Energy specialist BBEnergy has commissioned its 150 kW concentrated solar thermal demonstration plant at State-owned power utility Eskom’s research and development site, in Rosherville, and aims to deploy larger-scale solar thermal plants to provide process heat for the mining industry, says BBEnergy CEO Dr Steven Bluhm.
“We have had a test and development plant on site in Bryanston, Johannesburg, since 2010 and we have gone through several iterations over two years of testing to develop this solar thermal demonstration plant. From our tests, we have determined that we can increase the temperature and pressure in the plants, which we will install at mines to provide heat for mining and treatment processes.”
The demonstration linear Fresnel plant achieves a temperature of 250 ºC, operates at a pressure of 40 bar and generates about 1 400 kWh a day, but BBEnergy says future designs will enable its concentrated solar thermal plants to operate at significantly higher temperatures and pressures.
An 80 m × 80 m BBEnergy concentrated solar thermal plant, using its current design, will generate 3.6 MW of thermal power. Future plants will generate more thermal power from the same area.
Currently, mines use electricity to provide heat for several mine treatment processes, but they can substitute electrically generated thermal power with solar thermal power when conditions are favourable.
“We achieved a 95% localisation content with this demonstration plant, with only the gearboxes imported. “We have designed the system so that workers can easily assemble it and there is minimal working at height, owing to assembly methods that were considered during design. All maintenance work can be done using a simple scissor-lift.”
BBEnergy’s feasibility study found that its concentrated solar thermal plants have expected payback periods of less than four years.
“The applications that can use the heat from such a plant in industry and mining include gold mining elution systems, desalination plants and power station augmentation schemes, as well as process heating and absorption refrigeration, all of which are energy-intensive and costly to companies,” highlights Bluhm.
The plant uses global-positioning system data to determine its latitude and weather instruments to track the sun and measure its intensity, which, in turn, are used to align the mirrors to follow the sun and reflect this up to the pressurised water pipes in the receiver. The system automatically detects adverse weather conditions and determines when to protect itself from hail or high winds by turning the mirrors down to face the ground.