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Glossary of energy terms

In the context of renewable generation, additionality is about whether the customer’s action or decision has made a genuine reduction in emissions above and beyond what would have happened anyway.

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.

Advanced Conversion Technology
It is a new and developing thermal processes, such as gasification and pyrolysis, which can be utilised to dispose of Municipal Solid Waste (MSW).

Agreed Capacity
An agreed amount of electrical load for a property, as stated in the property’s Connection Agreement with the local Distribution Network Operator (DNO).

Air Handling Unit (AHU)
An equipment package that includes a fan or blower for providing heating, ventilation, and air conditioning (HVAC) to a building. Efficiency is improved through enabling control.

Air Source Heat Pump (ASHP)
The heat pump absorbs heat from the outside air and transfers the heat to the space to be heated in the heating mode. In the cooling mode the heat pump absorbs heat from the space to be cooled and rejects the heat to the outside air.

Alternating Current (AC)
Electricity that changes direction periodically. The period is measured in Cycles per Second (Hertz, Hz). 

The unit that measures the rate of flow of an electrical current.

Anaerobic Digestion
A biological process that produces a gas principally composed of methane (CH4) and carbon dioxide (CO2) otherwise known as biogas. These gases are produced from organic wastes such as livestock manure, food processing waste, etc.

Annual Quantity (AQ)
It is the sum of the annual consumption of all meters on a site. This comes from National Grid, and is based on historical usage from previous years. Measured in kWh (electricity) or Therms (gas). Supply Point AQ is the total annual consumption of all meters on a site. Meter Point AQ is the AQ for a particular Meter Point.

Apparent Power
The product of the voltage (volts) and the current amps. Comprises both active and reactive power. Measured in kVa or MVa.

Automatic Meter Read (AMR)
AMR is the term given to a system that provides automatic meter readings remotely. It uses telephone technology and holds the ability to transfer data into a billing system.

Availability (KVA)
Availability (kVA) or Agreed Capacity refers to the limit of capacity for a site. E.g. if a site has an Availability of 150 kVA then maximum demand should not exceed that figure at any time. It is set and charged by the local Distribution Network Operator (DNO), according to the kVA of a premise. This fee covers investment and maintenance of the electricity network and can also be called the Capacity Charge. Customers pay a fee (per unit) according to the agreed capacity for that site. In theory, maximum demand should not exceed the agreed capacity at any time.

Available Supply Capacity (ASC)
Also known as the Agreed Capacity, this is an agreed amount of electrical load for a property, as stated in the property’s Connection Agreement with the local Distribution Network Operator (DNO).

Landfill Gas 
Municipal solid waste contains significant portions of organic materials that produce a variety of gaseous products when dumped, compacted, and covered in landfills. Anaerobic bacteria thrives in the oxygen-free environment, resulting in the decomposition of organic materials and the production of primarily carbon dioxide and methane.

Large Site Peak Day Demand 
Defined as the sum of Supply Offtake Quantity (SOQ) for all large sites.

Large Supply Point 
A supply point where the reference consumption actual quantity (AQ) is equal to or exceeds 732,000 kWh/25,000 therms per annum.

Line Loss Factor 
Line Loss Factor codes are used to calculate the related DUoS charges for an MPAN. The figure gives us the voltage scale of the Mpan and reflects both the amount of transmission infrastructure used to supply the point and the amount of energy lost through heat etc

Liquified Natural Gas (LNG) 
When natural gas is cooled to a temperature of approximately -160 degrees Celsius at atmospheric pressure, it condenses to a liquid called LNG.

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 
Where sites are flexible as to when they use their electricity. This means that they can schedule their production and shift patterns according to the price of pool electricity. Consumers who can load manage are able to significantly reduce their consumption at the three times in the year when the National Grid takes the Triad maximum demand readings which are used to calculate the transmission charges.

Local Distribution Zone (LDZ) 
Local Distribution Zone is a Transco defined area for which the total input and output demand can be measured each day.

