Wind turbines are an increasingly popular way to generate clean energy with large-scale wind farms springing up all over the world. However, many residents near proposed wind farm sites have raised concerns over the aesthetics and the low frequency vibrations they claim are generated by wind turbines. An interesting Windstalk concept devised by New York design firm Atelier DNA could overcome both these problems while still allowing a comparable amount of electricity to be generated by the wind.
Devised as a potential clean energy generation project/tourist attraction for Abu Dhabi’s Masdar City, the Windstalk concept consists of 1,203 carbon fiber reinforced resin poles, which stand 55 meters (180 feet) high and are anchored to the ground in concrete bases that range between 10 and 20 meters (33-66 ft) in diameter. The poles, which measure 30cm (12 in.) in diameter at the base, tapering up to a diameter of 5cm (2 in.) at the top, are packed with a stack of piezoelectric ceramic discs. Between the discs are electrodes that are connected by cables that run the length of each pole – one cable connects the even electrodes, while another connects the odd ones.
So, instead of relying on the wind to turn a turbine to generate electricity, when the pole sways in the wind, the stack of piezoelectric discs are compressed, generating a current through the electrodes. In a nice visual way to indicate how much – if any – power the poles are generating, the top 50cm (20 in.) of each pole is fitted with an LED lamp that glows and dims relative to the amount of power. So when the wind stops, the LED’s go dark.
As a way to maximize the amount of electricity the Windstalk farm would generate, the concept also places a torque generator within the concrete base of each pole. As the poles sway, fluid is forced through the cylinders of an array of current generating shock absorbers to convert the kinetic energy of the swaying poles into electrical energy.
Because the electricity generation capabilities of a Windstalk field site would depend on the wind, the designers have devised a way to store the energy. Below the field of poles would be two large chambers located on top of each other and shaped like the bases of the poles but inverted, (see the cross section image of the pole base section below). When the wind is blowing, part of the electricity generated is used to power a set of pumps that moves water from the lower chamber to the upper one. Then, when the wind dies down, the water flows from the upper chamber down to the lower chamber, turning the pumps into generators.
The WIndstalk project is still only a concept, so the designers haven’t determined the optimal shape for the stalks, saying computer simulations could be used to devise the best profile for maximizing the pole’s movement and variation. Even so, the design team estimates that the overall electricity output of the concept would be comparable to that of a conventional wind turbine array because, even though a single wind turbine that is limited to the same height as the poles may produce more energy than a single Windstalk, the Windstalks can be packed in much denser arrays.