Glossary

  • Active Power
    Also known as 'Real Power' or simply 'Power'. Active power is the rate of producing, transfer or using electrical energy. Measured in watts and often-expressed in kW or MW.
    Amp
    An Amp is a unit that measures the rate of flow of an electrical current.
    Annual Quantity (AQ)
    The annual volume of gas consumed, measured in Kilowatt hours (kWh).
    Apparent Power
    The product of the voltage (volts) and the current amps. Comprises both active and reactive power. Measured in kVa or MVa.
    Availability Charge
    The charge for the amount of power made available to the clients premises. It is related to the agreed supply capacity. The distribution company sets the rate and it is expressed in kVA.
    Available Supply Capacity (ASC)
    The agreed maximum supply capacity, measured in kVA, which a customer is allowed to take from the distribution system through their connection point. Customers pay a monthly charge for each unit of capacity. The maximum demand should not exceed the ASC.
  • Base Load
    The minimum amount of electricity being used during non-operational hours.
    Bearish
    Believing that market prices are about to fall.
    BETTA
    The British Electricity Transmission and Trading Arrangement introduced in 2005 covering England, Wales and Scotland, replacing NETA which did not cover Scotland.
    Bilateral Energy Trading
    Trading whereby two parties (for example a generator and a supplier) enter into a contract to deliver electricity at an agreed time in the future.
    Bullish
    Believing that market prices are about to rise.
  • Calorific Value
    The ratio of energy to volume measured in mega joules per cubic meter (MJ/m).
    Capacitor
    These are used to add capacitance to the supply to eliminate the reactive element of the load.
    Carbon Emissions Trading Scheme
    A scheme in which greenhouse gas emissions are controlled by setting a cap on total emissions and allowing the market sectors to reach an economically balanced response via trading of emissions allowances. Allowances are allocated initially, perhaps through a free distribution or through an auction, and the total allocation is adjusted periodically.
    Carbon Footprint
    A carbon footprint is "the total set of GHG (greenhouse gas) emissions caused directly and indirectly by an individual, organization, event or product" (UK Carbon Trust 2008).
    Carbon Offsetting
    A carbon offset is a financial instrument aimed at a reduction in greenhouse gas emissions. Carbon offsets are measured in metric tons of carbon dioxide-equivalent (CO2e) and may represent six primary categories of greenhouse gases. [1] One carbon offset represents the reduction of one metric ton of carbon dioxide or its equivalent in other greenhouse gases.
    Carbon Trust
    An independent not-for-profit company set up by the government with support from business to encourage and promote the development of low carbon technologies. Key to this aim is its support for UK businesses in reducing carbon emissions through funding, supporting technological innovation and by encouraging more efficient working practices.
    CCGT (Combined Cycle Gas Turbine)
    A gas fired electricity generation plant.
    CCL Discount
    The benefits of the Climate Change Levy Discount Scheme result in up to 80% discount on the CCL in return for meeting energy or carbon saving targets.
    CCL Relief
    A reduction of the CCL agreed as part of a trade sector Climate Change Agreement.
    Climate Change Agreement (CCA)
    An agreement between the Government and a business user, whereby a reduced rate of Climate Change Levy is payable in return for a commitment by the user to achieve certain pre-determined targets for energy usage or carbon emissions.
    Climate Change Levy (CCL)
    A charge introduced by the Government on 1 April 2001 on UK non-domestic fuel. The Government's aim when introducing the levy was to encourage business to use less energy, and contribute to the reduction of Carbon Dioxide emissions.
    Climate Change Programme
    Published in 2000, it sets out the government and Devolved Administration strategic approach to tackling Climate Change and meeting the UK's Kyoto target of a 12% reduction in greenhouse gas emissions from 1990 levels by 2008-2012 and the domestic goal of reducing C02 emissions by 20% by 2010.
    Cogeneration
    The simultaneous production of electricity and another form of useful energy (such as heat or steam) through the sequential use of energy, resulting in increased efficiency of fuel use.
    Combined Heat & Power (CHP)
    CHP is very efficient technology for generating electricity and heat together. A CHP plant is an installation where there is simultaneous generation of usable heat (normally for space heating) and power (usually electricity) in a single process. CHP typically achieves a 35-40% reduction in primary energy usege compared with power stations and heat only boilers. An example is a gas fired power station where the waste heat is used in manufacturing or district heating.
    Communication Charge
    The monthly fee payable by a customer, which covers the collection of half hourly data by the meter operator. This can be billed direct by the MOP or passed on through the current supplier.
    Connection Agreement
    Agreement between client and the local distribution company (for example Central Networks in the Midlands) setting out the terms and conditions with which each are bound concerning the provision and use of the connection.
