People and Environment Notes (UGC NET Paper 1 Free Study Material)


Conventional  Sources  of Energy

1. Coal

Coal is one of the most important  sources of energy. Most of the coal, which is obtained  today, is from underground   mines of different types depending  on their distance from the Earth’s surface. Coal comprises three-fourth  of the total fossil fuels of the world.  India has large proven  resources  and still  larger geological reserves. India ranks   third in terms of world production of coal. In India, there would be enough  coal for more than 100 years, however,  it is concentrated  largely in the eastern  and central parts of the country.

2. Oil and Natural Gas

In India, efforts made by the Oil and Natural Gas Corporation   (ONGC and Oil India since the late 1950s have led to the identification  of a number  of oil and gas deposits both offshore and onshore. The onshore  fields were mainly  discovered  in the Mumbai.  Gujarat, Assam and Arunachal  Pradesh;  and the offshore fields in the sea were notably the Mumbai High fields such as North  and South Basin and South  Tapti. Oil and  gas has  also been  discovered  in the Godavari   Basin and  on the East Coast. The new exploration  strategy developed  during  the first two years of Seventh Plan places emphasis on intensive  exploration  survey and drilling in order to add to petroleum  reserves  and to augment  production  as early as possible.

Natural  gas is emerging  as an important   source in India’s  commercial  energy  scene in view of large reserves of gas that have been established  in the country. In view of growing  importance  of natural  gas in the country, the Gas Authority of India Limited (GAIL), a wholly-owned   Government of India undertaking,   was established  in 19841The main objective of the company  are processing,  marketing,  transportation   and distribution  of natural  gas in all its forms.

3. Hydro Energy

Hydro energy can also be considered  as an indirect source of solar energy. The potential  energy of water  stored  at a height  is converted  into mechanical  and  electrical  energy  as this water  falls and drives turbines  and electric  generators.Today, about 23 per cent of the total electric power  in the world comes from hydro power.  The total hydro-electric  potential  in India has been estimated  at about 472x 10kilowatt hours  or 472 terrawatt hours normally. But, we have exploited  only a little more than 16 per cent of the total potential.

Electrical energy generation  by hydro-electric  power plants is not polluting  and uses a renewable source of energy. However, there are several problems  associated with the construction  of giant dams on natural  waterways.  The construction  of such dams alter the downstream  ecology as well as that in the lake area behind  the dam.  Huge  areas get submerged,   and  flora and  fauna  or any agricultural produce  of this land  get affected. People  and towns in this area have to be removed  and relocated, causing disturbance  and sometimes  hardship.  Again, the time taken for such larger schemes to fructify is usually  quite long. For these reasons,  emphasis  is now being given to supplement   such large projects with small size hydro  projects called mini-hydro or micro-hydel  projects  which can be built on small streams  and even on canals, without  large dams.

4. Tidal Energy

Tides are created by the combined  gravitational  effect of the Earth, the Moon and the Sun. Though the tide is the universal  phenomenon   of the Earth’s sea-water body, some regions are more favourable for the establishment   of such power  plant  for the commercial  production   of tidal  energy. Primary requirements  for the construction  of an installation  having a capacity over 200 MW, are

(i) an average tide of 5-12 metres;

(ii) the possibility  of linkage to a grid in order to accommodate  the variable power

(iii) favourable  geographical  location and favourable  socio-economic  and ecological conditions.  Bulb type turbines  as used in conventional  hydro-electric  stations have proved to be reliable for generating  power  from the tides.

In India, three potential  sites have so far been Identified,  namely, the Gulfs of Kutch and Cambay on the west coast in Gujarat  and the Sundarbans  along the east coast in West Bengal.

