Airborne wind turbine

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Kiwee One: an airborne wind turbine Kiwee One.jpg
Kiwee One: an airborne wind turbine

An airborne wind turbine is a design concept for a wind turbine with a rotor supported in the air without a tower, [1] thus benefiting from the higher velocity and persistence of wind at high altitudes, while avoiding the expense of tower construction, [2] or the need for slip rings 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. [3]

Contents

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. When the generator is on the ground, [4] 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. Kites and helicopters come down when there is insufficient wind; kytoons and blimps may resolve the matter with other disadvantages. Also, bad weather such as lightning or thunderstorms, 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 zone. As of 2022, few commercial airborne wind turbines are in regular operation. [5]

Aerodynamic variety

An aerodynamic airborne wind power system relies on the wind for support.

Crosswind kite generator with fast motion transfer Crosswind kite power station with fast motion transfer having two wings offshore.jpg
Crosswind kite generator with fast motion transfer

In one class, the generator is aloft; an aerodynamic structure resembling a kite, tethered to the ground, extracts wind energy by supporting a wind turbine. In another class of devices, such as crosswind kite power, 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.

The principle of the kite airborne wind turbine. Image source: Kitesforfuture Principle of kite energy.png
The principle of the kite airborne wind turbine. Image source: Kitesforfuture
A possible flight path of the kite airborne wind turbine. Image source: Kitesforfuture KiteEight.png
A possible flight path of the kite airborne wind turbine. Image source: Kitesforfuture

Aerodynamic wind energy systems have been a subject of research interest since at least 1980. [6] Multiple proposals have been put forth but no commercial products are available. [7] [8] Other projects for airborne wind energy systems include:

Aerostat variety

An aerostat-type wind power system relies at least in part on buoyancy to support the wind-collecting elements. Aerostats vary in their designs and resulting lift-to-drag ratio; 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 by Domina Jalbert.

Balloons 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 based company called Magenn [17] was developing a turbine called the Magenn Air Rotor System (MARS). [18] A future 1,000-foot (300 m)-wide MARS system would use a horizontal rotor in a helium 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. [19] The first prototypes were built by TCOM[ who? ] in April 2008. No production units have been delivered. [20]

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. [21] [22]

Another concept, released in 2023, proposed a helium-filled balloon with attached sails, which create pressure and drive the rotation of the system around its horizontal axis. The kinetic energy is transferred to a generator on the ground through ropes in circular motion. [23]

See also

Related Research Articles

<span class="mw-page-title-main">Aircraft</span> Vehicle or machine that is able to fly by gaining support from the air

An aircraft is a vehicle that is able to fly by gaining support from the air. It counters the force of gravity by using either static lift or the dynamic lift of an airfoil, or, in a few cases, direct downward thrust from its engines. Common examples of aircraft include airplanes, helicopters, airships, gliders, paramotors, and hot air balloons.

<span class="mw-page-title-main">Unpowered aircraft</span> Aerial vehicle capable of sustaining flight without onboard propulsion

Unpowered aircraft can remain airborne for a significant period of time without onboard propulsion. They can be classified as gliders, lighter-than-air balloons and tethered kites. In the case of kites, lift is obtained by tethering to a fixed or moving object, perhaps another kite, to obtain a flow of wind over the lifting surfaces. In the case of balloons, lift is obtained through inherent buoyancy and the balloon may or may not be tethered. Free balloon flight has little directional control. Gliding aircraft include sailplanes, hang gliders, and paragliders that have full directional control in free flight.

<span class="mw-page-title-main">Aerostat</span> Lighter-than-air aircraft

An aerostat is a lighter-than-air aircraft that gains its lift through the use of a buoyant gas. Aerostats include unpowered balloons and powered airships. A balloon may be free-flying or tethered. The average density of the craft is lower than the density of atmospheric air, because its main component is one or more gasbags, a lightweight skin containing a lifting gas to provide buoyancy, to which other components such as a gondola containing equipment or people are attached. Especially with airships, the gasbags are often protected by an outer envelope.

