Coal and Petroleum
Natural resources are the naturally occurring substances that are considered valuable in their relatively unmodified form.
Natural resources are classified as exhaustible and inexhaustible. Exhaustible resources are present in limited quantity in nature. These are exhausted by human activities. Inexhaustible natural resources are not likely to be exhausted by human activities.
A fuel is a material that is burnt or changed in order to obtain energy. Fuels are classified as natural fuels and processed fuels. Some of the natural fuels are found as fossil fuels. Fossil fuels are formed by the decomposition of dead plants and animals buried under Earth over millions of years ago.
Coal, petroleum and natural gas are fossil fuels. Under high pressure and temperature, buried plants got converted into coal over millions of years ago. When coal is heated in air, it burns and mainly produces carbon dioxide gas. Coal is processed to make useful products, like coal gas, coal tar and coke. Coal is the most primitive source of energy but it is the most polluting fuel also.
The term ‘petroleum’ has been derived from the Latin words: ‘petra’- rock and ‘oleum’- oil. It is formed from the decay of remains of sea organisms. Most of the petroleum is trapped inside porous rocks, which act as a reservoir, covered by layers of impervious rocks. Petroleum is extracted from oil fields and then refined. Refining is the process by which different constituents of petroleum are separated. Refining is carried out in a petroleum refinery. The constituents of petroleum are separated by the fractional distillation process.These fractions are petrol, diesel, petroleum gas, paraffin wax and lubricating oil.
Natural gas is a gaseous fossil fuel. Natural gas consists of mainly methane gas along with small amounts of propane, ethene and ethane. Natural gas is comparatively cleaner fuel than the other fossil fuels. Chemicals obtained from petroleum and natural gas are known as petrochemicals. These are used in the manufacturing of detergents, synthetic fibres, polythene, plastics and fertilisers. Burning of fossil fuels is a major cause of air pollution. As the amount of fossil fuel is limited, Petroleum Conservation Research Association (PCRA) advises people on how to save petrol or diesel while driving.There are some alternative energy sources such as wind energy, solar energy, geothermal energy, tidal energy, hydro energy.