Wind blade manufacturer LM Wind Power (Kolding, Denmark) reported on June 15 that its newest blade, expected to be the world’s longest when it was announced (minus data on its precise length) in February, is certainly that. The newly christened LM 73.5P, as its name suggests, is 73.5m/241 ft long. When mounted, three to a rotor, the diameter of its swept area will be 150m/492 ft.
Developed by the company’s Denmark-based specialist engineers for offshore wind farms, the LM 73.5P will be installed on 6-MW turbines manufactured by Alstom (Levallois-Perret, France), mainly in European waters. The giant blades — equivalent in length to a 24-story building — will travel at a blade tip speed of more than 320 kmh/200 mph and help generate green power equivalent to the yearly requirements of more than 6,000 European households. LM’s VP of product development, Jan Kristiansen, says the company is looking forward to the presentation of the first prototype blade in Denmark at the end of 2011. “The size of these impressive structures has more than doubled over the past decade alone, and although this has, of course, demanded the development of new materials, design and technology along the way, the new 73.5m blade is built on our progressive accumulation of know-how. This ensures that even though it is more than 10m [32.8 ft] longer than our recent world-record blade, it is still based on a proven concept.” LM Wind Power reports that it is in discussions with a number of Asian wind turbine manufacturers about making blades of 80m/263 ft and longer.
Kristiansen adds that speed to market is important in the fast-moving wind energy industry, and it requires that LM’s product development and manufacturing engineers work very closely together. He cites an example of the company’s in-house mold experts who have produced a special prototype mold with a transparent surface. “This allows for full-scale manufacturing trials where our engineers are able to follow the critical polyester infusion by visual inspection,” he explains.