Taking a tough stand against turbine blade erosion

Increasing numbers of wind turbines are expected to operate in challenging climatic conditions, onshore and offshore, for 25 years or more. Rain, hail, salt spray, as well as extremes in cold and warm temperatures, all take their toll on turbine rotor blades.

Leading edge erosion, characterised by pitting, pinholes and flaked off paint, increasing the surface roughness of the leading edge, impacts aerodynamic performance of the blade.

The impact on turbine performance
Studies have found that leading edge erosion can reduce annual energy production (AEP) by 5% (Sandia National Laboratory). Even minimal erosion can lead to a significant increase in drag of turbine blades. The Offshore Renewable Energy Catapult in the UK has concluded, following work with industry and academia, that leading edge erosion is a key priority for blades for all operators and wind turbine manufacturers and that development of effective solutions to protect blades contribute to reducing levelised cost of energy of wind. 

Typical solutions available to the industry include special paints and tapes that can be applied to the blade’s leading edge. But, some products must only be applied in certain temperature and humidity ranges, limiting when the application can be done.

In 2016 Danish blade technology company PolyTech launched a product designed to provide leading edge protection. The Ever Lasting Leading Edge (ELLE) system comprises a polyurethane “shell” which is applied to the leading edges of the turbine blades, providing a resilient protective layer that absorbs kinetic energy from rain, hail and other causes of erosion.

The data speaks for itself 
Since its launch PolyTech’s leading edge protection solution has been installed on more than 30,000 turbine blades worldwide, including proven offshore installations since 2015 on turbines with tip speed above 95 m/s, with tests continuing on many of these.

These thousands of applications have enabled PolyTech to generate extensive data on the performance and longevity of the ELLE system.

“We work closely with our customers in the wind energy industry to ensure that our product is able to deliver the protection they need and expect. So far, the combined experience from hundreds of different sites show that in most cases you only need to apply ELLE once to achieve end of lifetime protection”, says PolyTech’s CEO Mads Kirkegaard.

Ease of application within wide temperature and humidity rang
ELLE is designed to be applied between 5 and 35 degrees Celsius (up to 50 degrees Celsius surface temperature) and up to 90% humidity, facilitating a wide application window either by rope or platform.  

“As a rule of thumb, ELLE can be installed on existing turbines in all weather conditions where it is safe for the service crew to work on the turbine”, Kirkegaard adds.  

Wind farm operators also prefer solutions that are simple to apply, minimising turbine downtime from interruptions to production, while leading edge protection is implemented. 

Over the past six years, PolyTech has also streamlined the application of ELLE. A trained blade service team can apply ELLE to the blades of a typical 3MW turbine in a day and a half. PolyTech offers training to turbine owners and third-party service providers, both on-site and at its facilities around the world.

For further insights from Polytech, sign up to the Blades Global digital event and hear Rasmus Konge Johansen, lead specialist, discuss The Data behind the trends: Developments in leading Erosion and what that means for the future.

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