Glossary of Terms

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D

Decontracting: Substantially reducing commitment by local distribution companies for firm space on pipelines when transportation contracts expire.
Deficiency Period: Used in association with the EQUITABLE SHARING MECHANISM. A period during which the current take-or-pay liabilities of the pipeline were incurred. A customer’s cumulative deficiency in purchases during this period, in comparison to a BASE PERIOD, is compared to the system’s total cumulative deficiencies to determine that customer’s proportionate share of fixed take-or-pay charges. See BASE PERIOD, EQUITABLE SHARING MECHANISM and PURCHASE DEFICIENCY METHODOLOGY.
Degree Day, Cooling: A measure of the need for air conditioning (cooling) based on temperature and humidity. Although cooling degree days are published for many weather stations, a specific procedure has not been generally accepted.
Degree Day, Heating: A measure of the coldness of the weather experienced, based on the extent to which the daily mean temperature falls below a reference temperature, usually 65 degrees farenheit.
Dekatherm: A unit of heating value equivalent to 10 therms or 1,000,000 Btu’s.
Deliverability: The volume of gas a well, field, pipeline, or distribution system can supply in a given period of time. Also, the practical output from a storage reservoir. Compare CAPACITY, INSTALLED; STORAGE, UNDERGROUND.
Delivery Point: Point at which gas leaves a transporter’s system completing a sale or transportation service transaction between the pipeline company and a sale or trans-portation service customer.
Demand: The rate at which gas is delivered to or by a system, part of a system, or a piece of equipment, expressed in cubic feet or therms or multiples thereof, for a designated period of time called the demand interval. Compare LOAD.
Demand Charge: The charge based on the peak rate the customer used electricity in a billing period. The peak is determined by a demand meter that measures the customer's demand at regular 15 min. intervals.
Demand Charge: The portion of a rate for gas service which is billed to the customer whether they use the service or not. Depending on the rate design this charge is based on actual or estimated peak usage (1 or 3 days), annual needs or a combination of the two. Compare COMMODITY CHARGE.
Demand Costs (Rate): That part of the total cost of service which must be recovered through use of a demand rate; i.e., a rate for each Mcf of gas representing the customer’s demand on the Company’s system.
Demand Day: That 24-hour period specified by a supplier-user contract for purposes of determining the purchaser’s daily quantity of gas used (e.g., 8 AM to 8 AM, etc.). This term is primarily used in pipeline-distribution company agreements. It is similar to, and usually coincides with, the distribution company “sendout day”.
Demand Load: The rate of flow of gas required by a consumer or a group of consumers, often an average over a specified short time interval (cf/hr or Mcf/hr). Demand is the cause; load is the effect.
Demand Side Bidding: Process in which a utility issues a request for proposals to acquire DSM resources from energy service companies and customers, reviews proposals, and negotiates contracts with winning bidders for a specified amount of energy savings.
Demand Side Management (DSM): Utility activities designed to influence the amount and timing of customer demand.
Demand Side Management Program: Demand Side Management Program is an energy-efficiency program aimed to reduce energy use by consumers during peak and off-peak periods. The programs substitute advanced technology equipment to produce the same (or higher) level of end-use services with less electricity.
Demand Side Resource Portfolio: Comprehensive collection of DSM resources, both viable and non-viable, that are available, both currently and in the future to the utility.
Demand Side Resources: Resources obtained through the implementation of DSM that may be used as an alternative to traditional supply-side resources.
Demand, Average: The demand on a system or any of its parts over an interval of time, determined by dividing the total volume in therms by the number of units of time in the interval.
Demand, Contract: The daily quantity of gas which the supplier agrees to furnish and for which the buyer agrees to pay, under a specific contract.
Demand, Maximum: The greatest of all the demands under consideration occurring during a specified period of time.
Demand, Minimum: The smallest of all the demands under consideration occurring during a specified period of time.
Department of Energy (DOE): The Department of Energy is the twelfth Cabinet Position, and it consists of the Office of the Secretary of Energy and the Federal Energy Regulatory Commission. It was created on August 4, 1977 as a result of the Department of Energy Organization Act of 1977. There are many subdivisions within the DOE, but the Economic Regulatory Administration and Energy Information Administration are two groups which have significant bearing on gas utility operations.
Depreciable Plant: Usually tangible plant in service which is subject to depreciation, depletion, or amortization.
Depreciation: Return of investment through inclusion in cost of service (and rates) of a pro rata part of the cost of property, calculated to spread the total investment cost over a certain period of time or number of units that measure the useful life of the investment. Depreciation (in the Code of Federal Regulations) is to reimburse the company for “...the loss in service value not restored by current maintenance, incurred in connection with the consumption or prospective retirement of gas plant in the course of service from causes which are known to be in current operation and against which the utility is not protected by insurance. Among the causes to be given consideration are wear and tear, decay, action of the elements, inadequacy, obsolescence, changes in the art, changes in demand and requirements of public authorities, and, in the case of a natural gas company, the exhaustion of natural resources.”
Depreciation Expense: The cost of plant (less net salvage) recovered over the life of the plant through a reduction of income. This expense reflects the “using up” of plant (due to wear and tear, obsolescence, etc.) in the generation of income.
Derating: Running a generator below the manufacturer’s rating, which could damage or destroy the unit. For example, if the rating is 10 revolutions per minute and you run it at 5, it will (1) get hot and (2) stop running.
Deregulation: To halt or reduce government regulations.
