A technical Report from Scope e-Knowledge Center

1. Airborne Wind Turbines –
A Technical Report
Scope e-Knowledge Center Pvt Ltd
July 2013

2. Table of Contents
1. Wind – The Ultimate Renewable Energy Source ...............................................1
2. Energy High at High Altitudes ..............................................................................2
3. Airborne Wind Energy on the Rise ......................................................................4
4. Research & Development......................................................................................6
5. Conclusion ..............................................................................................................7
6. References ..............................................................................................................8

3. Page # 1
1. Wind – The Ultimate Renewable Energy Source
The origin of wind energy technology traces back to 7
th
century AD in Iran. Today, it is spread the world
over. The technology has become increasingly affordable due to reductions in manufacturing and
installation costs, and hence, is more prevalent.
With the growing increase in the demand for alternate sources of sustainable energy worldwide, wind
power is gaining importance across the globe. Wind energy currently accounts for nearly half of the clean
energy produced worldwide and is predicted to grow 25% each year.
Below are the different segments of the wind turbine market:
Horizontal Axis Wind Turbine (HAWT)
Vertical Axis Wind Turbine (VAWT)
Small Wind turbines
Airborne wind turbines
According to data from the Global Wind Energy Council (GWEC) and Greenpeace International, by the
year 2020, wind turbines will supply 12% of the global electricity and also will be a major contributor in
reducing CO2 emissions (a reduction of 1.5 billion tons of CO2 per year). In addition to the environmental
benefits, wind energy will be a sustainable solution to the mounting concerns over the security of energy
supply and volatile fossil fuel prices.

4. Page # 2
2. Energy High at High Altitudes
The traditional wind turbines also face a few challenges as below.
Conventional wind turbines
 Produce varying power due to
inconsistent and unpredictable wind
conditions
 Are noisy
 Impact visual and aesthetic of the region
 Affect wild life
Wind doesn’t blow all the time in most places. To harness the available wind energy, scientists and
engineers are now seeking a new wind resource at very high altitudes, i.e., Airborne Wind Energy
Systems (AWE). When compared to the conventional wind turbines, the high altitude wind power
(airborne wind turbines) extracts 100 times greater kinetic energy.
Wind at high altitudes is almost constant and hence, is a vast energy resource than surface winds. Since
high altitudes have fast and more consistent wind blowing, airborne wind turbines (ATW) can generate
more power compared to traditional wind turbines. Further, ATWs make energy harvesting possible even
at inaccessible locations, such as offshore, but at lesser installation costs. Given these merits, the
airborne wind energy industry is uniquely positioned to contribute to the growth of the overall wind
industry.
Airborne wind turbines are suspended in the air without a tower, thus saving any expenses on tower
construction. This type of turbines can operate in low or high altitudes, and the variants include,
AWT supported by balloon buoyancy
AWT working on kites
AWT based on tethered auto gyros
Functioning of an airborne wind turbine is a combination of kite and balloon, and the kytoon (a
compressed name for kite and balloon) is kept aloft by steady breezes. Airborne wind turbines are
secured to the ground using electrically conductive tethers, which transmit energy to the ground.

5. Page # 3
Airborne wind turbine
Source: http://enturkenerji.com/news/16/airborne_wind_turbine_technology
The different methodologies used in AWTs to convert wind energy into electricity are:
Employing an aircraft, similar to an airplane, with several propellers that serve as wind turbines,
flying at high altitudes
Flying generators suspended using balloons
Using a blimp, a lighter-than-air, pressurized airship comprising a gas-filled elliptical bag for
propelling
Though airborne wind turbine technology innovations started during 1970’s, its effective evolution was
during 2008-2009. In the year 2010, AWT technology innovations recorded a remarkable growth of 35%,
compared to 14% in the previous year. However, the growth phase has declined in 2011 and 2012.
Nevertheless, in the following years, there are possibilities of some more interesting innovations.
Technology trend of airborne wind turbines

6. Page # 4
3. Airborne Wind Energy on the Rise
The airborne wind turbine technology can be categorized under four major types based on their design
concept:
Kite type
Balloon type
Kytoon type (Combined Kite & Balloon)
Tethered auto gyro type
A research on airborne wind turbine technology innovations reveals that the “Kite type AWTs” technique,
the most common type, has high scope of growth in the future; it has contributed for about 44% of the
total airborne wind energy during 2008 – 2012. The kite type AWTs extract energy through wind turbines
suspended at high altitudes using kites such as multi-tethered kite, kite and dual purpose circular fan,
rotary wing kites etc.
The next popular technology is the “Tethered gyro type AWT”, which has shown a growth rate of 29% in
the last five years. In the tethered autogyro type, wind turbines are floated by means of either tethered
crankshaft, unmanned aerial vehicle, gyroplane, or gyrocopter arrangements along with an unpowered
rotor in autorotation to develop lift and engine powered propeller to provide thrust.
Technology spread across four major categories
“Balloon type AWTs” and “Kytoon type AWTs” are the other two types of airborne wind turbine design
techniques, but they have shown minimal and inconsistent growth over the period of 2008 - 2012. The
“Balloon type AWTs” extract energy from wind turbines carried aloft using balloons (of varied types) or
blimp/inglatable bodies/envelope filled with lighter-than-air gas such as helium gas to provide buoyancy to

