Wind turbine blade manufacturing is a developing business as the wind energy industry looks to have fewer, larger turbines offshore, which presents performance challenges for composite materials. The situation is complicated by the cost pressures in the renewable energy markets, wanting turbines at a cheaper price, so some of the types of technology used in aerospace are not cost-effective here. The global windmill blade manufacturing community came together in December last year to network on common issues for the industry - Wind Turbine Blade Manufacture 2011 is scheduled again for in Dusseldorf, Germany. The exhibition provides leading suppliers with the opportunity to demonstrate their products to decision makers and R&D experts. The conference kicks off this year with a review of the wind blade industry from Frank Virenfeldt Nielsen, the CTO of LM Windpower and a leading figure in the market.
There are a variety of factors to consider in wind rotor design including aerodynamics, lightning and icing resistance, and load-bearing. The new Vestas designs are aiming for lightweight blades with good durability under extreme conditions: production involves a unique semi-automated process. The Danish Technical University (DTU) at Riso is focusing research on slim line blade design. In a new approach, Dassault Systemes has developed software that is not only useful in design, but can also be used to plan production in a process known as digital manufacturing.
Quality control and testing can cut maintenance costs to energy companies, and there are a variety of properties that can be measured. Germanischer Lloyd is a world-leading certification body and will be outlining the performance requirements for blades. A wide range of testing equipment and protocols will be discussed at this conference from expert institutes (the Fraunhofer Institute for Wind Energy and Energy System Technology (IWES) and Stuttgart University) and wind blade manufacturers like Euros Entwicklungsgesellschaft Fuer Windkraftanlagen. Several papers cover non-destructive testing (NDT) including the work by Force Technology.
The Materials Engineering Research Laboratory (MERL) is currently studying defects in blade composites in order to predict the overall effects. It is possible to monitor blade condition during use and this technology has been developed by companies such as Bosch Rexroth to check for damage, ice and overload.
There is still extensive use of manual labour in the wind blade manufacturing industry. However, there are some aspects that can be automated to provide greater uniformity and consistency in production: RE Power Systems is focusing on this aspect of manufacturing. Process monitoring and control is the subject of research by the National Technical University of Athens. The robotics company IDP Sistemas Y Aplicaciones has developed technology for finishing blades, which is a tedious process to carry out by hand.
Although the materials for wind blades appear to be simple, small variations can speed up production, save money and improve performance. For example, Huntsman has a new amine technology to improve liquid epoxy resin (LER) infusion times. There are a variety of core materials in use in blades, so the Composite Technology Centre Engineering has carried out a comparative study. With increased size of blades manufacturers are examining ways to supplement the strength of key load bearing structures. Zoltek and Wetzel Engineering are looking at cost-effective ways of using carbon fibre. For the assembly process 3M has developed an advanced epoxy adhesive and in terms of coating, Re-Turn has a new functional gel coat. As the industry has now been operating for several decades there are blades that are no longer required - there is a method of recycling on offer from Holcim. Wind Turbine Blade Manufacture 2011 provides a unique opportunity for members of the wind industry to get together and discuss the design and production of reliable, energy generating windmills.