Desiccant: Any absorbent or adsorbent, liquid or solid, that will remove water or water vapor from a material. In a refrigeration circuit, the desiccant must be insoluble in the refrigerant.
Design Day: A 24-hour period of demand which is used as a basis for planning gas capacity requirements.
Design Day Availability: The amount of each type of gas arranged to be available on the design day and the maximum combination of such supplies. (In the case of purchased natural gas, the maximum day allocation, maximum day contract quantity, or FERC authorization).
Design Day Temperature: The mean temperature assumed for the Design Day.
Design Load: The maximum average rate of gas use by a group of appliances or customers over a specified short time period, usually 15 to 30 minutes.
Design Pressure: The maximum operating pressure permitted by various codes, as determined by the design procedures applicable to the material and location involved.
Development Well: Well drilled to exploit proved undeveloped reserves.
Diaphragm: A bellows inside a displacement type gas meter. Also, a membrane separating two different pressure areas within a control valve or regulator.
Dig-in: When buried gas facilities are damaged by excavators.
Direct Current (DC): Electric current that flows in one direction, remaining as close to constant “magnitude,” or a certain flow, as possible (see also Alternating Current).
Direct Installation Program: DSM program in which the utility directly installs DSM measures within customers homes or businesses.
Direct Sale: Contract sale of natural gas by producer to end user or local distribution company, usually for a term of a year or longer.
Direct Vent Appliance: Gas appliance designed so that all combustion air is derived directly from the outside, and all fuel gases are discharged to the outside through an exterior wall.
Direct-Fired: A heating unit in which the combustion products are mixed with the air or liquid being heated. Compare INDIRECT-FIRED.
Disco: Short for distribution company; refers to a vertically disaggregated utility company (with distribution separated from generation and transmission), or one that has never owned power businesses other than retail distribution.
Discovery: Part of the ratemaking process, after a rate or other filing and after suspension by the Commission which orders a hearing, where parties including the filing company can, through requests for data, obtain more information about the (rate) filing and the particular issues set for hearing.
Dispatching: The control of product flow in a system involving the assignment of load to the various sources of supply to meet the desired objectives.
Displacement: Displacement transactions permit the lateral movement of gas through a transportation network. The configuration of many pipelines is such that it may not be apparent whether a given movement of gas is forward or backward from the point of receipt. It can be argued that all transportation service is performed by displacement as the physical delivery of the same molecules of gas is impossible. See BACKHAUL.
Dissolved (Solution) Gas: Natural gas originally in solution within the reservoir crude oil. As the reservoir pressure is reduced due to production, gas is released from solution in the oil, allowing it to migrate as free gas to a wellbore and be produced or to the crest of the reservoir where it can collect and form a secondary gas cap. In addition, gas is released from solution in the oil within the wellbore as the oil is produced. Thus, most oil wells, except stripper wells producing from reservoirs where the pressure and solution gas has been depleted, produce gas with the oil. Even oil fields with no free gas originally present can produce large volumes of gas since considerable gas can be present in solution in the oil.
Distributed Generation: Any technology that provides electricity closer to an end-user’s site, like a home or business. It may involve a small on-site generating plant or fuel cell technology.
Distribution: The act or process of distributing gas from the city gas or plant that portion of utility plant used for the purpose of delivering gas from the city gate or plant to the consumers, or to expenses relating to the operating and maintenance of distribution plant.
Distribution Company: Gas Company which obtains the major portion of its gas operating revenues from the operation of a retail gas distribution system, and which operates no transmission system other than incidental connections within its own system or to the system of another company. For purposes of A.G.A. statistics, a distribution company obtains at least 90 percent of its gas operating revenues from sales to ultimate customers, and classifies at least 90 percent of mains (other than service pipe) as distribution. Compare INTEGRATED COMPANY; TRANSMISSION COMPANY, GAS.
Divertible Gas Supplies: Gas supplies that are free to be sold to the highest bidder. They must be uncommitted, or committed under contract to a buyer for no longer than some short period (such as one year). They may be totally uncommitted to any buyer. In addition, they must be available to a pipeline’s customers at delivered city-gate prices that are competitive enough to prevent the pipeline from exercising market power. In GAS INVENTORY CHARGE proceedings, the Commission has stated that there must be sufficient divertible gas supplies, as well as COMPARABILITY OF SERVICE, in order to find that the pipeline is operating in a competitive environment.
Docket: A formal proceeding with the Federal Energy Regulatory Commission or local Public Utility Regulatory Commission for construction or abandonment of facilities, changes in rates and rulemaking.
Downstream: Any point in the direction of flow of a liquid or gas from the reference point. Compare UPSTREAM.
Downstream Pipeline: The pipeline receiving natural gas at a pipeline inter-connect point.
Drip: A container or segment of piping placed at a low point in a system to collect condensate, dust, and foreign material, enabling their removal. Also known as Drip Leg and Drip Pot. Compare SERVICE DRIP.
DSM Costs, Non-Utility: DSM expenses incurred by customers and trade allies associated with participation in a DSM program that are not reimbursed by the utility.
DSM Costs, Participant: Costs associated with participation in a DSM program that are paid by the participating customer and not reimbursed by the utility.
DSM Costs, Utility: All expenses incurred by a utility in a given year for operation of a DSM program, including administrative, equipment, marketing, and any others, regardless of whether the costs are capitalized or expensed.
Dual Fuel: An energy use for which there is an alternative fuel.
Dual-Fuel Capability: Ability of an energy-using facility to alternately use more than one kind of fuel.