WEG has manufactured wood epoxy blades for its own wind turbines since 1984. Now it is expanding the company's blade manufacturing facility at Southampton. Over the years WEG says it has carried out development work to improve the wood composite technology, making the material lighter and cheaper. The company's wealth of data from materials tests goes back to 1981.
"We have made significant developments in both the blade design and the production processes since the early days," explains WEG's Greg Warner Harris. "Various testing programmes carried out at universities have proven the fatigue life and clearly demonstrated the advantages of wood composite technology."
Calculation and testing work has already begun in preparation for Germanischer Lloyd certification of the blades for the WindMaster machine. The next stage will be to develop and engineer the mould extension before blade production begins in the summer. WindMaster's Hans Kursten says: "After reviewing carefully all the technologies, we selected wood composite technology for our 750 kW turbines. Blades of this length are required to be strong and lightweight and we felt wood composites provided the best material."
The blades will be manufactured to WindMaster's own tested design using NACA 63-2 series profiles. However, Mark Hancock from WEG says the company is fully capable of producing blade designs and testing them. "Every customer is different, that is what makes the work so fascinating," he says. The market has become a lot more sophisticated since the earlier days of wind energy when smaller wind turbine companies would buy their blades off the peg and bolt the them onto their hubs, he explains. "Now customers want to talk to people who understand all the aspects of blade design and are able to integrate it with their machine design -- and that is where we are at. We haven't got a standard blade that we are offering. Instead we offer a complete service. The customers tell us what they would like and we produce solutions matched to what they require," he says. "It's an interactive process."
Work on blades for the Swedish turbine has also started. WEG is carrying out a design study for an 80 m rotor for a 2-3 MW machine. Kvaerner has already used steel and carbon fibre blades for its current 70 m machine and has contracted WEG to produce a more cost effective blade design.