German mine owners Geiger Group have contracted gravity energy storage specialist Gravitricity to investigate the potential of storing energy at a decommissioned mine.

The decommissioned shafts of the Grube Teutschenthal mine are based near Halle, about 150 km southwest of Berlin, and were used to produce potash and rock salt.

The 760-m-deep mine is now being used as a long-term waste disposal facility, with Geiger using deep underground cavities to soundly dispose of mineral waste especially from thermal energy plants and industry.

The group is planning to use green energy to power existing operations at the site, and optimise electricity supply through gravity energy storage.

Gravitricity will launch a study in May looking to assess the technical and commercial feasibility of using the Saale shaft to optimise the supply and demand of green energy.

If this initial phase of the study proves positive, Gravitricity will then deliver a concept design and project development plan, offering Geiger the option to consider building a full-scale gravity energy storage plant.

“We are very interested in the potential to use a decommissioned mine shaft to help us store and deliver low carbon power. We are committed to decarbonising our activities and this study will give us the information we need to understand if gravity energy storage can form a part of our renewable energy mix,” states Geiger shareholder Stephan Geiger.

Gravitricity MD Charlie Blair adds that this contract with Geiger demonstrates the growing interest in the potential to use below-ground gravity storage technology as a cost-effective and flexible way of storing and delivering renewable energy.

“We are now having conversations with mine owners worldwide seeking to explore opportunities to develop first-of-a-kind schemes.”

In February, Gravitricity signed a memorandum with Czech State-owned enterprise DIAMO, to help mitigate the consequences of coal mining in that country. The two parties are seeking to turn a decommissioned mine into a 4 MW energy storage facility, equivalent to the power needs of 16 000 homes.

Gravitricity estimates there are about 14 000 mines globally which could be suitable for gravity energy storage.