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APX - Amsterdam Power Exchange
The Amsterdam Power Exchange (APX) is a virtual electricity trading platform. Consumers, distributors, producers and traders in electricity buy and sell on the APX spot market. The APX plays an important role in resolving the problem of the limited import capacity of electricity on the Dutch border. The APX is used primarily for trade in electricity between energy companies and for the supply of regulator current to compensate imbalances. The APX index is a measurement index for the electricity spot market.
Balance volume
The aggregate balance up to and including a certain hour in a certain contract year (in m³). The balance volume is calculated for each hour in the contract year. Balance volume can be both positive and negative.
Calorific value
Calorific value refers to the amount of heat released when gas is fully combusted and is essential for the proper functioning of gas-fired appliances. In the Netherlands, a standard cubic metre of G-gas has a calorific value of 31.65 – 38.69 MJ/m³.
CHP
CHP stands for Combined Heat and Power. This is the simultaneous generation of electricity (power) and heat. The heat generated through CHP is generally at a high temperature (steam, hot
water) and can therefore be used for other purposes (industrial process heat, ambient heating, urban heating). This co-generation in CHP plants yields a high level of efficiency.
Commercial flexibility
The demand for flexibility that arises when an individual shipper has to balance his individual portfolio.
Conversion factors
1 MMBtu = 1 million British Thermal Units
1 MMBtu = 292.7 kWh = 1.055 GJ = 30.0 m³ natural gas (n;35.17)
1 kWh = 0.0036 GJ = 0.0034 MMBtu = 0.103 m³ natural gas (n;35.17)
1 m³ of natural gas (n;35.17) = 9.77 kWh = 0.035 GJ = 0.033 MMBtu
Day flexibility
The degree to which the permitted disparity between the input and offtake of gas for a network user is increased by a user period of up to one day, through the contracting of day flexibility.
Degree day
A measurement of the average daily temperature below the given base temperature of 180C, or 18 degrees Celsius minus the average daily temperature measured at the De Bilt meteorological station.
Entry point
A point in the gas transmission system at which transport capacity can be contracted or traded in order to bring gas into the national gas transport network. Entry points are classified as follows: domestic production points (43), border points (17), underground storage points (7) and TTF points (4).
Exit point
A point in the gas transmission system at which transport capacity can be contracted or traded in order to remove gas from the national gas transport network. Exit points are classified as follows: industrial points (420), local distribution points, also known as pseudo GOS’s, (682), border points (22), underground storage points (7) and TTF points (4).
Flexibility service
A service that enables network users (shippers) to balance the margin between the amount of natural gas they introduce into the gas transmission system and the amount of gas they take out, should there be a disparity between the volume of gas introduced and taken off.
G-gas / Groningen gas
Natural gas from the Slochteren field near Groningen consists of 81% methane, 3.6% higher gaseous hydrocarbons, 0.4% H2S (hydrogen sulphide), plus quantities of nitrogen and carbon dioxide. Gronings gas yields an average of 31.7 MJ/m³ of energy on combustion. This is equivalent to 8.8 kWh of energy. |
GOS
Custody transfer station. These are local stations where the gas is transferred from the national or regional transmission grid to the urban or industrial grid. Cities have several GOS’s.
H-gas / High calorific gas
Gas that consists almost entirely of hydrocarbons.
L-gas / Low calorific gas
Gas that contains substantial amounts (up to 25%) of nitrogen and/or carbon dioxide, in addition to hydrocarbons.
LNG / Liquefied Natural Gas
Natural gas in liquid form; under normal pressure, gas is liquid when it is cooled to temperatures of approximately -162°C. LNG is frequently used as a way of transporting gas by sea (in LNG tankers). Liquefied natural gas takes up about 1/600th the volume of natural gas at standard temperatures and pressures. This makes it cheaper to transport if no pipeline is available; it is generally transported in special LNG sea vessels.
Natural gas
A fossil fuel whose constituent components include hydrocarbons (C and H), carbon dioxide (CO2) and nitrogen (N2).
NBP - National Balancing Point
A virtual UK trading location on the gas transport network of Gastransport Services where the position of a network user is determined and gas can be purchased and sold. The National Balancing Point is reached by introducing gas at an entry point and left by removing gas at an exit point.
Nomination
The announcement by a producer or supplier concerning the volume of gas he will be supplying or transporting in a given period in the future.
Shipper
A (legal) entity who uses the transport services of the national network operator for the transport of natural gas. In the Netherlands, Gas Transport Services (GTS), which is based in Groningen, is the Transport System Operator.
Swing in production
The opportunity for a producer to vary the volume of gas above or below a constant production level.
TTF - Title Transfer Facility
A virtual Dutch market place where both Dutch and foreign market parties are given the opportunity to buy and sell gas. Gas that is brought into the national gas transmission grid can be transferred to another party before it leaves the system. The seller creates a virtual exit point, while the buyer creates a virtual entry point.
Transport capacity
The volume of gas that can be transported to an entry or exit point, or between a combination of entry and exit points, within a specified unit of time, measured in standard cubic metres per hour.
Wobbe index
A yardstick for measuring the combustion of gas in an appliance, based on the following Wobbe bands:
H-gas: 48 - 56 MJ/m³
G-gas: 43.5 – 44.4 MJ/m³
L-gas: 42.5 - 47 MJ/m³
Working volume
The difference between the highest and lowest values of the balance volume in a given hour during a specific contract year (in m³). The working volume is calculated at the end of the contract year.
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