Coal and Petroleum

On a daily basis we use various kinds of materials. Some of these are man-made while others are not i.e., they are derived from nature or are natural resources.

Natural Resources can be classified into two types:

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1. Inexhaustible Natural Resources –

These are natural resources that are present in unlimited amounts and cannot be exhausted by human activity. Examples include sunlight, air.

2. Exhaustible Natural Resources –

These are resources which are found in a fixed amount on earth and therefore must be used carefully to prevent complete depletion. Such resources can be exhausted by human activity. Examples include forests, wildlife, minerals, coal, petroleum, natural gas etc.

Let’s take a look at three of the most common exhaustible natural resources : coal, petroleum and natural gas. These are obtained from the decaying remains of living organisms and hence are called fossil fuels.

Fossil Fuel is a fuel that is formed by decomposition of buried dead organisms over millions of years.

1. Coal

Coal is as hard as stone and is black in colour
Coal burns in air to mainly release carbon dioxide
It is used a fuel to generate heat for cooking
It is used to produce electricity in thermal power plants
Earlier it was used to produce steam to run railway engines

Formation of Coal:

300 million years there were dense forests in the low lying areas of the earth
Due to natural processes such as flooding, these forests were buried and compressed under the soil
The temperature rose and these forests were buried deeper and deeper with time
Due to the high temperature and pressure, the dead plants eventually got converted to coal
Since the main component of plants is carbon, the process of conversion of buried plants and trees into coal is known as carbonisation.

Processing of coal yields three useful products :

Coke

Almost pure form of carbon
Tough, porous and black
Used in the manufacture of steel and the extraction of many metals

Coal Tar

Black, thick liquid with an unpleasant smell
Mixture of about 200 substances
Products obtained from coal tar are used for manufacturing substances such as drugs, synthetic dyes, explosives, perfumes, plastics, paints, photographic materials, roofing materials, etc.
Naphthalene balls are obtained from coal tar
Earlier coal tar was used for surfacing of roads but now the more suitable bitumen is used

Coal Gas

Coal gas is obtained during the processing of coal to obtain coke
It was used for street lighting in the 1800s; it is more commonly used a source of heat than light now
It is used as a fuel in industries close to coal processing plants

2. Petroleum

Used as a fuel for light automobiles such as motorcycles, scooters and cars

Formation of petroleum:

The word petroleum is derived from the words petra(rock) and oleum(oil) as it is mined from between rocks under the Earth.
As organisms die at sea, their bodies settle at the bottom and are gradually covered by layers of sand and clay
In the absence of air, these are organisms are compressed under high pressure and temperature over millions of years and are transformed into petroleum and natural gas
In India, oil is found in Assam, Gujarat, Mumbai High and in the river basins of Godavari and Krishna

Refining Petroleum:

Petroleum is a dark, oily liquid with an unpleasant odour
It is a mixture of various materials such as petroleum gas, petrol, diesel, lubricating oil, paraffin wax, etc.
The process of separating the constituents of petroleum is known as refining and is carried out in a petroleum refinery.

Constituents of Petroleum and their Uses :

1.	Liquid Petroleum Gas (LPG)	Used as fuel in homes and industries
2.	Petrol	Fuel for light automobiles, solvent for dry cleaning
3.	Kerosene	Fuel for stoves, lamps and jet aircrafts
4.	Diesel	Fuel for heavy motor vehicles, electric generators
5.	Lubricating Oil	Used for lubrication
6.	Paraffin Wax	Used in ointments, vaseline, candles. etc.
7.	Bitumen	Used for road surfacing and in paints.

3. Natural Gas

It is an important fossil fuel as it can be easily transported through pipes
It is stored under high pressure as compressed natural gas (CNG)
It is increasingly being used as a fuel for transport as it produces far lesser amount of harmful gases as compared to petrol and diesel
It is used as a starting material for production of various chemicals and fertilisers
In India, natural gas is found in Tripura, Rajasthan, Maharashtra and in the Krishna Godavari delta

Drawbacks of Using Exhaustible Natural Resources:

Coal, petroleum and natural gas are all fossil fuels that require millions of years for their generation while the reserves we have will only last a couple of hundred years.
These resources are therefore exhaustible.
Burning of these fuels generate huge amounts of carbon dioxide and therefore are a major of source of pollution and global warming
Because of the above reasons, it is advised to use these resources scarcely and only when absolutely essential.

In India, the Petroleum Conservation Research Association (PCRA) advises people how to save petrol/diesel while driving. Their tips are: