Sources of Energy [NCERT Geography Notes for UPSC, SSC, Railways]

Sources of Energy [NCERT Geography Notes for UPSC, SSC, Railways]
Posted on 18-03-2022

Sources of Energy

Fossil fuel

  • Wood was the most common source of thermal energy in ancient times. The energy of wind and running water was also used for some limited activities.
  • The use of coal as a source of energy made the Industrial Revolution possible. Growing industries have increased the quality of life all over the world.
  • Due to this, the demand for energy is increasing at an astonishing rate all over the world. Most of the growing demand for energy was met from fossil fuels – coal and petroleum.
  • Along with the increase in demand, there were also developments in technologies to use these energy sources. But these fuels have been made over millions of years and now only their limited reserves are left. Fossil fuels are non-renewable sources of energy, so they need to be conserved.
  • If we continue to use these energy sources at this alarming rate, then these reserves of ours will soon be depleted.
  • In order to avoid such a situation, alternative sources of energy were discovered. But even today we continue to rely heavily on fossil fuels to meet most of our energy needs.
  • There are other disadvantages of burning fossil fuels as well. Oxides of carbon, nitrogen, and sulfur, released when fossil fuels are burned, are acidic oxides. These cause acid rain which affects our water and soil resources.
  • The pollution caused by the burning of fossil fuels can be reduced to some extent by increasing the efficiency of the combustion process.
  • Along with this, the harmful gases and ash released as a result of combustion can be reduced by various techniques that reduce the escape into the atmosphere.
  • In addition to being used directly in gas stoves and vehicles, fossil fuels are also used as a major fuel for generating electricity.


Status of petroleum in India

  • Petroleum is a flammable liquid composed mainly of hydrocarbons (90–98%). Its remaining organic compounds are oxygen, nitrogen, sulfur, and organic-metal compounds.
  • India has an estimated 15 lakh sq. km. Oil field. India's oil fields are spread over the Ganges-Brahmaputra basin, the offshore continental shelf as well as the two coastal regions, the Gujarat plains, the Thar Desert, and the Andaman-Nicobar Islands.
  • After the establishment of the Oil and Natural Gas Commission in 1956, extensive and systematic oil exploration and production began in India. Till the time of independence, there was only one oil refinery in the country at Digboi in Assam.
  • Although the oil well is small, it is the only well to run continuously for 100 years. After independence, petroleum deposits were discovered in the Gujarat plains and the Gulf of Cambay, but unexpectedly, the largest reserves of oil were found at a distance of 115 km from Bombay. Found in the distant sea, which is known as Bombay High. It is the largest oil reserve ever found in the country.

Distribution :

  • There are 13 basins with potential for oil reserves in India, which can be classified into three categories:
  • Cambay Basin, Assam-Arakan Belt, and Bombay Offshore Basin in Gujarat, where oil is being produced commercially.
  • Rajasthan, Krishna, Cauvery, Godavari Basin, Andaman, Bengal, Himalayan Terai region, Ganga valley and Tripura, Nagaland, have natural oil reserves but commercial production has not started;
  • Kutch-Saurashtra, Kerala-Konkan, and Mahanadi regions; Where natural oil reserves are likely to be found, but the discovery is yet to be made. It is estimated that there are 130 million tonnes of oil reserves. In 1950-51, the production of crude oil in the country was only 2.5 lakh tonnes, which has now increased to about 320 lakh tonnes. Still, only 30% of the country's demand can be met by this. The rest has to be imported, for which a large amount of foreign exchange has to be paid.

Oil refinery factory

  • Oil refineries in India are as follows: - Barauni (Bihar), Bogaigaon (Assam), Cochin (Kerala), Digboi (Assam), Haldia (W. Bengal), Koyli (Gujarat), Manali and Narimanam (Madras), Mathura ( Uttar Pradesh), Noonmati in Guwahati (Assam), Trombay (Bombay), Visakhapatnam (Andhra Pradesh).
  • Two new refineries are being constructed in the joint area at Mangalore (Karnataka) and Panipat (Haryana).


