High altitude wind power - AbsoluteAstronomy.com

High-altitude wind power (HAWP) has been imagined as a source of useful energy since 1833 with John Etzler's vision of capturing the power of wind

Wind

Wind is the flow of gases on a large scale. On Earth, wind consists of the bulk movement of air. In outer space, solar wind is the movement of gases or charged particles from the sun through space, while planetary wind is the outgassing of light chemical elements from a planet's atmosphere into space...

s high in the sky by use of tether
Tether
A tether is a cord, fixture, or signal that anchors something movable to a reference point which may be fixed or moving. There are a number of applications for tethers: balloons, kites, tethered wind-energy conversion systems, anchors, tethered water-flow energy conversion systems, towing, animal...

and cable technology. An atlas of the high-altitude

Altitude

Altitude or height is defined based on the context in which it is used . As a general definition, altitude is a distance measurement, usually in the vertical or "up" direction, between a reference datum and a point or object. The reference datum also often varies according to the context...

wind power resource has been prepared for all points on earth.

Various mechanisms are proposed for capturing the kinetic energy

Kinetic energy

The kinetic energy of an object is the energy which it possesses due to its motion.It is defined as the work needed to accelerate a body of a given mass from rest to its stated velocity. Having gained this energy during its acceleration, the body maintains this kinetic energy unless its speed changes...

of winds such as kites, kytoon

Kytoon

A kytoon is a kite with a significant amount of aerostatic lift from a lighter than air gas carried within.The primary advantage of a kytoon is that it remains up and at a reasonably stable position above the tether point, irrespective of the wind.The kytoon has been used in peace and war...

s, aerostat

Aerostat

An aerostat is a craft that remains aloft primarily through the use of buoyant lighter than air gases, which impart lift to a vehicle with nearly the same overall density as air. Aerostats include free balloons, airships, and moored balloons...

s, gliders

Glider (sailplane)

A glider or sailplane is a type of glider aircraft used in the sport of gliding. Some gliders, known as motor gliders are used for gliding and soaring as well, but have engines which can, in some cases, be used for take-off or for extending a flight...

, gliders with turbine

Turbine

A turbine is a rotary engine that extracts energy from a fluid flow and converts it into useful work.The simplest turbines have one moving part, a rotor assembly, which is a shaft or drum with blades attached. Moving fluid acts on the blades, or the blades react to the flow, so that they move and...

s for regenerative soaring, sailplanes with turbines, or other airfoils, including multiple-point building- or terrain-enabled holdings. Once the mechanical energy is derived from the wind's kinetic energy, then many options are available for using that mechanical energy: direct traction, conversion to electricity aloft or at ground station, conversion to laser or microwave for power beaming to other aircraft or ground receivers. Energy generated by a high-altitude system may be used aloft or sent to the ground surface by conducting cables, mechanical force through a tether, rotation of endless line loop, movement of changed chemicals, flow of high-pressure gases, flow of low-pressure gases, or laser or microwave power beams.

High-altitude wind for power purposes

Winds at higher altitudes become steadier, more persistent, and of higher velocity. Because power available in wind increases as the cube of velocity (the velocity-cubed law), assuming other parameters remaining the same, doubling a wind's velocity gives 2x2x2=8 times the power; tripling the velocity gives 3x3x3=27 times the available power. With steadier and more predictable winds, high-altitude wind has an advantage over wind near the ground. Being able to locate HAWP to effective altitudes and using the vertical dimension of airspace for wind farming brings further advantage using high-altitude winds for generating energy.

High-altitude wind generators can be adjusted in height and position to maximize energy return, which is impractical with fixed tower-mounted wind generators.

In each range of altitudes there are altitude-specific concerns being addressed by researchers and developers. As altitude increases, tethers increase in length, the temperature of the air changes, and vulnerability to atmospheric lightning changes. With increasing altitude, exposure to liabilities increase, costs increase, turbulence exposure changes, likelihood of having the system fly in more than one directional strata of winds increases, and the costs of operation changes. HAWP systems that are flown must climb through all intermediate altitudes up to final working altitudes—being at first a low- and then a high- altitude device.

Methods of capturing kinetic energy of high-altitude winds

Energy can be captured from the wind by kites, kytoons, tethered gliders, tethered sailplanes, aerostats (spherical as well as shaped kytoons), bladed turbines, airfoils, airfoil matrices, balloons, parachutes, drogues, variable drogues, spiral airfoils, Darrieus turbines, Magnus-effect VAWT blimps, multiple-rotor complexes, fabric Jalbert-parafoil kites, uni-blade turbines, flipwings, tethers, bridles, string loops, wafting blades, undulating forms, piezoelectric materials, and more.

When a scheme's purpose is to propel ships and boats, the objects tether-placed in the wind will tend to have most of the captured energy be in useful tension in the main tether. The aloft working bodies will be operated to maintain useful tension even while the ship is moving. This is the method for powerkiting sports. This sector of HAWP is the most installed method. The folklore is that Benjamin Franklin used the traction method of HAWP. George Pocock

George Pocock (inventor)

George Pocock was an English schoolteacher and inventor of the "Charvolant", a kite-drawn carriage.Pocock was interested in kites from an early age, and experimented with pulling loads using kite power, gradually progressing from small stones to planks and large loads. He taught at a school in...

was a leader in tugging vehicles by traction.

Controls

HAWP aircraft need to be controlled. Solutions in built systems have control mechanisms variously situated. Some systems are passive, or active, or a mix. When a kite steering unit (KSU) is lofted, the KSU may be robotic and self-contained; a KSU may be operated from the ground via radio-control by a live human operator or by smart computer programs. Some systems have built sensors in the aircraft body that report parameters like position, relative position to other parts. Kite control units (KCU) have involved more than steering; tether reeling speeds and directions can be adjusted in response to tether tensions and needs of the system during a power-generating phase or return-non-power-generating phase. Kite control parts vary widely.

Methods of converting mechanical energy to other forms of energy

The mechanical energy

Mechanical energy

In physics, mechanical energy is the sum of potential energy and kinetic energy present in the components of a mechanical system. It is the energy associated with the motion and position of an object. The law of conservation of energy states that in an isolated system that is only subject to...

of the device may be converted to heat

Heat

In physics and thermodynamics, heat is energy transferred from one body, region, or thermodynamic system to another due to thermal contact or thermal radiation when the systems are at different temperatures. It is often described as one of the fundamental processes of energy transfer between...

, sound

Sound

Sound is a mechanical wave that is an oscillation of pressure transmitted through a solid, liquid, or gas, composed of frequencies within the range of hearing and of a level sufficiently strong to be heard, or the sensation stimulated in organs of hearing by such vibrations.-Propagation of...

, electricity

Electricity

Electricity is a general term encompassing a variety of phenomena resulting from the presence and flow of electric charge. These include many easily recognizable phenomena, such as lightning, static electricity, and the flow of electrical current in an electrical wire...

, light

Light

Light or visible light is electromagnetic radiation that is visible to the human eye, and is responsible for the sense of sight. Visible light has wavelength in a range from about 380 nanometres to about 740 nm, with a frequency range of about 405 THz to 790 THz...

, tension, pushes, pulls, laser

Laser

A laser is a device that emits light through a process of optical amplification based on the stimulated emission of photons. The term "laser" originated as an acronym for Light Amplification by Stimulated Emission of Radiation...

, microwave

Microwave

Microwaves, a subset of radio waves, have wavelengths ranging from as long as one meter to as short as one millimeter, or equivalently, with frequencies between 300 MHz and 300 GHz. This broad definition includes both UHF and EHF , and various sources use different boundaries...

, chemical changes, or compression of gases. Traction is a big direct use of the mechanical energy as in tugging cargo ships and kiteboarders. The methods of getting the mechanical energy from the wind's kinetic energy are several. Lighter-than-air (LTA) moored aerostat

Aerostat

s are employed as lifters of turbine

Turbine

s. Heavier-than-air (HTA) tethered airfoil

Airfoil

An airfoil or aerofoil is the shape of a wing or blade or sail as seen in cross-section....

s are being used as lifters or turbines themselves. Combinations of LTA and HTA devices in one system are being built and flown to capture HAWP. Even a family of free-flight airborne devices are represented in the literature that capture the kinetic energy of high-altitude winds (beginning with a description in 1967 by Richard Miller in book Without Visible Means of Support) and a contemporary patent application by Dale C. Kramer, soaring sailplane competitor, inventor.

