Eskom Holdings has initiated a two-stage process to identify and select a possible strategic partner to implement the 1.5 GW Tubatse Pumped Storage Scheme in Limpopo alongside Eskom Green, which is in the process of being incorporated as a new Eskom subsidiary.

The State-owned entity has issued a request for qualification (RFQ) document through which it aims to qualify experienced and financially capable organisations that will be invited to participate in a subsequent request for proposal (RFP) stage.

Should the project proceed, it would be the biggest pumped-storage scheme yet undertaken in South Africa and could add some 21 GWh of energy storage through four reversible pump-turbine units.

Following significant delays and budget overruns, Eskom commissioned the 1.33 GW Ingula scheme in the Drakensberg in 2017, increasing the capacity of its pumped-storage fleet to over 2.7 GW across Ingula, Drakensberg and Palmiet.

Located near Roossenekal in Limpopo province, the proposed Tubatse project has been a feature of Eskom’s project pipeline for decades and has been classified by Infrastructure South Africa as one of the country’s top 12 Strategic Integrated Projects.

Eskom says the required land is secured, that an environmental authorisation has been granted, and that the Department of Water and Sanitation has confirmed water availability from the De Hoop dam.

Grid connection and technical studies have also advanced, alongside access-road designs.

Any partner selected after the RFP stage, meanwhile, will be expected to develop and structure a bankable investment case for Tubatse, which could be housed in a ring-fenced special purpose vehicle.

Eskom is, therefore, aiming to select a partner with the ability to finance and deliver a bankable project, with the detailed partnership, ownership and commercial terms to be set out in the RFP issued to qualifying respondents.

“By combining Eskom’s development experience with private-sector expertise and investment, we aim to unlock the full potential of this project while supporting economic growth, localisation and skills development,” group executive for renewables Rivoningo Mnisi says.

Eskom indicates that several offtake avenues are possible and will be explored.

However, it indicates that its preferred route is to have a pumped-storage allocation under the Integrated Resource Plan of 2025, followed by a Ministerial determination under Section 34 of the Electricity Regulation Act, which would support a long-term power purchase or capacity agreement with the National Transmission Company South Africa as the buyer.

Alternatively, the offtake model might be based on bilateral offtake and wheeling arrangements with private buyers. 

Tubatse’s development is described as supportive of a higher penetration of variable renewable energy into the South African electricity system, as it will be able to generate at full output for up to 14 hours and complement shorter generation storage options such as battery energy storage systems (BESS).

“As South Africa advances its energy transition, long-duration storage will be essential to maintaining a reliable and resilient power system,” Eskom Holdings CEO Dan Marokane said in a statement confirming the RFQ.

“Tubatse will provide the flexibility needed to integrate increasing volumes of renewable energy while strengthening grid stability and security of supply.”

The deadline for responses to the RFQ has been set for 10:00 on November 30, and a virtual, non-compulsory clarification meeting will be held at 11:00 on October 29.

The Tubatse RFQ follows on from an initiative by Eskom Holdings to identify and qualify experienced partners for up to 6 GW of utility-scale renewable-energy and BESS projects, also to be implemented by Eskom Green, once it is fully incorporated.

Through that separate RFQ process, Eskom aims to identify entities for the establishment of a panel of pre-qualified co-development and co-investment partners for what Eskom terms the ‘Phase 1 Programme’, with Eskom Green having set a goal of implementing up to 32 GW of new renewables generation capacity by 2040.