London Climate Change Agency (LCCA) 
A body set up to work closely with the private sector to tackle climate change. The LCCA has been formed as a Mayoral led agency by the London Development Agency to enable and deliver sustainable and renewable energy and energy efficiency projects that will lead to a reduction of carbon dioxide emissions in London.

Low Carbon Building Programme (LCBP)
Launched in 2006, the LCBP is a UK government porgramme that provides funding towards the cost of installing microgeneration and other low carbon technologies.

Low Voltage (LV) 
Low Voltage, normally at 240 or 415 Volts.

Low-enriched uranium 
Uranium enriched to less than 20% U-235. (That in power reactors is usually 3.5 - 5.0% U-235.).

{C}6363'>UN Framework Convention on Climate Change (UNFCCC) 
The international framework established in 1992 to tackle the issue of climate change and greenhouse gas emissions. The UNFCCC aims to prevent dangerous man-made climate change and commits developed countries to take the lead in tackling climate change.

Unit Price 
The price per unit of energy which includes 3 components only – energy wholesale price (energy at NBP), infrastructure costs and a cost to serve element

Uranium (U) 
A mildly radioactive element with two isotopes which are fissile (U-235 and U-233) and two which are fertile (U-238 and U-234). Uranium is the basic fuel of nuclear energy.

M Number Database 
A web based application held by National Grid used by suppliers to view basic site details of sites not in their ownership. See xoserve.

Mains Electricity 
Electricity supplied to our homes from the National Grid.

Marine Generation (Tidal And Wave) 
The principle behind tidal generation is similar to wind turbines, except that instead of wind turning the turbine blades, the process uses underwater current caused by tides. One of the benefits of tidal power over wind power is the predictability of tidal currents, enabling the developers to know exactly when the turbines will be producing power. Electricity can also be generated by harnessing the energy waves. The aim is to capture the vertical movement in the water surface caused by waves and to convert that energy to electricity by turning a generator, Both tidal and wave power are in the early stage of commercial use in the UK. Currently they are significantly more expensive that other renewable technologies such as wind and hydro, but it is hoped that costs will decrease in future.

Market Code Sector 
A classification if a site is Industrial & Commercial or Domestic.

Maximum Annual Quantity (MAQ) 
Total quantity of gas to be delivered to the customer sites during the contract year. Usually defined in a Take or Pay clause.

Maximum Demand 
Maximum Demand is the highest peak of usage (kWH) in any Half Hour during a calendar month or between two meter readings measured in either kW or kVA. This value is multiplied by 2 to give the MD on an hourly basis.

Mega Watt (MW) 
Mega Watt - a measure of power, one million watts.

Metal fuels 
Natural uranium metal as used in a gas-cooled reactor.

Meter Asset Manager (MAM) 
A role that can be taken on by a number of parties who will manage a portfolio of meters on behalf of their client. They could control the meter replacement program, arrange Meter Work. The MAM will act as the point of contact for a meter point and can supply all known information regarding that meter point.

Meter Asset Provider (MAP) 
The party responsible for the ongoing provision of the meter installation at that meter point. Where a MAP provides the meter, the MAM may be the owner (title owner) of the meter or the MAM could lease or rent the meter from a third party.

Meter Operator (MOp) 
The organisation appointed to maintain metering equipment.

Meter Operator Charges (MOp Charges) 
This charge covers the cost of maintaining metering equipment.

Meter Point Administration Service (MPAS) 
Organisation that holds all information of MPANs.

Meter Serial Number 
The number stamped on the front of the meter. This changes when meter is exchanged.

CHP (as above), but in very small scale, typically below 5kW electrical output, (e.g. in the residential and commercial sectors). It is likely to operate in place of a domestic central heating boiler.

The small-scale generation of energy, for example solar panels or domestic wind turbines. These are often referred to as generation from renewable sources at a domestic or small community level.

Million Cubic Meters (MCM) 
1 MCM is approximately 360,000 therms.

