Eskom, Energy Vault Sign Deal on Gravity-Based Energy Storage Projects

South African power utility Eskom has entered into a strategic partnership with United States-based Energy Vault Holdings to develop gravity-based long-duration energy storage projects in South Africa and across the wider Southern African region.

The agreement will see the first Gravity Energy Storage System project deployed at Eskom’s Hendrina Power Station, one of the country’s oldest coal-fired plants.

According to a joint statement released on Tuesday, the initial phase of the project will deliver 25 megawatts of power capacity with four hours of storage, equivalent to 100 megawatt-hours, using Energy Vault’s EVx 2.0 gravity storage technology.

The companies said the system is designed to be scalable, with the potential to expand capacity to as much as 4 gigawatts over time.

Under the partnership, Energy Vault will provide the technology, engineering expertise, equipment, project management services and technical training required for implementation.

The agreement also includes plans to jointly develop and license up to 4 gigawatt-hours of gravity-based energy storage projects across the 16-member Southern African Development Community region by 2035.

Energy Vault explained that its EVx 2.0 platform incorporates improvements in software coordination, automated construction systems and mechanical operations compared with earlier versions of the technology.

The company further disclosed that the storage system would utilise coal ash in the production of the composite blocks used in the gravity storage process, creating an additional pathway for the reuse of waste generated by coal-fired power stations.

The partnership forms part of Eskom’s broader Just Energy Transition strategy, which seeks to gradually reduce the utility’s dependence on coal while maintaining electricity reliability, supporting employment and encouraging local economic development.

South Africa remains heavily dependent on coal for electricity generation, with coal accounting for more than 80 per cent of the country’s power supply in 2024.

Governments and utilities across Southern Africa have increasingly accelerated investments in renewable energy and storage infrastructure as part of wider efforts to improve energy security, diversify electricity generation and expand access to power.

Industry analysts averred that long-duration energy storage systems are becoming increasingly important for grid stability as countries integrate larger volumes of intermittent renewable energy such as solar and wind into electricity networks.