Offering a total solution for everything from foundation to rotor tip allows Sika to keep pace with the ever-increasing demands of the wind market. For over 100 years now, Sika has been at the forefront of providing solutions in the areas of sealing, bonding, damping, protecting and reinforcing. Sika is a globally integrated company supplying speciality chemicals and application knowledge, with more than 120 production and marketing subsidiaries in 76 countries. It is therefore no coincidence that today so many of the world’s leading wind turbine producers rely on Sika, with over 25% of the total accumulated global wind power in operation today bonded with Sika products.

From the very beginning

Since the development of the first utility-scale wind turbines in the early 1990s, Sika has been supplying solutions for blade manufacturing. From this point in time there has been an exponential increase in turbine size and blade length, and Sika’s solutions continue to evolve to meet these needs.

The two fundamentally different blade design concepts in the market have led to mainly epoxy and polyurethane adhesives being used to meet the design demands. Using experience gained from developments in the automotive market, Sika has adapted these to the wind market requirements and has specifically developed toughened epoxy formulations and GL-approved polyurethane adhesives for blade bonding to reinforce its existing range of high-performance epoxy and polyurethane adhesives.

Additionally, Sika offers a range of resins, model boards, pastes and gel coats for mould and model-making as well as GL-approved high-performance infusion resins for blade and part manufacture. The increasing hub height needed for larger turbines has led to higher-performance foundations and hybrid towers to be constructed. For concrete towers and foundations, Sika has developed super plasticisers to improve strength and casting, as well as epoxy adhesives for pre-setting concrete elements and fast- strength-gain grouts for sealing the vertical joints in the concrete tower sections.

Protection systems

Wind turbines operate in some of the harshest working environments possible. Sika has formulated corrosion protection coating systems for steel tower sections that cover the full range of defined corrosion categories to protect onshore steel towers and offshore steel towers and foundations.

Similarly, the cast iron parts of the hub, generator and gearbox are also protected using Sika’s protective coating systems.

It is essential to protect sensitive electrical equipment housed in the nacelle from loss and damage caused by water ingress. Sika has pioneered the development of hybrid sealant/adhesives selected for their UV and weather-resistant characteristics, and proven through their in-service performance over many years. To ensure the long-term performance of the blades, Sika has developed a range of surface-finishing and repair products to allow rapid and reliable repairs to wind turbine blades to minimise downtime and maximise generation efficiency.

Looking to the future

Demands to reduce the cost of energy from wind power will largely shape the way the market develops. More powerful turbines to maximise the generation potential per site will place increasing demands on the materials used to withstand the extra loads. With onshore and near-coast, shallow-water sites diminishing, more challenging sites will also add further complexity.

As the rate of turbine change stabilisers, repair and maintenance will become ever more important to maximise the service life of wind turbines.

Sika secures construction in the sky – Germany’s first commercial wind farm

The remotest wind farm in the world is also Germany’s first commercial wind farm – Bard Offshore 1, located 125 km off the German coast in international waters. This high-sea wind power plant with 80 windmills has a nominal capacity of 400 MW, which is enough to cover the energy requirements of about 400,000 four-person house- holds. The energy produced is transported through a 125 km long direct current sea cable to the mainland and then another 75 km inland.

Rope Access Sverige AB (IRATA-member) specializes in methods of safe working at high and confined spaces. The company works on the BorWin Alpha platform, which connects the wind farm to the grid by HVDC cables.

“Doing high-quality work in this extreme environment means that from the very beginning you need the right partner and the right durable products which are strong enough to withstand the great strains induced by the corrosive and exposed environment,” states Petter Gellerstam, CEO of Rope Access, “that is why we chose Sika Sweden as our partner and why we are using Sika products.”

Liquid Applied Membrane and Sika solutions for Romanian Wind Farm

A wind farm of 40 wind turbines in Dorobantu, Constanta, Romania contributes to environmental-friendly production of power for the Romanian market by making use of renewable energy resources. The turbines’ foundations are each roughly 800m3, made of high strength concrete, so cracks were expected to show up in such cases. These cracks in the foundations needed to be bonded and the joint between foundation and the first ring of metallic tower had to be thoroughly sealed.

The cracks were first opened by a diamond cutting wheel, then filled with Sikadur®-31 N, applied by trowel. Injection packers were put both on the left and on the right side of the crack and Sikadur®-52 was injected through them until the full filing of the crack. Total length of the cracks was on average 50m per foundation. Sealing of the joint between the tower and concrete foundation was solved by using crack-bridging systems composed of reinforced liquid applied membrane (LAM).

The LAM system was applied onto the surrounding area of the joint, on both the UV exposed side of the concrete and the vertical wall, which was ballasted with gravel. The corresponding Sika solution included Sikalastic®-601 BC/ -621 TC for the UV exposed area and Sikalastic®-602 BR/ -622 TR for the ballasted area. The systems were reinforced with Sika Reemat Premium and applied with 1,20mm thickness on average, which is standard for Sikalastic® MTC-12. The surface was prepared by power washing at 350 bar in order to remove mud and cement milk. The concrete substrate was primed with Sika concrete primer applied by roller.

These are just two examples of how Sika provides solutions to yesterday’s, today’s and tomorrow’s technological advancements for the benefit of the environment and humanity.