Mega Watt hour, one thousand kWh. A 1 MW power-generating unit running for 1 hour produces 1 MWh of electrical energy.

National Balancing Point (NBP) 
The point where wholesale gas is traded within the UK.

National Grid 
The National Grid owns the main transmission systems and is responsible for transmitting the electricity from the generator to the local RECs area. All electricity generated in mainland UK is put into the National Grid before fed into distribution networks.

National Transmission System (NTS) 
National Grid’s high pressure gas network.

Natural Uranium 
Uranium with an isotopic composition as found in nature, containing 99.3% U-238, 0.7% U-235 and a trace of U-234. Can be used as fuel in heavy water-moderated reactors.

Network Code (NWC) 
The rules and procedures that govern the way National Grid and all shippers operate within the deregulated market.

New Electricity Trading Arrangements (NETA) 
In England and Wales these arrangements replaced ‘the pool’ from 27 March 2001. The arrangements are based on bi-lateral trading between generators, suppliers, traders and customers and are designed to be more efficient, and to provide greater choice for market participants.

A notice to National Grid from a Shipper to indicate the request for the offer details for a supply point (transportation, metering, capacity, commodity costs, etc.).

Nomination Flow 
A notice to xoserve from a Shipper to indicate the request for the offer details for a Supply point (transportation, metering, capacity, commodity costs, etc.)

Non Half Hourly (NHH) Meters 
Unlike HH meter a meter reader must visit the site to obtain readings. There are different tariffs (SSC) available.

Non-Daily Metered (NDM) Supply Point 
Volume of gas consumed at supply point is recorded at monthly, quarterly or longer intervals by traditional meter reading.

A supply point with an AQ of 73,200 kWH (2,500 therms) is deemed as a domestic site. A supply point with an AQ of over 73,00 kWh is deemed as non-domestic.

Notional Balancing Point (NBP) 
NBP is where entry gas is brought to a virtual point in the system from which network users can transport to an exit point, thus becoming a trading hub.

Nuclear is a low carbon energy source. Even when all the processes such as construction, uranium mining and enrichment are included, its overall emissions are very low, and surprisingly, comparable to wind power.

Nuclear Power 
Generates electricity using heat produced by an atomic reaction. The process of generation produces negligible amounts of carbon which is why nuclear is put forward as one way of reducing global carbon footprints.

Nuclear reactor 
A device in which a nuclear fission chain reaction occurs under controlled conditions so that the heat yield can be harnessed or the neutron beams utilised. All commercial reactors are thermal reactors, using a moderator to slow down the neutrons.

Million Cubic Meters (MCM) 
1 MCM is approximately 360,000 therms.

Mega Watt hour, one thousand kWh. A 1 MW power-generating unit running for 1 hour produces 1 MWh of electrical energy.

A notice from XOSERVE to a Shipper in response to a nomination indicating the charges to be levied on a Supply Point.

Office Of Gas And Electricity Markets (OFGEM) 
OFGEM is the government regulator for Gas and electricity markets.

An emissions reduction, commonly resulting from a project undertaken in the developing world, which has been sold to compensate for emissions elsewhere. Offsets are commonly used to net off corporate emissions so that an organisation can claim to be carbon neutral.

Gas consumed by a site or customer.

Organisation of Petroleum Exporting Countries (OPEC)

Communications method used to communicate with a meter i.e. GSM, modem, packnet.

Parallel grid mode 
This is where the Cogeneration unit runs in parallel with the grid.

Pass Through Charges 
Charges that appear on bills to cover the costs of third parties involved in the energy supply chain to deliver power.

Peak Demand 
Point of maximum electricity demand on the national system.

Percentage Day 
This refers to the percentage ratio of electricity used in the daytime against that used in the night. This information is used by suppliers to quickly identify the type of profile.

Photovoltaics (PV) 
The direct conversion of solar radiation into electricity by the interaction of light with the electrons in a semiconductor device or cell.

