Wake steering: Researchers say turbine realignments could add double digit power gains to wind farms

Researchers in Denmark have discovered that subtle realignments of wind turbines can produce output gains of as much as 23 per cent.

That’s potentially good news for wind farms – particularly those suffering declines in output because too many turbines have been placed in the same area. But they warn that the strategy is not without risks – getting the angle wrong by a few degrees could turn a promising production into a power loss.

The authors of the paper – published in the latest edition of Wind Energy Science – say “wake steering” involves turning the nacelle of a wind turbine slightly away from the wind.

The new rotation, or yaw, redirects the eddying airstream behind it, reducing the impact of the wake on turbines further back on the site.  

The strategy is that by slightly reducing the power of turbines at the front of a wind farm, those further back will produce more power.

It’s become an issue in offshore wind farms in the North Sea, where some project developers have accused others of “stealing” stealing their wind.

It’s an idea that could potentially be useful in Australia where renewable energy zones in New South Wales and Victoria will see wind farms packed closely together, and as developers are pushed towards second and third tier sites with lower wind speeds.

The Danish data also finds that wake steering can measurably improve blade fatigue, suggesting it could place a role in extending the life of Australia’s middle aged and older wind farms.

Renew Economy understands that wake steering is on the radar of some wind farm owners in Australia, although the issue is not serious enough tough here for anyone to try it out just now.

“The only way to find out if it works is to do it and measure it, and that will take years,” says Adam Gray, chief of developer Exceed Energy.

“You couldn’t design a project now to incorporate that kind of operational paradigm without measuring an operating wind turbine.”

Factor in Australia’s regulatory and planning frameworks, which are “laden with risk delay”, and few are likely to waste time tweaking wake effects, he says.

It might be a strategy offshore wind developers consider.

Star of the South chief Charles Rattray says they’re keeping tabs on wake steering as a way to extract as much power as possible from turbines. 

“Wake steering is one of several rapidly evolving wind farm control techniques with the potential to unlock more clean energy from offshore wind farms by optimising how turbines operate together,” he said in a statement sent to Renew Economy.

“We’re closely following developments and exploring opportunities to maximise energy production from Star of the South. 

“Once we’ve appointed a turbine supplier, we’ll work closely with them to implement the most effective solutions available at that time.”

More sophistication needed

There is one major obstacle in the way of wind farm owners testing wake steering on their assets however, and that’s the contract with the wind farm operator.

Consultant Rosemary Barnes thought it was a great idea to test when she returned to Australia several years ago, but was repeatedly told it was too much of a hassle to try.

She says contracts in Australia tend to favour the requirements of operators, who pay up if maintenance costs are higher than expected but reap none of the upside from better power gains.

“The tricky thing in Australia is everyone is on these full service agreements so the incentive to do better is not really there,” she says.

“It’s a lot of extra faff and it might also cause accelerated fatigue damage because you’re not operating the turbine in the way it was designed for, so the research is split on whether it makes it better or worse but there is a risk it makes it worse.”

But with about two decades of wind farm ownership under Australia’s belt, Barnes says owners should be becoming more savvy about what they can demand in an operating contract, and how hands on they want to be in determining strategies that might increase profitability.

“The one thing they should do is write the contract with [strategies such as wake steering] in mind, if they might want to be allowed to do something like this,” she says. 

Pinpoint accuracy needed

Wake effects on wind farms are a well known issue: more turbulence and lower wind speeds for turbines towards the back of a site mean lower energy generation and higher maintenance costs as turbines deal with air flows they weren’t built for.

Wake steering has been the subject of serious research for some time, with Siemens Gamesa bringing out a specific product to do this on offshore turbines in 2019.

Field tests of the company’s Wake Adapt system, published in 2024, show a measured energy benefit of 0.64 per cent and a higher impact on brakes and brake pads, but no overall impact on maintenance costs.

The Danish study looked at how changing how individual turbines operate can reduce wake-induced losses.

Get it right, or within a yaw window of just 8.5º, and the power gain across a wind farm could lift between 7.5 per cent and 23 per cent. 

But introduce an error of up to 4º and gains could turn to losses for the whole wind farm. 

And with more uncertainty around wind direction, the smaller the possible gains. 

When simulating that higher uncertainty, the Danish researchers found the number of degrees a nacelle could be tilted off-wind narrowed at real wind farm sites, and the peak gains for a single turbine strategy plunged from 7.5 per cent to just 2 per cent.

Yet even at those very low gains, wake steering still delivered measurable improvements in blade fatigue, suggesting it could have a role to play around maintenance.

The effects of wake steering are also incredibly difficult to predict.

“While exact numbers depend on turbine spacing, the substantial decrease in peak power and narrow range of power gains signify that wake steering is highly sensitive to wind direction uncertainty and small biases in mean inflow wind direction, even in favourable atmospheric conditions,” Technical University of Denmark researchers Emily Louise Hodgson and Søren Juhl Andersen write.

“Therefore, accurate measurement of these quantities and inclusion of them in prediction models is essential to the operational implementation of wake steering.”

The researchers found that tilting a nacelle anticlockwise works best in the Northern Hemisphere.

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