From Popular Science:
Doug Selsam's Sky Serpant uses an array of small rotors to catch more wind for less money
WIND WIZARD: Doug Selsam sits beneath a prototype 25-rotor turbine that can produce three kilowatts of power. The other end is held aloft by a balloon. Photo by John B. Carnett
Cost to Develop: $250,000
Time: 9 years
Prototype | | | | | Product
Today’s largest wind farms are the size of small towns, made up of turbines 30 stories tall with blades the size of 747 wings. Those behemoths produce a great deal of power, but manufacturing, transporting, and installing them is both expensive and difficult, and back orders are common as the industry grows by more than 40 percent a year. The solution, says inventor Doug Selsam, is to think smaller: Capture more power with less material by putting 2, 10, someday dozens of smaller rotors on the same shaft linked to the same generator.
“The wind-turbine design out there right now is a thousand years old,” Selsam points out, as he lets one of his carved wooden blades speed to a blur in the makeshift wind tunnel he’s made of the alley behind his Fullerton, California, apartment. He brainstormed his multi-rotor approach in the early ’80s, in a fluid-dynamics class at the University of California at Irvine. “The textbook said, this single-rotor turbine design is the most power you can get. I knew then it wasn’t right. More rotors equals more power.”>>>MORE