Gordon Rae and Dr Gareth Erfort from the Department of Mechanical and Mechatronic Engineering used geographic information system methods to survey the potential of South Africa’s offshore wind energy. Their report, published recently in the Journal of Energy in Southern Africa, is the first comprehensive assessment of South Africa’s offshore wind energy resources.
Their research found the six most suitable regions for the development of offshore wind farms in South Africa: Richards Bay (within the 10 km coastline buffer and approximately 15 km offshore south of Richard Bay), Durban (within the 10 km buffer and approximately 25 km offshore of KwaDukuza) and Struisbaai (within the 10 km buffer zone and approximately 15 km offshore) in the Western Cape.
“If we were to install wind turbines at different depths off the KwaZulu-Natal and Western Cape coast, they could potentially supply approximately 15% and 800% of South Africa’s annual electricity demand,” the researchers found.
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If wind turbines were to be installed in these regions’ deep waters (depths less than 1,000m), they could theoretically deliver 2,387.08 terawatt hours (TWh) in electricity every year. Turbines in the shallow waters (depths of less than 50m, closer to the coast) could deliver 44.52 terawatt hours.
South Africa’s annual electricity consumption is slightly less than 300 TWh. This means that – theoretically – deep-water turbines could satisfy the country’s annual electricity demand eight times over.
Wind farms in only the shallow areas, close to coastlines, have the potential to supply 15% of South Africa’s national electricity demand – or power to four million households.
According to the American Geosciences Institute, offshore winds tend to be faster than on land, which means that offshore-wind farms may be able to generate more energy than land-based wind farms. According to the institute, a turbine in 24km/h wind can generate twice as much energy as a turbine in 19km/h wind. Offshore wind is also usually more stable than land wind, which means a more reliable source of energy.
But Rae and Erfort say that South Africa is still lagging behind in the development of offshore wind energy at a time when there is big growth in Europe and Asia.
“Although the Renewable Energy Independent Power Producer Procurement Programme was launched in 2011 to procure renewal energy projects, it is yet to exploit or consider the abundance of offshore wind energy resources available.” By tapping into these resources, South Africa could also decrease its carbon emissions significantly, they believe.
Their report, which quantifies these resources, could help to develop the local market for offshore wind energy.
Last year, the Swedish floating windfarm developer Hexicon became one of the first companies to express interest in offshore wind in SA. It launched a new join venture with a local company to explore the possibility of generating electricity from offshore wind in South Africa.
Hexicon is currently working with Shell to build what could eventually be the world’s first large scale floating wind farm in South Korea.