Electric generator position in a HAWP system

Electricity generation is just one of the optional choices of using captured mechanical energy; however, this option dominates the focus of professionals aiming to supply large amounts of energy to commerce and utilities. A long array of secondary options include tugging water turbines, pumping of water, or compressing air or hydrogen. The position of the electric generator is a distinguishing feature among systems. Flying the generator aloft is done in a variety of ways. Keeping the generator at the mooring region is another large design option. The option in one system of a generator aloft and at the ground station has been used where a small generator operates electronic devices aloft while the ground generator is the big worker to make electricity for significant loads.

Aerostat-based HAWP

One method of keeping working HAWP systems aloft is to use buoyant aerostats whether or not the electric generator is lifted or left on the ground. The aerostats are usually, but not always, shaped to achieve a kiting lifting effect. Recharging leaked lifting gas

Lifting gas

Because of the Archimedes' principle, a lifting gas is required for aerostats to create buoyancy. Its density is lower than that of air . Only certain lighter than air gases are suitable as lifting gases.- Hot Air :...

receives various solutions.

W. R. Benoit US Patent 4350897 Lighter than air wind energy conversion system by William R. Benoit, filed Oct 24,1980, and issued: Sep 21, 1982.

The TWIND system is based on the use of a sail surface elevated by the climbing force of an aerostatic balloon connected to the ground by a cable used also for energy transmission. The wind present at high altitudes creates a horizontal push on the sail which in its movement transmits this energy to the ground via the connecting cable. At the end of its movement forward, the sail surface is reduced allowing it to move upwind with reduced energy waste.

The Magenn aerostat is a vertical-axis wind turbine held with its axis horizontal by bridling the axis traverse to the wind so that Magnus-effect lift obtains during autorotation; the electricity is generated with end-hub generators.

The LTA Windpower PowerShip uses lift from both an aerostat and wings. It operates close to neutral buoyancy and doesn't require a winch. Power is generated by turbines with the propellers on the trailing edge of the wings. The system is designed to be able to take off and land unattended.

Airbine proposes to lift wind turbines into the air by use of aerostats; the electricity would return to ground loads by way of conductive tether.

Airship power turbine by William J. Mouton, Jr., and David F. Thompson: Their system integrated the turbine within the central portion of a near-toroidal aerostat, like putting a turbine in the hole of an aerostat donut.

Non-airborne HAWP

Conceptually, two adjacent mountains (natural or terrain-enabled) or artificial buildings or towers (urban or artificial) could have a wind turbine suspended between them by use of cables. When HAWP is cabled between two mountain tops across a valley, the HAWP device is not airborne, but borne up by the cable system. No such systems are known to be in use, though patents teach these methods. When non-cabled bridges are the foundation for holding wind turbines high above the ground, then these are grouped with conventional towered turbines and are outside the intent of HAWP where the tethering an airborne system is foundational.

HAWP Safety

Lightning

Lightning is an atmospheric electrostatic discharge accompanied by thunder, which typically occurs during thunderstorms, and sometimes during volcanic eruptions or dust storms...

, aircraft traffic, emergency procedures, system inspections, visibility marking of system parts and its tethers, electrical safety, runaway-wing procedures, over-powering controls, appropriate mooring, and more form the safety environment for HAWP systems.

Challenges of HAWP as an emerging industry

There have been several periods of high interest in HAWP before the contemporary activity. The first period had a high focus on pulling carriages over the lands and capturing atmospheric electricity and lightning for human use. The second period was in the 1970s and 1980s when research and investment flourished; a drop in oil price resulted in no significant installations of HAWP. Return on investment

Return on investment

Return on investment is one way of considering profits in relation to capital invested. Return on assets , return on net assets , return on capital and return on invested capital are similar measures with variations on how “investment” is defined.Marketing not only influences net profits but also...

