Connected Party

Gas Quality and Metering

  • Two qualities of gas are transported in GTS’s transmission grid, i.e. H-gas (high-calorific gas) and G-gas (low-calorific or Groningen gas). An important measure for gas quality is the Wobbe index. The "Regeling gaskwaliteit" contains the Wobbe ranges for each type of gas including a summary of the gas composition. Please refer to for more information about gas compositions.
    You can indicate a preference for H-gas or G-gas on the "Application form new connection". Whether the preference indicated by a connected party can be honoured depends on the proximity of an H-gas or G-gas pipeline and the available capacity in the H- or G-gas system.

  • The connected party can state the desired pressure or pre-pressure at the connection point in bar (o). The gas transmission grid has two networks, the RTL (regional transmission line) and the HTL (high-pressure transmission line). The RTL has a maximum pressure of 40 bar(o) and the HTL a maximum pressure of 67 or 80 bar(o). The effective pressure at the connection point is dependent on the distance from a compressor station or a metering and pressure-regulating station. The RTL network has a minimum pressure of ca. 8 bar(o) and the HTL network a minimum pressure of ca. 40 bar(o). If possible, we will take account of the desired pressure put forward by a connected party.

  • Gas, which is odourless in its original state, has an odorant (THT) added to it at metering and pressure-regulating stations within the gas transmission grid. You can indicate a preference regarding whether it wants to receive odorised gas or not. In some cases, pipelines with non-odorised and odorised gas lie alongside each other and sometimes a choice has to be made. Ultimately we decide the network to which a connected party will be connected. In the event that we offer a connection point to the non-odorised gas network, you must take your own safety precautions in the form of gas detection or by fitting an odorant production unit in its gas receiving station.

  • In Gasport, under “Historical/Offline Metering /Quality per run”, connected parties can see which calorific value in a specified hour has been used for the energy determination for their exit point(s). The density, Wobbe, CO2 and N2 percentages are also shown here.
    Please note; the energy determination requirements as set out in the Metering Conditions for Gas – NNO do not require the hourly calorific values determined by GTS at a delivery point to correspond exactly to the calorific value of the gas made available at that moment.

  • In Gasport, under “Dispatching/Near real-time metering/Quality per run” details of gas composition are shown for every fifteen minutes. The calculated parameters such as Wobbe, density and calorific value are also shown here.
    These values are determined by GTS on the basis of the gas quality system as set out in the Metering Conditions for Gas - NNO. A description of the current gas quality system can be found on this website. The consequence is that the value shown does not need to correspond every hour with the value of the gas made available at that moment. And so, for those reasons, the measurements reported are not suitable to be used for, for example, process control. These data are suitable for invoice control, however, provided they are not shown as being ‘unreliable’.

  • This cannot be predicted exactly. Having said that, we have made a number of information services available for H-gas customers. These information services supply information about gas composition and/or flow duration in the network. Some services supply customer-specific information (for a specific connection point) and consequently require the connection points to be configured in a specific manner. After configuration, the information services can, in many situations, make valuable  – near real time – predictions about gas compositions to be expected over the short term. More information can be obtained from the document “Gas Composition tracking for connected parties”.

  • We present a global view of the following on our website under ‘Transport information’:

    • what the current flow situation is in the H-gas transmission network for the Wobbe index, the Propane Equivalent (PE number) and the Methane number.
    • and what the forecast is for the expected H-gas composition of the Maasmond LNG influx into our transmission network.
  • The composition of the natural gas being offered to the market in the Netherlands is gradually changing. The Dutch gas supply is declining and, as a result of this, producers and gas suppliers will be using more and more gas from other countries in Dutch networks. Gas is also becoming increasingly sustainable: consider developments in green gas. These developments have been launched by the government and will rapidly pick up pace over the coming years. By responding, in good time, to the situation concerning future gas supplies, we can ensure that our country links up smoothly with international gas supplies.

    The effect on large-scale, industrial applications is different to that which it has on domestic customers’ equipment. On the site you can find information about how you can prepare properly for the gas of the future and you will also find background information about the changing gas composition.

  • Gasport contains a “Historical/Offline metering/Request run information” page. Clicking on the “Send Information” button for each metering run causes an automatic request to be generated to send the relevant calibration certificates and control results to you, digitally, by email. This information will be in your possession by the following (working) day.