<span class="mw-page-title-main">Balloon (aeronautics)</span> Type of aerostat that remains aloft due to its buoyancy

In aeronautics, a balloon is an unpowered aerostat, which remains aloft or floats due to its buoyancy. A balloon may be free, moving with the wind, or tethered to a fixed point. It is distinct from an airship, which is a powered aerostat that can propel itself through the air in a controlled manner.

<span class="mw-page-title-main">Hybrid airship</span> Partially aero-static aircraft

A hybrid airship is a powered aircraft that obtains some of its lift as a lighter-than-air (LTA) airship and some from aerodynamic lift as a heavier-than-air aerodyne.

<span class="mw-page-title-main">Allsopp Helikite</span>

The Allsopp Helikite is a type of kite-balloon or kytoon designed by Sandy Allsopp in the UK in 1993. The Helikite comprises a combination of a helium balloon and a kite to form a single, aerodynamically sound, tethered aircraft, that utilizes both wind and helium for its lift.

Airborne wind energy (AWE) is the direct use or generation of wind energy by the use of aerodynamic or aerostatic lift devices. AWE technology is able to harvest high altitude winds, in contrast to wind turbines, which use a rotor mounted on a tower.

<span class="mw-page-title-main">Unconventional wind turbines</span> Wind turbines of unconventional design

Unconventional wind turbines are those that differ significantly from the most common types in use.

Southwest Windpower (SWWP) was a wind turbine manufacturer established in 1987 based in Flagstaff, Arizona, United States. The company specialized in small, reliable battery charging wind generators that complement photovoltaics (solar energy or PV) in supplying energy to rural areas.

<span class="mw-page-title-main">Tethered balloon</span>

A tethered, moored or captiveballoon is a balloon that is restrained by one or more tethers attached to the ground and so it cannot float freely. The base of the tether is wound around the drum of a winch, which may be fixed or mounted on a vehicle, and is used to raise and lower the balloon.

<span class="mw-page-title-main">Tethered Aerostat Radar System</span> Type of aircraft

The Tethered Aerostat Radar System (TARS) is an American low-level airborne ground surveillance system that uses aerostats as radar platforms. Similar systems include the EL/M-2083 and JLENS.

<span class="mw-page-title-main">Wind-powered vehicle</span> Vehicle propelled by wind

Wind-powered vehicles derive their power from sails, kites or rotors and ride on wheels—which may be linked to a wind-powered rotor—or runners. Whether powered by sail, kite or rotor, these vehicles share a common trait: As the vehicle increases in speed, the advancing airfoil encounters an increasing apparent wind at an angle of attack that is increasingly smaller. At the same time, such vehicles are subject to relatively low forward resistance, compared with traditional sailing craft. As a result, such vehicles are often capable of speeds exceeding that of the wind.

<span class="mw-page-title-main">Kytoon</span> Aircraft

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.

Unpowered flight is the ability to stay airborne for a period of time without using any power source. There are several types of unpowered flight. Some have been exploited by nature, others by humankind, and some by both.

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.

An aerostat is an aircraft that remains aloft through the use of lighter-than-air gases. A narrower and more technical meaning refers only to tethered balloons.

<span class="mw-page-title-main">Crosswind kite power</span> Form of wind-powered mechanical or electrical generation

Crosswind kite power is power derived from airborne wind-energy conversion systems or crosswind kite power systems (CWKPS). The kite system is characterized by energy-harvesting parts flying transverse to the direction of the ambient wind, i.e., to crosswind mode; sometimes the entire wing set and tether set is flown in crosswind mode. From toy to power-grid-feeding sizes, these systems may be used as high-altitude wind power (HAWP) devices or low-altitude wind power (LAWP) devices without having to use towers. Flexible wings or rigid wings may be used in the kite system. A tethered wing, flying in crosswind at many times wind speed, harvests wind power from an area that exceeds the wing's total area by many times.

