Wind power

Siemens B75, when size matters


Sometimes size matters, and how! According to "Wind Energy Equation“, A bigger turbine will produce even more energy. To exploit this equation was the Siemens that launched the B75, the wind turbine 75 meters long, almost as long as the wingspan of an Airbud A380. There gargantuan wind turbine is made of fiberglass and earned Simens the World Record for the longest blade ever made. The Blade does not need fittings or joints.

The B75 they will be installed in an offshore turbine that will rise in autumn 2012 as the first prototype, with a power of 6 MW. The offshore turbine will be installed at the Østerild test station in Denmark. Once put into operation, the rotor is able to cover 18,600 square meters, i.e. the area of ​​two and a half football fields, managing to move the tips of the blades up to a speed of 80 meters per second.

But why does size matter? According to Wind Energy Equation, the energy produced by a wind turbine it is directly proportional to the bearing surface. Since the covered area is usually a circle - in the case of wind turbines horizontal axis - there is a square ratio to the length of the blade. For mathematicians, thewind energy equation translates as follows:

Power in kilowatts = kx Cp x 1/2 Xpx A x V ^ 3

A few hints: k is the constant and is equivalent to 0.000133 to produce energy in kilowatts. Cp is the power coefficient of the turbine, p is the density of the air and A is the rotor area (usually pi radius squared x is used for horizontal axis turbines). V is the wind speed and it is a very important variable, which is why it is expressed cubed.

But how did Siemens come up with such large, jointless or jointless blades?
The technology he used is called IntegralBlade, with which the entire blade is obtained by working a single fiberglass module. The module is already pre-impregnated with epoxy resin and balsa wood so as not to require further welding. Given the materials used, the blade weighs 20% less than conventional blades. The first two turbines equipped with B75 they are currently being tested at the Gunfleet Sands wind farm off the south coast of England.

edited by Anna De Simone


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