The Electricity Pool of England and Wales - the now defunct wholesale market through which an authorised Supplier purchased electricity - the price for electricity in this market was determined by market forces and was not regulated.

Power Exchange (PX) 
A cleared market for electricity trading, for example APX.

Power Factor 
This relates to how efficiently electricity is used on your site. Certain types of equipment cause poor power factor which reduces the capacity of the network to supply power. Distribution Network Operators' (DNO) can charge customers for this through power factor charges.

Power Line 
Electrical wires that carry electricity from the point of generation to the point of use.

Power Station Gate (PSG) 
Point at which power station output is metered.

Pre-Network Code (PNC) 
The operating methods and procedures used prior to the introduction of the Network Code.

Public Registration System (PRS) 
Used to register suppliers, meter operators and distribution companies for settlement purposes for all premises in the UK.

A large metal tower that carries very high voltage power lines.

Thermal degradation of waste in the absence of air to produce char, pyrolysis oil and syngas.

d kWh. A 1 MW power-generating unit running for 1 hour produces 1 MWh of electrical energy.

Qualifying Use Limit
The percentage of domestic use gas on a mixed use site, above which the entire supply is charged at the reduced rate.

Certain Distribution Networks apply Ratcheting to their MPANs in case the customer should use over their agreed Availability (kVA). Once the account has been billed for Excess Availability, the level up to what they were billed becomes their new Availability (kVA), depending on the specific Networks policy.

Reactive Charges 
Charges applied to a client’s invoice in cases where certain suppliers and distribution companies enforce a penalty for Reactive Power use.

Reactive Power (KVAR) 
This is the difference between the electricity supplied and the electricity converted into useful power. If the difference is large, i.e. there is a large amount of power being wasted, its puts an additional strain on the distribution network. The loss of power can be caused by kinetic energy (heat) or through defective machinery. This is measured via the Reactive register on a meter and is charged to the customer depending on how much they accumulate.

Regional Economic Strategies (RES) 
Produced by RDAs with partners and stakeholders in their region. These documents set out the framework of regional economic priorities which guide the activities of organisations promoting regional economic development, and are revised at least every three years.

OFGEM is the Office of Gas and Electricity Markets, regulating the gas and electricity industries in the UK. This is a statutory body representing the interests of gas and electricity consumers in the UK.

Remote Non Half Hourly Meters 
These meters have a NHH set up but they are connected to a communication device.

Renewable Energy 
‘Renewable energy’ is used to describe the energy produced using naturally replenishing resources. 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 renewables.

Renewable Energy And Energy Efficiency Partnership (REEEP) 
An international partnership to promote the growth of renewable energy and energy efficiency systems, launched by the UK at the World Summit on Sustainability Development (WSSD).

Renewable Energy Certificates (REC's) 
RECs, also known as ‘Green Certificates’, green tags, or tradable renewable certificates, represent the environmental attributes of the power produced from renewable energy projects and are sold separate from commodity electricity.

Renewable Energy Guarantee of Origin (REGO)
Electronic certificate used to provide evidence that a unit of electricity has been produced by a renewable generator. One REGO representing one kilowatt/hour of electricity. In some countries they are called Guarantees of Origin - GoOs.

Renewable Obligation (RO) 
This is the main government market mechanism to support renewable energy. It is an obligation on all electricity suppliers to supply a certain amount of their electricity sales from accredited renewable sources under the Climate Change Levy exemption scheme.

Renewable Power Association (RPA) 
The Renewable Power Association is a trade association open to all companies supportive of the UK renewable energy industry.

Renewables Obligation (UK) 
The new Renewables Obligation and associated Renewables (Scotland) Obligation came into force in April 2002 as part of the Utilities Act ( 2000 ). It requires power suppliers to derive a specified proportion of the electricity they supply to their customers from accredited renewable sources. This starts at 3% in 2003, rising gradually to around 10% by 2010 and 15.4% in 2015/16.

