Danish wind power technology specialists K2 Management say that new installation methods and new materials could take hub height up to 170 meters in the foreseeable future. In the past few years, the average turbine size installed in Germany, for instance, has continued to increase. Since 1999, the average hub height has increased by 48 percent. The higher you get, the stronger the winds blow, and they come more constantly from the same direction with less turbulence.
K2 estimates that a 3MW turbine installed in a forest would have average wind velocities of six meters per second. Double the hub height from 70 to 140 meters, and you increase wind velocity by 13 percent. But average energy production increases even further – by up to 30 percent – because of lower aerodynamic surface resistance and better air viscosity. “Increasing from 70 to 170 meters is therefore expected to raise energy yield by 35 percent on average,” the company says. And the more complex the terrain is, the greater the benefits are from taller turbine towers.
Turbines already on the market already have blade tips reaching taller than the London skyscraper called the Gherkin, which stands at 180 meters. To go further, modular concrete structures will be used, and K2 is also working on hybrid turbine concepts already for hub height up to 170 meters. The blade tips would then approach 250 meters.
The result is also more even power production across the day, resulting in improved capacity factors. Turbines can then be productively built in a wider range of areas, thereby spreading out distributed energy generation even further. Our Bernard Chabot has been predicting this outcome for several years now in his work on the “silent wind revolution.”
Source: Renewables International. Reproduced with permission.
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