As a committed player in the energy transition, Storengy offers its industrial clients throughout the world innovative solutions in energy storage. In France, Germany and the United Kingdom, Storengy designs, develops and operates three types of underground natural gas storage sites. Let’s explore an aquifer storage site together!
During periods of low consumption, usually in summer, the gas is transported to the storage site through pipelines. The entering volume is measured and, if necessary, the gas is compressed in compressors. After that, it passes through a manifold, which is a set of pipes equipped with valves to distribute the gas to the buried pipelines which lead to the different wells located around the plant. To guarantee the safety and containment of the gas, the wells are systematically equipped with protection devices at the surface and underground. The gas is then injected through metal pipes with a diameter of about 10 centimetres into the aquifer, a permeable layer of water-impregnated rock which is located at a depth of 450 to 2,000 metres and which spreads over several kilometres. In some cases, gas may be injected into a former oil or natural gas reservoir. This is what we call storage in depleted reservoirs. As the gas pressure is higher than the water pressure, the water is pushed away by the gas which partially takes its place in the rock without disturbing the underground’s natural structure. This reservoir is located below an impermeable cap rock which keeps the gas from escaping. Its containment is monitored with observation wells.
During peak consumption periods (in the winter), the gas is withdrawn from the reservoir. It naturally rises inside the well, which reduces the reservoir pressure. Then, it circulates through buried pipelines again, towards the manifold. It is then subjected to a treatment linked to its underground stay, a desulphurisation to eliminate traces of hydrogen sulphide and a dehydration process to remove the water it contains. This “withdrawal water” is collected for treatment. If the gas pressure is not sufficient to supply the transmission network, it needs to be compressed. For safety reasons, it is odorised and its quality is monitored in a laboratory. After measuring the outgoing volume, it goes into the transport pipelines.
All operations are remotely controlled from a control room. Thanks to their large capacity and their local anchorage, aquifer storage sites ensure a reliable and continuous supply of natural gas throughout the year. They are indispensable to cover the necessary needs during winter consumption peaks and guarantee a territory’s security of supply.
And for the future, Storengy is already thinking about renewable gas storage in its reservoirs to support the energy transition.