State-owned power utility Eskom is “reasonably confident” that it will commission its 100 MW concentrated solar power (CSP) demonstration plant in the Northern Cape, by 2016, technology and planning manager Barry MacColl said on Monday.

Speaking at the Solar South Africa conference, in Johannesburg, he said that the parastatal wanted to push the technology boundary through the completion of what would be the largest CSP plant in the world.

The design of the plant would have to be finalised by 2013, MacColl said. “We hope to commission the plant by 2016, which gives us two-and-a-half years of build time. By mid-2013, we have to finalise the design for the plant, with molten salt central receiver our preferred option,” he told Engineering News Online.

In line with the environmental-impact assessment (EIA), Eskom hoped to build a 100-MW central receiver demonstration plant with molten salt as a heat transfer fluid. It would appoint an owner's engineer as the first step in the commercial process, to support it in the development and execution of the project.

But, the engineering design, finding a suitable firm to work with Eskom as an owners engineer and preparing the package to go out as an engineering, procurement and construction (EPC) contract to the market, remained a challenge, MacColl said.

The utility was currently assessing a large number of applications, after a request for expressions of interest for the provision of EPC services was put out in April.

It would appoint an EPC contractor and a planning and design contractor by 2012.

Should Eskom not start construction by 2015, and should it change the proposed design from the envisaged central receiver plant, it would have to revise its approved EIA.

Possible plant specifications included capacity factors suitable for base-load operation, and two tank storage systems, with molten salt, designed to operate the power plant as a base-load plant. The plant would have a dry-cooled or hybrid-cooled design to ensure efficient use of water. Further, all auxiliary power would be sourced from the national grid and backup would be sourced from diesel generators, with the life-of-plant being a minimum of 25 years. A water supply contract has also been secured with the Upington municipality.

The land on which the CSP plant would be built was adjacent to the 5 000 MW solar park, in Upington, for which the South African government has committed R18.6-million to complete a feasibility study.

“This is exciting in that we are now collaborating with government to do a conceptual layout that would add value to both solar parks as opposed to treating them as separate entities.

“Eskom is working quite closely with government and their consultants on a design for the park that will share a common ground, servitude and services – this will make  more sense for the country than working as separate entities,” MacColl told Engineering News Online.

Advantages of the land selected for the demonstration site included it being a good solar resource, with a plant capacity factor of 70% and high solar insolation of 8 kWh/m² a day, and that it had the potential capacity of at least 600 MW, made up of the 100 MW from the CSP demonstration plant and the 500 MW from a commercial plant.

It was also in close proximity to existing transmission lines, national and main roads.

Meanwhile, Eskom is also changing its position on photovoltaic (PV), driven purely by the need to better understand PV, he said. “Eskom is taking progressive, small steps with regard to this technology, which we believe is an emerging and mature technology.”

Two tenders to generate 1 MW of power from PV for the Kendal power station, in Mpumalanga, and the Lethabo power station, in the Free State, were out. The 1 MW would be used internally, for example, to power pumps and compressors.

Eskom is also installing PV at a parking facility at its Megwatt Park offices, in Sandton.

However, he said in line with moving towards cleaner technologies, CSP was the “technology of choice”. But, MacColl said the utility would also look to PV and a combination of other technologies in future.

“Eskom strategic drivers require a large scale diversification into lower carbon technologies, and this diversification will be based on South Africa’s solar resources and the advantages of central receiver with storage, making the choice of the CSP demonstraion plant project an attractive option, ” he concluded.