ENERGY KITES

PREPARED BY,

ASWATHY K

S8 ECE

ROLL NO. 21

PRESENTATION OVERVIEW

• Introduction

• Energy sources

• Limits of present renewable technologies

• Cross wind kite power

• Constructional details

• Operating principles

• Limitations

• Advantages

• Comparison with other renewable resources

• Summary

• References

INTRODUCTION

• Energy Kites, a revolutionary technique of power

generation.

• Conventional source of energy causes pollution.

• Renewable energy is very low in cost.

• It does not have much negative impact on the

environment.

• Airborne wind energy replaces the traditional

structure of wind turbine by Kites tethered to

ground.

ENERGY SOURCES

• Conventional energy sources: Coal, petroleum

and natural gas, fuel woods, hydropower, nuclear

energy.

• Non-conventional energy sources: Solar energy,

wind energy, tidal energy, geothermal energy,

biomass, biogas, energy from urban waste

LIMITS OF PRESENT

RENEWABLE TECHNOLOGIES

• High production costs

• Large occupation of land

• The electricity generation capacity is still not large enough.

• Unreliable

• Low-efficiency levels

CROSSWIND KITE POWER

• Traditional wind turbine is replaced by Energy

Kite, a wind turbine with a rotor supported in the

air.

• Avoids the expense of tower construction.

• The Kite tethered to ground, flies in a crosswind

direction.

• After achieving certain altitude this Kite obtains

a circular trajectory.

• The power generated by energy Kite is

transmitted to ground simultaneously.

CONSTRUCTIONAL DETAILS

• Three main components:

• Kite

• Tether

• Ground Station

• Kite:

• The main component of the power generation system.

• Material used must be light as well as strong to sustain

various types of forces acting on it.

• Consists of small turbines that generate power by using

the velocity of wind.

• Increase in number of rotors increases power output.

• Tether:

• Acts as a link for Kite to ground contact.

• Used to transmit energy generated by energy Kite to the

ground station.

• Made of thick Aluminium wires surrounded by a high

strength composite fibre covering.

• When tether length exceeds a limit, it may lead to minor

instability of the system.

• To overcome this and to get efficient power generation

at short tethering distance, multiple Kites are used.

• Ground station:

• Holds the tether.

• Used as a resting place for the energy Kite, when not in

flight.

• Occupies less ground space.

• The ground station strength decides the length up to

which the Kite can be tethered.

OPERATING PRINCIPLE

• Power generated by the energy kite can be given by,

where,

A- area of the kite wing

CL- lift coefficient

CD- drag coefficient

VW- velocity of wind

• A ratio of lift coefficient to that of drag coefficient is the drag ratio.

• Initially the Kite is taken to a considerable height by the on board

rotors attached to the Kite, which are powered by electricity from the

ground station.

• When it reaches at suitable altitude, the Kite gets into its circular

trajectory.

• After this stage the same rotor generates energy when Kite gets into

circular motion.

• Tether length plays an important role in setting diameter of rotation

of the Kite.

• The total power Pwind that a flying wing extracts from this wind

field is given by

where,

Fa- total aerodynamic force that the wing experiences

γ- angle between the direction of this force and the wind

LIMITATIONS

• The non aerodynamic forces acting on the kite

reduces the total usable power that can be

harvested to a great extent.

• Kites come down when there is insufficient wind.

• Bad weather such as could temporarily suspend

use of the machines.

• A prohibited airspace zone is required.

• During bad whether conditions, kite must be

brought back down to the ground and covered.

ADVANTAGES

• Minimal effort in terms of

a) generator structure.

b)cost

c)land occupation.

• Operates at significantly higher altitudes above

the ground where stronger and more constant

winds can be found and thus higher amounts of

energy is generated.

COMPARISON WITH OTHER

RENEWABLE RESOURCES

• Power generation of energy Kite is 150 times

more than photovoltaic cell with much less land

requirement.

• Power output of conventional wind turbines has

increased at a cost of increase in rotor diameter as

well as high cost to build such a huge structure.

• The mass of only 39 tons of Energy Kite generate

30 MW with wing area of 845msq.

• This equals to power output of four largest wind

turbines in the world each with a rated power

output of 7.5MW

• Each Blade has a weight of 65 tons and a rotor

diameter of 126 meter. Hence total weight of

twelve blade of these four turbines goes to 780

tons. Including the weight of the tower total

weight goes up to 12,400 tons.

SUMMARY

• Use of Energy Kites opens a new world of

opportunities in the field of wind power

generation by making complete use of air at high

altitude too.

• If such technology is implemented on a large

scale, the use of power plants that burn out

conventional resources could be decreased to a

great extent, thereby decreasing air pollution.

• Use of this clean energy will decrease the rate of

global warming significantly.

REFERENCES

• http://www.creativeworld9.com/2011/04/abstract-and-full-paper-on-renewable.html

• http://www.environmentalpollution.in/energy/sources-of-energy-conventional-and-nonconventional-sources-explained/292

• http://www.preservearticles.com/201104235869/what-are-the-non-conventional-sources-of-energy.html

• http://www.solarschools.net/resources/stuff/advantages_and_disadvantages.aspx

• http://www.kitenergy.net/technology-2/key-points/

• http://www.conserve-energy-future.com/advantages-and-disadvantages-of-renewable-energy.php

THANK YOU