Winds of change: Windmills now come in all sorts of new forms and shapes to be more efficient.
Wind energy provides 432 000 megawatts (MW) of energy capacity worldwide. That’s 20% of all electricity. A tenth of this was built last year. Most of this is produced by giant wind turbines, with blades of more than 100m long.
The technology is constantly evolving. More wind farms mean more money for research and development. That means new ways of harnessing wind power, while also tinkering with old turbines to improve their efficiency.
South Africa’s contribution will be 3 000MW of wind energy, provided for by the government’s Renewable Energy Independent Power Producer Procurement Programme. Thirteen wind farms are already operational, with 495 turbines spinning.
According to the South African Wind Energy Association, the newest wind farms sell electricity to the grid for 60c a kilowatt-hour (kWh). Eskom’s coal-fired Medupi power station will sell it for 97c a kWh. But farms built two years ago have to sell electricity at double the cost of their new peers. That’s because of the rate of development in wind technology and production.
New solutions to old problems
This means the problems that threatened the industry a decade ago have been quickly solved.
In the early 2000s, turbines were known to shatter. The constant vibration of 400-tonnes of turbine also broke up foundations. Gearboxes had to be replaced every five years at 10% of the cost of the entire turbine.
In 2006, insurance company Allianz said it had received a thousand claims for damaged turbines in that year.
A 2013 study, published in the journal Biological Conservation, said turbines had killed 328 000 birds that year in the United States. Although this was a fraction of the four million birds killed by domestic cats that year, it still brought the industry into disrepute. Public perception became such a problem – driven by a movement dubbed “Not In My Backyard” – that, globally, dozens of wind farms have had planning permission rejected.
But the economic success of wind farms – and the drive to move power generation away from fossil-fuel power stations – have led to an explosion in the industry.
In South Africa, about R100-billion has been invested in wind farms. The International Energy Agency says all renewable technologies received R1.6-trillion in subsidies globally last year.
Space is no longer a major issue
More money has meant more start-ups, with new ideas and a lot more research. Here are some developments that could blow away the competition.
- Tweaking: Why break something that can just be tweaked? The majority of wind research is in tweaking existing plants. Whale Power is putting serrated edges on blades, an idea taken from humpback whales. This allows them to spin in less wind. EcoROTR is placing what it calls “UFO domes” on where the blades meet. The grey domes divert wind from the centre, where it isn’t used, towards the edges of the blades. This alone can increase a turbine’s efficiency by 20%.
- Segmented ultralight morphing rotor: Bigger can be better. Instead of thinking up a whole new type of turbine, Sandia National Labs in Virginia is working on a behemoth with 200m long blades. That’s twice the length of a football field. Its blades are inspired by palm trees – they are segmented to allow them to shift in strong winds. They can survive a tropical cyclone, so are ideal for wind farms in the ocean. Their size and flexibility mean that one turbine can generate 50MW of capacity (most turbines generate 2MW). The company believes this will make each unit of electricity produced by their turbines 60% cheaper than current turbines.
- Quiet revolution qr5: Unlike solar, wind power has had a problem with scaling down. Large farms have dominated. The qr5 is changing this. Instead of spinning blades, it has three limbs that spin around a central shaft and catch wind coming from any direction. Each unit can generate enough electricity to provide 60% of a home’s electrical requirements. Hundreds have been built in the United Kingdom.
- Clustered vertical axis turbine: An elaboration of the qr5, this has been upscaled by Stanford University so that each turbine is 10m in height. Whereas traditional wind turbines need a relatively large space – so the wind deflected by one doesn’t disturb the others – these turbines thrive in numbers. The absence of large vanes means they can be built close to one another. They can also be built next to older turbines to improve their efficiency.
- Sky Serpent: More blades are better, especially if they are attached to the same turbine. The Serpent uses seven blades on a single shaft. Each one is angled in a way to ensure that they all get a good supply of wind. These turbines use a tenth of the space of traditional turbines to generate the same capacity.
- The Archimedes: Taking inspiration from the Greek creator, a Dutch team have made a turbine that resembles a human-sized screw lying on its side. It can generate electricity in all sorts of wind. Critically, it is almost silent so it can be mounted on a roof without turning neighbours into would-be intra-neighbourhood murderers.
- Bladeless wind turbine: The Spanish company Vortex Bladeless uses a single tower to capture energy. There are no blades. Instead, it relies on the vortices of disturbed air that spin off the tower when the wind hits it to make the tower vibrate, which creates electricity. Vortex says its turbine will have a 40% lower carbon footprint, and will cost 50% less to manufacture than traditional turbines.