Flying a kite has often been considered child’s play, but a group of inventors think the concept could be used to make wind energy cheaper and more reliable than ever before, potentially revolutionizing wind power forever.
energyNOW! correspondent Josh Zepps met the innovators working to turn the idea of flying a kite into an airborne wind turbine that’s lighter and more powerful than traditional wind turbines. The full video is available below:
If you’ve ever flown a kite, you’re familiar with the strength and consistency of wind hundreds of feet off the ground, higher up than most land-based wind turbines. What if that same concept could be applied to harness wind power – could it help solve the intermittency, siting, and cost problems that have put a damper on wind energy?
Enter the Makani Airborne Wind Turbine, an innovative design that combines the concept of kite surfing with wind turbines. Its goal is to achieve the same motion of a turbine without the structure itself. “The difference between a wind turbine and what we’re doing is we have a wing that is free-flying and tethered to the ground,” said Corwin Hardham, Makani CEO. “You have this kite flying the same pattern as wind turbine blade, but up higher in the sky.”
The secret to the air turbine design lies in using a fraction of the material necessary for a standard wind turbine. A conventional 1-megawatt wind turbine can weigh more than 100 tons, but Makani’s airborne turbine only uses a carbon-fiber wing and lightweight rotors of their own creation. The company says its 1-megawatt airborne turbine system will weigh a tenth as much and have an installed price half a normal turbine, but with the same rated power. “We expect the cost to be around 3 cents a kilowatt-hour,” said Hardham. “That’s getting lower than a lot of coal-fired generation at the moment.”
Imagine a fleet of 26-feet wide, motorized fixed-wing gliders tracing circles in the air at 150 miles per hour, sending a constant stream of electricity to the grid via the tether connecting them to the ground. The wing’s rotors function as both propeller and generator: when the wing launches, it uses backup or stored power to reach its cruising altitude. At about 1,000 feet high, they switch to creating resistance against the high-altitude winds and generate electricity the same way an electric vehicle generates power from its brakes.
But what about when the wind doesn’t blow? The wings can stay aloft using steady breezes or their own power, but once the wind speed drops below nine miles an hour, they become net consumers of electricity, and would be landed if periods of low wind speed are forecast. Makani says the system will generate power twice as consistently as the best wind farms operating today. “The wind is about twice as powerful at that altitude,” says Hardham.
Makani’s future seems bright. Their airborne turbine system won this year’s Breakthrough Award in energy from Popular Mechanics, received a $3 million dollar grant from the Department of Energy’s ARPA-E program, and $20 million in venture capital funding from Google.
But, like most energy start-ups, the airborne wind turbine will ultimately succeed or fail based on how much power it can generate. That’s why Makani is developing a bigger turbine system to fly at 1,600 feet and produce enough electricity to power 600 homes. It plans to launch a prototype of the new design by 2013 and enter commercial production by 2015.
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