The company, headquartered in Edinburgh, said it has been contracted by mine owners Geiger Group to investigate a decommissioned shaft of the Grube Teutschenthal mine, about 150 km southwest of Berlin. The 760-m-deep mine originally produced potash and rock salt. Geiger Group is now using the facility as a long-term mineral waste disposal facility.

Gravitricity’s technology uses a heavy weight suspended in a deep shaft by cables attached to winches. When there is excess electricity, the weight is winched to the top of the shaft ready to generate power. This weight can then be released when required – in less than a second – and the winches become generators, producing either a large burst of electricity quickly, or releasing it more slowly depending on what is needed.

Work was to begin in May. If the initial phase of the study is positive, Gravitricity said it would then deliver a concept design and project development plan, offering Geiger Group the option to consider constructing a full-scale gravity energy storage plant.

In February, Gravitricity signed a memorandum with DIAMO, the Czech state enterprise charged with mitigating the consequences of coal mining in the republic, where the two parties committed to work in tandem to seek EU funds to turn a decommissioned mine into a 4MW / 2MWh energy store – equivalent to the power needs of 16,000 homes, according to Gravitricity.

Gravitricity said it has already demonstrated a scale version of its technology in Edinburgh – built in partnership with Dutch winch specialists Huisman – and now plans to build full-scale schemes in the U.K. and worldwide. Future multiweight systems could have a capacity of 25 MWh or more, according to the company. Worldwide, Gravitricity estimates there are around 14,000 mines which could be suitable for gravity energy storage.