(ROI) has been the key parameter; that ROI remains in focus in the current development activity while in the background is the renewable and sustainable energy movement supporting wind power of any kind; but HAWP must compete on ROI with conventional towered solutions.

HAWP patents

Patents for kite and kytoon systems that work with energy obtained from upper winds are one of the significant tools being employed to advance the nascent HAWP industry.

Timeline for HAWP

Early centuries of kiting demonstrated that the kite is a rotary engine that rotates its tether part about its mooring point and causes hands and arms to move because of the energy captured from higher winds into the mechanical device. The tension in the lofted devices performs the work of lifting and pulling body parts and things. Airborne wind energy (AWE) for HAWP was birthed th ousands of years ago; naming what happened and developing the implied potentials of tethered aircraft for doing special works is what is occurring in AWE HAWP. What is "low" for some workers is "high" for others.

1796 George Pocock (inventor)
George Pocock (inventor)
George Pocock was an English schoolteacher and inventor of the "Charvolant", a kite-drawn carriage.Pocock was interested in kites from an early age, and experimented with pulling loads using kite power, gradually progressing from small stones to planks and large loads. He taught at a school in...

used traction mode to travel in vehicles over land roads.

1827 George Pocock's book ‘The Aeropleustic Art’ or 'Navigation in the Air by the Use of Kites or Buoyant Sails' was published. The book was to be republished again several times. The Charvolant or Kite Carriage was described. Importantly Pocock described use of kites for land and sea travel.

1833 John Adolphus Etzler saw HAWP blossoming at least for traction.

1864? Book's chapter Kite-Ship well describes key dynamics of HAWP used for tugging ships by kites. John Gay's: or Work for Boys. Chapter XVIII in the Summer volume.

1943 Stanley Biszak instructed using potential energy in free-flight for converting ambient winds impacting turbine to drive electric generator to charge batteries.

1967 Richard Miller, former editor of Soaring magazine, published book Without Visible Means of Support that describes the feasibility of free-flight coupled non-ground-moored kites to capture differences in wind strata to travel across continents; such HAWP is the subject of Dale C. Kramer's contemporary patent application.

1973? Hermann Oberth
Hermann Oberth
Hermann Julius Oberth was an Austro-Hungarian-born German physicist and engineer. He is considered one of the founding fathers of rocketry and astronautics.- Early life :...

In the appendix of his book Primer for Those Who Would Govern there are sketches and a photograph of a model of the Kite Power Station from the Oberth Museum.

1977 April 3, 1977, invention declared. On September 21, 1979, Douglas Selsam notarized his kite-lifted endless chain of airfoils HAWP system, generic type that would later show in Dutch astronaut Wubbo Ockels' device called LadderMill described in a patent of 1997. Douglas Selsam conceived his Auto-oriented Wind Harnessing Buoyant Aerial Tramway on April 3, 1977. On the Selsam notarized disclosure of invention was placed a date of Sept. 20, while the notary placed the final signing on Sept. 21, 1979. notes and drawings.

1979 Professor Bryan Roberts begins giromill gyrocopter-type HAWP wind generator development.

1986 Bryan Roberts' AWE HAWP rotor generates electricity and lifts itself in tethered flight.

1992 Free Rotor WO/1992020917 Free Rotor by JACK, Colin, Humphry, Bruce (one man). Colin Jack. Colin Bruce. Multi-rotors are treated. Faired tethers are recognized. 1992.

2001 September 6. Method of Utilization a Flow Energy and Power Installation by physicist Alexander Bolonkin details ground generator of huge AWECS systems.
2001 Founding of SkySails
SkySails
SkySails GmbH & Co. KG is a Hamburg-based company that sells equipment to propel cargo ships, large yachts and fishing vessels by the use of wind energy. The company was founded in 2001 by engineers Stephan Wrage and Thomas Meyer...

company. As leader in ship traction HAWP, in 2010 they note having just less than 10 installations.

2002 Drachen Foundation awarded a grant to David Lang so that he would explore the use of kites to generate practical power.

