CSP technology is inherently environmentally friendly and has the potential to attract funding from carbon reduction mechanisms.
Test data being generated by a pilot linear Fresnel concentrated solar power (CSP) heated plant constructed by BBEnergy at Eskom’s research and innovation centre in Rosherville, Johannesburg, indicates that the system is performing above its design objectives.
Last year BBEnergy became the first South African company to design, develop and implement its own CSP heated plant and Manager Chris Nell describes the latest data as “positive and exciting”. BBEnergy is an independent business unit within the BBE Group, specialising in power and energy management in mine ventilation, refrigeration, compressed air and renewable energy systems.
BBEnergy is also a registered ESCo with Eskom(Energy Services Company). Based on the performance of two earlier prototypes at the company’s Bryanston premises, Eskom awarded the company a contract to construct the 150 kW thermal pilot plant at Rosherville. The plant was completed towards the end of 2012 and is now in the final stages of testing.
Investigations at the pilot plant have included practical operational issues, such as stowing during storms, maintenance effects, start-up and shut-down, remote monitoring and control. The thermodynamic test programme included a closed system test that demonstrated that in less than one hour the system exceeded 40 Bar and 250°C when relief valves blow off.
A daily cycle variable temperature test with a range of flow rates from 1 kg/s to 4 kg/s achieved a maximum of 162.3 kW, while fixed temperature duty tests indicated an 11.2% variation in heat duty, as the operating temperature varied from 230°C to 250°C. “This third-generation plant has exceeded our design expectations and, based on all the development to date, we’ve recognised its immense potential for power station augmentation and have now set our sights beyond the mining industry with new research on an independent site,” says Nell.
Eskom go-ahead for three mine plants Eskom has also approved separate BBEnergy proposals to construct three larger projects of 600 kW, 1200 kW and 2400 kW thermal, at Gold Fields and AngloGold Ashanti mines through its Integrated Demand Management (IDM) budget. Once operational, these systems will probably be the only concentrated solar power (CSP) heated plants of their kind in the world.
All three of the gold mine plants are for elution heating systems, with two mines using steam and one using thermal oil in the CSP collector to provide heat. “This is a local design, built by a local company, with more than 95% local content,” BBE CEO Steven Bluhm adds. “It’s poised to bring meaningful energy savings to the national grid and has potential for significant job creation.
“The Linear Fresnel process has been used extensively around the world to generate electricity, but this is the first time that it is being harnessed in South Africa to assist BBEnergy clients in the mining industry to save on energy costs in a predictable and meaningful way. CSP systems are able to produce energy more cost-effectively than existing electrical and fossil-fuelled boilers, thereby easing the burden on the already over-loaded national grid, particularly during the high-demand daytime periods.”
The design strikes a balance between cost, reliability and efficiency, resulting in a commercially-viable, modular, solar steam generator that provides industrial companies with a strategic source of energy. The system generates heat using mirrors and tracking systems to focus a large area of sunlight into a fluid-carrying, thermal, receiver-tube. Concentrated energy from the sun heats the fluid flowing through the tube and the resulting thermal energy can then be used for various industrial processes such as absorption refrigeration. CSP technology is also inherently environmentally friendly and has the potential to attract funding from carbon reduction mechanisms.