WindLift Harnesses Kites for Off-Grid Power
The good ol’ kite is making a comeback for clean power’s sake. While Earth2Tech readers might be familiar with Makani, the high-altitude wind startup backed by Google, another group of kite enthusiasts based in North Carolina is looking to fly kites to produce power: WindLift. Founders Robert Creighton and Bart Bartlett explained to us this week that they are looking to build a kite package that costs $5,000, can produce 10 kW of power and will fly up to 300 feet in the air.
The ideal application for the initial version of their kite power package is water pumps and irrigation systems in geographies off the grid, according to the duo. The kite provides a significant amount of energy — about a kilowatt per meter for a 5- to 20-meter kite — says Bartlett, and explains the company is initially looking to replace the diesel generator market. Customers could be industrial farmers in developing nations or even rural parts of the U.S.
Launching the kite is pretty much the same process you used when you were a kid — you have to get it up manually, which can be done in about 5-10 minutes in 6-10 mph winds, says Creighton. But once the kite is in the air it will be able to fly itself; when the wind dies down it will be automatically reeled in. Eventually WindLift would like to offer a grid-connected version of its kite, but that would add at least $10,000 to the cost of the system. While Makani hasn’t revealed much about its technology, some have speculated to us that the startup is aiming more for the utility, grid-connected market.
So far WindLift has raised a seed round from a small group of investors in Wisconsin — the company started off trying to fly kites in the chilly winters in Wisconsin and later moved to just south of Kitty Hawk, in North Carolina, where the Wright Brothers developed their flying innovations. This week Creighton and Bartlett have come to Redwood City, Calif., for the Dow Jones Alternative Energy conference, and they are looking to raise a Series A of about $6 million to start production and packaging of their kite power. They’ll present at the conference on Wednesday if you’re interested in learning more.
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this is a similar Magenn Power high altitude wind turbine, which is much further in their development process. These types of “flying” turbines sound great for rural areas, I am not sure about urban settings. The only problem with high altitude wind turbines is you need a special permit from the FAA if you are planning to fly one, which depends on how far you fly it up. reguardless this is great innovation in the wind turbine sector. 10kW is a lot of juice and for $5,000 the cost per watt is much lower then solar power.
I’ve seen number of this type of article but I have not been able to find a good explaination of how it generates electricity. Is there a good reference anywhere so I can learn more about this?
This article has incorrect information.
It says “The kite provides a significant amount of energy — about a kilowatt per meter for a 5- to 20-meter kite”
This is nonsense. The maximum wind power density is 800 watts/sq meter in Class 7 winds – US Dept of Energy standard info. Turbines cannot in reality be more than 40% efficient. That’s 320 watts per meter, not 1 kW. That’s basic physics.
Either the post author is in error or the developers are un credible.
I am developing micro hydrokinetic turbines for in stream flows, and have spent 2 years working on power estimates for various fluid power technologies. While I am not the world expert, I know enough basic physics to call out egregious errors when I see them.
Burt, The founders said everything in the post was correct, but I’ll circle back with them on that number and see if they have any clarifications. – KF
Burt, a power kite takes advantage of its relative velocity to the wind and these highly efficient kites (they are more like flexible wings) move quite rapidly, just like the blade tips of a large wind turbine move 8-10 times faster than the wind speed. In a 10 kph wind these kites move 40-50 kph as they sweep back and forth across their power zone which allows them to extract energy from large swaths of oncoming air. So the maximum 800 watts/sq meter is correct, it is just that these kites sweep through tens of square meters every second. Also, the 40% Betz factor that you mention really only applies to turbines. Free flying wings can theoretically be more efficient.
so what’s the formulae for the relationship between, wind speed and the surface area of a kite (supposing the kite is,say flat). is it the same as for a turbine ?