Huntsman Advanced Materials helps to harness more of the wind’s energy

Increased expectations for energy generation from wind power have led to the growth in the size of wind turbines, particularly in offshore wind farms. In what has become a rapid growth phase for the industry, certain technical and quality-related issues have emerged, creating significant challenges which manufacturing and material innovations offer the power to overcome. Here Nastassja Rothe, Wind Energy Marketing Manager for Europe, from Huntsman Advanced Materials reports.

The trend in increasing turbine size has created the need for bigger rotor blades to broaden the sweep area and ability to capture more energy. Rotor blades over 50 metres are now gaining an increasingly larger market share and 60 metre blades are set to become more commonplace. The development of 70-80 metre blades has started and the 100 metre is also being considered for offshore applications.

The increasing length of offshore wind turbine blades has prompted the more widespread use of advanced composite materials which in turn has led to growing requirements for new materials and manufacturing methods.

With larger blades come more complex tooling and composite mold designs, longer production times and higher processing costs. Larger blades also create greater stress on the structural, mechanical and gear components of the turbine. Taking all these factors into account, the manufacturers are very much focused on the continuous improvement of wind turbine performance.

As blades get bigger, weight and cost needs to decrease and quality needs to improve.Manufacturing and material innovations are mandatory for making this a cost effective renewable technology.

Requirements for higher performance materials, with an emphasis on lowering toxic risk while offering very good, cost-effective processing conditions is a key area for Huntsman Advanced Materials.

The company continues to invest in these market developments in order to provide a solution to the advanced processing requirements and mechanical property demands of today’s larger wind blades.

Huntsman offers a comprehensive range of Germanischer Lloyd (GL) approved Araldite® epoxy resin systems which meet stringent processing and performance requirements for composite mold production and wind blade manufacturing.

As the industry looks to save time and money and improve efficiencies, fabrication processes for composites have come under the spotlight.The formulation of epoxy-based resin systems that can be used to vacuum infuse dry fibres or preforms holds significant structural benefits for producing
large, complex composite parts with less than 1% void content and controllable resin-to-fibre ratio.

This leads to increased strength as well as predictable performance and integrity of the finished part.The company’s GL approved epoxy resins are designed with enhanced mechanical and processing properties to improve product quality, lower consistent blade weight,deliver high strength and fatigue properties and enhance impact resistance.

The low viscosities of these systems facilitate fast infusion processing and all importantly,reduced production cycles.

Araldite® infusion system for blade component production

Araldite® LY 1568 / Aradur 3489 is an example of the latest epoxy-based resin infusion system from Huntsman which offers more control in the manufacturing process. The combination of its low mix viscosity (200-300mPas at 25°C) and its low exothermic reaction and long pot life (850- 950 minutes) provides a major benefit for its users in the infusion of very long or thick composite parts.

High temperature systems for tooling

Araldite® LY 8615 / Aradur® 8615 and Araldite® LY 8615 / XB 5173 are examples of the latest high temperature infusion systems which provide significant advantages for high temperature composite blade mold production. It can withstand significantly higher temperatures than the curing temperature of the component production process.Both systems can be processed from room temperatures up to 40°C and offer heat resistance up to 180 -200°C. The Tg can reach over 210°C after post curing, making these systems particularly suitable for the production of blades made of high performance prepregs, requiring high post cure cycles. In the drive to realise greater cost efficiencies while achieving quality without compromise, these systems are proven to be particularly useful, offering excellent operational features including low viscosities, long pot
lives and rapid de-molding times of 24 hours at 40°C. Another example of a high temperature infusion system that Huntsman has developed for the production of large composite tools for wind blade production is RenLam® LY 120 / Ren® HY 99. What makes this system different is its easy handling and mixing and low viscosity which enables a very good impregnation combined with a long pot life and low exotherm. This system can also be precured at a very low temperature (40°C). Once fully cured its high heat resistance (up to 150°C) makes it suitable for molds used for part
production with 120°C cure prepregs or infusion systems. It has been developed as a non-toxic system in accordance with the most recent legislation.

Wind energy is undisputedly the number one choice in Europe's efforts to move towards clean, renewable power and is expected to power industry, business and homes with clean electricity for many years to come.

With more than ten years’ experience operating in this market, Huntsman Advanced Materials’ R&D and technical team is working with the industry to develop the advanced technology needed to improve the structural integrity and mechanical requirements of the wind turbine blades of tomorrow as the
trend towards bigger units continues.

From mold to blade production, the company offers the added value of combined application expertise, understanding of the whole manufacturing process and products ranging from tooling materials and composite resins to adhesives.