As the market for wind energy grows, new business segments are opening up to the chemical industry, which can provide products for unsolved problems. There are new opportunities for sales in polymer materials, paints and adhesives.

Wind power, wind energy – these terms leave no doubt about what is vital for this ­technology: power and energy, the power­ful models of physics. When converting air flows into ­electricity, consider­able forces have an impact, in particular, on the rotors. Nacelles and towers are also exposed to harsh weather conditions – from the sun in North Africa to the rough sea climate in the North Sea.

The wind energy market is growing because of plans to substitute fossil and nuclear primary energy with energy from renewable sources in Europe. North Africa also aims to supplement, substitute and build its energy supply ­using renewable sources. Against this backdrop, the wind power industry’s demand for polymeric materials, paints and adhesives is growing, creating profitable business fields for the chemical industry.

Resistant materials

A physical perspective of the basic conditions for the application of materials for wind power reveals that the ­bigger the rotor‘s radius, the larger the area that the wind can ­affect and therefore the more energy that can be ­harnessed from the wind. For this reason, the rotor blades must be as long as possible, which in turn makes high ­turbine ­towers ­necessary. Another reason is that wind speeds accelerate with increasing heights. Total heights of up to 200 m are needed offshore in order to fully ­exploit the turbines’ ­capacity. Rotor blades can be up to 75 m long in such cases. Multi-megawatt ­capacities can already be achieved with blade lengths of 50 m.  Then ­centrifugal ­forces ­occur that may be equivalent to 18 times ­gravitational ­acceleration. Wind turbines need to achieve the load ­resistance ­required, under varying ­climatic ­influences, in constant operation for up to 25 years.

The rotors of larger turbines are mostly made of fibreglass and, in some cases, carbon fibre-reinforced plastics. They are characterized by consistent lightweight construction and a targeted use of material combinations, says Holger Ruckdäschel, head of system research for wind energy at BASF SE in Ludwigshafen, Germany. The matrix systems mostly consist of epoxy resins, which companies such as Momentive, Dow Chemicals and BASF can supply. ­Alternatively, Bayer MaterialScience offers polyurethane, while other manufacturers supply polyester.

In some cases, fibreglass is replaced with carbon fibre for high loads and long blade lengths. The large structures in the shell area and the shear webs use the sandwich construction method, where two fibre-reinforced coating layers envelop a stable, light-weight core material. This results in a high bending stiffness and dent resistance at a low overall weight. Balsa wood, PVC and, increasingly, PET structural foams are used as core materials.

Epoxy and polyurethane-based adhesives join a blade’s individual segments together, such as the shear webs to the spar caps. Finally, polyurethane coatings and form fillers ensure good aerodynamics and resistance against the weather and erosion, BASF’s Ruckdäschel explains.

Cost pressure boosts innovations

Bayer MaterialScience provides solutions based on ­polyurethane and polycarbonate as well as raw ­materials for varnishes, adhesives and other specialities. ­“Polyurethanes are an alternative to the matrix materials that have been used so far,” explains Marc Schütze, head of Bayer’s department for the production of rotor blades using polyurethane infusion resins. Bayer has already presented their in-house developments to a specialist audience at K 2013, a trade fair for plastic technologies.

Wind energy is a young industry that has had to overcome some challenges over the last few years. Because of the cost pressure to achieve grid parity with fossil and nuclear electricity, the innovation cycle is moving along at a quick pace. “We’re seeing similar developments here in line with those in other industries that have a need for our composite products, such as the automotive industry. Companies in the chemical industry, especially plastics, are essential to the wind energy industry, since setting up wind turbines would not be possible without today’s plastics and composites,” Schütze says when asked about his expectations for the market. “This market, strongly driven by technology and innovation, is therefore important for Bayer MaterialScience.” However, he is not ready to say more, much less provide concrete figures, about his expectations at this moment.

BASF also plans to supply increasingly more powerful materials for turbines to the wind industry. The company provides products and solutions for all main turbine components (rotor blade, nacelle, tower and foundation). The chemical group believes the market will continue to grow in the future. Wind power is considered to be one of the growth areas within their current strategy, Ruckdäschel states.

Thomas Isenburg

This article was published in our magazine CHEMICALS IN WIND INDUSTRY.