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Chapter 14 : Sources Of Energy
In Class IX, we learnt that the total energy during a physical or chemical process is conserved. Why, then, do we hear so much about the energy crisis? If energy can neither be created nor destroyed, we should have no worries! We should be able to perform endless activities without thinking about energy resources!
14.1 What Is A Good Source Of Energy?
What can then be considered a good source of energy? We, in our daily lives, use energy from various sources for doing work. We use diesel to run our trains. We use electricity to light our street-lamps. Or we use energy in our muscles to cycle to school.
14.2 Conventional Sources Of Energy
14.2.1 Fossil Fuels
In ancient times, wood was the most common source of heat energy. The
energy of flowing water and wind was also used for limited activities. Can
you think of some of these uses? The exploitation of coal as a source of
energy made the industrial revolution possible. Increasing
industrialisation has led to a better quality of life all over the world. It has
also caused the global demand for energy to grow at a tremendous rate.
The growing demand for energy was largely met by the fossil fuels – coal
and petroleum. Our technologies were also developed for using these
energy sources. But these fuels were formed over millions of years ago
and there are only limited reserves. The fossil fuels are non-renewable
sources of energy, so we need to conserve
them. If we were to continue consuming these
sources at such alarming rates, we would
soon run out of energy! In order to avoid this,
alternate sources of energy were explored.
But we continue to be largely dependent on
fossil fuels for most of our energy
requirements (Fig. 14.1).
14.3 Alternative Or Non – Conventional Sources Of Energy
With technological progress, our demand for energy increases day by day. Our life-styles are also changing, we use machines to do more and more of our tasks. Our basic requirements are also increasing as industrialisation improves our living standards.
14.4 Environmental Consequences
We have studied various sources of energy in the previous sections. Exploiting any source of energy disturbs the environment in some way or the other. In any given situation, the source we would choose depends on factors such as the ease of extracting energy from that source, the economics of extracting energy from the source, the efficiency of the technology available and the environmental damage that will be caused by using that source. Though we talk of ‘clean’ fuels like CNG, it would be more exact to say that a particular source is cleaner than the other. We have already seen that burning fossil fuels causes air pollution. In some cases, the actual operation of a device like the solar cell may be pollution-free, but the assembly of the device would have caused some environmental damage. Research continues in these areas to produce longer lasting devices that will cause less damage throughout their life.
14.5 How Long Will An Energy Source Last Us?
We saw earlier that we cannot depend on the fossil fuels for much longer. Such sources that will get depleted some day are said to be exhaustible sources or non-renewable sources of energy. On the other hand, if we manage bio-mass by replacing the trees we cut down for fire-wood, we can be assured of a constant supply of energy at a particular rate. Such energy sources that can be regenerated are called renewable sources of energy.
