Thyssenkrupp, Wismut to study potential to repurpose old South African gold mines for energy storage

6th October 2021 By: Simone Liedtke - Writer

Diversified industrial group Thyssenkrupp Uhde South Africa and German uranium mining company Wismut have been appointed to execute a prefeasibility study for a renewable underground pumped hydroelectric energy storage (Ruphes) project on a specific but undisclosed site owned by a South African mining company.

Thyssenkrupp Uhde South Africa is collaborating with international specialist companies to facilitate mine repurposing and has already signed a cooperation agreement with Wismut.

The international cooperation has now been expanded through an agreement with Pumped Hydro Storage Sweden to join the project.

With the increase in renewable energy generation, there is an increased need for energy storage, and Ruphes, coupled with solar and wind power, “can reliably provide green energy when it is needed”, Thyssenkrupp said.

Repurposing depleted gold mines for Ruphes enables short construction schedules and significantly reduced costs. The main reason for going this route, the companies explain, is that gold mining has already created the underground water storage reservoirs that are usually the mostly costly component of pumped hydro plants.

These reservoirs just have to be adapted to their new purpose.

This is where Pumped Hydro Storage Sweden gets involved, as it is currently developing a 2 MW or 8 MWh underground pumped energy storage project in an abandoned iron mine in Aland, Finland.

The project has the support of both the European Commission and the Swedish Energy Agency, and they are planning to commission the project in December 2023.

This project demonstrates the reduced construction schedules and costs associated with using mine tunnels for pumped energy storage as did a similar project at the Kidston gold mine, in Australia.