SA’s abandoned gold mines are being eyed as potential hydroelectric energy sites
- South Africa has approximately 6,000 abandoned mines.
- Some of these, with particularly deep shafts, could be used to generate electricity through renewable underground pumped hydroelectric energy storage systems.
- A feasibility study is being conducted by Swedish, German, and local firms to find out.
- The capital costs to convert a depleted mine will be less than constructing a new above-ground hydroelectric plant.
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South Africa’s abandoned mines could hold some of the answers to the country’s ongoing energy crisis. A new feasibility study on renewable underground pumped hydroelectric energy storage (Ruphes) looks to find out.
South Africa’s energy grid is under severe pressure, with breakdowns at unreliable power stations plunging the country into bouts of darkness due to load shedding. In addition to an energy infrastructure, Eskom, the country’s power utility, has been named the world’s biggest emitter of sulphur dioxide because of its reliance on coal.
It’s this combination of factors which has directed attention to renewables, with Independent Power Producers (IPPs) playing an important role in diversifying South Africa’s energy mix. The country’s Integrated Resource Plan (IRP2019) wants 33.8% of power to come from renewable sources, namely wind and solar, by 2030.
Renewable energy contributed 11% to South Africa’s total energy mix in the first half of 2021, according to the Council for Scientific and Industrial Research (CSIR). Capacity from hydroelectricity and pumped storage, solar photovoltaic (PV) and Concentrating Solar Power (CSP), and wind have an even share.
Pumped storage is a type of hydroelectric energy which generates power through reversible pump-turbines. To generate power on demand, these turbines are fed by water flowing from an upper reservoir to a lower reservoir. During times of low demand, the pump function feeds water back up to the top reservoir.
South Africa already has at least four operational large pumped storage schemes, but companies are on the hunt to find new ways of implementing these renewable energy systems. Attention has turned to Ruphes, which is still a relatively new concept.
And the study of depleted mines potentially being converted into Ruphes systems has received a lot of attention over the past two years. There are approximately 6,000 abandoned mines in South Africa.
United Kingdom-based company, Gravitricity, announced its plans to investigate South Africa’s deep mine shafts in 2019. Gravitricity’s novel concept relies on weights – not water – being dropped to generate and store gravitational energy at times of high demand.
Now, a collaborative project between Sustainable Energy Solutions Sweden (SENS), German uranium mining company Wismut, and Thyssenkrupp Uhde South Africa is the latest to embark on a study of South African mines for the purpose of Ruphes.
“Together, we will now explore the potential of deep gold mines and use these for a more sustainable tomorrow together with one of the world's leading industrial companies,” said SENS’ acting CEO Lise Toll, in announcing its inclusion in the project.
“The very deep gold mines in South Africa have excellent conditions with regard to fall height and geology and thus constitute optimal places for storage of energy from pumped storage power plants. The conditions in the gold mines mean significantly reduced costs as the necessary components for implementing pumped storage power plants are already available.”
SENS is already piloting a similar project on the Åland Islands with support from the European Union, showing “that it will be efficient and cost-saving to use abandoned mines for pump power.” This project is expected to deliver between 2 MW and 8 MWh.
(Compiled by Luke Daniel)
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