Thermal power plant

  • In power plants, large amounts of fossil fuels are burned every day by boiling water to make steam, which spins turbines to generate electricity. Electricity transmission is more efficient than transporting coal and petroleum over equal distances.
  • This is the reason why many thermal power plants have been set up near coal and oil fields.
  • The reason these plants are called thermal power plants is that in these plants, by the combustion of fuel, thermal energy is generated which is converted into electrical energy.

Hydroelectric plant

  • Another traditional source of energy is the kinetic energy of running water or the potential energy of water at a height. In hydroelectric power plants, the potential energy of falling water is converted into electricity.
  • Since there are very few waterfalls that can be used as a source of potential energy, hydroelectric power plants have been linked to dams.
  • A large number of dams have been built all over the world in the last century. In India, one-fourth of our energy demand is met by hydroelectric power plants.
  • High-rise dams are built to collect water in large reservoirs (artificial lakes) by stopping the flow of rivers to generate hydroelectricity. Water keeps on accumulating in these reservoirs, as a result of which the level of water filled in them rises.
  • Water from the top of the dam through pipes falls freely on the blades of the turbine installed near the base of the dam, as a result of which the turbine blades rotate and the generator generates electricity.
  • Since the reservoirs refill with water every time it rains, hydroelectric power is a renewable energy source.
  • Therefore, we do not have to worry about the exhaustion of hydropower sources like fossil fuels, which will definitely run out someday. However, there are some problems associated with the construction of large dams.
  • Dams can be constructed only in a limited number of areas and hilly areas are considered good for them. Due to the construction of dams, many arable land and human habitation are destroyed due to submergence.
  • Large ecosystems are destroyed due to the submergence of dam waters. Plants, plants, etc., which are submerged in water, begin to rot under anaerobic conditions and decompose to produce methane gas, which is a greenhouse gas.
  • The problem of satisfactory rehabilitation and compensation of displaced people also arises due to the construction of dams.
  • The opposition to the construction of the Tehri dam on the river Ganga and the construction of the Sardar Sarovar dam on the river Narmada was due to similar problems.


Improvements in technology for the use of traditional sources of energy


  • Wood has been used as a fuel since ancient times. If we ensure that enough trees are planted, a continuous supply of firewood may be possible.
  • You are well acquainted with the combustion of cow dung as a fuel. The huge number of livestock in India can also assure us about the availability of a sustainable source of fuel. Since these fuels are plant and animal products, we call the source of these fuels bio-mere.
  • These fuels do not generate much heat and emit a lot of smoke when they are burned, therefore, the use of technology is necessary to increase the efficiency of these fuels.
  • When wood is burnt with a limited supply of air, the water and volatile substances present in it are removed and charcoal remains in the form of residue.
  • Charcoal burns without a flame emitting relatively little smoke and have a high heat generation efficiency.
  • Similarly, various plant wastes such as dung, crop residues, vegetable wastes, and sewage when decomposed in the absence of oxygen, biogas are released. Since the starting material used in making this gas is mainly cow dung, hence its popular name is gobar gas.
  • Biogas is generated in a plant. The plant has a dome-like structure made of bricks. A thick solution of cow dung and water, called slurry, is made in the mixing tank to make biogas, from where it is poured into the digester.
  • Collateral is a closed chamber that does not contain oxygen. Anaerobic microorganisms, which do not require oxygen to survive, decompose the complex compounds of the dung slurry.
  • It takes a few days for the decomposition process to complete and results in the production of gases such as methane, carbon dioxide, hydrogen, and hydrogen sulfide.
  • The biogas is stored in the gas tank above the compactor. The biogas is taken out from the gas tank through pipes for use.
  • Biogas is an excellent fuel as it contains up to 75 percent methane gas. It burns without producing smoke.
  • Unlike wood, charcoal, and coal, no waste like ash remains after the burning of biogas. It has a high heating capacity. Biogas is also used as a source of light.
  • The remaining slurry in the biogas plant is taken out from the plant from time to time. Nitrogen and phosphorus are abundant in this slurry, so it works as good manure.
  • In this way, by using bio-wastes and sewage, many of our objectives are fulfilled by producing biogas.
  • This gives us a convenient efficient source of energy, good compost, and a safe way to dispose of waste materials. Biomass is a renewable source of energy.

