Page 13 - Sources of Energy

Renewable energy is available in our natural environment, in the
form of some continuing or repetitive currents of energy, or is stored in
such large underground reservoirs that the rate of depletion of the
reservoir because of extraction of usable energy is practically negligible.

Activity 14.9
Activity 14.9
Activity 14.9
Activity 14.9
Activity 14.9
 Debate the following two issues in class.
(a) The estimated coal reserves are said to be enough to last us
for another two hundred years. Do you think we need to worry
about coal getting depleted in this case? Why or why not?
(b) It is estimated that the Sun will last for another five billion
years. Do we have to worry about solar energy getting
exhausted? Why or why not?
 On the basis of the debate, decide which energy sources can be
considered (i) exhaustible, (ii) inexhaustible, (iii) renewable and
(iv) non-renewable. Give your reasons for each choice.

Q U E S T I O N S
?

1. Name two energy sources that you would consider to be renewable. Give
reasons for your choices.
2. Give the names of two energy sources that you would consider to be
exhaustible. Give reasons for your choices.

What you have learnt

 Our energy requirements increase with our standard of living.
 In order to fulfil our energy requirements, we try to improve the efficiency of energy
usage and also try and exploit new sources of energy.
 We also need to look for new sources of energy because the conventional sources of
energy like fossil fuels are in danger of getting exhausted soon.
 The energy source we select would depend on factors like the ease and cost of
extracting energy from the source, the efficiency of the technology available for
using that source of energy and the environmental impact of using that source.
 Many of the sources ultimately derive their energy from the Sun.

EXERCISES

1. A solar water heater cannot be used to get hot water on
(a) a sunny day. (b) a cloudy day.
(c) a hot day. (d) a windy day.

254 Science