5. Geothermal Energy

Geothermal  energy  is the exploitation  of heat energy of Earth within  the 10 km of the Earth’s  upper crust. Geothermal  energy can be processed  for generation  of power, where the geothermal  fluid has a temperature   of 130 degree C. Geothermal  manifestations   are widespread   in India in the form of 340 Hot Springs  localities.  Only a few direct  utilization  schemes  have been launched  by various  agencies. They are in Puga,  Chhumuthang (Leh District),    Manikaran   and  Bakreshwar ( West Bengal).  Of these,  India’s  most  promising geothermal  field is in  in Puga va11ey in Laddakh.  Tatapani  in Himachal  Pradesh  is another  promising geothermal area in India.

6. Bio-energy .

Bio-energy  includes  those processes where biological forms of matter, such as plants, vegetables, enzymes etc. provide the basis for energy  for its conversion from one form to another form of energy. The widest use of bio energy is in the traditional ways, where wood, plants and agricultural matter are directly burnt to provide heat.


Biogas means a gas produced by the anaerobic digestion or fermentation of organic matter. The organic matter can be manure, sewage sludge, municipal solid waste, biodegradable waste or any other biodegradable feedstock. Biogas is primarily methane (CH4) and carbon dioxide (CO2) and may have small amounts of hydrogen sulfide (H2S), moisture and siloxanes. The gases methane, hydrogen, and carbon monoxide (CO) can be combusted or oxidized with oxygen. This energy release allows biogas to be used as a fuel; it can be used for any heating purpose, such as cooking. It can also be used in a gas engine to convert the energy in the gas into electricity and heat.


Biomass covers a wide range of materials, encompassing all kind of animal, organic and synthetic wastes and a special variety of vegetation-wild grass, shrubs and some plants and tress, especially cultivates to derive energy.  The major components of biomass are mainly carbohydrates-sugars, starches and cellulose-with variable nitrogen an phosphorous contents. There are three basic systems for conversion of biomass into energy resources.

(a)   Combustion Pyrolysis – Chemical  decompose   l 0n       oil (methanol)  and  charcoal.

(b)    Biogasification   – Anaerobic  digestion  of biomass  to produce combustible gas (biogas) comprising of methane, hydrogen.

(c)   Fermentation – Conversion   of sugar  and  starch into alcohol to produce ethanol and solid residual  fuel.

Non-Conventional     Sources

1. Solar Energy

Solar radiant energy falling on the surface of the Earth in the form of visible lights can be converted into thermal energy. The heat generated in a solar collector can be utilized for variety of applications such as cooking of food, heating of water, drying of food grains and vegetables, wood seasoning, desalination of water, generation of mechanical and electrical power etc.

2. Wind Energy

Wind energy is the kinetic energy associated with movement of large  masses of air resulting  from the differential heating of the atmosphere by the Sun. Hence wind energy is nothing but converted form of solar energy. It is estimated that about 10   to 107 MW of usable power is continuously available in the Earth’s winds. Though the total quantity of this resource is extrememly large, it is concentrated in certain regions, and can vary a great deal with time at given location. For the utilization of wind energy, the speed of wind must be between 8 to 22m per second. Wind energy is renewable and posses no major environmental threats.

3. Ocean Energy

The sea, which is constantly receiving solar radiations and act as the world’s largest natural solar collector, has potential to provide a means of utilizing renewable energy. It acts not only as collector, but also has an enormous storage capacity. Energy from the ocean is available in several forms such as ocean thermal energy, wave energy, tidal energy, salinity gradients, ocean currents, ocean winds and bio-mass.

4. Wave Energy

Movement    of large  quantities    of water   up  and  down   can,  in principle,    be harnessed    to convert   it into  usable  form  of energy,  such  as, electricity   or mechanical    power.  Several  types  based   on flats,  flaps, ramps   and  oscillating    air water   columns   have  been  worked   UpOl1 to harness   wave   energy.   It is more reliable   than  the wind   energy   because   here  the fluctuation    is less than  the wind.   However    at present, due  to infant   stage  of its technology,    the  cost per  unit  of energy   converted    is high  because   of the need for special   structures    at sea,  corrosion   problem    associated    with  the use  of sea water   and  the problem of transmitting     the power   onshore.

