ENERGY KITE

Department of ECE Energy kite
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CHAPTER 1: INTRODUCTION
1.1 BACKGROUND
1.1.1 Introduction
Wind is rapidly becoming an important renewable energy source as the worry about
declining fossil fuel reserves and the global warming associated with their use continues to
grow. There has been a great deal of success in generating power from large windmills,
which accounted for 160 GW of power production in 2009. While this accounts for only
2% of worldwide electrical energy consumption, wind-powered generation increased 31.7%
from 2008 to 2009 while worldwide primary energy consumption slightly decreased in the
same timeframe.
Even though wind power generation is growing, there are a number of shortcomings
of current generating techniques using windmills. In particular, wind intermittency, costly
and easily damaged machinery, and large land usage requirements (in addition to aesthetic
and wildlife safety concerns) are some of the problems that need to be overcome. A
relatively new idea for wind power generation that can overcome many of these
shortcomings uses large kites to extract power from high-altitude winds. In this scheme,
very large and relatively inexpensive kites are tethered to ground-based generators. As the
kite pulls on the tethers, power is generated. The details of the generation depends upon the
exact scheme, but at the time of writing of this paper, many groups are working to achieve
practical power generation with kites (KiteGen, FlygenKite, Windlift, Festo, and kPower
are just a few companies working on this). In this report, one particular kite-powered system
will be explained, followed by a detailed analysis of estimates for the power production and
cost for this system. Lastly, kite-powered generators will be compared to current windmills
To overcome the limitations of current wind power technology, the KiteGen project
was initiated at Politecnico di Torino to design and build a new class of wind energy
generators in collaboration with Sequoia Automation, Modelway, and Centro
StudiIndustriali.The project focusis to capture wind energy by means of controlled tethered
airfoils, that is, kites; The KiteGen project has designed and simulated a small-scale
This yo-yo configuration is under the control of the kite steering unit,which includes
the electric drives, the drums, and all of the hardware needed to control a single kite. The

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aims of the prototype are to demonstrate the abil- ity to control the flight of a single kite, to
produce a significant amount of energy, and to verify the energy production levels
predicted in simulation studies
India is the home of 1.25 billon people i.e. 17.5% of the total world population, which
makes it second most populous country in world. India has the second fastest growing
economy of the world. India’s substantial and sustained economic growth over the years is
placing enormous demand on its energy resources. The electricity sector in India had an
installed capacity of 253.389 GW as of August 2014 .India became the world's third largest
producer of electricity in the year 2013 with 4.8% global share in electricity generation
surpassing Japan and Russia. Power development in India was first started in 1897 in
Darjeeling, followed by commissioning of a hydropower station at Sivansamudram in
Karnataka during 1902. Thermal power stations which generate electricity more than 1000
MW are referred as Super Thermal Power Stations. India's electricity generation capacity
additions from 1950 to 1985 were very low when compared to developed nations. Since
1990, India has been one of the fastest growing
markets for new electricity generation capacity .India's electricity generation capacity
has increased from 179 TW-h in 1985 to 1053 TW-h in 2012. Wind energy is indigenous
and helps in reducing the dependency on fossil fuels. Wind occurrence is due to the
differential heating of the earth's crust by the sun. Approximately 10 million MW of
wind energy is continuously available to India. India's Power Finance Corporation
Limited projects that current and approved electricity capacity addition projects in India are
expected to add about 100 GW of installed capacity between 2012 and 2017. This growth
makes India one of the fastest growing markets for electricity infrastructure equipment. Of
the 1.4 billion people of the world who have no access to electricity in the world, India
accounts for over 300 million.
The International Energy Agency estimates India will add between 600 GW to 1,200
GW of additional new power generation capacity before 2050 .To fill the needs of the
energy of this population, India have to look towards non conventional energy resource
which can fill a huge demand of energy
generated by the population of India. India is fulfilling its 85% of energy demand
from

