![Kiwee One](https://upload.wikimedia.org/wikipedia/commons/5/58/Kiwee_One.jpg)
An airborne wind turbine is a design concept for a
wind turbine
A wind turbine is a device that converts the kinetic energy of wind into electrical energy. Hundreds of thousands of large turbines, in installations known as wind farms, now generate over 650 gigawatts of power, with 60 GW added each year. ...
with a rotor supported in the air without a tower, thus benefiting from the higher velocity and persistence of wind at high altitudes, while avoiding the expense of tower construction, or the need for
slip ring
A slip ring is an electromechanical device that allows the transmission of power and electrical signals from a stationary to a rotating structure. A slip ring can be used in any electromechanical system that requires rotation while transmitting p ...
s or
yaw mechanism. An electrical generator may be on the ground or airborne. Challenges include safely suspending and maintaining turbines hundreds of meters off the ground in high winds and storms, transferring the harvested and/or generated power back to earth, and interference with aviation.
Airborne wind turbines may operate in low or high altitudes; they are part of a wider class of Airborne Wind Energy Systems (AWES) addressed by
high-altitude wind power and
crosswind kite power
Crosswind kite power is power derived from a class of airborne wind-energy conversion systems (AWECS, also AWES) or crosswind kite power systems (CWKPS). The kite system is characterized by energy-harvesting parts flying transverse to the directio ...
. When the generator is on the ground, then the tethered aircraft need not carry the generator mass or have a conductive tether. When the generator is aloft, then a conductive tether would be used to transmit energy to the ground or used aloft or beamed to receivers using microwave or laser.
Kite
A kite is a tethered heavier than air flight, heavier-than-air or lighter-than-air craft with wing surfaces that react against the air to create Lift (force), lift and Drag (physics), drag forces. A kite consists of wings, tethers and anchors. ...
s and helicopters come down when there is insufficient wind;
kytoon
A kytoon or kite balloon is a tethered aircraft which obtains some of its lift dynamically as a heavier-than-air kite and the rest aerostatically as a lighter-than-air balloon. The word is a portmanteau of kite and balloon.
The primary advantage ...
s and
blimp
A blimp, or non-rigid airship, is an airship (dirigible) without an internal structural framework or a keel. Unlike semi-rigid and rigid airships (e.g. Zeppelins), blimps rely on the pressure of the lifting gas (usually helium, rather than hydr ...
s may resolve the matter with other disadvantages. Also, bad weather such as
lightning
Lightning is a naturally occurring electrostatic discharge during which two electric charge, electrically charged regions, both in the atmosphere or with one on the land, ground, temporarily neutralize themselves, causing the instantaneous ...
or
thunderstorm
A thunderstorm, also known as an electrical storm or a lightning storm, is a storm characterized by the presence of lightning and its acoustic effect on the Earth's atmosphere, known as thunder. Relatively weak thunderstorms are someti ...
s, could temporarily suspend use of the machines, probably requiring them to be brought back down to the ground and covered. Some schemes require a long power cable and, if the turbine is high enough, a
prohibited airspace
A prohibited airspace is an area (volume) of airspace within which flight of aircraft is not allowed, usually due to security concerns. It is one of many types of special use airspace designations and is depicted on aeronautical charts with the l ...
zone. As of 2022, few commercial airborne wind turbines are in regular operation.
Aerodynamic variety
An
aerodynamic
Aerodynamics, from grc, ἀήρ ''aero'' (air) + grc, δυναμική (dynamics), is the study of the motion of air, particularly when affected by a solid object, such as an airplane wing. It involves topics covered in the field of fluid dyn ...
airborne wind power system relies on the wind for support.
![Crosswind kite power station with fast motion transfer having two wings offshore](https://upload.wikimedia.org/wikipedia/commons/9/91/Crosswind_kite_power_station_with_fast_motion_transfer_having_two_wings_offshore.jpg)
In one class, the generator is aloft; an aerodynamic structure resembling a
kite
A kite is a tethered heavier than air flight, heavier-than-air or lighter-than-air craft with wing surfaces that react against the air to create Lift (force), lift and Drag (physics), drag forces. A kite consists of wings, tethers and anchors. ...
, tethered to the ground, extracts wind energy by supporting a wind turbine. In another class of devices, such as
crosswind kite power
Crosswind kite power is power derived from a class of airborne wind-energy conversion systems (AWECS, also AWES) or crosswind kite power systems (CWKPS). The kite system is characterized by energy-harvesting parts flying transverse to the directio ...
, generators are on the ground; one or more airfoils or kites exert force on a tether, which is converted to electrical energy. An airborne turbine requires conductors in the tether or some other apparatus to transmit power to the ground. Systems that rely on a winch can instead place the weight of the generator at ground level, and the tethers need not conduct electricity.
Aerodynamic wind energy systems have been a subject of research interest since at least 1980.
