The Redstone Solar Plant is in the Humansrus Solar Park between Tsanstabane and Kgatelopele in the Northern Cape, with construction underway. On completion, which is expected around 2023, 100 megawatts (MW) of power will be added to the national grid. The plant will be operational by early 2024.

The South Africa Department of Energy (DOE) awarded the project to ACWA Power and SolarReserve in 2015 under South Africa’s Renewable Independent Power Producer Programme (REIPPP) Bid Window 3.5.

Other prominent investors in the project include Public Investment Commission (13.5%), Old Mutual Life Assurance South Africa (10%), Community (12.5%), and Pele Green (4%).

WorleyParsons conducted the environmental management program (EMPr) for the Redstone Solar Thermal power plant, and Savannah Environmental was engaged to review the EMPr. First National Operation and Maintenance (NOMAC) will be responsible for the operation and maintenance of the project.

The park is close to the 96-megawatt Jasper and the 75-megawatt Lesedi photovoltaic (PV) solar power projects. The three projects have become the world’s first combined Concentrated Solar Power and PV solar park, with a total generation capacity of 271 megawatts.

Key components of the plant include:

  • a solar field;
  • molten salt receiver;
  • thermal energy storage; and
  • connection to the grid.

The solar field comprises a set of heliostats that absorb the sun’s energy and concentrate it towards the molten salt receiver atop a 250 metres tall tower. This is then converted into thermal energy.

The thermal-to-electric power conversion unit will consist of 115-megawatt high-temperature subcritical steam turbine generator units.

Auxiliary infrastructure includes two molten salt storage tanks, air-cooled condensers, a water purification system, and a sewage treatment facility. Other components are an evaporation pond, emergency diesel generators, an electrical switchyard, step-up transformers, and associated facilities.

The solar power plant will also have dry cooling of the power generation cycle to minimize water usage during operation.

Eskom entered a 20-year power purchase agreement with the construction consortium for the off-take of power generated at the Redstone Solar Thermal Power plant. The project will be connected to the national grid by a new 132 kV switching station and a 34-km long 132-kV transmission line.

The project will eliminate 480 kilotons of carbon dioxide emissions yearly and use less than 200,000 cubic metres of water per annum. US$162.45 is the total investment for the project. It is expected to have an operational life of over 30 years.

With 12 hours of full-load energy storage, it will ensure a stable electricity supply to at least 200,000 households.

Redstone has facilitated US$98 million in foreign direct investment for the funding and support of the strategic energy transition goals of the country. ACWA Power’s co-shareholders in the project include the Central Energy Fund, Pele Green Energy, and the local community. Brightsource Energy has been selected as the project’s provider of advanced precision drives.

The project will close the energy supply gap, reduce coal dependence, limit carbon emissions, create jobs, and promote a national solar industry. It will provide South Africa with clean energy and reduce peak-hour production costs.

Chriselle Moraes,