Wind power

  • Due to the uneven heating of the land and water bodies by the radiations of the sun, there is movement in the air and there is a flow of winds.
  • The kinetic energy of the wind can be used to do work. Wind energy has been used for centuries by windmills to perform mechanical work.
  • For example, a windmill-powered water pump (pumps that lift water) uses the rotational motion of the windmill petals to draw water from the well. Nowadays wind energy is also being used to generate electricity.
  • The structure of a windmill is actually like a giant electric fan that is mounted on a firm base at some height.
  • The rotational motion of the windmill is used to rotate the turbine of an electric generator to generate electricity.
  • The output (i.e. generated electricity) of a single windmill is very low, which is not possible for commercial use.
  • Therefore, many windmills are installed in a large area and this area is called a wind power farm.
  • To obtain electricity on a commercial scale, all the windmills of an energy farm are interconnected, as a result of which the net energy obtained is equal to the sum of the electrical energy generated by all the windmills.
  • Wind energy is an eco-friendly and efficient source of renewable energy. Through this, there is no need to spend money again and again for the generation of electricity. But the use of wind energy has many limitations.
  • The first limitation is that wind power farms can only be set up in areas with strong winds for most of the year.
  • The wind speed must also exceed 15 km/h to maintain the required speed of the turbine. Along with this, there should also be some replenishment facilities like accumulator cells which can be used to meet the energy requirements when the wind is not blowing.
  • A huge plot is required to set up an energy farm.
  • The wind farm requires about 2 hectares of land to generate 1MW. The initial cost of setting up a wind power farm is exorbitant.
  • Apart from this, due to the strong base and petals of windmills being open to the atmosphere, they tolerate natural thunderstorms, storms, sun, rain, etc., so they require a high level of maintenance.

Alternative or non-conventional energy sources

  • With the advancement in technology, the demand for our energy is increasing day by day. Our lifestyle is also constantly changing.
  • We use more and more machines to do our work. As our standard of living is improving due to industrialization, our basic needs are also increasing continuously. As our energy demand increases, we need more energy sources.
  • We develop technology and discover new sources of energy for more efficient use of available and known energy sources.
  • Any new source of energy that we search for, specific strategies are developed keeping in mind the use of it.

Solar energy

  • The Sun has been radiating a huge amount of energy at the present rate continuously for about 50 million years and will continue to radiate energy at this rate for about 50 million years in the future as well.
  • Only a small fraction of solar energy reaches the outer layers of the Earth's atmosphere. About half of it is absorbed while passing through the atmosphere and the rest reaches the surface of the earth.
  • The black (black) surface absorbs more heat than the reflective surface or white surface under similar conditions.
  • This property is used in the working of solar cookers and solar water heaters. In some solar cookers, mirrors are used to focus the rays of the sun, thereby increasing their temperature. Solar cookers have a glass sheet cover.
  • This limit of use of solar energy is overcome by using solar cells. Solar cells convert solar energy into electrical energy.
  • A typical solar cell develops a voltage of 0.5-1.0 V when placed in sunlight and can generate about 0.7 W of electricity.
  • When a large number of solar cells are combined, this arrangement is called a solar panel, from which enough electricity is obtained for practical use.
  • The major advantages associated with solar cells are that they do not contain any moving parts, are cheap to maintain, and perform fairly satisfactorily without any focusing device.
  • Another advantage of using solar cells is that they can be installed in remote and inaccessible places. They can also be installed in sparsely populated areas where cabling for power transmission is very expensive and not commercially viable.
  • Silicon is used to make solar cells, which are available in abundance in nature, but the availability of specific grades of silicon used in making solar cells is limited.
  • The whole process of producing solar cells is still very expensive. Silver is used to make solar panels by interconnecting solar cells, due to which the cost increases further.
  • Despite their high cost and low efficiency, solar cells are used for many scientific and technological applications.
  • Solar cells are used as the main energy source in man-made satellites and space exploration devices such as the Mars Orbiter.
  • Radio or wireless communication systems or TVs in remote areas. Solar cell panels are used in relay centers.
  • Traffic signals, calculators, and many toys have solar cells. Solar cell panels are installed on specially designed inclined roofs so that maximum solar energy is incident on them. However, due to their high cost, the domestic use of solar cells is still limited.