Renewables Obligation Certificate (ROC) 
Eligible renewable generators receive Renewable Obligation Certificates (ROCs) for each MWh of electricity generated. These certificates can then be sold to suppliers. In order to fulfil their obligation, suppliers can either present enough certificates to cover the required percentage of their output, or they can pay a ‘buyout’ price of £34.30 per MWh (set by Ofgem for 2007-2008) for any shortfall. All proceeds from buyout payments are recycled to suppliers in proportion to the number of ROCs they present.

Review of Gas Meter Arrangements (RGMA) 
A project to determine industry wide business processes supporting data flows to underpin competition in gas metering services.

Seasonal efficiency database of boilers in the UK (SEDBUK) 
The percentage efficiency of a boiler model from this database is used in the calculation of the energy saving.

Service Industry Code (SIC) 
The SIC is a standard classification code which identifies the types of business conducted at the site.

Settlement Agency Fee 
Elexon, the UK’s Balancing and Settlement Code Company, charge for making sure all parties involved in distributing, supplying and measuring energy supply are paid appropriately.

Settlements Agency 
This is the body that "settles" the distribution of electricity to establish where and to whom the generated load has been distributed to.

A shipper buys gas from producers / importers, transports this through the gas network by National Grid, and sells the gas to its customers. The shipper may have a contract directly with the customer, or may act on behalf of a 3rd party.

Shipper Interface Document 
A document produced under the auspices of the (National Grid)

Shipper Reference 
The unique reference defined by a Shipper to allow for all deliveries to be tracked.

A geographic location at which gas is consumed by the customer. There may be several gas meters at a site, which measure the volume of gas consumed.

Small Site Peak Daily Demand 
Small site PD Demand = Sum of (reference consumption) for all small sites.

Smart Metering 
The ability to remotely read non-half hourly (NHH) meters. Data is more reliable and more accurate bills are produced.

Spark Spread 
A form of analysis used to compare gas prices with electricity prices, by converting the gas price into a price per MWh and subtracting it from the electricity price in that period, taking into account power station efficiency. A negative spark spread indicates that it is more beneficial to sell gas than to produce and sell electricity.

Standing Charge 
Is a daily or monthly charge to contribute towards installation, maintenance and administration costs for the local Distribution Network Operator (DNO).

Sub Station 
These play an important part of the national grid. They contain transformers which increase or decrease the voltage of an electric current.

The term often used when a property owner installs a separate meter to monitor the consumption of a utility such as water, gas or electricity.

A person authorised by a supply licence to supply electricity or gas to the National Grid Network, via the Shipper.

Supplier Activity 
Energy efficiency work undertaken by suppliers to meet their energy efficiency targets.

Supplier Nominated Interruptible (SNI) 
A site where the supplier has the right to interrupt the supply for commercial reasons.

Supply Hourly Quantity (SHQ) 
SHQ is the maximum hourly consumption for a supply point.

Supply Number 
S-Number (also known as MPAN - Meter Point Administration Number). A unique number identifying the distribution company and the location of the metering point.

Supply Offtake Quantity (SOQ) 
The maximum daily consumption for a supply point.

Supply Point (SP) 
A group of one or more meters for which National Grid shall make Natural Gas available for offtake by the Shipper.

Supply Point Administration (SPA) 
The process by which Shippers and National Grid agree ownership of supply points.

Take Or Pay 
Percentage of gas purchased by the buyer from the seller against the Minimum Bill Quantity.

Tariff Structure 
Suppliers quote for electricity in numerous different formats. These range from simple one-rated structures (the same price per kW at all times throughout the year) to complex "Seasonal Time of Day" tariffs which are multi-rated. i.e. the price changes three, six or eight times a day.

Temperature And Pressure 
Gas either expands or contracts slightly under varying temperature and pressure. It is also known as the Conversion Factor and usually set at 1.02264. The Conversion Factor is taken into account when converting gas usage from volume to energy.

Thermal efficiency 
Quantity of heat produced in relation to fuel input.

A unit of energy measurement. To calculate equivalent value in kWh, multiply by 29.3071.