The  tropical   coastline    of India,   especially    south-west     coastline,    is very  suitable    for  establishing such  energy   plants.   Department of Ocean Development   has  estimated    the wave  energy   potential   in India about  40,000 MW. Ocean  Energy  Cell has established    a pilot  power   plant  at Vizhinjam   (Kerala),  of 120

MW capacity   during   monsoon    period   and  30 MW  during   non-monsoon     period.   OEC  is also  develop- ing  five  other   similar   plants   at Thangaserry     in Kerala.

5. Nuclear  Energy

Nuclear energy can  be obtained    both  through   fusion and  the fission processes.    Enormous    amounts of energy   is released   from  small  quantity    of fuel  in both  these  processes,    e.g., if one  tonne  of Uranium is totally   fissional,   it can  theoretically     yield  energy   equivalent    to about   3 million   tonnes   of coal.

Nuclear    Reactor

The  nuclear reactor or  atomic reactor  is a kind   of furnace    for  carrying    out  the controlled    fission   of a radioactive     material   like  Uranium-235 for producing     atomic   power.   It’s  in the reactor   that  the heat  energy   is produced    from  fission  reactions,   which  is then  taken  out  and  converted into   electricity.    Thus,   it’s  an  assembly    in  which   nuclear    fission   chain   reaction    is  maintained     and controlled    for  producing     nuclear    energy,   radioactive     nuclides    or  artificial   elements.    In  order   that reaction   should   not  get  out  of     is regulated    by  neutron absorbers  – the  control   rods  made   of graphite  or beryllium, which   allow  only  sufficient   free  neutrons    to exist  in reactor   core  to maintain    the reaction   at constant   level.

Nuclear    Fuel

The  fissionable    material   used   in nuclear   reactors   for producing     energy   by  the  fission  process   is called   a nuclear  fuel. The  fuel  used   in nuclear   power   plants   is enriched    uranium-235 isotope.   The remaining    being  U-238 isotope,   which  does  not get fissioned   easily.  The natural   uranium, which   contains    a very   low  percentage     of U-235  in  it. Thus   the  natural    uranium     cannot   sustain   or maintain    a nuclear   chain   reaction.   Since  naturally    occurring    uranium    has  very  little  U-235,  so it has first  to be processed    to increase   the percentage    of fissionable    U-235  in it. This  process   is called  enrich- ment of uranium and uranium, thus  obtained,    is called  enriched  uranium.

Even  the  enriched    uranium    used  in reactors   contains   both  type  of atoms  – U-238  and  U-235.  But, it’s  the  U-235  atoms,   wh~ch  act  as real  fuel  and  are  used   in the  reactors   in the  form  of long  rods  or strips,   called  fuel.

6. Atomic Energy

The prime   objective   of the atomic  energy   programmes     as defined   in the Atomic Enrrgy 74.ct of 1948, are  the  development,      control   and   use  of atomic   energy   solely  for  peaceful    purposes,     namely,   the generation    of electricity   and  ,the development     of nuclear   applications     in research,    agriculture,    indus- try, medicine   and  other  areas.  To achieve   this objective,   Tata Institute   of Fundamental     Research   (TIFR) and  Bhabha   Atomic   Research   Centre   (BARC)  were   established    in  1945 and   1967, respectably     as the grass   root   Research    Institution     which   is catering    the ‘diverse    programmes      related    to  research    and training.  Besides  these,  there  are a number   of research,   training   institutions    and  department     which   are involved   in exposing   its new  dimensions.

The Atomic Energy Commission, set up in 1948, is responsible for formulating the policy for all atomic energy activities in the country. The Department of Atomic Energy (DAE), set up in 1954, is the executive agency for implementing the atomic energy programme.

The Nuclear Power Corporation of DAE is responsible for design, construction and operation of nuclear powere stations. Nuclera Power Corporation is at present operating the nuclear power stations: Tarapur Plant (2X220 MW), Trombay Plant (2X220 MW), Kalpakkam Plant (2X235 MW), Kaiga Plant (2X 235 MW).

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