Energy from the oceans

Tidal energy

  • The water level in the oceans keeps rising and falling mainly due to the gravitational pull of the Moon on the rotating Earth.
  • If you live near the sea or at some point near the sea, how does the level of water in the sea change during the day. This phenomenon is called tides.
  • We get tidal energy from the rise and fall of water levels in tides. Tidal energy is harnessed by building a dam on a narrow area of ​​the ocean. The turbine installed at the entrance of the dam converts the tidal energy into electrical energy.

Wave energy

  • Similarly, the kinetic energy of giant waves near the coast can also be trapped in a similar way to generate electricity.
  • Strong wind blowing across the surface of the oceans produces waves. Wave energy can be of practical use only where the waves are very strong.
  • Various devices have been developed to trap wave energy so that it can be used to generate electricity by rotating a turbine.

ocean thermal energy

  • The water on the surface of the oceans or oceans is heated by the sun while the water in their deeper part is relatively cold. This difference in heat is used to obtain energy in the Ocean Thermal Energy Conversion Plant (OTEC power plant).
  • OTEC power plants operate only when there is a difference of 2°C between the temperature of the water at the surface of the ocean and the temperature of the water at a depth of 2 km.
  • Hot surface water is used to boil volatile liquids such as ammonia. The vapor of the liquid thus formed then spins the turbine of the generator.
  • The cold water from the depths of the ocean is pumped out by pumps to cool the vapor and condense again into a liquid.
  • The energy potential of the oceans (tidal energy, wave energy, and ocean thermal energy) is enormous, but there are difficulties in its efficient commercial exploitation.

Geothermal energy

  • Due to geological changes, molten rocks are pushed up in hot areas at depths in the earth's crust, which collects in some areas. These areas are called hot spots. When underground water comes in contact with these hot spots, steam is generated.
  • Sometimes this hot water finds a way to exit from the surface of the earth. These exit routes are called hot glasses or heat sources.
  • Sometimes this steam gets trapped in the middle of the rocks where its pressure becomes very high. This steam is taken out by putting pipes up to the hot spots.
  • This steam, released under high pressure, spins the turbine of the electric generator, which generates electricity. The cost of producing electricity through this is not high but there are very few areas where it is practical to harness this energy from a commercial point of view.
  • Several electric power plants based on geothermal energy are operating in New Zealand and the United States.

Natural gas as a source of energy

  • Natural gas reserves are also found in association with independent and natural oil reserves. But most of the production of natural gas is happening with natural oil reserves.
  • Natural gas deposits have been found in Tripura, Rajasthan as well as offshore areas of Gulf of Cambay in Gujarat, Bombay High, Tamil Nadu, Andhra Pradesh and Orissa. The country is estimated to have 647 billion cubic meters of gas reserves.
  • Natural gas is a natural boon for energy-deficient countries like India. It is used as a source of energy (in the form of thermal energy) and as a raw material for the petrochemical industry.
  • It also takes less time to build a power plant with natural gas. Indian agriculture can be encouraged by setting up fertilizer plants based on natural gas in India.
  • They can also be easily distributed through gas pipelines, eliminating the need for transportation. In 1984, the Gas Authority of India Corporation (GAIL) was formed for the transportation, processing, and marketing of natural gas.
  • It is built on a 1,730 km of natural gas supply capacity of 180 lakh cubic meters per day. The task of laying the long Hazira-Bijapur-Jagdishpur (HBJ) pipeline was entrusted.
  • This pipeline starts from Hazira (in Gujarat), Bijapur (M.P.), and from there ends at Jagdishpur (U.P.). A branch leaves from Bijapur and goes to Sawai Madhopur (Rajasthan).

Nuclear energy

  • How is nuclear energy generated? A nuclear fission reaction is a process in which the nucleus of a heavy atom (such as uranium, plutonium, or thorium) can be broken into lighter nuclei by bombardment with low-energy neutrons.
  • When this is done, a huge amount of energy is released. This occurs when the mass of the parent nucleus is only slightly greater than the sum of the masses of the individual products.
  • For example, the energy released in the fission of an atom of uranium is 10 million times greater than that produced by the combustion of a carbon atom of coal.
  • In nuclear plants designed to generate electricity, this type of nuclear fuel is part of an autotrophic fission chain reaction in which energy is released at a controlled rate. This free energy can be used to generate electricity by making steam.


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