| ACMMO | The Association of Coal Mine methane Operators |
| AD | Anaerobic digestion; the production of methane rich biogas from the process of decomposition in the absence of oxygen |
| ADL1; ADL2 | Building Regulations Approved Documents L1 and L2 on conservation of fuel and power in dwellings (ADL1) and other buildings (ADL2) |
| AEP | Association of Electricity Producers; trade association representing generators |
| Availability | The percentage of the time that electricity generating plant is available to produce electricity (also see capacity factor) |
| BETTA | The British Electricity Transmission and Trading Arrangements; due to be introduced in 2005, extending NETA to Scotland |
| Biogas | Methane-rich gas produced by anaerobic digestion of biodegradable material, e.g. landfill gas and sewage gas |
| Biomass | Renewable fuels derived from purpose grown energy crops and the biodegradable proportion of industrial, municipal, agricultural and forestry residues |
| BiPV | Building-integrated photovoltaics |
| BHA | The British Hydropower Association; trade association representing the hydroelectric power industry |
| BRE | The (now privatised) Building Research Establishment |
| BSC | The Balancing & Settlement Code; The governance of electricity dispatch and settlement in England & Wales (and Scotland following the introduction of BETTA) |
| BSUoS | Balancing Services Use of System Charges; the means by which the TSO can recover the costs of balancing the system |
| Buy-out fund (of the RO)
| The fund derived from suppliers who �buy-out� from their obligation to submit ROCs in respect of a proportion of their electricity sales |
| Buy-out fund recycling | The redistribution of the buy-out fund back to the electricity suppliers in relation to their proportion of the total ROCs redeemed in that year |
| BWEA | The British Wind Energy Association; trade association representing the wind energy industry |
| Capacity | See Rated capacity and DNC |
| Capacity factor | The ratio of the electrical energy produced by a generating unit relative to the electrical energy that could have been produced at continuous full-power operation during the same period |
| Carbon Trust | A Government-funded organisation to promote carbon reduction in business and the public sector |
| CBM | Coal Bed Methane; gas actively extracted from coal seams |
| CCA | Climate Change Agreement; consumer contract to mitigate climate change impacts linked to concessions under the Climate Change Levy |
| CCL | The Climate Change Levy |
| CDM | Clean Development Mechanism; means whereby Parties not included in Annex I in of the Kyoto Protocol can achieve sustainable development and to assist Parties included in Annex I in achieving compliance |
| CH4 | Methane |
| CHP | Combined Heat & Power; the use of both heat and electrical power from a thermal power station |
| CHPA | The Combined Heat and Power Association; trade association representing CHP operators and developers |
| CMM | Coal Mine Methane; the gas continuously emitted by coal mines especially non-working mines |
| CO2 | Carbon dioxide |
| Co-firing | The burning of mixed fuels (typically refers to biomass with fossil fuel in a coal-fired power station) |
| CUSC | Connection & Use of System Code; Governance arrangements for connection to the transmission system |
| CVA Metering | Metering that is registered in the Central Volume Allocation system (typically larger generation and consumers at the �wholesale� level). See also SVA metering |
| DC | Data collector; agent responsible for obtaining metering data on behalf of the electricity supplier and preparing it for electricity settlement |
| DEFRA | The Department for Environment, Food and Rural Affairs of the UK Government |
| DETI | The Department of Enterprise Trade and Investment of the UK Government in Northern Ireland; equivalent of DTI |
| DGCG | The Distributed Generation Co-ordination Group; body advising Ofgem and the DTI on the effects of distributed generation on the UK electricity network |
| Disclosure | The requirement (under the IEMD) on electricity suppliers to provide details to consumers of the fuel sources of the electricity they have purchased |
| Distributed generation | Power generation embedded in (connected to) an electricity distribution network (as compared to centralised generation connected to the transmission network) |
| Distribution Code | The code of practice, which covers all major technical aspects relating to connections to, and the operation and use of, licensed distribution networks |
| Distribution network | The network for electricity distribution at voltages below that of the transmission network |
| DNC | Declared Net Capacity; a correction factor applied to the rated capacity of some intermittent generation sources to enable like-for-like comparisons with typical thermal plant capacity |
| DNOs | Distribution Network Operators |
| DTI | The Department of Trade and Industry of the UK Government |
| DUKES | The Digest of UK Energy Statistics |
