Inexhaustible Natural Resources
These resources are present in unlimited quantity in nature and are not likely to be exhausted by human activities. Examples are: sunlight, air.
Exhaustible Natural Resources
The amount of these resources in nature is limited. They can be exhausted by human activities. Examples of these resources are forests, wildlife, minerals, coal, petroleum, natural gas etc.
You may have seen coal, or heard about
it (Fig. 5.1). It is as hard as stone and is
black in colour.
Coal is one of the fuels used to cook food. Earlier, it was used in railway engines to produce steam to run the engine. It is also used in thermal power plants to produce electricity. Coal is also used as a fuel in various industries.
You know that petrol is used as a fuel in
light automobiles such as motor cycles/
scooters and cars. Heavy motor vehicles
like trucks and tractors run on diesel.
Petrol and diesel are obtained from a
natural resource called petroleum.
Do you know how petroleum is formed?
Petroleum was formed from organisms living in the sea. As these organisms died, their bodies settled at the bottom of the sea and got covered with layers of sand and clay. Over millions of years, absence of air, high temperature and high pressure transformed the dead organisms into petroleum and natural gas.
Natural gas is a very important fossil fuel because it is easy to transport through pipes. Natural gas is stored under high pressure as compressed natural gas (CNG). CNG is used for power generation. It is now being used as a fuel for transport vehicles because it is less polluting. It is a cleaner fuel.
You have studied in the beginning of
the chapter that some natural resources
are exhaustible like fossil fuels, forests,
You know that coal and petroleum are fossil fuels. It required the dead organisms millions of years to get converted into these fuels. On the other hand, the known reserves of these will last atmost a few hundred years. Moreover, burning of these fuels is a major cause of air pollution. Their use is also linked to global warming. It is therefore necessary that we use these fuels only when absolutely necessary. This will result in better environment, smaller risk of global warming and their availability for a longer period of time.