Sources of Energy (part – 2)

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Fossil fuels

These are the remains of prehistoric plants and animals which got buried deep inside the earth millions of years ago due to some natural processes. Fossil fuel is the major source of energy for generating the electricity in power plants.

Coal: It is the most abundant fossil fuel on the earth. It is mainly used as combustion fuel. It is the complex mixture of carbon, hydrogen and oxygen and some free carbon. Small amount of sulphur and nitrogen compound.

Coal formation

Coal is the product of plants which died millions year ago. The action of certain bacteria causes release of oxygen and hydrogen and its residue rich in carbon. As more material accumulated water squeeze out. Due to high temperature and pressure material becomes condensed and gases expelled out. The proportion of carbon continued to increase till it slowly changed into coal over a period of millions of years. This layer of carbon is called PEAT and show 27% of carbon.

  • Apart from peat, there is three another type of coal: lignite (28% – 30%), bituminous (78% – 87%) and anthracite (94% – 98%).
  • When coal is burnt, carbon is present in it react with oxygen to produce carbon-di-oxide and lots of heat.   

Coke is produced when coal is heating strongly in absence of air. Coke has high energy value and produce less smoke.

India has about 7% of world’s known coal reserves and these are mainly found in Bihar, Orissa and Madhya Pradesh. Coal supplies 50% of the country’s total energy requirement.  

Uses of coal

  • It is used as fuel in industries
  • It is used to produce electricity.
  • It is used to manufacture of fuel gases like coal gas.
  • When coal is heating strongly in the absence of air it changes into coke.
  • It is better quality fuel than coal because it produces more heat.

Sources of energy (part – 1)

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Energy defined as the capacity to do work. By the process of eating we provide us energy to do various life activities such as walking, writing, breathing, etc. A source of energy is that which is capable of providing enough useful energy at a steady rate.

A good source of energy should be

  • Safe and convenient to use: nuclear energy can be used only by highly trained engineers with the help of nuclear power plants. It cannot
  • Easy to transport: coal, petroleum, LPG, etc.
  • Easy to store: LPG, diesel, etc

Classification of sources of energy

Renewable sources of energy

These are those which are inexhaustible i.e. which can be replaced as we use them and used to produce more energy again and again. It is estimated that it provide 10% energy of world energy requirement. Such as: solar energy, wind energy, water energy, etc.


  • These sources will last as long as the earth receives light from the sun.
  • These sources are freely available in nature.
  • They do not cause pollution.

Non-renewable sources of energy

These are those which are exhaustible and cannot be replaced once they have been used. These sources accumulated in nature over a long period of time. Such as: coal, oil, natural gas, etc.


Classification of sources of energy helps us to differentiate which non-renewable sources of energy need to conserve for future generation.

  • Certain sources are non-renewable has compelled us to look for alternative sources of energy which in turn has accelerated the pace of technologies suitable for harnessing new sources of energy.


  • Due to their extensive use, these sources are fast depleting.
  • These are major cause of environmental pollution.

Conventional and non-conventional sources of energy

  • Conventional sources of energy are those which are used extensively and meet a major portion of our energy requirement. Such as: fossil fuels and hydro-energy (energy of flowing water)
  • Non-conventional sources of energy are those which are not used as extensively as the conventional ones. They meet our energy requirement only at a small scale. Such as the solar energy, nuclear energy, etc.

What Bioluminescence

Bioluminescence is the production of light by living organisms like glow worms, Fireflies etc. The light is produced when a substance called luciferin present in these organisms combined with oxygen in the presence of luciferase. light produced in this way does not give out any heat.

what is mermaid’s purse?

Mermaid’s purse is a hard cylindrical protective case for the eggs of some fish like dogfish raise etc. They remain attached to the seaweeds by long, curly strands present at both the ends till the embryos mature into fish capable of coming out into the water.

This whole process of transformation may take a period of 6 to 9 month.

What are identical Twins

Twins produced from a single fertilized ovum are called identical twins. The two cells resulting from the first cleavage of the zygote separate and develop into independent embryos. They have the same chromosome set in their body cells and thus possess identical genes.

They are identical in every respect and it is difficult to differentiate between them.

What are fraternal twins

Twins produced from two different fertilization are called fraternal twins. When two separate ova are fertilized by two separate sperms two zygotes having different sets of genes are obtained they are not identical to each other.

They differ from each other in their traits, development and Often sex.

Which day is called the Black September day in Olympic history

September 5, 1972 is known as Black September day in the history of Olympics. on this day in Munich, The Palestinian terrorists invaded the Israeli quarters in the Olympic village and took several players as Hostage besides killing two on the spot.

11 more Israeli team mates lost their lives in an encounter between German police and Palestinians belonging to the Black September group. Many countries called for the immediate closure of the games but Olympics carried on.

why common salt becomes wet in rainy season

common salt is slightly hygroscopic in nature due to the presence of a small amount of magnesium chloride in it. when it is kept open in rainy season the magnesium chloride in it absorbs moisture from air and the salt gets wet.