of the supplier's costs, an amount to cover operation and maintenance expenses, and other necessary costs such as taxes, including income taxes, depreciation, depletion, and amortization of the property not covered by ordinary maintenance. Included also is a fair return in order that the utility can maintain its financial integrity, attract new capital, and compensate the owners of the property for the risks involved.

Cost of Service Tariff

A special type of tariff which allows a gas pipeline to adjust periodically for any overage or underage in recovery of its cost of service (including per unit adjustments for loss of load). In contrast, a normal fixed-rate tariff, while specified based upon a cost of service estimate, does not provide for recovery of any previous underage or return of any overage above actual costs incurred.

Cubic Foot

The most common unit of measurement of gas volume. It is the amount of gas required to fill a volume of one cubic foot under stated conditions of temperature, pressure, and water vapor.


Curtailment of 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 Charge

A fixed amount to be paid periodically by the customer without regard to demand or energy consumption.

Customer Choice

A utility program that allows customers to purchase kilowatt hours of electricity from any of a number of electricity suppliers that compete with each other.

Cycle Billing

A billing procedure which provides for the billing of a portion of utility customers each working day so that all customers are billed within a predetermined period, such as one month, two months, etc. (In some companies, each day's billing is referred to as a "billing cycle day," "billing day," or "billing cycle." Other companies use "billing cycle" to refer to the total period which covers billing of customers within a spec.

Energy Facts

Energy Facts

Natural gas can be used as a raw material in a variety of products, including paint, fertilizer, plastics and medicines.

Natural gas produces fewer emissions than other fossil fuels, with less nitrogen, sulfur, carbon and fine particulates.

Texas produces the largest amount of natural gas in the USA.

The biggest consumer of coal in the US is the electric power sector.

There are 17,658 electric utility generators in the USA.

Energy Delivery Chains

Energy Delivery Chains

Find out more about how your energy is produced and delivered to your business.

Learn More

Energy & the Environment

Energy & the Environment

How we assist clients in responding to national environmental concerns.

  • Initiate and manage a "Green" energy procurement program
  • Evaluate national legislative and regulatory initiatives
  • Research state and local energy efficiency programs and incentives
  • Track energy use and related emissions estimate