Glossary of Terms - C

The glossary of terms is arranged alphabetically. Click on the letters below to find terms beginning with that letter.


Capacity Release (also called Capacity Assignment): The ability of a holder of firm transportation rights ("capacity") to allocate, release or assign, permanently or temporarily, all or part of that capacity to others.

Cash-out: Mechanism that allows shippers to resolve imbalances (above or below those that are resolved through "book-out" procedures) by selling gas to the pipeline, or purchasing gas from the pipeline.

City gate: Physical location (facility) where gas is delivered by a pipeline to a local distribution company.

CME Group: The largest, most diverse financial exchange in the world for trading futures and options for both individual and institutional traders. Formed by the 2007 merger of the Chicago Board of Trade and Chicago Mercantile Exchange; followed by the 2008 acquisition of New York Mercantile Exchange (NYMEX). The exchange where the natural gas futures and options and other energy futures are traded.

Cogeneration: The sequential production of electricity and useful thermal energy from the same energy source. Natural gas is a favored fuel for combined-cycle cogeneration units, in which waste heat is converted to electricity.

Commodity Charge: That portion of a natural gas sales or transportation rate based upon the volume actually used or shipped.

Contract Demand: The daily, monthly or annual quantity of gas or transportation a supplier or transporter agrees to furnish and for which a buyer agrees to pay a set charge. Often expressed in monthly fees for daily maximum quantities.

Contract (Futures): The natural gas futures contract is in reality a set of regulations under which buyers and sellers adhere. The standard contract for natural gas is 10,000 MMBtu. The contract specifies the unit of sale, how it is quoted in dollars, minimum and maximum price fluctuations, when and at what times the contract is traded, how delivery is made and over what period, and penalties for failure to make or take delivery if one is holding along or short position at the termination of trading.

Cubic Foot: The most common unit of measurement of gas volume. The amount of gas required to fill a volume of one cubic foot under standard conditions of temperature, pressure and water vapor, usually referenced to 14.7 PSI and 60 degrees Fahrenheit. Very roughly, one cubic foot equals 1,000 Btu's (1 Cf= 1 MBtu).

Curtailment: Reduction of gas deliveries due to a shortage of supply or because demand for service exceeds a pipeline's capacity. Usually there is a hierarchy of customers, in which some may be required to partially or totally cut back takes of gas before others. Industrial users, for example, are usually curtailed before service to residential users.

Customer Classes: The common classes of customers that receive service from a utility are: residential, commercial, industrial, electric generation and sale for resale. The state of California designates customer classes as core (residential and small commercial/ industrial users) and non-core (large users who qualify for interruptible transportation). California also has a core subscription class of non-core customers who choose to buy from the distributor.