Makani Power, a company that innovates in the field of wind turbines, has recently received a grant from ARPA-E for developing their Airborne Wind Turbine (AWT), they call Makani M1. Unlike other wind turbines, this one is made of a wing equipped with three small propellers which spin endlessly around its ground anchor point.
It uses cheap materials and Makani says the price of the energy it generates can even compete with the price of coal, also being 40 percent cheaper than the power produced by ordinary wind turbines.
The airborne wind turbine is pretty versatile and easy to use. The wing that carries three propellers can self-launch when winds have proper speeds (7.8 mph), and doesn’t carry fuel or batteries. The launch is done vertically, by using the propellers.
When it reaches 656 feet (200 meters) up in the air, the propellers change their position from vertical to horizontal and the wing begins to hover like an airplane around its central ground point, generating energy through the spinning propellers and passing it to the base station through its tether. The circular space the Makani M1 needs to float is just as big as a regular wind turbine’s.
When the wind slows down to speeds lower than 7.8 mph, the wing is again put in vertical position and slowly winched back to the base.
An on-board computer controls the entire operation and helps maintaining “a stable flight path, while also maximizing power output. To do this, hundreds of times each second the controller calculates the wing’s position and heading from sensor data and adjusts the control surfaces (aileron, elevator, and rudder) to maintain the correct flight path. This fast response allows the wing to easily handle disturbances such as gusts. The control system has been proven, both in simulation and reality, to fly stable and reproducible paths.”
The altitude that the airborne wind turbine uses to harness wind’s power is higher than that of wind turbines, so interferences with bats or other birds are minimized. The company even has a complete prototype that is able to generate 10 kW, and has plans to develop a 1MW system that could be sold to utilities.
A prototype producing up to 3kW (impressive, for a system this cheap and small, compared to a classic wind turbine) has been tested at Sherman Island, CA, this June. You can watch the video and pull your conclusions as to the efficiency of Makani’s airborne wind turbine. Looks promising to me…