Discovery targets mining with 24-hour renewables plan

DISCOVERY Green has signed several mining companies to a renewable power offering that targets 90% of their electricity needs.

A mix of wind, solar and batteries can help meet the round-the-clock power needs of mining operations, the company says.

Dan Ginsberg, head of actuarial and R&D at Discovery Green, said the company had signed “quite a range of mining clients”, although it could not disclose the full number because some contracts remained confidential. “90% is the target,” Ginsberg told Miningmx after the launch of Discovery Green’s new EnergyOS platform in Johannesburg on Tuesday. “It’s actually the target standard.”

Impala Platinum (Implats) and Glencore are among the mining groups that have previously signed renewable electricity deals with Discovery Green.

Implats has a five-year agreement under which solar and wind power will supply up to 90% of the electricity used by its Impala Refineries operation in Springs. Glencore signed a 20-year agreement in 2025 covering four operations at its Goedgevonden, Tweefontein and iMpunzi coal mine complexes near eMalahleni.

Discovery Green is not the only energy trader supplying the mining sector. Sibanye-Stillwater signed 10-year renewable power agreements with NOA and Etana Energy in February. NOA will supply 138MW from a portfolio of solar and wind projects, while Etana will supply about 220MW to Sibanye-Stillwater’s South African operations.

Different routes

Large miners have taken different routes to cut their reliance on Eskom. Some have developed their own renewable plants, while others have signed power purchase agreements with independent producers or turned to traders that pool electricity from several projects.

Gold Fields, for example, built the 50MW Khanyisa solar plant at South Deep. The plant was commissioned in 2023 and supplied 17% of the mine’s electricity in 2024.

Exxaro’s wholly owned renewable energy business Cennergi developed the 68MW Lephalale solar plant to supply its Grootegeluk mine. The plant reached commercial operation in April this year and supplies power directly to the mine through a behind-the-meter arrangement.

A key problem for miners is matching renewable supply with operations that need electricity throughout the day and night.

Ginsberg said this meant Discovery Green had to secure the right mix of generation. Wind can help supply power at night, while batteries can shift electricity generated by solar plants during the day for use later.

“You need wind, because wind produces during the night, and/or some sort of battery solution that can move daytime procurement via solar into the nighttime,” he said. He said the mix would allow Discovery Green to raise renewable coverage while protecting expected savings and making the outcome more predictable.

The company’s new EnergyOS platform is designed to manage that mix. It models renewable generation, a customer’s electricity use and future power prices, and then allocates electricity from Discovery Green’s portfolio to customers.

Ginsberg said the aim was for the system to fit around a mine’s electricity needs rather than requiring the operation to change its consumption pattern. “Ultimately, it completely adapts around their needs,” he said.

Risks

Discovery Green argues that simply contracting renewable power does not remove the risks facing a large electricity user.

Solar and wind output changes, while a mine’s own electricity demand can also rise or fall. In his presentation, Ginsberg pointed to the PGM sector as an example of an industry where commodity cycles can affect electricity use. Maintenance, force majeure and other disruptions can also change demand.

That creates the risk that a customer contracts more renewable electricity than it needs, or receives less than expected. “With oversupply … you pay for what you don’t need, and it becomes expensive. It’s wasted,” Ginsberg said.

With undersupply, the customer may not achieve the savings it had expected.

Discovery Green says EnergyOS tries to manage these changes by modelling a range of possible outcomes instead of relying on a single forecast. Its allocation model can then adjust how renewable electricity is divided among customers as generation and consumption data comes in.

The company said simulations carried out on EnergyOS showed an average 105% increase in savings and an 88% reduction in the volatility of financial outcomes compared with conventional renewable procurement. These are modelled outcomes rather than savings already achieved by customers.

Ginsberg said the comparison included buying solar, wind, batteries or hybrid solutions separately, as well as using a traditional aggregator. The savings were assessed over a 20-year period.

Discovery Green has 740MW of renewable generation that has reached financial close. CEO André Nepgen said the company now serves more than 50 businesses and that projects under construction had spurred more than R15bn in investment.

Ginsberg said Discovery Green still expected to start wheeling electricity in the fourth quarter of this year. Discovery’s website also continues to give the fourth quarter of 2026 as its target for the start of wheeling.

The full EnergyOS offering, however, needs several generating plants and customers in the portfolio at the same time.

The company expects to start using the fuller portfolio approach next year as more plants come online.

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