Wind power has great potential as a form of renewable energy, but in order to really efficiently produce it, turbines need to be optimally positioned and dimensioned. A newly designed 200-meter high wind measuring mast that delivers precise data will be able to help with that, by very accurately forecasting energy yields.
In order to run a wind farm as efficiently as possible, the designers need know before building what wind speeds are most common at the site, and what type of turbulence to expect.
The problem: “With conventional methods, it is almost impossible, or possible only at great effort and expense, to measure projected power when planning modern, large-scale facilities,” says Tobias Klaas, a scientist at the Fraunhofer Institute for Wind Energy and Energy System Technology IWES in Kassel, and also the head of the “Inland Wind Energy Use” research project sponsored by the German Federal Ministry for the Environment. “Moreover, forests and hills hamper the analysis of wind conditions. Experts refer to this aspect as ‘complex terrain,’ where topography influences wind conditions, even at great heights.”
Because of these factors, Klaas and his colleagues at IWES designed and built a 200-meter wind-measuring mast. Operational since January, and located on a tree-covered hill near Kassel, they have created a collection of wind speed measurements, turbulence, and other meteorological data. This new mast is the largest in Europe — conventional masts are only around 100 meters in height, not tall enough to approximate wind turbines. The rotating blade of a modern wind turbine is easily twice as tall. It may seem strange, but researchers know little about how the wind up there behaves.
“Indeed, there are theories about how wind speed increases with height, yet these no longer apply at such great heights. Hence, actual measurement values are needed to further develop the models,” explains Klaas.
The very specific measurements taken with the mast help not only to optimally alignment the wind turbines, but also to decide the appropriate size and proportions. This helps a great deal with the efficiency of the turbine, and also helps to cut down expenses.
“With the aid of the wind measuring mast, it should additionally be possible to develop standards for LIDAR (light detection and ranging), the new ground-based remote measurement process. The laser-optical measurement process is considered the key to wind profile measurements up to heights of several hundred meters. Due to the lack of standards, LIDAR remains unapproved as the sole measurement process for expert reports on wind, which are the basis for yield calculations. If successfully granted one day, thanks to the Fraunhofer measuring mast, then such approval would make expert reports on wind superfluous, because LIDAR would render measuring masts obsolete.”
Image Credits: © Fraunhofer IWES / Klaus Otto
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