CSP prototype plant exceeds expectations

17th May 2013

By: Zandile Mavuso

Creamer Media Senior Deputy Editor: Features

  

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The 150 kW concentrated solar power (CSP) heated prototype plant at State-owned power utility Eskom’s research and innovation centre, in Rosherville, Germiston, has exceeded design expectations, as it presents immense potential for power station augmentation.

This finding comes after power and energy management and renewable-energy company BBEnergy’s investigations at the Linear Frensel pilot plant, in Rosherville, which included practical operational issues, such as stowing during storms, maintenance effects, startup and shutdown, 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 blew 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 was highlighted at BBEnergy’s media open day on April 22, where Eskom research and development senior GM Barry MacColl said CSP technology was the beginning of a successful future in renewable energy in South Africa, owing to its predictability in dispatch and its potential to become cost competitive, compared with conventional generation options.

BBEnergy’s Linear Frensel pilot proved that CSP with thermal storage was a viable alternative energy source over other renewable-energy technologies, said MacColl.
Eskom is building a 450 MW CSP thermal plant near Upington, in the Northern Cape, and commissioning is expected to start in 2015.

BBEnergy became the first South African company to design, develop and implement its own CSP heated plant last year. Manager Chris Nell, who also spoke at the media briefing, described the latest data as positive and exciting, as a result of the progress made in its thermodynamic test programme results.

Based on the performance of two earlier prototypes at the company’s Bryanston premises, Eskom awarded the company a contract to construct the thermal pilot plant at Rosherville. The plant was completed towards the end of 2012 and is in the final stages of testing.

“The design strikes a balance between cost, reliability and efficiency, resulting in a commercially viable and modular solar steam generator that provides industrial companies with a strategic source of energy. “The system generates heat using mirrors and tracking systems focus a large area of sunlight onto a fluid-carrying, thermal and receiver tube. “Concentrated energy from the sun heats the fluid flowing through the tube and the resulting thermal energy can be used for various industrial processes such as absorption refrigeration,” explained Nell.

The Linear Fresnel CSP has been used extensively worldwide, particularly in Europe and North America, to generate electricity, but BBEnergy CEO Steven Bluhm told the media that this was the first time that the technology was being harnessed in South Africa to assist the company’s clients in mining and other indus-tries to save on energy costs in a “predictable and meaningful way”.

“CSP systems can produce energy more cost effectively than existing electrical and fossil-fuelled boilers to ease the burden on the already overloaded national grid, particularly during peak-demand periods in the day.

“This is a local design, built by a local company, using more than 95% local content. It is poised to manifest in meaningful energy savings for the national grid and has the potential for significant job creation,” he added.

Eskom also approved separate BBEnergy proposals to construct three larger projects of 600 kW, 1 200 kW and 2 400 kW at Gold Fields and AngloGold Ashanti mines, as part of its Integrated Demand Management initiative. BBEnergy stated that, once operational, these systems would probably be the only CSP heated plants of their kind in the world.

“Additionally, solar electricity generation has the highest power density among renew-able energies and, with thermal storage, can generate electricity in a predictable manner even when the sun is not shining,” explained MacColl.

The 89 000 TW of sunlight reaching the earth’s surface is plentiful – almost 6 000 times more than the 15 TW equivalent of average power consumed by humans, notes Eskom’s website.

CSP power plants can also meet a significant percentage of the future global electricity demand and are especially suited to South Africa, Namibia and Botswana, says the utility.

Edited by Creamer Media Reporter

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