A new solar tower in the Northern Cape will be the second tallest building in SA

Business Insider SA
A render of the Redstone solar thermal power project. (supplied)
  • The new Redstone Solar Thermal Power Tower in Northern Cape will be 27 meters higher than the Carlton Centre, making it the second highest concrete building in South Africa. 
  • It will provide enough electricity to power 200,000 households. 
  • It joins 26 others renewable energy projects in South Africa which will add 2,300MW of electricity to the national grid. 

At 250 metres, the Redstone solar thermal power tower in Postmasburg, Northern Cape, is set to become the second highest concrete building in South Africa.

It will be 27 meters higher than the Carlton Centre in Johannesburg, which is currently the place second place, but still short of the 269 metre tall Hillbrow Tower. 

The project will join 26 similar renewable energy projects across South Africa which will add 2,300 MW of electricity to the national grid over the next five years. 

The Independent Power Producer (IPP) agreements between the South African government and the electricity providers were signed on Wednesday afternoon. 

The tower will feed the South African power grid with electricity 17 hours a day in order to meet peak energy demands, construction consortium head SolarReserve says.  

"The project’s electricity price is set to be the lowest of any solar thermal project awarded in the country to date," SolarReserve's Esta Lissimore told Business Insider South Africa. 

It will be able to reliably supply a stable supply of clean electricity to the equivalent of more than 200,000 South African homes each year. 

How it will work

1. Sunlight is concentrated by a large field of mirrors that track the sun, and directed to a receiver on the  tower.

2. Liquid salt from a "cold" salt tank ('only' 288 °C) is pumped up the tower and through the receiver, where it is heated to 566 °C.

3. The heated salt travels back down the tower and is stored in a "hot" salt tank.

4. The hot salt is pumped through a steam generator, which drives a steam turbine, generating electricity.

The Redstone tower will be built next to existing photovoltaic (PV) solar power projects.

The Redstone tower will join the 75 MW Lesedi and 96 MW Jasper photovoltaic (PV) solar power projects already constructed by SolarReserve in the area. 

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