Eskom seeks partner for proposed 1.5GW Tubatse storage scheme

Eskom has launched a strategic-partner selection process for the proposed 1.5GW Tubatse pumped-storage scheme in Limpopo, Business Day reported on October 13. The project near Roossenekal is intended to become South Africa’s largest energy-storage programme and a flagship development of Eskom Green.

The utility’s primary statement clarifies the business’s current status: Eskom Green is still being incorporated. Eskom Holdings will administer procurement meanwhile and own 100% of the business after incorporation. The project has therefore entered partner selection before that corporate separation is complete.

The qualification stage seeks organisations with financial strength, technical expertise, development experience and a long-term commitment. Successful respondents will proceed to a later proposal stage, where detailed partnership, ownership and commercial terms will be set out.

An optional online clarification meeting is scheduled for October 29, from 11:00 to 13:00 SAST. Electronic responses close on November 30 at 10:00 SAST, according to Eskom.

Tubatse is proposed to provide about 21GWh of storage through four reversible pump-turbine units, generating at full output for up to 14 hours. Its 1.5GW rating measures power—the rate of electricity delivery—while GWh measures accumulated energy. Dividing the stated energy by the rated power gives the stated duration.

Pumped storage consumes electricity to raise water to a higher reservoir and later generates electricity as water flows back through turbines. Eskom says Tubatse would store surplus electricity when demand is low and release it at peaks, when wind and solar output decline, or when the network is under strain.

Chief executive Dan Marokane said long-duration storage would help integrate renewable electricity and improve grid stability and security of supply. Eskom also envisages rapid responses to grid-frequency changes, reserve capacity and voltage support. The proposed duration would complement shorter-duration battery systems.

Renewables executive Rivoningo Mnisi said combining private expertise and investment with Eskom’s development experience could support local economic activity, skills and localisation.

Electricity and Energy Minister Kgosientsho Ramokgopa has prioritised procurement of 4,600MW of battery storage and 5,000MW of gas-to-power, totalling 9,600MW. The programme responds to a need for storage, flexible generation and dispatchable supply—electricity available when called upon.

Curtailment occurs when available generation cannot be accommodated because of network constraints or operating conditions, including supply exceeding demand. Storage can shift some electricity into useful periods, while new transmission capacity is needed to move power between locations. Business Day reported plans for 14,000km of high-voltage lines over the next decade at an estimated R440 billion cost, connecting wind, solar, batteries and gas generation.

Eskom Green targets up to 6GW by 2030, 21GW by 2035 and up to 32GW by 2040, including 5GW of hydro and pumped storage. Tubatse is among twelve national priority projects identified by Infrastructure South Africa and forms part of the transition to cleaner energy.

Eskom operates 2,732MW of pumped-storage capacity across Drakensberg, Palmiet and Ingula, and 661MW of conventional hydropower, primarily at Gariep and Vanderkloof. It cites more than two decades of experience and describes its 1,332MW Ingula scheme as commissioned in 2017.

Eskom says the required land is secured and environmental authorisation granted. Technical studies, access-road designs and grid connection work have advanced; the Department of Water and Sanitation has confirmed water availability from De Hoop Dam.

The preferred sales route is a long-term power-purchase agreement or capacity contract with the National Transmission Company South Africa after a regulatory allocation, which Eskom is seeking. A partner must also prepare a viable investment case using private bilateral or competitive-market contracts if the whole project, or part of it, receives no allocation.

Eskom envisages a separate project company and conditional financing options, including debt supported primarily by project assets and cash flows, potentially supplemented by development-institution or favourable funding. Those arrangements and commercial terms remain to be developed.