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the conventional recourses such as coal, nuclear energy, natural gas and petroleum
which generate many greenhouse gases. Green houses gases- carbon dioxide (CO2), sulfur
dioxide (SO2), nitrous oxide (N2O) etc. are produced in the energy generation process are
not only harmful for people’s health but it also deteriorates the environment vis-à-vis
global warming and hole in the ozone layer. Thus it is the need of time that country
should look towards the green & renewable methods for the generation of energy so that the
energy demands of the country. Present paper has divided into three parts;
Sources of the wind energy in India, future scope of the wind energy in India &
Conclusion. Wind power was widely available and not confined to the banks of fast-
flowing streams, or later, requiringsources of fuel. Wind-powered pumps drained the
polders of the Netherlands, and in arid regions such as the American mid-west or the
Australian outback, wind pumps provided water for live stock and steam engines.
With the development of electric power, wind power found new applications in
lighting buildings remote from centrally-generated power. Throughout the 20th century
parallel paths developed small wind plants suitable for farms or residences, and
larger utility-scale wind generators that could be connected to electricity grids for remote
use of power. Today wind powered generators operate in every size range between tiny
plants for battery charging at
isolated residences, up to near-gigawatt sized offshore wind farms that provide
electricity to national electrical networks.
1.2 MOTIVATION
A kite is traditionally a tethered heavier-than-air craft with wing surfaces that react
against the air to create lift and drag. A kite consists of wings, tethers and anchors. Kites
have a bridle to guide the face of the kite at the correct angle so the wind can lift it. A kite
may have fixed or moving anchors.
The lift that sustains the kite in flight is generated when air flows around the kite's
surface, producing low pressure above and high pressure below the wings. The interaction
with the wind also generates horizontal drag along the direction of the wind. The resultant
force vector from the lift and drag force components is opposed by the tension of one or

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more of the lines or tethers to which the kite is attached. The anchor point of the kite line
may be static or moving.
The same principles of fluid flow apply in liquids and kites are also used under water.
Fig 1.1 example of energy kite
1.3 Wind Power Availability
Most available wind studies have been from ground level to approximately 100 m.
However, Archer and Caldiera have compiled available wind data as a function of altitude
and consistency to estimate available wind power. In order to compare these values to the
numbers given by KiteGen, a step must first be taken to convert their numbers to wind
power densities. According to Archer and Caldiera, the power available in the wind is is the
air mass density at 800 m (approximately 1.12 kg/m from standard exponential barametric
equations), and v is the wind velocity. From this equation, we find that 9 m/s corresponds to
0.4 kW/m2
. Comparing this to the plotted wind power densities in Fig. 3 of Archer and
Caldiera, we see that even at 1000 m, most of the world exceeds 0.2 kW/m2
less than 68% of
the time annually. In order to get winds with enough power density, the kites need to be
extended to much higher altitudes. Certainly there are locations around the world where
wind power is available at lower altitudes, but the large benefits of high-altitude wind are
only available at much greater heights.

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CHAPTER 2
TYPES OF KITE WIND GENERATORS
2.1 Multiple unit kites
Fig 2.1Multiple unit kites
A multiple unit kite may be made of a single wing, several wings, or several sub-
kiteunitsarranged as trains, chains, coterie, single-branching, multiple-branching, arch-
kite,"ladder" mill dynamic kite-chain, or combinations of these patterns. World records for
the number of kites in a kite train are in the literature; teams of people are used to fly kites
of high-count sub-kite units.Parafoil stacks have been built with over 200 kite units.

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2.2 Multiple pilot
Fig 2.2Multiple pilot
Large kite systems may require more than one pilot. In a team like the "Flying Squad"
of nine kite pilots each person might fly his own sub-kite while, as a team, its kites form a
unified display. One pilot may simultaneously fly several kites; the pilot with several kites
forms one kite system of two, three or more kites in the system.
2.3 Airplane kites:
Fig 2.3 Airplane kites

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Large kite planes are finding an application in renewable energy generation.
2.4 Aqua-glider
Fig 2.4 Aqua-glider
These various-formed manned kites were kited behind tow boats over water. Air
Force Lt. Col. Bill Skliar in 1959 designed a biplane kite glider nicknamed Bayou Bird. In
1961, Tom H. Purcell designed and flew an aluminum-framed Fleep-like Rogallo hang
glider kite over land; in 1962, he kited the same wing while over water. His effort was
imaged and noted in
Skysurfer Magazine in its May/June issue of 1973, published by EAA inductee
Michael Markowski, author of Hang Glider's Bible. The 1962 Mike Burns SkiPlane and
1963 Dickenson wings closely matched the Purcell, Barry Hill Palmer, and the Charles
Richard NASA Paresev 1B wing; minor control sticks derived from the triangle control
frame were
used in each of these kites. These kites, towed high, could stop their kiting and release
into a glide.