    Contract Price Structure
    This indicates the type of supply offer, and what charges (i.e. DUoS & TUoS) are built into the unit rates for the supply of electricity.
    Current Transformer
    These are used to measure a load on a supply. They clamp round the cable and measure the EMF which is then converted into a current reading (A)
    Customer's Installation
    Any structures, equipment, lines appliances or devices used or to be used by any customer and connected directly or indirectly to the DNO's network.
  • Dark Spread
    The difference between market price and the cost of production for coal fired generators.
    Data Aggregator (DA)
    The organisation appointed to aggregate the meter-reading data received from the appointed Data Collectors and forward it to suppliers.
    Data Collector (DC)
    The organisation responsible for collecting, processing and validating the meter reading data, who then passes the information to the Data Aggregator.
    De-energisation
    The interruption of supply, so that electricity cannot flow from the network to the premises.
    DEFRA
    Department for Environment, Food and Rural Affairs.
    Demand Site Management
    The planning, implementation, and monitoring of activities designed to encourage consumers to modify patterns of electricity usage, including the timing and level of electricity demand.
    Disconnection
    The permanent removal of the meter, cabling and service from the property once it is established that a supply will not be required in the future. This permanently removes the MPAN.
    Distribution System
    The local wires, transformers, substations and other equipment used to distribute and deliver energy to consumers.
    DNO (Distribution Network Operator)
    Companies licensed to distribute electricity in Great Britain by the Office of Gas and Electricity Markets (Ofgem)
    DUoS (Distribution Use of System)
    The charges incurred for distributing electricity across the local area system to the supplied premises.
  • Embedded Generator
    A generator with a direct connection to a PES's distribution system, rather than NGC's transmission system.
    Emission Reduction Units (ERUs)
    These units are specific to the EU Emission Trading Scheme (EU ETS), which started in 2005, and are equal to one tonne of carbon dioxide equivalent gases.
    Emissions Trading
    Emerging as a key instrument in the drive to reduce greenhouse gas emissions. Emission trading is to ensure that the emission reductions take place where the cost of the reduction is lowest thus lowering the overall costs of combating climate change.
    Energy Audit
    An inspection survey and analysis of energy flows in a building, process or system with the objective of understanding the energy dynamics of the system under study. An energy audit is conducted to seek opportunities to reduce the amount of energy input into the system without negatively affecting the output. Beyond simply identifying the sources of energy use, an energy audit seeks to prioritize the energy uses according to the greatest to least cost effective opportunities for energy savings
    Energy Display Certificates (EDC)
    Display Energy Certificates (DECs) show the actual energy usage of a building, the Operational Rating, and help the public see the energy efficiency of a building. This is based on the energy consumption of the building as recorded by gas, electricity and other meters.
    Energy Efficency
    Using less energy/electricity to perform the same function.
    Energy White Paper
    The White Paper is the first comprehensive, forward-looking statement of UK energy policy for over 20 years. The white paper sets four new goals for energy policy: to put ourselves on a path to cut the UK's carbon dioxide emissions by 60% by the year 2050, with real progress by 2020, to maintain the reliability of energy supplies, to promote competitive energy markets in the UK and beyond and to ensure that every home is affordably heated.
    Enhanced Capital Allowance
    Enhanced Capital Allowances (ECAs) enable a business to claim 100% first-year capital allowances on their spending on qualifying plant and machinery.
    EU Allowance (EUA)
    These units are specific to the EU Emission Trading Scheme (EU ETS), which started in 2005, and are equal to one tonne of carbon dioxide equivalent gases.
    European Union Emissions Trading Scheme (EU ETS)
    The EU ETS is one of the policies being introduced across Europe to tackle emissions of carbon dioxide and other greenhouse gases and combat the serious threat of climate change. The scheme will commence on 1 January 2005. The phase runs from 2005-2007 and the second phase will run from 2008-2012 to coincide with the first Kyoto Commitment Period. Further 5-year periods are expected subsequently.
    Excess Availability Charges
    A penalty charge being applied by certain suppliers to clients who are drawing kVa above their Available Supply Capacity (ASC). This can be three times the contracted pence per kVa rate.
    Exit Point
    A point of connection at which a supply of electricity may flow between the Rec's system and the client's installation, suppliers installation or the distribution system of another person.
    Extra High Voltage
    22,000 volts or higher voltage
  • Feasibility Study
    A methodology for identifying where and how energy is used on a site within core processes and then making recommendations for reducing usage and or eliminating waste.
    Firm Gas
    Gas supplied to a customer on a guaranteed basis, without interruption.
    Fixed Charge
    A monthly or quarterly charge levied by the supplier and is in addition to the standing charge.
