Name of the Project
Redstone concentrated solar power (CSP) plant.

Location
Northern Cape, South Africa.

Project Owner/s
The project will be owned by Acwa Power SolarReserve Redstone Solar Thermal Power Plant comprising Acwa Power Redstone Holdings (50%) and SolarReserve (10%); GEPF Renewable Energy Investment 1 (13.5%), a vehicle incorporated by the Government Employees Pension Fund and managed by the Public Investment Corporation; the Redstone Community Trust (6.5%), a broad-based black economic-empowerment entity; Old Mutual Life Assurance Company of South Africa 10%; and Pele Green (10%).

Project Description
The Redstone CSP was procured under round 3.5 of the Renewable Energy Independent Power Producer Procurement Programme (signed in April 2018).

According to the International Finance Corporation, the project entails the construction and operation of a concentrated solar thermal power plant with associated infrastructure and services to generate renewable electricity for the national power grid, in Postmasburg, near Kimberley, in the Northern Cape.

The power plant will be built adjacent to the 75 MW Lesedi and 96 MW Jasper photovoltaic (PV) solar power projects. These three projects comprise the world’s first combined concentrated solar thermal power and PV solar park, with a total generating capacity of 271 MW.

The project, which will have a footprint of about 8 km2, will produce an estimated 480 GWh/y net of renewable energy, with a nominal net generating capacity of about 100 MW.

The project will comprise a circular heliostat field with a mirror-reflective surface that reflects the sunlight to a 200-m- to 220-m-high central receiver tower, rated at an estimated 565 MW thermal (MWt), where the heat transfer fluid and molten salts are heated.

Each heliostat will be between 12 m and 15 m high. A thermal energy collection and storage system, with a molten salt loop, and hot and cold salt storage tanks, will harness the heat used in the steam generation system that drives the steam turbine generator. The electricity will be connected to State-owned power utility Eskom’s overhead distribution power lines using pylons about 32 m high.

The power plant will be dry cooled, with 12 hours of energy storage.

The project infrastructure includes a collector field consisting of:
• about 6 500 to 500 000 dual-axis tracking heliostats, providing a reflective surface area of about 1.08-million cubic metres;
• a thermal to electric power block, with a 115 MW reheat and multiple extractions high-temperature subcritical steam turbine and generator;
• two molten-salt thermal storage tanks;
• an air-cooled condenser for the steam cycle to minimise the consumption of water;
• water reticulation and purification works, including water reticulation from the Sedibeng bulk water supply pipeline for industrial water use, and a water treatment and purification system to provide water for domestic and process use;
• sewage reticulation and treatment works;
• an evaporation pond/s comprising three compartments, with a combined area of about 26 ha, to completely contain all rejected water from the water treatment system and the steam cycle;
• roads and stormwater infrastructure;
• two liquid diesel auxiliary burners for startup;
• two emergency diesel generators;
• a substation and switchyard of about 100 m × 100 m, containing transformers and associated structures;
• two power lines to connect the proposed plant to the national grid – a 16 km, 132 kV overhead line from the plant to the Karats substation, and a 34 km, 132 kV overhead line from the plant to the Olien substation;
• a construction camp, accommodation and associated facilities for about 800 people;
• administrative and office buildings;
• a visitors centre;
• an equipment and materials lay-down area;
• an assembly plant;
• a concrete batching plant;
• vehicle workshops and wash bays;
• a fuel storage area;
• a temporary, general-waste storage facility; and
• a hazardous-material storage facility.

State-owned power utility Eskom is the offtaker for 100% of the energy generated by the project, as per the power purchase agreement (PPA) signed between Eskom and the Acwa Power SolarReserve Redstone Solar Thermal Power Plant in 2018.

Potential Job Creation
The project is expected to create 2 000 jobs during construction and 73 during operations.

Capital Expenditure
The total project cost is estimated at R12-billion.

Planned Start/End Date
Not stated.

Latest Developments
The project requires approval from Eskom for an extension of the PPA term to start with construction. According to the project developer, there have been numerous fruitful discussions with Eskom on the matter since their formal application to Eskom for the extension in August 2019, but have not yet received approval for the extension.

Key Contracts and Suppliers
None stated.

Contact Details for Project Information
Acwa Power South Africa, tel +27 11 722 4100 or fax +27 11 722 4113.
SolarReserve, tel +27 11 582 6880 or fax +27 11 784 7549.