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CHAPTER 3
WORKING PRINCIPLE
3.1 OPERATION
Fig 3.1OPERATION
The KSU is the unit that allows to automatically piloting a power kite.
At the very core of the project stays the software that, receiving data also from on-
boardavionic sensors.
The KiteGen project has designed and simulated a small-scale prototype. The two kite
lines are rolled around two drums and linked to two electric drives, which are fixed to the
ground. The flight of the kite is controlled by regulating the pulling force on each line.
Energy is collected when the wind force on the kite unrolls the lines, and the electric drives
act as generators due to the rotation of the drums. When the maximal line length of about

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300 m is reached, the drives act as motors to recover the kite, spending a small percentage
of the previously
This yo-yo configuration is under the control of the kite steering unit, which includes
the electric drives the drums, and all of the hardware needed to control a single kite. The
aims of the prototype are to demonstrate the abil- ity to control the flight of a single kite, to
produce a signifi-cant amount of energy, and to verify the energy production levels
predicted in simulation studies. The potential of a similar yo-yo configuration is investi-
gated, by means of simulation results, in one or more kites linked to a single cable.
Thus, the control inputs are not only the roll angle ψ and the cable winding speed, as
considered
in this article, but also the lift coefficient CL. For medium-to-large-scale energy
generators, an alter- native KiteGen configuration is being studied, namely, the
carousel configuration. In this configuration, several airfoils are controlled by their KSUs
placed
on the arms of a verti- cal-axis rotor. The controller of each kite is designed to
maximize
the torque exerted on the rotor, which transmits its motion to an electric generator. For
a given wind direction, each airfoil can produce energy for about 300◦ of carousel rotation;
only a small fraction of the generated energy is used to drag the kite against the wind for the
remaining 60◦. According to our simulation results, it is estimated that the required land
usage for a kite generator may be lower than a current wind farm of the same power by a
factor of up to 30–50, with electric energy
Expert kite-surfers drive kites to obtain energy for propulsion. Control technology can
be applied to exploit this technique for electric energy generation.
The kite lines are linked to two electric drives. The flight of the kite is controlled by
regulating the pulling force on each line, and energy is generated as the kite unrolls the lines.
The kite steering unit, which provides auto- matic control for KiteGen, includes the
electric drives, drums, and all of the hardware needed to control a single kite.
Production costs lower by a factor up to 10–20. Such potential improvement over
current wind technology is due to several aerodynamic and mechanical reasons.This
dependence is due to the fact that the aerodynamic forces on each infinitesimal section of
the blades are proportional to the square of its speed with respect to the air, and this speed

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increases toward the tip of the blades. In KiteGen, the tethered airfoils act as the outer
portions of the blades, without the need for mechanical support of the tower and of the less-
productive inner blade portions. Indeed, a mean generated power of 620 kW is obtained in
the simulation reported for a single kite of 100-m2 area and 300-m line length.
3.2 SYSTEM AND CONTROL TECHNOLOGIES NEEDED
FOR KITEGEN
3.2.1 Control Design
The main objective of KiteGen control is to maximize energy generation while
preventing the airfoils from falling to the ground or the lines from tangling. The control
problem can be expressed in terms of maximizing a cost function that predicts the net
energy generation while satisfying constraints on the input and state variables. Nonlinear
model predictive control (MPC) is employed to accomplish these objectives, since it aims to
optimize a given cost function and fulfill constraints at the same time. However, fast
implementation is needed to allow real-time control at the required sampling time, which is
on the order of 0.1 s. In particular, the implementation of fast model predictive control
(FMPC) based on set membership approximation methodologies.
3.2.2 Model Identification
Optimizing performance for Kite- Gen relies on predicting the behavior of the system
dynamics as accurately as possible. However, since accurately modeling the dynamics of a
nonrigid airfoil is challenging, model-based control design may not perform satisfactorily
on the real system. In this case, methods for identifying nonlinear systems can be applied to
derive more accurate models.

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3.2.3 Sensors and Sensor Fusion
The KiteGen controller is based on feedback of the kite position and speed vector,
which must be mea- sured or accurately estimated. Each airfoil is thus equipped with a pair
of triaxial accelerometers and a pair
fulfilled, the DVS gives the same accuracy as the theoreti-cal minimal variance filter.
Moreover, in the presence of modeling errors and nonlinearities, the DVS guarantees
stability and performs tradeoffs between optimality and robustness, which are not
achievable with EKF.
Fig3.1 sensor

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CHAPTER 4
APPLICATIONS
4.1 Teaching
The kite is frequently the vehicle for teaching aerodynamics, mathematics, art, history,
culture, materials, cooperation, physical education, and problem solving
4.2 Transport
Long-distance travel across land, ice, and sea started centuries ago, but today
significant tasks of moving people and goods from point A to point B are occurring; this is
so in great part from the advances in kites and kite systems designs and technology, better
understanding of winds, and use of computers.In 1889 kite sailing was carefully instructed
via controlling large kite systems towing boats.
Free-flight cross-country hang gliding kites both in the hang glider style and the
paraglider
style are permitting trips of hundreds of miles; records are recorded by the FAI.
George Pocock was an early pioneer in kites for transportation. NASA continues to explore
free- flying kites for delivering goods to earth surface and non-earth planet surfaces,
including Mars. There are several projects for using very large kites to sail cargo ships
currently underway: KiteSail(tm) and KiteShip along with a series of patents and
improvements in control of large ship-carried kite systems aim to save significant amounts
of fuel.

