Power Plant Engineering

Fig 2.3. Fixed Dome type.
Biomass +
water
Biogas
Slurry
Outflow
tank
Digester
Fig 2.4. Floating gas holder type.
Floating Gas Holder Type. In this design a dome made floats above the slurry in the disaster.
In the Fig. 2.4, The disaster tank is of cylindrical masonry construction. The floating dome is of fabri-
cated steel construction. The dome guide shaft provides the axial guide to the floating dome. As the gas
is collected in it. The sliding bearing provides smooth sliding surface and guide to the floating dome.
The gas generated in the slurry gets collected in the dome and the dome arises. The water seal tank
provides separation between the gas in the dome and the outlet gas.
2.15 WIND ENERGY
Wind energy is another potential source of energy. Winds are the motion of air caused by un-
even heating of the earth’s surface by the sun and rotation of the earth. It generates due to various
global phenomena such as ‘air-temperature difference’ associated with different rates of solar heating.
Since the earth’s surface is made up of land, desert, water, and forest areas, the surface absorbs the
sun’s radiation differently. Locally, the strong winds are created by sharp temperature difference be-
tween the land and the sea. Wind resources in India are tremendous. They are mainly located near the
sea coasts. Its potential in India is estimated to be of 25 × 10
3
mW. According to a news release from
American Wind Energy Association the installed wind capacity in India in the year 2000 was 1167 mW
and the wind energy production was 2.33 × 10
6
mWh. This is 0.6% of the total electricity production.

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NON-CONVENTIONAL ENERGY RESOURCES AND UTILISATION
59
During the day, air above the land heats more quickly than air above water. The hot air over the
land expands and rises, and the heavier, cooler air over a body of water rushes in to take its place,
creating local winds. At night, the winds are reversed because air-cools more rapidly over land than
over water. Similarly, the large atmospheric winds that circle the earth are created because land near the
equator is heated more by the sun than land near the North and South Poles.
Today people can use wind energy to produce electricity. Wind is called a renewable energy
source because we will never run out of it. Winds are natural phenomena in the atmosphere and have
two different origins.
(1) Planetary winds are caused by daily rotation of earth around its polar axis and unequal
temperature between Polar Regions and equatorial regions.
(2) Local Winds are caused by unequal and heating and cooling of ground surface of ocean 1
lake surfaces during day and night.