By INGI SALGADO Water was the biggest constraint to rolling out a concentrating solar power (CSP) programme, but should not stop South Africa�s efforts to develop the technology, Eskom manager Barry MacColl said on Tuesday.
�We can�t let water stop us from doing it,� MacColl told an International Solar Energy Society congress in Johannesburg, suggesting that technology options like dry-cooling and desalination needed to be pursued as solutions to the water challenge.
In the absence of dry cooling, water is needed for a CSP facility�s wet cooling towers. It is also needed for regular cleaning of the vast field of heliostats that reflect solar energy towards a central receiver.
Eskom plans to build a 100 megawatt (MW) CSP demonstration plant around Uppington in the Northern Cape, provided the power utility can secure funding for the project, estimated to cost between R6 billion and R7 billion.
Congress delegates heard Tuesday that four provinces in South Africa had CSP potential of 547.6 gigawatts (GW), equivalent to between 3.3 and 5.4 times the total electricity requirement forecast for South Africa in 2025.
Tom Fluri, from the University of Stellenbosch�s centre for renewable and sustainable energy studies, presented research showing that Northern Cape held the most potential at 510.3 GW, followed by Free State at 25.3 GW, Western Cape at 10.5 GW and Eastern Cape at 1.6 GW.
The Free State�s potential appears comparatively small, but nonetheless amounts to nearly two thirds of South Africa�s current generating capacity.
Fluri said there was �good potential� in the Free State, and pointed out that water availability in the Northern Cape could strain its huge CSP potential � apart from certain �really nice sites� with high radiation close to the Orange River.
�In the long-run, I think you need to go for dry-cooling,� Fluri said. �The water people say there is already a crisis.�
South Africa has already allocated 98 percent of water capacity.
Other delegates pointed out that coal-fired plants faced similar water constraints.
Fluri�s research restricted site suitability to those areas offering more than 7 kilowatt hours of solar radiation per square metre, those with a slope of less than 1 percent and those within a 20-kilometre radius of existing transmission lines.
He pointed out that previous studies assessing the potential for CSP in the US and Spain had set a lower threshold for optimal solar radiation, that certain types of CSP technology could work on a steeper gradient and that South Africa�s CSP potential could become �enormous� if transmission lines were built to high-radiation areas chosen for large plants.
MacColl said Eskom could build transmission lines to areas of high potential.
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