Scalable wind turbine might fit on your roof

Sky Serpent
(Left) Doug Selsam with a prototype 25-rotor turbine that can generate 3,000 watts, while the other end is held up by a balloon. Credit: Popular Science. (Right) Selsam holds a model with 14-inch rotors that can power the 50-watt headlight at his feet. Credit:

When you think of wind power, you probably picture gigantic wind turbines spinning gracefully in the middle of large open areas.

But an entrepreneur from Fullerton, California, has invented a new wind turbine design that is smaller, scalable, and could potentially fit on the roofs of homes like a long satellite antenna.

Rather than a single giant rotor with 50-foot-long blades, Doug Selsam´s "Sky Serpent" design uses several small rotors attached to a single shaft. By placing the rotors in precise positions and angles, each rotor can harvest its own wind, and avoid simply stealing the wake from the adjacent rotor. The entire turbine is hooked up to a single generator, which produces about the same amount of power as a turbine that uses 10 times as much blade material, Selsam says.

The shaft that holds the rotors can vary in length, and use any number and size of rotors, depending on its application. The rotors can even be mounted on poles that are light enough to be hand-held or attached to the roof of a house. Using ten 18-inch rotors, for example, one Sky Serpent model can generate between 100 and 400 watts, depending on wind speed.

Selsam has been working on the Sky Serpent design since 1999, with support from a $75,000 grant from the California Energy Commission. Working out of his garage and doing tests in a makeshift wind tunnel, he´s built a seven-rotor turbine that can generate 3,000 watts, as well as a dual-rotor turbine that generates 2,000 watts. He´s already sold 20 of the 2,000-watt devices to homeowners.

Another 3,000-watt prototype uses 25 rotors, where the shaft is attached to the ground at one end and held in the sky by a balloon at the other. In another concept, the turbine can float near the surface of water, its shaft and propellers extended in the air over the open ocean.

In the early ´80s, Selsam attended classes at but never graduated from the University of California at Irvine. However, his multi-rotor designs have received positive feedback from former General Electric turbine tester Brent Scheibel, who now runs a wind-testing facility in Tehachapi, California.

"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," Scheibel said in an interview with Popular Science.

As the wind turbine industry grows by more than 40 percent per year, Selsam hopes that the simple Sky Serpent design will simplify the manufacturing, transportation, and installation compared with conventional turbines - as well as provide more energy and be less of an eyesore.

via: Popular Science,, and

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Citation: Scalable wind turbine might fit on your roof (2008, May 26) retrieved 18 October 2019 from
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May 26, 2008
I suspect this will kill a lot of birds.

May 26, 2008
I'm more interested in why so many people think normal wind turbines are an 'eye sore'.

Also I agree with x646d63, at least birds can avoid the normal types of wind turbines.

May 26, 2008
unlike glass windows in buildings, which never kill birds...

May 26, 2008
Normal wind turbines become visually annoying because of the eye's reflex action of glancing at movement. It is difficult to train your eyes to not do this.

Initially, the usual reaction is "Cool. Look at that big propeller! How green and graceful!" But after repeated exposure it starts to become annoying as your eyes inexorably continue to grab quick glances.

Small diameter turbines that spin fast enough to become "invisible" can help. Or if the blades could change color to match the background sky. This also explains why most people eventually discover that cieling fans that match the cieling color are preferable to contrasting ones.

May 26, 2008
The bird issue is a problem. The only solution may be to breed more durable birds.

May 27, 2008
Mayday... that is one of the funniest comments I have ever read. :)

May 27, 2008
I'm more interested in why so many people think normal wind turbines are an 'eye sore'.

I think it's a combination of attracting attention by spinning and being taller than most of the landscape.

I think people could overlook that if they weren't so noisy and provided so expensive power that they have to be subsidized.(1/3 capacity factor means using expensive natural gas or (mis)using highly limited peak hydro; high degree of unpredictabillity means more spinning reserves and more overproduction from base load to keep the grid stable. Not being able to just build them next to the power-lines, transmissions costs are higher than other types of generation.

Cheap, efficient and reliable storage is desperately needed.)

May 27, 2008
In the netherlands we have got rid of all the TV antennas many years ago, just to have them been replaced with satellite disks and now of course the to be wind turbines. what a mess!

i think that it's better to have rainworm energy, cuz as it rains they move up in the soil and when it gets dry again, they move further down in the earth. so if we could extract the energy from their vertical movements the energy supply would be located from undergound just like with the TV cable network. Prettier sight!

May 27, 2008
Yeah! but then the worms would unionize and then wed really be screwed!

May 27, 2008
These guys should make a water driven version to put in every rain pipe, drain pipe, downspout and drainage water sewer line. The amount of gravity-driven water energy going to waste every day must be staggering.

Plus the slicing action would work like a garbage disposal to keep the whole system clean.

Where's my grant!? I want my grant!

May 28, 2008
why not put these on top of cars?
and turn that drag that all cars fight against and use it to harvest energy?

Jun 09, 2008
I now have wind mills built into my sunglasses.
There is only one disadvantage because I do get dry eyes sometimes.

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