03-05-2013, 02:51 PM
NON-CONVENTIONAL ENERGY SOURCES
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Introduction to energy
The energy of a body is its capacity to do work. It is measured the total
amount of work that the body can do.
Energy is the primary and most universal measure of all kinds work by
human beings and nature. Every thing what happens the world is the
expression of flow of energy in one of its forms.
Primary Energy Sources
Primary energy sources can be defined as sources which provide a net
supply of energy Coal, Oil, Uranium etc., are examples of this type. The
energy required to obtain these fuels is much use than what they can produce
by combustion or nuclear reaction. The supply of primary fuels is limited. It
becomes very essential to use these fuels sparingly.
Energy sources and their availability
Introduction
Today every country draws its energy needs from a variety of sources.
We can broadly categorize these sources as commercial and noncommercial.
The commercial sources include the fossil fuels (coal, oil and
natural gas), hydro-electric power and nuclear power, while the noncommercial
sources include wood, animal waste and agricultural wastes. In
an Industrialized country like U.S.A. most of the energy requirements are met
from commercial sources, while in an Industrially less developed country like
India, the use of commercial and non-commercial sources are about equal.
Fossil fuel energy
Coal, petroleum, and natural gas are called Fossil fuel as these are
formed by the decomposition of the remains of dead plants and animals
buried under the earth for a long time. These are non-renewable sources of
energy, which, if exhausted, can not be replenished in a short time. Their
reserves are limited and are considered very precious. These should be used
with care and caution to let them last long. These are also contributing to the
global environmental pollution.
Petroleum
It is a dark coloured, viscous and foul smelling crude oil. The
petroleum means rock oil. It is normally found under the crust of earth
trapped in rocks. The crude oil is a complex mixture of several solid liquid
gaseous hydrocarbons mixed with water, salt and earth particles. It is a
natural product obtained from oil wells.
Natural gas
It consists about 95% Methane and rest ethane and propane. It occurs
deep under the crust of the earth either alone or a long with oil above the
petroleum deposits. It is a product of petroleum mining.
The gas is available in Tripura, Jaisalmer, off-shore areas of Bombay
High and in the Krishna – Godavari delta. It is used as a domestic and
industrial fuel. The natural gas is now also available as CNG (Compressed
Natural Gas) a substitution of petrol in automobiles.
Hydraulic energy (or) Water power
Water power is developed by allowing water to fall under the force of
gravity. It is used almost exclusively for electric power generation, in fact, the
generation of water power on a large scale became possible around the
beginning of the twentieth century only with the development of electrical
power plants or Hydro electric plants were usually of small capacities usually
less than 100 KW.
Potential energy of water is converted into Mechanical energy by using
prime moves known as hydraulic turbines. Water power is quite cheap where
water is available in abundance. Although capital cost of hydro electric power
plants is higher as compared to other types of power plants but their operating
Costs are quite low, as no fuel is required in this case. The development rate
of hydropower is still low, due to the following problems:
1. In developing a project, it will take about 6-10 years time for planning,
investigation and construction.
2. High capital investment is needed, and some parts of the investment have
to be designed from foreign sources.
3. There are growing problems on relocation of villages, involved,
compensation for damage, selecting the suitable resettlement area and
environmental impact.
Because of long transmission line to the villages with low load factor,
the electric power will be available to the people in rural areas may not be
economical. This leads to the development of Mini or Micro hydroelectric
projects to supply the electric power to remote areas. The Importance of
Micro hydroelectric projects have been observed in some parts of the country
with availability of river flow through out the year.
Nuclear energy
According to modern theories of atomic structure, matter consists of
minute particles known as atoms. Heavier unstable atoms such as U235,
Th239, liberate large amount of heat energy. The energy released by the
complete fission of one Kg of Uranium (U235), is equal to the heat energy
obtained by burning 4500 tonnes of coal (or) 220 tons of oil. The heat
produced by nuclear fission of the atoms of fissionable material is utilized in
special heat exchangers for the production of steam which is then used to
drive turbogenerators as in the conventional power plants.
However there are some limitations in the use of nuclear energy
namely high capital cost of nuclear power plants, limited availability of raw
materials, difficulties associated with disposal of radio active waste and
shortage of well trained personnel to handle the nuclear power plants.
SOLAR ENERGY
Introduction
Energy from the sun is called solar energy. The Sun’s energy comes
from nuclear fusion reaction that takes place deep in the sun. Hydrogen
nucleus fuse into helium nucleus. The energy from these reactions flow out
from the sun and escape into space.
Solar energy is some times called radiant energy. These are different
kinds of radiant energy emitted by sun. The most important are light infrared
rays. Ultra violet rays, and X- Rays.
The sun is a large sphere of very hot gases. It’s diameter is
1.39x106KM. While that of the earth is 1.27x104 KM. The mean distance
between the two is 1.5x108KM. The beam radiation received from the sun on
the earth is reflected in to space, another 15% is absorbed by the earth
atmosphere and the rest is absorbed by the earth’s surface. This absorbed
radiation consists of light and infrared radiation with out which the earth would
be barren.
All life on the earth depends on solar energy. Green plants make food
by means of photosynthesis. Light is essential from in this process to take
place. This light usually comes from sun. Animal get their food from plants or
by eating other animals that feed on plants. Plants and animals also need
some heat to stay alive. Thus plants are store houses of solar energy.
Solar Radiation at the Earth’s Surface
The solar radiation that penetrates the earth’s atmosphere and reaches
the surface differs in both amount and character from the radiation at the top
of the atmosphere. In the first place. Part of the radiation is reflected back in
to the space, especially by clouds. Further more, the radiation entering the
atmosphere is partly absorbed by molecules in the air. Oxygen and Ozone
(o3), formed from oxygen, absorb nearly all the Ultraviolet radiation, and water
vapour and carbon dioxide absorb some of the energy in the infrared range.
In addition, part of the solar radiation is scattered (i.e. its direction has been
changed) by droplets in clouds by atmosphere molecules, and by dust
particles.