South Africa Turns Coal Waste Into Clean Energy Storage

An aging coal power station in South Africa is getting a second life as a cutting-edge energy storage facility that recycles the very waste it once created.

Energy Vault just signed a deal with Eskom, South Africa's state-owned utility, to build a 25 MW gravity energy storage system at the Hendrina Power Station in Mpumalanga. The facility will store 100 MWh of clean energy using massive blocks made from recycled coal ash.

Here's how it works: the system lifts heavy blocks (weighing up to 30 tons each) when electricity is plentiful and cheap, then generates power by lowering them when demand is high. It's essentially a massive battery that uses physics instead of chemicals.

The Hendrina site is one of Eskom's oldest coal stations, making it a perfect symbol of energy transformation. Instead of tearing down old infrastructure, this project breathes new purpose into existing facilities while cleaning up coal waste that would otherwise sit in landfills.

The agreement extends far beyond South Africa. Eskom and Energy Vault plan to develop up to 4 GWh of storage across 16 Southern African nations, including Zimbabwe, Mozambique, Angola, Botswana, Tanzania, and Zambia. That's enough storage to power hundreds of thousands of homes during peak hours.

Long-duration energy storage solves one of renewable energy's biggest challenges: what happens when the sun isn't shining or the wind isn't blowing? Gravity batteries can store energy for hours or days, making solar and wind power more reliable.

The technology includes smart software that coordinates when to store and release energy based on grid needs. Energy Vault's CEO Robert Piconi calls it "advancing long-duration storage at unprecedented scale" while "pioneering a new model for sustainable industrial development."

The Ripple Effect

This project represents a triple win for Africa. It provides clean energy storage that countries desperately need as they expand renewable power. It transforms environmental liabilities (coal ash waste) into valuable resources. And it creates a blueprint for repurposing aging coal infrastructure across the continent instead of abandoning it.

For a region where many communities still lack reliable electricity, long-duration storage could be transformative. It makes renewable energy projects more viable and helps stabilize power grids that have struggled with blackouts.

The technology also travels well. What works at Hendrina could work at decommissioned coal plants worldwide, turning yesterday's pollution into tomorrow's clean energy solution.

South Africa is proving that the path to clean energy doesn't require leaving old infrastructure behind.