Groundwater can store tremendous quantities of cool. This thermodynamic principle makes aquifers ideal for energy storage.
In winter, groundwater is cooled down and stored in a groundlayer that transports water (aquifer). In summer, this water can be used for cooling purposes.
The two most important systems are:
- Storage systems, where the water in winter is pumped from one well (the warm well) and after cooling down is pumped into another well (the cold well). In summer the cool water is pumped from the cold well and after warming up, it is returned into the cold well.
Such system of 2 wells is called a doublet or twin system. When necessary, several doublets are used.
- Recovery systems, where the water is always distracted at natural temperature from the positive well and injected in the negative well, where this will be at higher temperature in summer and at lower temperature in winter. These systems are somewhat simpler to construct, but are disadvantageous from a geothermal point of view as the water to use is not preheated or precooled.
It is applicable for both systems that they should be in a geothermical equilibrium, meaning that the amount of cold that is used, is fully equivalent with the amount of cold being brought in the aquifer.
Aquifer Thermal Energy Storage offers considerable environmental advantages in areas with moderate climate; for this reason these systems are subject to governmental promotion in the Netherlands.
As a member of NVOE (Dutch Association for Geothermal Storage), we are amongst the companies that can present the complete groundwater circuit of such system. Our clint can be sure that construction will take place according to the latest views and the standards, as presented in the NVOE-manual.
For a proper return on investment, it is important that these sytems are being constructed in such quality, that they can operate trouble-free for years!