The opening of the Kathu concentrating solar power (CSP) plant on 4 April adds a further 100 MW to the operating CSP capacity in South Africa. Part of Window 3 of the renewable energy independent power producers procurement programme, Kathu Solar Park (KSP) was synchronised to the grid in November 2018 and started delivering power to the grid in January 2019. KSP is the 6th CSP plant in South Africa, the 5th parabolic CSP trough (with Bokpoort, Kaxu, Xina and Ilanga) and 4th CSP trough plant of 100 MW (with Kaxu, Xina and Ilanga). 

The Kathu solar park project was awarded under round 3.5 of the REIPPP on 15 December 2014 and comprises a mix of stakeholders aimed at meeting stringent commercial and social objectives. The multinational group includes South African investors SIOC Community Development Trust, Investec Bank, Lereko Metier Sustainable Capital Fund, and its co-investors FMO, the Dutch development bank and DEG, the German investment and development company, and the Public Investment Corporation.

The plant was constructed by the EPC consortium of Sener and Acciona and created 1700 jobs during construction, with 42% of the workforce being hired from the local community. The project achieved a 45% local content acquisition mark which represents a considerable skills transfer to the area. 

Isabelle Kocher, CEO of global energy company Energie, the lead developer and major shareholder in Kathu Solar Park, says the company is pleased to contribute a sustainable source of clean energy to the grid, in good time. “As this was the company’s first CSP project that required very complex implementation, we are delighted that we are now able to start to demonstrate the application of concentrated solar power to mitigate intermittence issues of PV and to continue to prove the benefits of the REIPPP plan to South Africa’s grid. The KSP project clearly demonstrates the group’s ambition to lead the way in the competitive energy transition,” says Kocher. 

The plant is equipped with a 45 000 t molten salt storage system which allows 4,5 hours of thermal energy storage and thus limits the intermittent nature of solar energy. The first requirement for storage is that there must be surplus energy to store, and this is achieved by oversizing the collector field. The degree of oversize is termed as solar multiple, and in a plant without storage it is typically about 1,4. A plant with storage needs an multiple of >2. Typical values are 2,4 to 3. 

Oversizing has another advantage: The direct normal irradiance (DNI) is obviously not constant throughout the day but reaches its maximum around noon. The turbine, however, is aimed to run at constant maximum capacity. For this to be possible the solar field needs to deliver the equivalent capacity long before noon and must therefore be oversized by a certain factor. As a result, the solar field provides extra capacity early in the cycle and late in the afternoon. In a CSP plant without storage, the surplus energy at the solar peak is dumped. Oversizing the plant gives the advantage that the plant can start operating at full output very early in the solar cycle and can continue operating at full output on solar energy until late in the solar cycle. 

The parabolic trough technology is a patented optimised collector technology by Sener. The collectors are designed to optimise the power storage capacity and keep costs to a minimum. The plant uses 384 000 large parabolic mirrors. The mirrors are 6868 m in aperture and the collector tube has a diameter of 80 mm giving a concentration factor of approximately 80 (80 suns). Collector tubes are mounted inside vacuum glass surrounds, to limit heat loss by convection. The collector uses oil as a thermal transfer fluid, operating at temperatures of 297°C (entry) and 393°C (exit). 

Operation and maintenance (O&M) is performed by Kathu operations. Shareholders in Kathu operations are Energie (80%) and TKM (20%). O&M personnel were contracted in more than a year before the start of commercial operations and went through extensive training on site. O&M will provide 81 jobs during operation for the next 20 years. In this regard, KSPark has taken a voluntary initiative to train and upskill 90 local people for potential positions in the operations and maintenance phase of the project. Of these, 38 have been employed after the training. 

Tariffs for CSP at the moment are considered high, in comparison to other renewable energy systems, but the system has the ability to produce power outside of sunlight hours, which others do not. Costs are also reported to be coming down rapidly, with prices of the order of $0,05 to $0,10/kWh for projects coming online from 2020 predicted by IRENA. 

In South Africa, Energie has interests in a wind farm (94 MW Aurora), two solar PV parks (21 MW) and two thermal power peaking plants (670 MW Avon and 335 MW Dedisa). The cpompany has invested extensively in local social investment projects, the most visible being involvement in the local TVET, where a cooking school has been established, new classrooms added as well as high speed fibre optic communications network.

China International CSP Conference（CPC2019） is to be held  on 10-12,July,in Suzhou, China. During the conference, Global CSP professionals will conduct in-depth exchanges to discuss the topics of concentrated solar power.

For more details of the conference, please contact: Catherine@cspplaza.com