14 DAY TRIAL // Think of a conventional wind turbine. You will most likely imagine a giant platform towering several tens of meters in the air on which a 15 meter long blade spins wildly. It doesn't seem to be very practical, does it? That's because it's not. The solution may be in scalable wind turbine designs, which could one day be placed directly onto the roof of your home, much like those invented by Doug Selsam.
His "Sky Serpent" design uses several small rotors attached to a single shaft, opposed to the single, large blade equipping conventional wind turbines. Each rotor is placed in precise positions and angles in relation to each other, so that they work together, rather than steal the wind from the neighboring rotor. The shaft the rotors are placed on connects to an electric generator, which is able to produce about the same amount of electric energy with the help of 10 times less material than in the case of conventional turbines.
The shaft is scalable so it can carry a various number of rotors. Such wind turbines are so lightweight that they can be lifted into the air with one hand and can be mounted either on poles or on house roofs. The models designed by Selsam can produce power varying between 100 and 3,000 watts, depending on the application.
With a grant of 75,000 US dollars received from the California Energy Commission, Selsam developed a series of Sky Serpent designs, among which a seven-rotor turbine capable of producing 3,000 watts of energy and a dual-rotor turbine that produces 2,000 watts. He has so far sold 20 such dual-rotor turbines to homeowners across the US.
Another model makes use of 25 rotors and is able to produce 3,000 watts. One end of the shaft the rotors are placed on connects to the generator, while the other end is sustained in the air by a balloon, allowing the turbine to pivot in relation to the wind direction. Selsam also said that one of its turbine designs can even be placed hovering above water surfaces.
Doug Selsam is a formed University of California student, although he never graduated. Nevertheless, ex-General Electric turbine tester Brent Scheibel says that: "Doug's idea is one of the very, very few that I've seen that actually has a strong chance of making strides into the commercial world."
