Gold mining company Gold Fields has revealed that it is investigating the feasibility of installing additional solar and wind power at its South Deep gold mine, in South Africa.

Interim CEO Martin Preece said on May 4 during the company’s first-quarter operational update that an additional 10 000 solar photovoltaic panels were planned for installation at the mine this year. However, he said the mine was reaching a limit in terms of how much solar could help before batteries had to be installed.

“I have a view that in an energy-starved country, frankly, spending money on batteries is probably not the best way to invest right now,” he said.

Rather, he said, the company was in talks with power utility Eskom to feed surplus energy into the grid and then get it back at a later stage when needed.

To supplement the solar farm, Preece said an additional 30 MW to 40 MW of wind energy was being considered, with installation and commissioning expected before 2035.

Preece said a 140-m-high met mast has been installed to help determine the viability of adding wind turbines at the mine, which he said could assist with providing power at night when solar power was unavailable.

He said that, so far, the met mast has helped show that 3 MW to 4 MW wind turbines could be viable, although more data needs to be collected before a decision can be made. However, a pre-emptive environmental impact assessment is being carried out in the interim.

Preece said each wind turbine could cost between R80-million and R100-million, with about ten being needed, bringing the expected cost to at least R1-billion.

The company commissioned its R715-million 50 MW Khanyisa solar power plant at the mine in the fourth quarter of last year, which Preece said was helping to keep mining operations going.

“We have forecasted about 24% of our annual electricity consumption from the solar plant as it is. We will keep on investing in renewables,” he said.

However, in terms of the current load factor, Preece said the mine currently consumes only about 72% of what the Khanyisa solar plant generates.

The reason for this is that much of the older equipment installed in the South Shaft was causing trips when being started up on load from the solar plant owing to the sudden spike in electricity. Gold Fields has therefore bought soft starters for the affected equipment, which Preece said would be installed in the coming months.

“We believe that by year-end we will be at about 90% consumption of what we are generating,” he explained.

Investing in more renewables makes financial sense for the company, because as State-owned Eskom electricity tariffs rise, so do the savings made by renewable energy users.

“When we initially motivated the solar project, we envisaged about R100-million a year coming out of our budgets in terms of our electricity spend. In August last year we budgeted a saving of R124-million. However, with Eskom prices going beyond what we envisaged, a saving of between R160-million and R170-million was made on our electricity bill,” Preece explained.

Currently, about 14% of Gold Fields’ total electricity requirements across its various projects comes from renewables.

In addition to the current 50 MW South Deep solar farm, a $20-million 12 MW solar farm was completed at the Gruyere gold mine, in Australia, and commissioned in June last year.

At the St Ives gold mine in Australia, an 85% renewable micro-grid feasibility study is currently underway. The microgrid will comprise solar-, wind-, battery- and gas-generated power. Public consultations were held with local communities last year and board approval is planned for the second half of this year.

Meanwhile, the Peruvian Cerro Corona mine’s hydro-generated electricity has been classified as 100% renewable according to the 2022 International Renewable Energy Congress, and a 10 MW to 12 MW solar plant at Salares Norte is currently undergoing a concept study, with the construction thereof scheduled for a year after the mine has been commissioned.