The present environmental pollution and its effects on global warming has resulted in priority to harness renewable energy sources. One such option is Wind Energy, which can be harnessed to generate constructive useful energy for application in a number of fields.
Wind energy is generally contained in the wind due to its motion. The energy may be kinetic or dynamic-which is generally referred to as aerodynamics. Uses of wind energy can be studied under two main different groups i.e. non-destructive winds and destructive winds. Winds in the first group have low to medium range speed/velocity and hence contain low to medium range energy, which can be beneficially and constructively used in different fields/applications. These are the most useful winds and almost continuous (of course seasonal variation will be there) flow without much variations in velocity ranging about 05 to 15 m/sec.
Though the energy in these types of winds is not much, it is almost constant; except whenever sudden gusts of winds occur. However, wind direction varies according to the heating of land and air by solar energy and also due to landscape. The study and understanding of usefulness of wind energy can be simplified by sub-grouping depending upon the usefulness in different fields.
Application of wind/ wind energy
One can identify a number of fields where wind/wind energy is used constructively to produce useful effect, product or energy.
Across the world one can identify innumerable types of religions/mythologies developed and practiced; since immemorial times. Winds are personified as gods in most of these religions. In Hindu religion the wind god is named as Vayu and is supposed to be the god of strength in fact the god of life itself. Hence he is also called Prana. One can find a number of mantras, hymn´s, spells, etc. in Hindu Vedas, tantras, shastras, yoga shastras, mantra shastras etc. Similarly, other religions also have a number of spells identified with the wind god.
Religion and Magic are inter-related. It is not yet clear whether religion gave birth to magic or magic paved the way for the development religion. In any case, in earlier days the magicians were believed to control winds, rains some times the weather/climate itself. It is said that magicians could create different types of winds by chanting the spells and harness the winds either for beneficial purpose (white magic) or destructive purpose (black magic) (2,5).
In almost all religions, winds/wind energy are personified as god. The Vedas which are supposed to be as old as 5,000 BC; give details account of all type winds, the energy contained and ways and means to control or pacify the winds. Vayu (wind) is one of the Panchabhutas (i.e. earth, water, sky, fire and wind). It is represented by the symbols Rudra (Storm god). In China, in I Ch´ing, one of the trigram represents soft wind (1).
The effect of winds to move the light matter/object is made use in developing kinetic art. In this type of art, light and movable compositions are created. These compositions are either suspended by using wires or nylon threads or hinged with various mechanical linkage systems. These compositions will get activated as and when wind flows through these composition giving visual (4).
Wind energy is used to play musical instruments like wind bag, wind pipe, Aeolian harp, harmonium, harmonica etc. Some of the instruments are directly activated by the natural wind.
For e.g. Aeolian harp when hung across an open wind, the wind flowing through this instrument produces drowsy, lulling and ethereal sounds. In villages; winds flowing through or around in telephone wires or the electrical wires stretched above the ground level, vibrate and produce a musical sound. Of course, the wind chime is most simple and popular wind musical instrument, producing notes as and when air flows through it.
One cannot overlook the recreational activities based on the use of wind power. Some of the recreational activities are ice boating, skate sailing, water sailing, kite flying, hang gliding, paragliding etc. Even paper glider competitions are held. Having such an encouragement different type recreational activities based on wind power are being continuously churned out. Toys activated by/using natural air have also been developed and are available in market.
Wind contains kinetic and dynamic energy, which is called as wind energy. This power is proportional to the cube of the wind speed or wind velocity. As per the Indian Renewable Energy Development Agency (IREDA) (3); wind power potential is 45,000 MW. However ,the installed capacity is merely 6.270 MW.
The extent to which wind can be harnessed as a source of energy depends on the probable density of occurrence of different wind speed. There are number of different types of wind energy harnessing machines/turbines have been developed. Mainly there are two class i.e. horizontal axis wind turbines and vertical axis wind turbines. We have sub-classification in each of the classes based on the type of blades; number of blades, applications; the amount of power developed etc.
Earlier, wind mills were used to mill the grains, pump water etc.
At present, most of the work is directed toward producing useful electrical energy. Since winds are seasonal and the speed varies; to provide continuous output, energy storage devices have also been developed. It is also being attempted to have wind energy conversion turbines called ducted turbines to be incorporated in the design of the building itself, to make the building self sufficient in its energy requirement. Modern high tech materials, design accessories etc. have resulted in developing efficient turbines. However, there is limit for conversion of wind energy, which in ideal condition will be 59.7 per cent. The technology push is towards attaining an efficiency ranging nearer to the energy conversion limit value.
