Abstract :
Ever since
1973 oil crises, many countries have justifiably maintained an abiding interest
in renewable energy sources and as a result many renewable energy programs were
developed. Since then, research and development in the field were more
promising and reliable. Main advantage of renewable energy is that its main
ingredient is renewable and it plays crucial role in meeting environmental
standards by combating global warming and other threats.
The five
renewable sources used most often include
1. Solar energy
2. Water energy
3. Wind energy
4. Geothermal energy
5. Biomass energy
SOLAR
ENERGY:
Energy from
sun. The sun gives out 3.7 × 10^26 watt of power in to space, out of which the
earth intercepted is equivalent to1.7 × 10^17 watt. Solar energy emitted by sun
within three minutes is equal to the world energy consumption during a year.
Photovoltaic (PV) panels use silicon cells, which transform solar radiation
into direct current. The energy is used simultaneously (for example to pump
water) or is stored in batteries to provide electricity. Solar energy can also
be used to cook food by trapping and concentrating the sun's heat in a cooker,
and to heat water or to generate steam which, in turn, can be utilized
for mechanical applications. This is usually done by flat plate collectors
which are exposing a large thin surface, containing a liquid, to the sun. The
sun's heat can be intensified with lenses and mirrors and stored in salts and
stones.
WATER ENERGY:
Hydropower
is a well-established technology, which has been producing firm power at
competitive price for about a century. It is the principal source of electric
power in some 30 countries, and provides about one fifth of the world's annual
electrical supply. Its power stations include some of the largest artificial
structures in the world. The dams, which are constructed during the process,
are considered as most vulnerable because much of the forests and fertile soil
is lost under the dam spread. Therefore, recent development in hydropower
concentrates on smaller projects.
The
potential energy of falling water, captured and converted to mechanical energy
by waterwheels, powered the start of the Industrial Revolution. The water wheel
gave way to the water turbine. This device uses jets of water to spin the cup
shaped blades of the turbine which drives an alternator, generating electricity.
How hydro
power work:
Understanding
the water cycle is important to Understanding
hydropower. Solar
energy heats water on the surface, causing it to
evaporate. This water
vapor condenses into clouds and falls back onto the
surface as precipitation. The water flows through rivers back into the oceans,
where it can evaporate & begin the cycle over again.
WIND
ENERGY:
Harnessing
wind energy was one of man’s earliest achievements. Winds results from
differential heating of the earth and its atmosphere by the sun and are
subjected to several forces altering their direction and speed of flow. The
flow of wind through the surface of wind
turbines, these wind turbines capture the kinetic energy and convert it into
electrical energy in the form of electricity.
GEOTHERMAL
ENERGY:
The earth’s
core consists of hot lava generates heat. In some places earth’s crust is very
thin layer and transfers heat to underground water. In this case the
underground water gets boiled and comes out with high pressure from these evaporation
can be collected used to turn the turbines to produce electricity. India has
nearly 250 geothermal sources (80 at Himalaya, 170 at Peninsula). It is
available at free of cost and environmental pollution is very less.
BIOMASS
ENERGY:
Biomass
includes residues from forestry, purpose-grown agricultural crops, trees and
plant types, organic waste, agricultural residue, agro-industrial and domestic
origin waste [sewage and municipal solid waste]. On a worldwide scale Biomass
contributes about 12% to today's primary energy supply, rising between 40% and
50% in most developing countries. Biomass fuel obtained from purpose-grown
energy crops as well as forests and agricultural waste are being used in power
plants and it is very competitive in price and quality with fossil fuels.
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