Wind energy is around half of all renewable energy currently produced in South Africa. As we lurch from one day of load shedding to the next, the sector is showing no sign of losing speed, rather the opposite.
Johan van den Berg, CEO of the South African Wind Energy Association, said in an interview that 2011 was the year government formally introduced it into the energy sector, with commercial wind farm construction beginning in 2013.
Today, wind power contributed around 740MW of electricity into the grid, “as a proportion of about 45GW of all power installed in South Africa”.
The average capacity factor for the entire fleet — as wind does not blow consistently — is currently over 70%.
“In terms of energy delivered, South Africa produces about 2,5% of what Denmark produces as a proportion of their ultimate electricity usage. So there’s a lot of space for us to still improve,” said Van Den Berg.
South Africa is a very large landmass, which is a very positive starting point. Mapped winds indicated that certain parts of the republic experienced very good winds by international standards.
“Almost everybody has agreed we can build a wind sector in excess of 20 000MW and then it depends. You can pick a number somewhat or way above that,” he says.
“Twenty thousand megawatts is a big windy industry and from there, anything above that, we will see where it goes. That equates to maybe 7 000 towers and turbines ultimately, considering that the towers are getting stronger and more powerful all the time.”
The mapped wind of interest to the industry showed a U shape from the south, starting 350km to 400km north and somewhat west of Cape Town, running down the South African coastline to almost the edge of the Transkei.
Winds were also found inland, somewhat surprisingly Van Den Berg said, in the central Karoo.
“It’s a surprisingly good wind area… Bloemfontein will not be your best place. Pretoria, I think, has the lowest wind speed in South Africa.”
The second phase of the South African Wind Energy Programme (Sawep), an initiative with the UN Development Programme which paid for the mapping, has recently been approved. The rest of the country would now be mapped, with Van Den Berg expecting some positive surprises.
An advantage of wind power was its relatively short up-time compared to fossil or nuclear power generation.
It could take three to four years to be ready to bid, with an environmental impact assessment taking a year and a half within that period. This has already taken place with many wind projects at the execution stage.
Wind measures are also done on site, with wind mast set-ups placed at the same height as the intended turbine for a period of one to two years.
“An international expert then comes and guarantees you a specific output if you use a specific machine with a specific blade, and you know exactly what you are going to get,” he said.
A giant is built
From bidding, the next phase moved to what is referred to as financial closure, where construction begins.
“That can maybe be eight to nine months and thereafter, if it’s a small wind farm, you build it in 12 to 14 months.”
Very large wind farms were being built in South Africa, “extremely large by international standards”.
“We are generally building 130, 140MW — 60 large turbines — and that normally takes about 18 months, which is still the blink of an eye compared to fossil fuel or nuclear power plants, that take 10 to 15 years.”
The turbines themselves were very big, though only around 5% of land at a site or farm is used by the end of construction, including infrastructure and roads. The rest remains available for use as it was before.
Each turbine is approximately four to six blade lengths apart, with the rectangular foundation being around 24sq m in size. Once covered, the base of the turbine itself is around 2mx2m.
“There’s an anecdote about a farmer who assured the developer that he had his workers ready to guard against theft when the blades came, not appreciating that the blade is 50m long, and the diameter 100m, sometimes 117m,” Van Den Berg said with a smile.
“The tower is normally about double the height of the blade, so the tower can be from 80m to 120m. It’s a large piece of infrastructure, with the nacelle weighing around 120t.”
A feature of the local wind energy industry is how wind power producers plough back a small percentage of their profits into surrounding local communities, speaking to the National Development Plan’s developmental state and public/private partnership.
“The relationship between ourselves and Government’s IPP (independent power producers’) office is an early successful example of that,” Van Den Berg said.
“That’s actually starting to work. A lot of people in other industries got this wrong, but I think we are mostly getting it right.”
The need in deep rural communities was very strong, with the prerogative being to try and develop those communities.
“I think the way in which the programme was structured, where you have to invest around 2% of your turnover into those communities, was a very far sighted move,” Van Den Berg said.
“I probably spend close to half my time on that aspect, to make sure everybody is coordinated and pulling in the right direction.”
Sawea and its partners were trying to see which examples were the good ones to follow, and even internationally, when Van den Berg went to conferences overseas, this is the aspect people were most excited about.
“If you are an engineer, you love mechanical stuff, then building a turbine is very interesting, but then the next one looks pretty much the same and so on,” he said.
“In South Africa we’re building the same things that other people are building in other countries, but we’re doing it in a very different way and in a very different context and that part is exciting.” — News24