    Forwards Contract
    An agreement to buy electricity from another party at a specified time in the future at a specified price with money changing hands at the delivery date.
    Fossil Fuel
    An energy source formed in the Earth's crust from decayed organic material. The common fossil fuels are oil, coal, and natural gas.
    Futures Contract
    Similar to a forwards contract these are normally trade through an exchange on standard contract terms with profits or losses calculated and paid daily.
  • Gas Substation
    A pressure reduction station located on the customers' premises where gas is reduced from mains pressure regulated at a medium or low pressure for domestic or industrial use.
    Gate Closure
    In relation to a settlement period, the time 3.5 hours before the start of that settlement period. It defines the moment when bilateral contracting ends and the Balancing Mechanism for each associated trading period begins.
    Generation
    This covers the production of electricity at power stations. At present the main fuels used are gas, nuclear and coal, although there is now a growing use of renewable forms of energy, such as wind power, the burning of gas from landfill and waste incineration.
    Gigawatt (GW)
    A unit of power equal to 1 billion watts; 1 million kilowatts, or 1,000 megawatts.
    Gigawatt-hour (GWh)
    A unit of energy equal to million kilowatt-hours. 1 GWh is equivalent to the total electricity typically used by 250 homes in one year.
    Grid Supply Point
    A point of supply from the national transmission system to the local system of the distribution network operator.
    GSS
    Guaranteed Service Standard - customer service standards of performance that are set by OFGEM.
  • Half-Hour Data (HHD)
    This is the product of the half-hour data meter. The data is used for invoicing, tendering and reporting purposes.
    HV
    High Voltage (Normally 11,000 Volts).
  • Imbalance
    A situation where there is a difference between the amount of power produced and the amount of electricity contracted or sold.
    Interconnector
    A connection or link between power systems that enables them to draw on each others' reserve capacity in time of need.
    Interruptible Gas
    Gas supplied to a customer whose site has an alternate fuel source, on the basis that the supply might be interrupted for a specified period.
  • Kilovolt Amperes (KVA)
    Also known as Total Power. The resultant effect of the active (kW) and reactive (kVAr) power is the total power measured in kVa. KVa = kW/power factor.
    Kilowatt (kW)
    A standard unit of electrical power equal to 1,000 watts, or to energy consumption at a rate of 1,000 joules per second.
    Kilowatt-hour (kWh)
    A unit of energy consumption. A typical home uses around 3,300 kWh of electricity per annum.
    Kyoto Agreement
    A protocol to the United Nations Framework Convention on Climate Change, it establishes legally binding commitment for the reduction of four greenhouse gases (carbon dioxide, methane, nitrous oxide, sulphur hexafluoride), and two groups of gases (hydrofluorocarbons and perfluorocarbons) produced by "annex I" (industrialized) nations, as well as general commitments for all member countries.
  • Liquefied Natural Gas (LNG)
    When natural gas is cooled to a temperature of approximately -160 degrees at atmospheric pressure, it condenses to a liquid called Liquefied Natural Gas (LNG). Natural gas is composed primarily of methane (typically at least 90%), but may also contain ethane, propane and heavier hydrocarbons.
    Load
    The amount of electric power delivered or required at any specific point or points on an electrical system. The requirement originates at the energy-consuming equipment of the customer.
    Load Factor
    Measures the relationship between unit consumption and maximum demand and is the percentage capacity utilisation figure of a site's power consumption. To calculate load factor take the total number of units of consumption, divide by the maximum demand, divide by the number of hours in the period, and multiply by 100.
    Load Management
    The process of shifting the use of electricity from periods of high demand to periods of lower demand, when the cost of electricity is usually lower.
    LV
    Low Voltage, normally at 240 or 415 Volts.
  • Managed Load
    The fixed energy base load of the total curve. This can be purchased either all at once or step-by-step.
    Maximum Demand
    The highest average demand (in kW or kVA) occurring in a half hour period.
    Megawatt (MW)
    The equivalent to one thousand kilowatts (kW).
    Meter Operator (MOP)
    The organisation appointed to install and maintain metering equipment.
    Meter Point Reference Number (MPRN)
    A unique reference number identifying each meter and used in the preparation of supply tenders.
    MPAN Core
    A 13-digit number (the bottom line of the Supply Number) made up of the: Distributor Identifier (first two digits), the company which provides the distribution network for the supply address. Meter Point unique reference (11-digit number), which is linked to the supply address.
    MPRS
    The Meter Point Registration System is owned by the distribution companies. It contains all the MPAN's for that distribution area.
  • National Grid Transco
    UK gas transportation and emergency service.
    Net Capacity
    The maximum load that a generating unit, station or other electrical apparatus can carry under specified conditions for a given period of time without exceeding approved limits of temperature.
