South Africa’s Eskom, Swiss Firm launch next-generation battery project

South Africa is stepping up efforts to overhaul its power sector as state-owned utility Eskom joins forces with Swiss energy storage company Energy Vault to develop a large-scale gravity battery project aimed at cutting the country’s dependence on coal. 

The project will be built at Eskom’s Hendrina Power Station in Mpumalanga, a coal-fired plant that has supplied electricity to South Africa for decades.

The initiative forms part of a wider plan to strengthen the national grid and support the country’s gradual shift toward cleaner energy sources. 

South Africa has spent years battling electricity shortages, aging infrastructure and rolling blackouts that have weighed on businesses and households.

While renewable energy projects have expanded rapidly, the country still faces a major challenge storing electricity generated from solar and wind farms. 

Eskom and Energy Vault say the agreement could help address that problem by introducing long-duration energy storage technology designed to hold excess power and release it during periods of peak demand.

The companies also plan to explore similar projects across Southern Africa over the next decade.

New storage system for aging grid 

The first phase of the project is expected to deliver 25 megawatts of electricity with four hours of storage capacity, equal to 100 megawatt-hours.

The system could eventually be expanded to 4 gigawatts, making it one of the largest energy storage projects planned on the continent. 

Unlike lithium-ion batteries, the gravity-based system works by lifting heavy blocks using excess electricity produced during low-demand periods.

When demand rises, the blocks are lowered through a winch system that drives turbines and generates electricity.

Push to support renewable energy 

Energy Vault will provide its EVx 2.0 technology platform, along with engineering support, project management and training for local workers.

The company said the updated system improves efficiency, automation and operating performance compared with earlier versions. 

Chief Executive Officer Robert Piconi said the agreement marks an important step for energy storage development in Africa and could help create local supply chains and jobs while supporting cleaner electricity generation. 

Coal still dominates South Africa’s power mix 

Eskom Group CEO Dan Marokane said the project supports the utility’s broader plan to repurpose older coal-fired power stations while improving energy security and lowering electricity costs over time. 

Coal remained the source of more than 80 percent of South Africa’s electricity generation in 2024, highlighting the scale of the country’s transition challenge as it works to balance economic growth, energy reliability and lower emissions.