2004 Physicist Alexander Bolonkin presented a strong analysis toward groundgen AWECS.

2004 Drachen Foundation had David Lang, former NASA expert, aerospace consultant, conduct a survey-study of kite-based power generation. He published a summary of methods in his view.

2005 HAWP conference held at AeroVironment
AeroVironment
AeroVironment Inc. is a technology company in Monrovia, California, and Simi Valley, California, that is primarily involved in energy systems, electric vehicle systems, and unmanned aerial vehicles . Paul B. MacCready, Jr., a famous designer of human powered aircraft, founded the company in 1971...

, Pasadena, CA; attendees: Paul MacCready, Dave Lang, Joe Hadzicki, Scott Skinner. The long meeting was videotaped; the tape is in the archives of the Drachen Foundation, open to researchers.

2006 on October 19: Jong Chul Kim, filed for international patent protection for "Electric power generation system using hydro turbine tracted by paraglider." His further studies has been for at-sea production of hydrogen and other chemicals using HAWP tethering kite systems.

2006 Kite Sailing Symposium, Seattle, Washington, September 28–30, 2006.

2006 Dr. Paul MacCready
Paul MacCready
Paul B. MacCready, Jr. was an American aeronautical engineer. He was the founder of AeroVironment and the designer of the human-powered aircraft that won the Kremer prize...

, American aeronautical engineer, Inventor of the Year Award in 1981, publishes an influential article In Using Kites to Tap Power of Wind.

2006 January 30: First International Workshop on Modelling and Optimization of Power Generating Kites KITE-OPT 07 held in Belgium featured keynote speaker astronaut Prof. Wubbo Ockels
Wubbo Ockels
Prof. Dr. Wubbo Johannes Ockels is a Dutch physicist and a former ESA astronaut. In 1985 he participated in a flight on a space shuttle , making him the first Dutch citizen in space. He was not the first Dutch-born astronaut, as he is preceded by the naturalized American Lodewijk van den Berg, who...

.

2006 September: http://www.youtube.com/watch?v=raWyvOs0RZM A 40 kW prototype of high-altitude wind genereator is tested in Italy by Kite Gen
Kitegen
KiteGen is a concept developed in Italy for a wind harnessing machine that takes power from high altitude winds. The vertical axis orientation of the rotation is intended to eliminate the static and dynamic problems that prevent the increase in size of conventional wind turbines...

Research Massimo Ippolito.

2007 Dave Santos demonstrated lofted Portland KiteMotor at alt-energy West Coast Climate Convergence; the generation success was announced in HIPFiSH Columbia-Pacific's Alternative Monthly (Aug.-Sept./2007). KiteMotor Growing Pains

2008 Dave Santos demonstrates flipwings for AWE passive-control generator systems.

2009 January 28, University of Texas hosted Airborne Wind Energy Seminar in its Aerospace Engineering Department. Keynote presenter: Dave Santos of KiteLab.

2009 Dave Santos demonstrated passive control of kite-lifted working dynamic kite operating a string tripod to transfer kite-gained mechanical energy to a ground-based generator via pulley and crank; this was not a reel-method scheme.

2009 Towered WECS companies open departments for AWE HAWP: Two ground-hugging towered wind-turbine companies open AWE HAWP departments: SpiralAirfoil Airborne and Selsam.

2009 A first international industry association was founded: Airborne Wind Energy Industry Association

2009 August. Dr. Hong Zhang, Kyle Fitzpatrick, and other students demonstrate working generation of electricity from powerkiting in preparation for further academic HAWP studies at Rowan University, New Jersey.

2009 Nov. 5-6 : HAWP conferece in Chico, CA and Oroville, CA. Scores of HAWP and AWE companies and inventors attended. Systems demonstrated: KiteLab's lifted bladed turbine with generator aloft, Selsam multi-rotor torque-tube hybrid with groundstationed generator, SkyMill Energy autogiro RC-controlled reel-in-out method.

