Riyadh’s Acwa Power together with the US company SolarReserve is developing the Redstone project, a molten salt central receiver in the Northern Cape province of South Africa. This is the first in the continent of a new generation of solar plants that are garnering interest around the world.
The technology uses a tower containing salt that is then heated by mirrors reflecting sunlight in a process known as concentrated solar power (CSP). As the salt heats, it is used to boil water which then turns a steam turbine, thereby generating electricity.
The novelty of using salt as storage is that it stays hot long after the sun is down, up to 12 hours in the Redstone case. Unlike photovoltaic solar, passing clouds have little effect on it. Redstone incorporates 1.2 gigawatt hours of energy storage, which enables it to produce during peak periods.
Owing to its ability to generate electricity when the sun is down or the array is under cloud cover, Masdar Institute scientists in Abu Dhabi are also looking at developing energy storage for the solar industry, The National has reported.
The Redstone project was slated for completion by 2018, and the South African government has already approved it. One of the last steps before construction was the signing of a purchase agreement with the state energy corporation Eskom.
Media reports say Eskom had twice declined to sign the agreement during a meeting with Acwa representatives in late August, a claim which the utility refutes. “Contrary to some media reports, Eskom has not decided to put on hold any renewable energy contracts,” Eskom spokesman Khulu Phasiwe told The National.
“In fact we have signed power purchase agreements with all successful bidders and we’re committed to signing all the remaining contracts under the current bid window 4.5 of the department of energy