On The Edge Of The Blade

New approaches to the challenge of ice on next-generation windfarms

In December 1991 the UK saw the birth of its first commercial wind farm in North Cornwall which comprised of just four turbines. 29 years later there are well over 340,000 commercial wind turbines in use globally, representing a combined capacity of approximately 430 gigawatts (GW). This is expected to rise to 175,000 GW by 2030¹ (global recessions notwithstanding, although with the end of fossil fuels seemingly nigh due to the Covid-19 outbreak this could well stimulate further investment into wind power).

Size matters…

Windfarms are getting larger both in geographical terms and also energy output. The most efficient way of producing more energy is increasing turbine size, and by extension turbine blades. The larger the blade, the more energy they can capture at higher altitudes where wind flow is more consistent.

It has reached a point where newer blade prototypes are as long as two Olympic-sized swimming pools. A single turbine this size, standing 260m tall in an offshore or onshore location has the potential to generate enough electricity to power 16,000 households. Current turbines cannot generate anything like that amount of power.

…but the bigger the blade, the bigger the challenge

Blades on giant turbines can reach speeds in excess of 200 miles per hour. The combination of high constant speed with volatile climates and extreme locations (where dust, water and extreme temperatures present significant O&M challenges) create problems which if left unchecked can cause untold damage. By far the biggest challenge for these new generation turbines is containing erosion to the leading edge of the blade tips. This is caused by salt, extreme weather or sand and if left uncorrected can lead to cracking, splitting and collapsing issues, resulting in energy losses of up to 5%. It has been reported that around 500 UK offshore wind turbines and 200 more off the Danish and German coasts need major blade edge repairs after only a few years at sea. Scaling these colossal structures manually is expensive and extremely dangerous.

Ice formation and ice shedding

Another major challenge is ice build-up. This is not limited to colder locations such as Canada or Siberia, as temperatures also drop significantly overnight in the arid deserts of the MENA region. Apart from causing operational issues (such as excess weight and drag which can impact performance by up to 20% annually), ice build-ups also pose a serious safety hazard in the form of ice shedding. This has the potential to cause damage to the surrounding area and poses injury risks to onsite workers.

‘Materials by design’ approach to blade coating manufacture

So how can windfarm operators/proprietors cost effectively maximise the resistance of turbine blades to the elements? Furthermore, how can they extend the blades’ service life without compromising on operational safety in an industry historically renown for being dependant on Government subsidies?

A possible solution could be to develop an industrial passive coating that reduces erosion and stops ice from forming in the first place. So far this has proved to be both technically challenging and not viable economically. The situation could be about to change, however, thanks to a disruptive approach to industrial coatings manufacture, being pioneered by a consortium of companies, scientific researchers and academic institutions.

The ICELIP Project

The consortium² is already in the advanced stages of developing an ice-repellent coating (commercial brand: ICEMART®) based on a materials by design approach to prevent ice build-up in aviation. The same coating could potentially be adapted to address the operational and safety challenges specific to wind energy production.

Not only does an industrial coating like ICEMART® offer the potential to prevent damage caused by ice shedding, it can help streamline ongoing O&M by removing the need for laborious, expensive and dangerous maintenance and ice-management processes, resulting in more efficient energy production.

Visit www.opusmaterialstechnologies.com/icemart to find out more.