Wind atlas available for South Africa

The South African National Energy Development Institute (Sanedi) has completed the third phase of its Wind Atlas South Africa project (WASA 3). This is the mapping of wind (as a resource) in the country that can be used for feasibility studies in support of wind energy projects.

Although it is possible to build a wind farm anywhere in the country – wherever land is available – there are some areas better suited to the production of electricity from wind than others. But how does one know where the best wind resources are found? This is where WASA comes into play.

WASA is financially supported by the United Nations Development Programme and Global Environment Facility, through the South African Wind Energy Project (Sawep). The government of Denmark co-funded WASA 1 and WASA 2. • WASA 1 (2009-2014) covers the Western

Cape and areas of the Northern Cape and

Eastern Cape. • WASA 2 (2014-2018) covers KwaZulu-Natal, the Free State and remaining areas of the

Eastern Cape. • WASA 3 (2017 to 2021) covers the remaining areas of the Northern Cape and the rest of South Africa. Ms Lethabo Manamela, interim CEO, Sanedi, explained that the wind atlas provides a graphical representation of the wind resources available in various areas of the country. This information is primarily used by investors wishing to build wind farms in South Africa. “In order to place wind turbines in areas where they will benefit from the available wind resource, one needs to know where the best wind resources are. Nineteen masts (covering 75% of South Africa’s land area) were erected over a period of 10 years to collect data about wind resources,” says Andre Otto from Sawep.

Over and above the data collected from the 19 masts, further data has been supplied by the South African Weather Service (SAWS). SAWS has 111 weather stations, which hold 50 years’ worth of wind data. This data has been compacted to a range of wind speeds between 36 m/s and 44 m/s. Where wind speeds were below 36 m/s, they were increased to 36 m/s; and where they exceeded 40 m/s, they were capped at 44 m/s. “Wind power is proportional to the cube of the wind speed. Therefore, the energy that can be extracted from the wind is highly affected by the speed of the wind. Computerderived digital (or numerical) modelling is used to convert global wind data through a process of meso- and microscale modelling, with each step increasing the resolution and incorporating the land topography to estimate the local wind resource,” Otto adds.

WASA 3 used new and improved software, which increased the speed of processing while reducing computer power requirements. Work on a prospective fourth phase – WASA 4 – is expected to begin soon.

The wind atlas provides a graphical representation of the wind resources available in various areas of the country