7. Page # 5
the entire arrangement irrespective of air motion. The “Kytoon type AWTs” utilize both kite and balloon
arrangements for generating power from high altitude winds.
In the airborne wind turbine sector, about 64% of innovations are held by companies, mainly on AWT
design technologies. Individual inventors account for the remaining 36%. This indicates that there is a
growing interest of independent inventors in this technology. Given the scenario, the new entrants have
wide opportunities to enter into technology licensing with the individual inventors to establish their AWT
market.
Contirbution of Individual inventors and Companies
As per citations/references on future innovative ideas, “Tethered auto gyro type AWT” is the technology
that is of high interest. The highly-referred technology discusses on the different arrangements of tethered
wind turbine comprising lighter-than-air structural design with an aerodynamic shape to concentrate
wind's forces, auto-pilot feature to maintain straight-level flight during wind current fluctuations, and
methods to yield higher power using high altitude wind.
Citation of different AWT technologies

8. Page # 6
4. Research & Development
Though many innovative designs and ideas are patented under this airborne wind energy sector,
commercialization of the technology ideas has not achieved great success due to various technology and
regulatory challenges, space constraints, noise and aesthetics. A large number of players in the airborne
wind turbine industry are still in R&D phase, and a few others are in their prototype stage.
Some of the companies involved in AWT research have not protected their intellectual property, while a
few individual innovators and companies have patented their technology, yet not commercialized their
innovative ideas.
The below tables have details of few major players working on airborne wind turbine prototypes and the
companies involved in technological research of AWTs, respectively.
Company Name
Patented
Technology
Prototype
KITE GEN  KITE GEN STEM
MAKANI POWER  MAKANI AWT
MAGENN  MAGENN AIR ROTOR SYSTEM (M.A.R.S.)
AMPYX POWER  POWERPLANES
SKYSAILS  SKYSAILS POWER
ALTAEROS ENERGIES INC.  ALTAEROS AIRBORNE WIND TURBINES
WINDLIFT INC  WINDLIFT MODEL 8 SYSTEM
WONGALEA HOLDINGS PTY LTD  
CROSSWIND POWER SYSTEMS INC  
OMNIDEA LDA  
CMNA POWER  
SEQUOIA AUTOMATION SRL  
BASELOAD ENERGY INC  
HONEYWELL INT INC  
BEIJING QIXIANG INNOVATION SCI&TECH  
ENERKITE  MOBILE AIRBORNE WIND ENERGY SYSTEM
EK30
KITENERGY SRL  KITENRG–YOYO GENERATORS
Company Name
Patented
Technology
Technology Under Research
JOBY ENERGY  JOBY - AIRBORNE WIND TURBINES
SKY WINDPOWER CORPORATION  WIND AIRBORNE TETHERED TURBINE
SYSTEM (WATTS)
SWISSKITEPOWER  SWISSKITEPOWER
ZANETTISTUDIOS S.R.L.  TWIND

9. Page # 7
5. Conclusion
With the demand for energy requirements increasing tremendously, it can be met by alternative energy
resources such as wind. Particularly, wind at high altitudes can generate more power compared to the
conventional wind turbines. In addition, this alternative energy source offers benefits such as easy
deploying, low installation cost and maintenance systems, and less wind fluctuations. In terms of
operational lifetime, installation cost and reliability, airborne systems attract the interests of many. While
airborne wind turbines are considered as a promising alternate for traditional power sources, their
advantages are questioned by many critics. Generating electricity at high altitudes has its own
challenges, such as unforeseen crashing, and therefore needs an automated control piloting to design
robust and reliable AWTs with additional safety. Like any other technology, airborne wind turbines too
have their own pros and cons, and great efforts are made across the globe to develop AWT as a great
supporting technology for the eco-friendly wind energy market.

10. Page # 8
6. References
http://www.gwec.net/publications/global-wind-energy-outlook/global-wind-energy-outlook-2012/
http://windturbinezone.com/wind-turbine/airborne-wind-turbine