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4.3 Military
Kites have been used for military uses in the past for signaling, for delivery of
munitions, for free-flight kiting payloads from aircraft to ground positions, for kiting troops
to points where they could parachute to destinations
Kim Yu-Sin,a Korean general, in 637 C.E. rallied his troops to defeat rebels by kite
lofting a burning ball.Kites were also used by Admiral Yi of the Joseon Dynasty of Korea.
During the Japanese invasions of Korea , Admiral Yi commanded his navy with kites. His
kites had specific markings directing his fleet to perform his order. Admiral Yi was said to
have over 300 such kites. The war eventually resulted in a Chinese and Korean victory; the
kites played a minor role in the war's conclusion.
4.4 Energy generation
Both air and hydro kites are used to generate electricity; the kite is set in the stream of
air or water; various schemes are used to extract some of the stream's energy for converting
that energy to electricity.
A major research and development project called Makani Power, based in California
and funded by Google.org, is investigating the use of kites in harnessing high altitude wind
currents to generate electricity.Tidal kites operate underwater, using the tidal stream's
greater mass to generate far more electricity than available in wind-borne environments.

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CHAPTER 5
ADVANTAGES & DISADVANTAGES
5.1 Advantages
The wind is free and with modern technology it can be captured efficiently
Once the wind turbine is built the energy it produces does not cause green house
gases or other pollutants
Although wind turbines can be very tall each takes up only a small plot of land.
This means that the land below can still be used. This is especially the case in agricultural
areas as farming can still continue
Many people find wind farms an interesting feature of the landscape
Remote areas that are not connected to the electricity power grid can use wind
turbines to produce their own supply
Wind turbines have a role to play in both the developed and third world
5.2 Disadvantages
The strength of the wind is not constant and it varies from zero to storm force. This
means that wind turbines do not produce the same amount of electricity all the time. There
will be times when they produce no electricity at all.
Many people feel that the countryside should be left untouched, without these large
structures being built. The landscape should left in its natural form for everyone to enjoy
Wind turbines are noisy. Each one can generate the same level of noise as a family
car travelling at 70 mph
For example, the largest single turbine available today can only provide enough
electricity for 475 homes, when running at full capacity.

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CHAPTER 6
FUTURE SCOPE & CONCLUSION
6.1 Future scope
Trading torque for tension
Pumping
Changing tacks
Blowing in the wind
Military
6.2 conclusion
Fig 6.1 example of kite gen

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It is a new class of wind energy generators able to overcome the main limitations of
the present Aeolian technology based on wind mills.
It is a new class of wind energy generators able to overcome the main limitations of
the present Aeolian technology based on wind mills.
According to the calculations above, the predictions published by KiteGen appear
quite optimistic, but perhaps not unrealistic. Significant improvement seems to be achieved
by going to 400 m altitude, but the real potential for consistent and powerful wind lies at an
even higher altitude. The drag and weight of lines will play an even more important role at
this height, and so more detailed studies will need to be performed. However, the kites are
able to extract sufficient power from the wind, and control systems are already effective
enough to keep a kite flying. Also, Kite systems have the potential to be competitively
inexpensive, and to be more scalable than current windmills. Wind intermittency will still
be a very large problem, and so wind power will need to be coupled with more consistent
power plants unless the current technology for energy storage is greatly improved. In
conclusion, While kite-powered generators will likely not replace traditional power plants
immediately, they have a lot of potential to start replacing windmill farms in the near future.

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Chapter 7
Reference
7.1 Reference:
[1]M.Canale,”http://ieeexplore.ieee.org/document/4282697/”AmericanControl Conference,
2007. ACC '07
[2]."Flugdrachen-SegelerzeugtbilligeWindenergie" [Kite produces cheap wind energy]
(in German). 2009-10-30. Retrieved 2011-03-15.
[3]."A big energy reservoir: the altitude wind". Retrieved 2011-03-15.
[4]."Kite Gen". Retrieved 2011-03-15.
[5]."Kite Gen: KonzeptversprichtbilligeWindenergie" (in German). 2009-10-28. Retrieved
16 March 2011.
[6]."NASA untersuchtMöglichkeitfürWindfarmen in luftigenHöhen" (in German). 2010- 12-
22. Retrieved 15 March 2011.

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