Airborne Wind Turbines
An Airborne Wind Turbine
(AWT) is a wind turbine with a
rotor supported in the air
without a tower.
It is connected to the ground
via tethers. And in some cases,
consist of a generator on
board, or sometimes on
History of Wind Turbines
• The first windmill used for
the production of electricity
was built in Scotland in July
1887 by Prof James Blyth of
• Throughout the 20th
century, many people
developed small wind
stations suitable for farms
or residences, and larger
utility-scale wind generators
Airborne Wind Energy
Ground-Gen systems - In
which the conversion of
mechanical energy into
electrical energy takes place
on the ground.
Fly-Gen systems - In which
such conversion is done on
the aircraft in the air.
Types of Airborne Wind Turbines
Wind Energy Systems
The different types Of Ground-
Gen AWES –
a) Leading Edge Inflatable (LEI)
b) Supported Leading Edge (SLE)
c) Foil Kite (design from
d) Glider (design from Ampyx
e) Swept rigid wing (design from
f) Semi-rigid wing (design from
Ground-Generator Airborne Wind Energy
Systems - Working
During the generation phase, the aircraft is driven in a way to produce a
lift force and consequently a traction (unwinding) force on the ropes
that induce the rotation of the electrical generators.
Fly-Gen Airborne Wind
Different types of Fly-Gen AWES –
a) Plane with four turbines,
design by Makani Power.
b) Aircraft composed by a frame
of wings and turbines, design
by Joby Energy.
c) Toroidal lifting aerostat with a
wind turbine in the center,
called BAT (Buoyant Airborne
Turbine), design by Altaeros
d) Static suspension quad-rotor
in autorotation, design by Sky
a) Makani Power
This AWT takes off with the wing
plane in a vertical position, driven by
propellers thrust. This flight mode is
similar to a quad-copter flight and
rotors on AWT are used as engines.
Once all the rope length has been
unwound, the AWT changes flight
mode and becoming a tethered flight
In this flight mode a circular flight
path is powered by the wind itself
and rotors on AWT are used as
generators to convert power from
In order to land, a new change of
flight mode is performed, and the
AWT lands as a quad copter.
b) Joby Energy
This is similar to Makani, but
turbines are installed in the
joints of the frame.
In Joby's concept, the system is
assembled with modular
components, constructed from
multiple similar frames with
The power generation method
and the take-off and landing
maneuvers are similar to those
of Makani concept.
c) Altaeros Energies
Instead of using wings lift to fly,
they use a ring shaped aerostat
with a wind turbine installed in its
The whole generator is lighter
than the air, so the take-off and
landing maneuvers are simplified,
and the only remaining issue is
the stabilization of the generator
in the right position relative to
The aerostat is aerodynamically
shaped so that the absolute wind
generates lift that helps keeping a
high angle of altitude together
with the buoyancy force.
d) Sky WindPower
It is a large quad rotor with at least three identical
rotors mounted on an airframe that is linked to a
ground station with a rope having inner electrical
Take-off and landing maneuvers are similar to
those of Makani's and Joby's but generator
operation is different.
Once it reaches the operational altitude, the frame
is inclined at an adjustable controllable angle
relative to the wind (up to 50°) and the rotors
switch the functioning mode from motor to
generator. At this inclined position, the rotors
receive from their lower side a projection of the
natural wind parallel to their axes. This projection
of wind allows autorotation, thus generating both
electricity and thrust. Electricity flows to and from
the generator through the cable.
Sky Windpower tested two prototypes. They
claimed that a typical minimum wind speed for
autorotation and energy generation is round 10
m/s at an operational altitude.
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.
High altitude wind energy is currently a very promising resource for the sustainable
production of electrical energy. The amount of power and the large availability of winds that
blow between 300 and 10000 meters from the ground suggest that Airborne Wind Energy
Systems (AWESs) represent an important emerging renewable energy technology.
• Airborne Wind Turbines – A Technical Report by Scope e-Knowledge Centre Pvt. Ltd. – July 2013
• Airborne Wind Energy Systems: A review of the technologies
by - Antonello Cherubini, Andrea Papini, Rocco Vertechy, Marco Fontana
PERCRO SEES, TeCIP Institute, Scuola Superiore Sant'Anna, Pisa, Italy
Department of Industrial Engineering, University of Bologna, Italy.
• Airborne wind energy: Optimal locations and variability
by Cristina L. Archer, Luca Delle Monache, Daran L. Rife
College of Earth, Ocean, and Environment, University of Delaware, Newark,DE, US;
National Center for Atmospheric Research, Boulder, CO, United States
GL Garrad Hassan, San Diego, CA, United States
• Open Energy Information –
• Turbines Info-