ELLE - Proven lifetime protection against leading edge erosion
ELLE - Proven lifetime protection against leading edge erosion

ELLE™ lifetime calculations

DNV-verified lifetime calculations confirm: our polyurethane softshell, ELLE™, in fact puts an end to leading edge erosion.

Methodology - from testing to lifetime estimation


The DNV-RP-0573 provides a methodology to evaluate and predict the durability of erosion protection systems. We followed this recommended practice to forecast the durability of ELLE™.

The process involved:


  1. Extensive rain erosion testing of ELLE™ according to DNV-RP-0171
  2. Statistical analysis of data as per ASTM E739 standard practice
  3. Combining the rain erosion testing and statistical analysis with material properties such as density, speed of sound and thickness allows us to calculate the erosion strength of ELLE™
  4. Utilizing site- and turbine-specific data, such as annual rainfall, average wind speed, TSR, tip speed and blade length, we can calculate the durability of ELLE™ for any given site


In addition to this, we also followed the extensive methodology outlined in DNV-RP-0573 to evaluate the risk of delamination of ELLE™.

The process to calculate LEP durability based on DNV-RP-0573

ELLE™ prevents several repairs over 25 years

Example field case showing that ELLE prevents 6 repairs over 25 years. (Input parameters: turbine type: 1.5 MW, rotor diameter: 77 m, blade length: 37.3 m, nominal RPM: 18.36, annual rainfall: 1,600 mm, mean wind speed: 8.5 m/s) 

LEP durability after 8 and 25 years of operation

Example field case showing the accumulated erosion damage on a blade after 8 and 25 years of operation with and without ELLE. ELLE protects the blade from erosion throughout the turbine’s lifetime. (Input parameters: turbine type: 1.5 MW, rotor diameter: 77 m, blade length: 37.3 m, nominal RPM: 18.36, annual rainfall: 1,600 mm, mean wind speed: 8.5 m/s) 

Onshore example case - 1.5 MW turbine

Onshore example case showing the return on investment (ROI) and payback period for an ELLE installation. 




Proven lifetime durability for ELLE™


We have calculated ELLE™’s durability for various sites and turbines around the world. The results show that:


  1. In most cases, ELLE™ remains in the incubation period for 25 years of operation. (i.e. it will not enter the erosion period, nor it will suffer from breakthrough, and no repair is needed) 
  2. For the most extreme sites with regards to tip speeds and rainfall, ELLE™ may show erosion damage that would require repairs of the tip sections maximum twice during the turbine’s lifetime. These repairs, however, would only entail exchanging the damaged shell(s).
  3. When using only conventional coatings at site with around 1,000 mm annual rainfall, the leading edges will have visible erosion damages after a few years, which will require repairs up to six times over 25 years. For more extreme sites, this number can be even higher.
  4. Conventional coatings will experience severe erosion in the tip section and along the entire blade, which will require repairs. Installing ELLE™, however, will not only protect the tip of the blade, but also the rest of the leading edges from experiencing severe erosion during 25 years of operation. 


DNV-verified calculations


In 2022, DNV verified our lifetime calculations, ELLE™’s estimated durability, and all related test results according to DNV-RP-0573.


In the verification letter, DNV states that "[…], DNV finds that the results are interpreted in a conservative manner that is likely to underestimate the calculated durability of the protection system."


Should you invest in ELLE™ ?


All sites and turbines are different, which has a trickle-down effect on your operating expenses and levelized cost of energy. This means that we need to investigate, whether ELLE™ is the right solution for you and if it is worth your investment. 


That is why we have created the “Leading Edge Erosion Calculator”.


Our calculator follows the DNV-RP-0573 to evaluate and predict the durability of erosion protection systems. This way, we can calculate leading edge erosion at your specific site for your specific turbine. By combining these results with leading edge protection installation costs, we can calculate your return on investment and payback period. You will also get to see how our ELLE™ softshell would protect your turbines compared to industrial coatings.


Try our erosion calculator and get the insights you need to decide what the best leading edge protection solution is at your site.





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