[M. Loyd]
"Crosswind Kite Power"
J. Energy, vol. 4, no. 3, pp. 106-111, 1980 Multiple proposals have been put forth but no commercial products are available.
Other projects for airborne wind energy systems include:
*
Ampyx Power
Ampyx Power is a Dutch company based in The Hague whose aim is to develop utility-scale airborne wind energy systems. The company was founded in 2008 by Bas Lansdorp and Dr. Richard Ruiterkamp and is currently focused on verification testing of a ...
*
Kitepower
Kitepower is a registered trademark of the Dutch company Enevate B.V. developing mobile airborne wind power systems.
Kitepower was founded in 2016 by Johannes Peschel and Roland Schmehl as a university spin-off from the Delft University of Techno ...
*
KiteGen
KiteGen is a concept for a wind harnessing machine for high altitude winds, developed in Italy. The vertical axis rotation is intended to eliminate the static and dynamic problems that limit the size of conventional wind turbines. The prototype S ...
* Rotokite
* HAWE System
*
SkySails
SkySails Group GmbH is a Hamburg-based company that sells kite rigs to propel cargo ships, large yachts and fishing vessels by wind energy as well as airborne wind energy systems for electricity production from high-altitude winds.
Busines ...
*
X-Wind technology
Crosswind kite power is power derived from a class of airborne wind-energy conversion systems (AWECS, also AWES) or crosswind kite power systems (CWKPS). The kite system is characterized by energy-harvesting parts flying transverse to the directio ...
*
Makani Power
Makani Technologies LLC was an Alameda, California-based company that developed airborne wind turbines. Founded in 2006, Makani was acquired by Google in May 2013. In February 2020, Makani was shut down by Alphabet, Google's parent company.
Hi ...
crosswind hybrid kite system
*Windswept and Interesting Kite Turbine Ring to Ring Torque Transfer
*Kitemill
Aerostat variety
An aerostat-type wind power system relies at least in part on
buoyancy
Buoyancy (), or upthrust, is an upward force exerted by a fluid that opposes the weight of a partially or fully immersed object. In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid. Thus the p ...
to support the wind-collecting elements. Aerostats vary in their designs and resulting
lift-to-drag ratio
In aerodynamics, the lift-to-drag ratio (or L/D ratio) is the lift generated by an aerodynamic body such as an aerofoil or aircraft, divided by the aerodynamic drag caused by moving through air. It describes the aerodynamic efficiency under give ...
; the kiting effect of higher lift-over-drag shapes for the aerostat can effectively keep an airborne turbine aloft; a variety of such kiting balloons were made famous in the
kytoon
A kytoon or kite balloon is a tethered aircraft which obtains some of its lift dynamically as a heavier-than-air kite and the rest aerostatically as a lighter-than-air balloon. The word is a portmanteau of kite and balloon.
The primary advantage ...
by
Domina Jalbert.
Balloons
A balloon is a flexible bag that can be inflated with a gas, such as helium, hydrogen, nitrous oxide, oxygen
Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the per ...
can be incorporated to keep systems up without wind, but balloons leak slowly and have to be resupplied with lifting gas, possibly patched as well. Very large,
sun-heated balloons may solve the helium or hydrogen leakage problems.
An
Ontario
Ontario ( ; ) is one of the thirteen provinces and territories of Canada.Ontario is located in the geographic eastern half of Canada, but it has historically and politically been considered to be part of Central Canada. Located in Central Ca ...
based company called Magenn was developing a turbine called the Magenn Air Rotor System (MARS). A future -wide MARS system would use a horizontal rotor in a
helium
Helium (from el, ἥλιος, helios, lit=sun) is a chemical element with the symbol He and atomic number 2. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas and the first in the noble gas group in the periodic table. ...
suspended apparatus which is tethered to a transformer on the ground. Magenn claims that their technology provides high torque, low starting speeds, and superior overall efficiency thanks to its ability to deploy higher in comparison to non-aerial solutions.
The first prototypes were built by TCOM in April 2008. No production units have been delivered.
Boston-based
Altaeros Energies uses a helium-filled balloon shroud to lift a wind turbine into the air, transferring the resultant power down to a base station through the same cables used to control the shroud. A 35-foot prototype using a standard
Skystream 2.5kW 3.7m wind turbine was flown and tested in 2012. In fall 2013, Altaeros was at work on its first commercial-scale demonstration in Alaska.
See also
*
High-altitude wind power
*
Ram air turbine
A ram air turbine (RAT) is a small wind turbine that is connected to a hydraulic pump, or electrical generator, installed in an aircraft and used as a power source. The RAT generates power from the airstream by ram pressure due to the speed o ...
References
External links
*Kitemill - Taking windpower to new heights
Energy Kite SystemsWhy Airborne Wind EnergyAirborne Wind Energy Labs
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{{DEFAULTSORT:Airborne Wind Turbine
Aerodynamics
Electrical generators
Electromechanical engineering
Energy conversion
Kites
Airborne wind power
Wind turbines