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 Technology’s airborne wind energy research group established by the former astronaut Wubbo Ockels. The company is located in Delft, Netherlands, and currently comprises 18 employees (2018).

References

  1. ↑ Elliot, Dave (2014-04-12). "Flights of fancy: airborne wind turbines". Institute of Physics, Environmental Research Web. Archived from the original on 2014-04-19. Retrieved 2014-04-17.
  2. ↑ Specter, Michael (May 20, 2013). "Inherit the Wind". The New Yorker.
  3. ↑ Levitan, David (2012-09-24). "High-Altitude Wind Energy: Huge Potential — And Hurdles". Environment 360. How do you safely suspend airborne turbines hundreds or thousands of feet off the ground? How do you keep them aloft for long periods of time in high winds without having to perform frequent, costly maintenance? And what about interference with aviation?
  4. ↑ "Airborne Wind Energy Generation Systems". www.energykitesystems.net.
  5. ↑ Jones, Nicola (9 March 2022). "The kites seeking the world's surest winds". BBC. Retrieved 2022-04-02.
  6. ↑ M. Loyd, "Crosswind Kite Power", J. Energy, vol. 4, no. 3, pp. 106-111, 1980
  7. ↑ Jha, Alok (3 August 2008). "Giant kites to tap power of the high wind". The Guardian.
  8. ↑ "Welcome to the WPI Kite Power Wiki". Archived from the original on 2011-07-20. Retrieved 2008-05-05.{{cite web}}: CS1 maint: bot: original URL status unknown (link)
  9. ↑ Canale, Massimo, Lorenzo Fagiano, Mario Milanese, and Massimo Ippolito. KiteGen project: control as key technology for a quantum leap in wind energy generators, In 2007 American Control Conference, pp. 3522-3528. IEEE, 2007. https://doi.org/10.1109/ACC.2007.4282697
  10. ↑ "Rotokite" (PDF). Archived from the original (PDF) on 2016-10-26. Retrieved 2011-02-12.
  11. ↑ pedro. "FP7". www.omnidea.net. Archived from the original on 2015-02-26. Retrieved 2015-02-26.
  12. ↑ "SkySails GmbH - Compelling Technology". www.skysails.info. Archived from the original on 2011-09-28. Retrieved 2011-10-22.
  13. ↑ "NTS X-Wind". www.x-wind.de.
  14. ↑ Stone, Brad (28 May 2013). "Inside Google's Secret Lab". Bloomberg. Retrieved 3 April 2018.
  15. ↑ "Main - Windswept and Interesting". www.windswept-and-interesting.co.uk.
  16. ↑ "77 folkeinvestorer skal holde det svevende, norske kraftverket i himmelen hele døgnet, hele året" [77 public investors will keep the floating Norwegian power plant in the sky around the clock, all year round]. Teknisk Ukeblad . 11 January 2017. Retrieved 11 January 2017.
  17. ↑ ""Magenn Air Rotor System"". Archived from the original on 2012-03-29. Retrieved 2012-07-09.
  18. ↑ Kumar, Moses Dhilip (18 July 2013). "Technical World : MAGENN AIR ROTOR SYSTEM (M.A.R.S.)".
  19. ↑ "Magenn Power Inc. corporate website". Archived from the original on 11 December 2008. Retrieved December 14, 2008.
  20. ↑ Mazzella, Diana (2008-04-03). "Airborne turbine tested at TCOM; Magenn: MARS makes wind power mobile". The Daily Advance. Archived from the original on 2010-01-31. Retrieved 2008-11-23.
  21. ↑ McGonegal, Joe (2013-09-04). "Two Alums Dream of Tethered Aerostat Wind Farms". Slice of MIT. Archived from the original on 2013-09-07. Retrieved 2013-09-05.
  22. ↑ Cardwell, Diane (2014-03-21). "Wind Industry's New Technologies Are Helping It Compete on Price". New York Times.
  23. ↑ Michailidis, Giannis (2023-01-09), High-Altitude-Wind-Turbine-Concept , retrieved 2023-02-22

Bibliography

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