There's a small cadre of companies trying to crack into the wind power business with a seemingly improbable approach: making machines that work in low-wind areas.
V Squared Wind (V2 Wind) today is competing as a finalist in the Clean Tech Open competition in Santa Clara, Calif., where it will reveal details on the technology it's developing. The company has been funded by friends and family until now and is looking to raise money.
The two founders of V2 Wind have designed an unconventional device which they say taps into an area of fluid dynamics that few other entrepreneurs have explored. The idea is to increase the speed of wind as it passes through a tube, where the interior has a geometry that roughly mimics the shape of an hourglass.
Stacking several of these plastic tube-shaped modules together into a cube-shaped framing will create a wind turbine. Since it's a modular design, the turbines can be placed on the top of buildings or made several hundred feet high.
In field tests of a scaled-down machine, the machine can roughly double the speed of incoming wind, said CEO Fred Ehrsam of V2 Wind, which was founded three years ago.
The inside of each tube is tapered so that it constricts the flow of wind, he explained. Part way down is essentially a small version of a large wind turbine's rotor with fan-like blades which generate electricity using a permanent magnet generator. The opposite "outtake end" of the tube is longer than the intake, which is crucial to the acceleration, explained Chief Technology Officer Rob Freda.
Based on its model, Ehrsam projects that a full-scale machine, where each tube has a diameter of about 10 feet, can generate electricity cheaper than current grid prices, he said.
But because it concentrates wind, this sort of machine would be well-suited for areas that don't have the best wind, which is the majority of the U.S.
"Low wind speed regimes are a real sweet spot because the majority of the U.S. population lives in these sites, it minimizes the requirements for transmission (lines), and it's (an area) relatively void of competition," Ehrsam said.
There are a handful of wind companies which have designed machines that can concentrate the wind to get more usable power.
FloDesign Wind Turbines, which received an $8 million ARPA-E grant, built a turbine based on the dynamics of a jet engine. Another company is OptiWind which has a cylinder-shaped tower which accelerates wind around the edges where fans are placed.
Ehrsam said that performance of a larger-scale prototype, which V2 Wind intends to build next, should be the same or better than its current model.
In terms of size, a machine suitable for an office building and able to generate 75 kilowatts would be about 25 feet by 25 feet by 25 feet. A very large 7-megawatt machine would be about 270 feet in each dimension. Full-scale land turbines can generate about two megawatts and can be about 300 feet at the top of the blade.
V2 Wind is in an earlier stage as a company than OptiWind and FloDesign, which have working prototypes they are testing. But if these machines manage to work economically in marginal wind areas, it would open up wind to many other places, such as retail parking lots, office buildings, and industrial facilities.
"This changes the decision. Instead of choosing between two of the big competitors, like GE and Vestas, it comes down to whether they want wind at all," said Ehrsam.