If the need for QC (see Dashboard for an explanation) is high, surplus H-gas will be converted into G-gas by means of nitrogen. The ‘Nitrogen meter’ and related graphical or numerical retrievals provide information about amounts of nitrogen that are available for and have been used in QC.
- Nitrogen is also used in the H-gas transport system (including WQA). This use is not part of the Nitrogen meter.
- There are some small G-gas entries that are made suitable for the G-gas system by means of nitrogen. This will almost always involve using a small amount of nitrogen, even though the total gas transport system is already in RQC mode.
- There are no historical measurements available about amounts of nitrogen available before 26-12-2015. Historical information about the “red and orange sections” are not available before 07-04-2016.
Subdivision of nitrogen capacity
The total quantity of nitrogen is subdivided into three categories:
- Firm nitrogen. All available nitrogen in this category can be used without restriction.
- Firm nitrogen (Volume Restricted). The nitrogen in this category comes from a nitrogen storage. So long as there is enough disposable volume in the storage, the available nitrogen in this category can be used without restriction. As soon as the storage is empty, this category is reported as not available via a REMIT report.
- Spare nitrogen. This category includes a reserve quantity of nitrogen. It is not possible to predict whether it can be used at any desired time. This depends on various gas transport technical factors. Once it is certain that the nitrogen in this capacity cannot be used, it is reported as unavailable via a REMIT report.
- Part of the total amount of nitrogen available (627.000 m3(n)/h) is regarded as reserve capacity to cope with minor failures/faults in conversion resources.
- The actual use of nitrogen does not have to take place in the order indicated above. Which nitrogen is used at which installation depends on various gas transport factors and optimisations in the gas transport system.
Change in availability and REMIT reports
Maintenance and long-term faults in GTS conversion installations and nitrogen production often mean that less nitrogen is available for conversion (see maintenance calendar). Acute and short-term faults also lead to a decrease in the availability of nitrogen.
REMIT reports will be submitted to indicate a change in the availability of nitrogen as soon as this change occurs.
The Nitrogen meter shows the status of the available amount of nitrogen and the nitrogen use in the past hour. The Nitrogen meter scale runs from zero (bottom left) to the maximum amount of nitrogen available (627.000 m3(n)/h, bottom right). This scale contains four colours. A green section on the left, if nitrogen use is in this section normal nitrogen is being used. There may be a grey section on the right, this is the total amount of unavailable nitrogen. There is an orange section and a red section in the middle. The orange section indicates when a REMIT warning is sent, see below. The red section shows the reserve nitrogen capacity (also a REMIT is sent, see below) . A pointer on this scale shows the actual use.
Underneath the meter the amount of used nitrogen is shown and a percentage which shows the relationship between the amount of nitrogen used and the amount of nitrogen available.
The Nitrogen graph shows the amount of nitrogen available and nitrogen use per hour in the past 14 days. The maximum amount of nitrogen that can be used is shown per category in three shades of grey. The yellow line shows the actual amount of nitrogen used. When the nitrogen used exceeds the orange dotted line a REMIT warning is sent, see below. When the nitrogen used exceeds the red dotted line the reserve nitrogen capacity is used (also a REMIT is sent, see below).
Normal Nitrogen usage.
The Nitrogen report shows the maximum volumes of nitrogen available and the volumes of actual nitrogen use. Users can choose among various aggregations (hour, day, month, calendar year and gas year) and various periods.
Nitrogen used and REMIT reports
As soon as the QC approaches its boundary (the amount of available nitrogen is almost used up), REMIT reports will be issued to announce the fact.
- Nitrogen use in orange section (see Nitrogen meter). An advance notification / warning is issued to indicate that the QC boundary is approaching. Market participants are asked to adjust their H-gas/G-gas balance to reduce nitrogen use.
- Nitrogen use in red section (see Nitrogen meter). Nitrogen from the reserve capacity is being used. A REMIT report is issued to indicate that the QC boundary has been reached. Market participants can be instructed to adjust their H-gas/G-gas balance to reduce nitrogen use.
The GTS transport system contains two physically separate networks that are linked together by blending stations. There is a low-calorific system intended to supply exits with G-gas or L-gas and an high-calorific system for H-gas exits.
Most entries are linked directly to the G-gas or H-gas system. However, some entries lie between G-gas and H-gas in terms of quality. They are incorporated into the G-gas or H-gas system via QC or RQC.
High-quality gases are converted into lower-quality gases by means of a process called QC (Quality Conversion) .
The G-gas system regularly experiences entry shortages, while there is a surplus of gases with a higher Wobbe ( H-gas). The surplus H-gas is converted into G-gas (QC) via blending stations. The amount of QC (converted H-gas) will be shown via the ‘QC-meter’ on the QC/RQC dashboard. If there is little QC, then the H-gas can be blended at no cost with other gases into G-gas quality (this is called enrichment). If a large amount of H-gas has to be converted, then it must be converted into G-gas by adding nitrogen (this gas is called ‘pseudo G-gas’).
When nitrogen is used, the gas transport network must be controlled in such a way that the H-gases with the lowest Wobbes are the first to be transported to the blending stations. This gives the greatest capacity for conversion at the lowest costs.
The amount of nitrogen available and the level of its use are shown on this dashboard via the Nitrogen meter on the QC/RQC dashboard. This means that the maximum QC limits can be clearly distinguished by the amount of nitrogen not yet used. See more detailed information at the Nitrogen report.
Part of the nitrogen may be delivered out of a nitrogen storage. The ‘N2-storage meter’ on the QC/RQC dashboard shows the actual volume available of this storage.
The process of converting low-quality gases into higher-quality gases (H-gas) is called RQC (Reverse Quality Conversion).
Sometimes the gas transport system has a shortage of H-gas entries and a surplus of gases with a lower Wobbe. The surplus low-Wobbe gases are added to the H-gas via blending stations.
It is impossible to indicate the RQC capacity in advance, as it depends on the current qualities of all gases. The RQC capacity can be between 0 m3(n)/h and approximately 1,5 mln. m3(n)/h. The amount of use of RQC will be shown by the ‘RQC-meter’ on the QC/RQC dashboard.
As already indicated, many entries lie between G-gas and H-gas in terms of quality. In general, the QC need is high, so all these gases are converted into G-gas by means of QC. But if the QC need decreases continuously, then gradually more of these gases will be converted to H-gas by means of RQC. At the borderline, both RQC and QC take place simultaneously. It is assumed by definition that the total transport system is in RQC mode if the amount of converted RQC gas exceeds the amount of converted QC gas.
About 40 minutes after every hour the information of that hour becomes available.The ‘meters’ show the status of the last available hour. The graphs and reports show the hourly data updated to include the last available hour. The daily, monthly and yearly aggregations contain data up to and including the last complete gas day.
One of the meters on the QC/RQC dashboard is the most important, depending on the current QC/RQC status. The current status is displayed below the meters on the dashboard. The most important meter is displayed on the home page of the GTS website.
If the gas transport system is using nitrogen for QC, then the Nitrogen meter is important and will be displayed on the home page. If no nitrogen is used but the transport system is still in QC-mode than the ‘QC-meter’ will be displayed. If the transport system is in RQC-mode than the ‘RQC-meter’ will be displayed.