Wind energy has been used for transportation purpose since the olden days. The knowledge of sea breeze and land breeze is the most useful information in transportation. Earlier, wind energy transportation was used on water bodies like sea, rivers etc., where ships/boats were fixed with sails. These sails caught the wind, which in turn impelled the ships/boats in water to any distance without spending any iota of fuel. Of course some disadvantages were there; one of them was that the ships/boats were almost out of control during storms, high winds etc. The same principle is being made use in machines used for transporting on land. At present, only a small number of vehicles with sails have been designed for recreation purposes only. Of course; Gliders; hang gliding, paragliding etc. are also some times used for transportation purposes.
There are different types of process industries, however almost all of them use wind energy in one way or the other. Wind energy is harnessed in this field for drying purpose, increasing the ¨ph¨ values of the chemicals to be processed, to exhaust noxious fumes, etc. In fact both solar energy and wind energy can be used simultaneous in the process industries (6, 7).
In present times, one can also see people using wind energy for various agricultural purposes, especially in rural areas. Most of these application are in the drying process of agricultural products, aquariums, pollination, seeding, energy exchange etc.
Ventilation is a very important application of winds/wind energy. All living organism require fresh air to breathe, which is made available by wind. Hence, without wind there is no life. The importance of wind in ventilation was recognized as earlier as the inception of the civilization itself. Human closely observed and studied winds/wind energy and developed a science called as vastu shastra (5) (Science of buildings/villages/cities) and Feng shui (1). Both these science give importance to the availability fresh and natural air. There is a number of active (mechanical ventilation) and passive (natural ventilation) devices have been developed to enhance ventilation in a given space. Active devices are the one which use auxiliary power and mechanical means to create ventilation. Passive devices use renewable/natural energy sources to in habit/enhance ventilation. However, the latter may either use only one or two types of energy or two types of energy available at the particular location.
As mentioned earlier, one can go on making the list of a number of applications/uses of winds and wind energy. Even, some of the destructive winds having speed more than 220 km/sec, some time temporarily reaching speeds of upto 500 km/sec, can produce waves called as wall of water/hurricane waves on water.
Although named as destructive winds, the study and understanding in details all the information pertaining to these winds, have increased the knowledge and also in fact it has paved way for the innovative, creative, high-tech designs, materials etc. for the structures, transport vehicles like ships, planes, buses and other applications, which in turn resulted in the efficient, sturdy design, materials etc. for space exploration, land exploration and water exploration.
Hence in a general sense although they have destructive qualities, they have helped develop better designs, materials etc., and one need not be surprised if in the near future, man develops a device to harness the energy in these destructive winds to produce constructive and useful energy.
In the present days of fossil fuel, its side effects like pollution, enlargement of ozone hole etc. clearly indicates that civilization has to turn about and give more attention to renewable energy and use them as much as possible. Since wind energy is also one of these energies, it has bright future being harnessed for producing useful energy.
Authors: Subramanya Krishna Bhat and Dr KM Balakrishna, Dept. of Physics, Mangalore University, Mangalagangotri - 574 199. Email: firstname.lastname@example.org
1) Derek Walters, The Feng Shui Hand Book. A Practical Guide to Chinese Geomancy and Environmental Harmony. Thorsons, An Imprint of Harper Collins Publishers. 1991.
2) Sir James George Fraza, The Golden Bough, Study of Magic and Religion. Mac Milan & Co. Ltd. London. 1933. Page (60-83).
3) Indian Renewable Energy Development Agencies (IREDA). New Delhi. www.iredaltd.com.
4) Michele Melaragno, Wind in Architectural and Environmental Design. Van Nostrand Reinhold Company. New York. 1982.
5) Science and Technology in India through Ages, Editors Sri BK Sri Vathsa, Sri MA Narasimha. Academy of Sanskrit Research, Melkote - 571 431. 2003.
6) S K Bhat, Integrated Fluidic Sol - Win Dryer. The Innovative ACR. Vol: 6 No: 3 July /September 1997. PP 72 - 74.
7) S K Bhat, Design Aspects of Integrated Re- generator Using Only Renewable Energy. Chemical Business Magazine, Vol: 10, No: 3, October 1996. PP 37 - 39.
8) http://en.wickipedia.org/ hang gliding
10) http://wallpaper_kid. Com