D Return(s) 


'D' Returns (D1 & D2) are forms issued on behalf of a Liquidator (Official Receiver) reporting on the Conduct of Directors (The Insolvent Companies (Reports on Conduct of Directors) (Amendment) Rules 2001). Disclaimer: This administrative process can form part of the disqualification of director(s). 


Dark Spread


Definition: The gross margin derived from a coal-fired plant in generating a unit

of electricity from the acquisition of the coal from the market requiring this unit

of electricity.


Data Collector (DC)


Definition: The organization responsible for collecting, processing, and validating the meter reading data, who then passes the information to the data aggregator.


Data Aggregator (DA)


Definition: The organization appointed for aggregating the meter reading data received from the data collectors and forwarded to the suppliers.




Definition: Device fitted to a meter that can record, store, and transmit readings

and measurements.


Day-ahead Market (DA)


Definition: A traded market for the delivery to be the following day.


Day-ahead Schedule


Definition: A schedule prepared by a Scheduling Coordinator or the Independent System Operator before the beginning of a trading day. This schedule indicates the levels of generation and demand scheduled for each settlement period that trading day.




Definition: A debenture is an instrument used by a lender (e.g. a bank) providing capital to the borrower (i.e. companies). It enables the lender to secure loan repayments against assets - even if they default on the payment. A fixed charge

is usually taken out against a tangible asset such as property. 




Definition: A persistent decrease in the level of consumer prices or a persistent increase in the purchasing power of money. The rate at which this decrease occurs 

is expressed as a percentage over a period of time, usually a year.



Degree Day


Definition: A measure of the variation of one day’s temperature against a standard reference temperature, typically 65 Fahrenheit/18 Celsius. Degree days are used as

a basis for temperature-related weather derivative deals.


Delivery Capacity


Definition: The maximum rate at which a natural gas buyer can request the seller

to deliver gas into the pipeline and which the seller has a firm obligation to deliver.


Delivery Only Providers


Definition: Owners and operators of transmission and distribution system equipment that provide billing and related energy services for the transmission and delivery of electricity.


Delivery Month


Definition: The month in which a futures contract matures and can be settled by physical delivery. Also known as the contract month.




Definition: The rate at which energy is delivered to loads and scheduling points by generation, transmission, and distribution facilities.


Demand (Electric)


Definition: The rate at which electric energy is delivered to or by a system, part of a system, or piece of equipment, at a given instant or averaged over any designated period of time.


Demand Bid


Definition: 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-side Management


Definition: Action by consumers of energy to control and alter their usage, typically in response to energy price signals or electrical spikes. It is usually done through a third-party organization with qualified in-house expertise and systems.




Definition: A financial instrument derived from a cash market, futures contract, or other financial instruments. Derivatives can be traded on regulated exchange markets or over-the-counter.




Definition: Where natural gas is input into a pipeline system at one end and the same volume is removed from the other.


Distribution Network Operator (DNO)


Definition: Manages the installation and upkeep of their cabling and the distribution of electricity from the point where it leaves the transmission system

to the supply point. They are also often referred to as the host Regional Electricity Company (REC).




An abbreviation for Debt Relief Order (DRO). A client may enter into this form of insolvency to deal with their unsecured debts.




Definition: Activities in the oil and natural gas industry from a refinery onwards – e.g. the distribution and marketing of hydrocarbon products.