2009 Dec. 9 : TU Delft University holds Kite Dynamics Symposium 09 for HAWP as central focus.

2010 January 13. An announcement that a large investment will be made to construct a commercial utility-scale HAWP project in the city of Foshan
Foshan
Foshan is a city in central Guangdong province in southern China. The prefectural area under the city's jurisdiction over an area of about 3,840 km² and a population of 5.4 million of which 1.1 million reside in the city proper ....

, China.

2010 March 1–3: Three HAWP companies had booths at ARPA-E Technology Showcase, Gaylord Convention Center, Washington, DC. Investment and showcasing by HAWP entities: Joby Energy, Sky Windpower, Makani Power directed visitors to each other's booths.

2010 March 6. Eight airborne wind energy technology entity leaders in USA held a telephone conference and decided without objection to propose a modification to bill HR 3165; the primary line-item proposed modification entered to a congressional member was the inclusion of "airborne wind energy technology."

2010 April 24. Multiple chaotic systems effectively captured for useful work: Full demonstration of working mini-AWECS involving Double Pendulum
Double pendulum
In mathematics, in the area of dynamical systems, a double pendulum is a pendulum with another pendulum attached to its end, and is a simple physical system that exhibits rich dynamic behavior with a strong sensitivity to initial conditions. The motion of a double pendulum is governed by a set of...

and flapping kite wing-mill under lifter kite to drive clockworks system's charging lithium battery by KiteLab of Ilwaco, Washington, USA. Designer and builder: Dave Santos.

2010 Another international organization has been formed: Airborne Wind Energy Consortium

2010 May: USA's NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...

firms attention on AWECS by establishing an AWT data web site: NASA Wind Energy Airborne Harvesting Stystem Study. The NASA 2010 Innovation Fund selected Airborne Wind Turbine Energy Harvesting UAV Systems; project leader is Dr. Mark D. Moore, Aeronautics Systems.

2010, June 16 An international partnership between Dutch and Norwegian entities provides second-round financing for classic reel-in HAWP method using tethered powerplane system. Airborne wind energy technology firm Ampyx Power partners with Byte and Statkraft.

16 June 2010 A unique treasure of 700+ drawings by airborne wind energy techologist Dave Santos made from 2006 and into 2009 were made available to the public. Seven-hundred pages of drawings made from 2006 into 2009 by hand and mind of Dave Santos Alternate full name: David Santos Gorena-Guinn, roboticist, artist, founder of KiteLab, master instructor for KitePilotSchool, and chief technical officer for Airborne Wind Energy Industry Association (AWEIA).

2010 July 9: World's First Gondola Turbine Array Demo by KiteLab.

2010 September 29–30 Airborne Wind Energy Conference 2010. This complements the 2009 November first major international conference.

2010 October: The Wayne German Prize for Contributions to Airborne Wind Energy stated its second year awardee.

2010 November 25: CONOPS
Conops
Conops is a genus of fly from the family Conopidae. The larvae of Conops are parasitic on bees, especially bumblebees. Adults feed on nectar.-Species:*Subgenus Conops Linnaeus, 1761*C. ceriaeformis Meigen, 1824...

are being drafted by KiteLab, Ilwaco, WA, USA, and also NASA AWT project leader for submission to the USA's FAA toward obtaining response for potentially having airborne wind energy conversion systems as an integral part of aviation and air space.

2010 December 15. IPP: Capturing Wind Energy Through Airborne Platforms (IPP :: Innovative Partnerships Program NASA)

2011 January 15: The 10th Annual Windless Kite Festival in Long Beach, WA (USA): Dave Santos successfully demonstated keeping a kite flying circling in no wind via use of tri-tether rig. Such proves a method for AWECS station-keeping when wind fails to keep the HAWP craft flying. The arrangement is a reverse of what Santos priorly demonstrated where kites can drive ground generator through a tri-tether rig.

2011 August 25: The 1st report on the high-altitude wind energy technologies and markets is published by GL Garrad Hassan. It is the first of it's kind and purely focuses on high-altitude wind energy systems. The Market Status Report on High Altitude Wind Energy provides an detailed overview on wind energy resources, different systems and technologies, involved companies and the market potential. The market part focuses on the offshore application of high-altitude wind energy.

External links

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