Time Pattern Regimes (TPR) 
Codes that state what date and time the meter registers start and finish.

Title (Meter) Owner 
This is also referred to as Legal Title Owner. The person or Organisation to which the asset belongs, and that makes such assets available for the purpose of the Gas Act Owner.

Equipment that is used to change the voltage of an electric current. Transformers can increase or decrease voltage.

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).

Transmission Losses (Line Losses) 
When transmitting electricity from generator to local distribution network areas some electricity is lost. Specific calculations have to be made by suppliers to determine the level of these losses.

Transmission Use of System (TUoS) 
The charges are 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.

Transportation Charge 
A charge made by National Grid for the national transport of the shippers’ gas through the gas network (National and Regional Transmission system and the low and medium pressure distribution system) to the customer. The transportation charge consists of three elements, which are dependent on the locations of the particular terminal and offtake site: capacity charge; commodity charge; and site charge.

It is used to calculate 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.

UK Kyoto Target 
Kyoto target – all greenhouse gases 12.5% below 1990 levels by 2008-12 National goal – CO2 20% below 1990 levels by 2010 Long-term goal – Reducing CO2 emissions by some 60% from current levels by 2050

UN Framework Convention on Climate Change (UNFCCC) 
The international framework established in 1992 to tackle the issue of climate change and greenhouse gas emissions. The UNFCCC aims to prevent dangerous man-made climate change and commits developed countries to take the lead in tackling climate change.

Unit Price 
The price per unit of energy which includes 3 components only – energy wholesale price (energy at NBP), infrastructure costs and a cost to serve element

Uranium (U) 
A mildly radioactive element with two isotopes which are fissile (U-235 and U-233) and two which are fertile (U-238 and U-234). Uranium is the basic fuel of nuclear energy.

Value Added Tax (VAT) 
VAT is a government-imposed tax on the supply of goods and services.  There are currently 2 rates of VAT applicable to supplies of electricity and gas – the standard rate and the reduced rate. On supplies used solely for business purposes, VAT will usually be charged at the standard rate.

Where supplies are wholly or partly for domestic or charitable non-business use, that part of the supply qualifies for the reduced rate of VAT.  This is known as ‘qualifying use’. 

Customers with qualifying use will need to submit a VAT Customer Declaration Certificate for each site, to advise us what percentage of the supply meets the qualifying criteria set by HM Revenue and Customs (HMRC).  Please note that VAT Declaration Certificates are not transferable between suppliers. 

A unit used to measure the electromotive force of an electric current.

Voltage Scales 
The Voltage Scale is not set by the customer, but determined by Networks when the premises supply is connected. Depending on what kVA is requested by the customer, and what Networks are faced with when installing the supply, will determine which voltage scale is required. The voltage scale can also be determined via the Line Loss Factor.

Voltage Transformer 
A device that reduces (or increases) the supply voltage for example a 11000/415 Volt transformer would convert volt supply to 415 volt supply.

Voluntary Withdrawal 
A notice issued by a shipper indicating that they wish to cease ownership of a Supply Point.

High-level waste (HLW) is highly radioactive material arising from nuclear fission. It can be recovered from reprocessing spent fuel, though some countries regard spent fuel itself as HLW. It requires very careful handling, storage and disposal. Low-level waste (LLW)is mildly radioactive material usually disposed of by incineration and burial.

Waste Residue 
The portion of the waste stream (domestic and commercial) which cannot currently be recovered or recycled.

Whole Current Meterering 
Metering that is 100 amp and below.

Wind power 
The conversion of energy in the wind into electrical power. The wind hits the blades of the wind turbine, which rotates like a giant propeller and powers the generator. Wind farms can be sited on land or at sea, with those offshore able to take advantage of the much stronger and consistent winds found off our coast.

Wobbe Index 
The gross calorific value of Natural gas divided by the square root of the Relative Density.

World Alliance for Decentralized Energy (WADE)

Xoserve, delivers transportation transactional services on behalf of all major gas transportation companies