1. 1.6 WIND ENERGY
Introduction
Wind was known to be a very useful source energy from even
ancient times. Wind power was used for propelling ships, driving
windmills, pumping water, irrigating field etc. for centuries. Now again
attention is focused in availing wind power on large scale. We are
going to see the advantages of wind power, some of the methods to
transform it into usable power and some quantitative measurements in
the context.
Wind Energy
Wind is air in motion. Wind energy is a manifestation of the solar
energy,because due to the sun radiation absorbed in the atmosphere,
ocean water and land temperature differences are produced which
cause pressure differences and air begins to flow as wind from a region
of higher pressure to low pressure.
The use of wind as a power was known for centuries in the history.
Wind power was used for propelling ships, driving wind mills, pumping
water, irrigating fields etc. But this resource was side tracked because
other resources of power like coal, petroleum oil, hydroelectric power
were available in plenty and cheap too. But since the petroleum-oil
price-crisis in 1973, there has been a continuous hike in petroleum oil
price, reserves of fossil fuel like coal are on the verge of getting
exhausted and hence becoming scarce and costly, attention was paid to
other alternative, renewable and cheap non-conventional sources like
solar energy, and wind, energy also has been looked upon now as one
of the top few resources of energy.
After collecting data about the availability of wind for ten years (1970
to 1980). in 1980 prototype wind generator was constructed and
installed. Then in every next generation of the generators,
improvements were made to utilise maximum wind energy at increasing
efficiency.
2. By 1990s technology was developed to convert wind-energy into
electrical energy at low cost and it has proved to be a boon in favourable
wind areas all over the world.Wind energy is one of the clean, safe,
pollution free, cheap natural
energy sources; it is available in plenty. By advanced technology it be
easily converted into mechanical and/or electrical energy at low cost
Seater efficiency.
Wind is nothing but the air mass in motion. The energy possessed by this
moving air mass is called as wind energy. The wind energy is considered
to be another form of solar energy. Hence wind energy is a manifestation
of solar energy. The formation of wind is a natural phenomena in the
earth's atmosphere and has two different origins.
(1) Rotation of earth on its axis (once in 24 hours) and unequal
temperatures at polar regions and equatorial regions. The winds caused
due to this are called planetary winds. These winds are named as
easterlies, westerlies and trade winds.
(2) Unequal heating and cooling of ground (land) surfaces and water
(ocean, lake) surfaces during day and night. The winds resulting due to
this are called local winds.
The wind energy is cheap, clean, pollution free, available during day
and night and all over the earth surface, and it is renewable energy
source. Wind energy is found to be used since long back in the history
for various purposes like propelling ships, pumping water, irrigation,
grinding etc. However, its use was limited upto 1973, when energy crisis
occurred. This alternative, non-conventional source of energy got
attention after the energy crisis. The efforts were made to obtain
electrical energy from wind energy in 1970's. First wind turbine was
constructed and installed in Denmark in 1985. This is followed by
installation of several wind farms particularly in Canada, Netherland,
Sweden, U.K., U.S.A., Germany, India, etc. In India, wind farms giving
electrical energy from wind energy are operating in Tamilnadu and
Gujarat since 1989 and now they are operating in other states also
including Maharashtra, Karnataka, Rajasthan.
3. The wind energy has very good scope in future because of its advantages
and rapidly depleting conventional sources, especially fossil fuels. The
increasing population, industrialization and other development projects
require more and more energy in future. The wind energy is one of the
options for energy in future. Further, the wind energy has found various
applications in transportation, agriculture and rural development and
generating electrical power.
1.7 WIND ENERGY CHAINS
Wind energy is a primary (raw) source of energy. Many times it needs to
be transformed into secondary (usable) source of energy. The
transformation of wind energy to usable energy involves one or more
intermediate steps which are called as wind energy chains. There are two
wind energy chains as given below.
Wind being air mass m moving with velocity v has kinetic energy
(mechanical energy) 1-mv . Hence wind is natural source of mechanical
energy. Therefore, wind energy can be used directly for certain
applications such as propelling ships, agricultural use of removing dust
and other lighter unwanted material from grains, etc. The wind energy
can be indirectly used by converting it into another form by using
different energy chains. In the energy chain 1, the wind energy is
converted into rotational mechanical energy at the shaft of wind turbine.
This rotational mechanical energy can then be used for pumping water
or grinding flour. In the second wind energy chain, the wind energy is
converted to rotational mechanical energy at the shaft of turbine. This
rotational energy is then given to electrical generator which converts
4. rotational mechanical energy to electrical energy. The output electrical
energy from the generator is commonly used form of energy and can be
used for different applications. Different types of wind turbines with
good efficiency (30%) give energy conversion. ,
1.8 ELECTRICAL ENERGY FROM WIND ENERGY :
Wind energy is mainly conv. ted into electrical energy.
(i) It can be generated from low ratings of 0.5 kW to nigh rating of 6000
kW or even higher.
(ii) A single wind turbine genrator can generate14MWof electrical power
and is convenient to use as stand-alonein suitable plenty-wind but remote
areas like sea-shores, hilly areas, desert areas.
(iii) In a low wind areas, wind farms have to be used which consists of a
number of wind turbine generators in a large area and are linked to gather
high power.(iv) Electrical energy generated can be easily converted into
desirable AC/DC form.
Electrical energy obtained from wind energy is used with standby or
supporting electrical power generating unit because wind energy may not
be available continuously. This is done in following ways :
i)When wind energy is harnessed as stand-alone, the unit is associated
with storage batteries. In case of no wind or insufficient wind power
available, storage batteries kept charged with wind energy in advance,
supply the necessary power partially or fully to the output.
ii)Wind-energy generators are used in parallel with electrical grid of
conventional supply-network. No battery storage is then required.
iii)Wind-Diesel hydrid for remoted stand-alone systems.
1.9 INDIA'S POSITION IN THE FIELD OF WIND ENERGY
India has a great potential of 20,000 MW of electrical power from wind-
power. It constitutes about 10% of national installed capacity. India has
long sea shores, large hot desert like areas, hence ample availability of
wind power. In Gujarat and Tamilnadu wind farms with unit ratings of
15 kW to 200 kWhave been installed. Projects of capacity of 45 MW and
155 MW are near completion and in a near future the capacity may cross
500 MW. Department of Non-conventional Renewable Energy (DNRE) is
5. keen on exploiting India's potential of wind energy to maximum to satisfy
growing demand for the fast development of India.
1.10 : APPLICATIONS OF WIND ENERGY
Applications of wind energy in various fields since the historic periods
have already been mentioned in the discussion so far. Let us a take rapid
review in tabular form
Table 1.4 : Application of Wind Energy
Field of
application
Period
Historic (Before
1973)
Present (After
1973)
TransportationPropelling ships
(since centuries)
Likely to be used
for local
transport at
some places
Agricultural and
rural
Wind mills for
• water
pumping
• irrigation of
field
• wood-saw
mills
• grinding
grain mills
Likely to be used
in remote rural
areas where
conventional
hydro electric
power network
cannot reach.
Electrical
power
• First
commercial use
in 1885 in
Denmark
• Several small
units of 5 to 25
KW were used
in Europe during
1920s
Large scaleuse
planned all over
the world and
likely to
constitute
sizeable
percentage of
total energy
consumption.