    NETA - New Electricity Trading Arrangements
    This came into force on the 27th March 2001 and replaced the old 'electricity pool'. NETA is a new wholesale market, comprising trading between generators and suppliers of electricity in England and Wales. Under NETA, bulk electricity will be traded forward through bi-lateral contracts and on one or more power exchanges. Those trading will include generators, suppliers, traders and customers.
    NHH
    Non Half hourly sites - sites that take a power supply less than 100kW.
  • OFGEM
    Office of Gas and Electricity Markets.
  • Peak Demand
    The maximum load during a specified period of time.
    Plant Mothballing
    When a plant is not operating because there is no demand for its services the plant is 'mothballed'.
    Power Factor
    A Power Factor is a measure of how effectively electricity is being used on a site. Certain types of equipment cause poor power factors, which reduces the capacity of the network to supply power. Distribution companies will charge customers for this through Reactive Power Charges.
    Power Purchase Agreement (PPAs)
    Power Purchase Agreements are contracts between two parties, one who generates electricity for the purpose of sale (the seller) and one who is looking to purchase electricity (the buyer). Contractual terms may last anywhere between 6 months and 20 years
  • Reactive Power Charges
    Charges applied to a client's invoice in cases where certain suppliers and distribution companies enforce a penalty for reactive power use. This charge is normally levied in situations where the site Power Factor is less than unity (1) and below a specific level, normally between 0.95 and 0.97.
    Real Power
    See 'Active Power'.
    Regulator
    OFGEM is the Office of the Gas and Electricity Markets, regulating the gas and electricity industries in the UK.
    Reinforcement
    Any alteration to the existing system designed to enable the system to distribute an increased amount of electricity.
    Renewable Energy
    Energy derived from resources that are regenerative. This includes solar power, wind, wave and tide and hydroelectricity. Wood, straw and waste are often called solid renewable energy, while landfill gas and sewerage gas can be described as gaseous renewable.
    Renewable Obligation
    The obligation placed on licensed electricity suppliers to purchase a specified amount of their electricity from renewable sources.
  • SOQ
    Supply Offtake (Daily) Quantity measures in kWh.
    Spark Spread
    The difference between market price and the cost of production for gas fired generators.
    Standing Charge
    A Monthly or quarterly charge levied by the local distribution company.
    Sub-Metering
    The term often used when a property owner installs a separate meter to monitor the consumption of a utility such as gas or electricity.
    Substation
    Facility equipment that switches, changes, or regulates electric voltage. An electric power station which serves as a control and transfer of power flow, transform voltage levels, and serve as delivery points to industrial customers.
    System Buy Price (SBP)
    The price paid in the Balancing Mechanism by a party that requires more energy to meet its contractual commitments. Prices are often volatile and very high.
    System Sell Price (SSP)
    The price paid in the Balancing Mechanism by a party that has produced more electricity than it had customers to buy. Prices are very volatile and often negative, meaning that a payment would need to be made to dispose of the unwanted electricity produced.
  • Terawatt-hour (TWh)
    The equivalent to one thousand gigawatt hours (GWh).
    The Carbon Trust
    The Carbon Trust is an independent, not-for-profit company, which was created by the UK government. The Carbon Trust helps business and the public sector cut carbon emissions, and supports the development of low carbon technologies.
    Therm
    This is a unit of measurement for gas. 1 therm is equal to 29.3071kWh.
    Top-up Load
    This is priced like a normal contract with fixed price all inclusive rate at agreed signing.
    Trade Association
    An association of firms that operate in a specific industry.
    Transmission
    The transfer of electricity at high voltage from the power stations across the UK through wires on pylons to points where it can be distributed to users. This is known as the Grid System and is owned and operated by the National Grid Company (NGC).
    TRIAD
    Used for the calculation of TUoS Charges, the TRIAD is calculated by looking at the three maximum demand points (in kW) of the supply at half hourly time periods, and then averaging the total. The figures used are usually selected from winter months, and at peak times, as these periods are set to reflect the point at which the highest demand occurs on the National Grid.
    TUoS (Transmission Use of System)
    The charges incurred for transmitting electricity across the National Grid network from the source of generation to the network of the local distribution company. The level of these charges is usually calculated by applying a rate charge to the TRIAD demand level.
  • UK Kyoto Target
    In 1997, representatives from over 170 nations met in Kyoto, Japan to put together a new global treaty - the Kyoto Protocol to the United Nations Framework Convention on Climate Change (UNFCCC) - laying down legally binding reductions in greenhouse gas emissions throughout developed countries.
  • Voltage Transformer
    A device that reduces (or increases) the supply voltage for example a 11000/415 Volt transformer would convert an 11,000 volt supply to a 415 volt supply.