Photo: Robert Werner / Heindl Energy GmbH

Location factors and geological potential

Gravity Storage plants should be located in areas with solid bedrock. The most favorable sites have stable, little-faulted rock such as granite or compact layers of otherwise solid rock material. The geological conditions must first be assessed in detail by a team of geologists. Heindl Energy provides all services required to evaluate potental sites.

In order to estimate how widespread suitable geological conditions for Gravity Storage might be, Heindl Energy has conducted a study analyzing different types of magmatic, metamorphic and sedimentary rock. A total of 117 globally distributed sites where analyzed, and a classification performed based on the internationally recognized Rock Mass Rating (RMR) system. The suitability of the geological conditions for construction of a Gravity Storage plant was found to be "very good" (RMR I) at 3% of the evaluated sites, and "good" (RMR II) at 43%. The remaining sites would require extensive, expensive rock stabilization measures, or would be suitable only for a relatively small Gravity Storage plant.

In addition, a large volume of water (depending on the size of the Gravity Storage – e.g. around 1.5 million cubic meters for a piston with a diameter of 150 m) must be available. This water is constantly re-used, and thus must only be provided once.

With Gravity Storage, the water is pumped underneath a large rock mass. Depending on the size of the storage, the water demand is variable. 


Gravity Storage plants should be located in areas with solid bedrock. The most favorable sites have stable, little-faulted rock such as granite or compact layers of otherwise solid rock material.


Due to its relatively high power, the Gravity Storage must be connected to at least the 110 KV grid. Correspondingly, a line to the grid should be as direct and short as possible, and not have to cover great distances.