Since January 2011 our world-class, fast-cycle gas storage facility is operational. We achieve high injection and withdrawal rates per hour, one of the highest turnover rates in the world and a switch time between injection and withdrawal of under 15 minutes.
Our facility is located in the north of the Netherlands and is connected to the reliable Dutch gas transmission network, in the heart of the TTF-market. Gas is stored in five salt caverns at a depth between 1,000 and 1,500 metres whose gas volume ranges from 5,000 MWh to 10,000 MWh. The technical lay out consists of two tubings per cavern in stead of one tubing that results in an exceptionally high injection and withdrawal rate. Gas is injected into the caverns using electric compressors and is withdrawn using equipment for heating, pressure reduction and gas drying.
Injection and withdrawal capacity is available 24/7 throughout the year. The facility has a high reliability with an efficient short period of yearly maintenance that is principally planned during summer.
|Number of caverns||5|
|Tubings per cavern||2|
|Gas quality||low caloric Groningen gas|
|Working gas volume||approx. 3,000 GWh|
|Total withdrawal capacity||18 GWh/h|
|Total injection capacity||10.5 GWh/h|
All parts off the facility explained
This interactive infographic explains the function of all parts of the installation. Click on a part of the image for a detailed description.
The facility has a control room where the processes can be monitored and controlled. In general, this only happens during maintenance. Normally, the facility is controlled from the Gasunie Central Command Post. There, the facility and caverns can be monitored and controlled in real time. Otherwise, the facility can be operated completely unmanned.
The customers of EnergyStock determine what is injected or withdrawn. Their requests ultimately result in gas either being injected or withdrawn from the facility.
The gas flow and quality is measured during injection and withdrawal. This enables us to know exactly how much gas goes into the caverns and how much gas is delivered to the gas transport network. The flow of gas is measured using ultrasonic flow metres. The quality of the gas is analysed using a gas chromatograph. These very accurate measurements show us exactly how much energy is in the cavern and what should be invoiced to the customers.
Before the gas can be measured, it will be cleaned using cyclone filters. This is done to prevent any of the particles in the gas from polluting the facility and measuring equipment.
When the gas is returned to the Dutch gas transport network, it is treated at the facility.
The gas coming from a cavern can contain solid and liquid particles. The particles are removed by the inlet separators through a simple and error-free process. The gas flows into these vessels under high pressure. The solid and liquid particles will settle at the bottom and the gas exits the separator through the top.
The pressure in the caverns is between eighty and one hundred and eighty bar. The pressure in the Dutch gas transport network is approximately sixty bar. Therefore the pressure is being reduced. The gas is then warmed up using hot water, which is heated by boilers. This is done because the pressure reduction causes the gas to cool down. After pressure reduction, the temperature should be fifteen degrees Celcius.
In the heater/choke trains, the gas is first heated up using hot water from the boilers. The pressure is then reduced to 60 bar using chokes, making the gas suitable for the Dutch gas transport network.
The last step in the process is the removal of moisture from the gas. The gas coming from the caverns is damp because the walls and the bottom of the caverns are wet due to the leaching process. In the glycol contactor, which is a high upright vessel, the gas comes in intensive contact with glycol, resulting in the gas being dried. The dry gas then flows on and the moisture-saturated glycol is collected. The glycol is then separated from the moisture so that it can be reused. This is done in a glycol regeneration unit.