Coal is the product of plants which died millions year ago. The action of certain bacteria causes release of oxygen and hydrogen and its residue rich in carbon. As more material accumulated water squeeze out. Due to high temperature and pressure material becomes condensed and gases expelled out. The proportion of carbon continued to increase till it slowly changed into coal over a period of millions of years. This layer of carbon is called PEAT and show 27% of carbon.
- Apart from peat, there is three another type of coal: lignite (28% – 30%), bituminous (78% – 87%) and anthracite (94% – 98%).
- When coal is burnt, carbon is present in it react with oxygen to produce carbon-di-oxide and lots of heat.
Coke is produced when coal is heating strongly in absence of air. Coke has high energy value and produce less smoke.
India has about 7% of world’s known coal reserves and these are mainly found in Bihar, Orissa and Madhya Pradesh. Coal supplies 50% of the country’s total energy requirement.
Uses of coal
- It is used as fuel in industries
- It is used to produce electricity.
- It is used to manufacture of fuel gases like coal gas.
- When coal is heating strongly in the absence of air it changes into coke.
- It is better quality fuel than coal because it produces more heat.
It means the rock oil. It is a complex mixture of many compounds of hydrogen and carbon which are called hydrocarbon. Small amount of other compounds of carbon containing oxygen, nitrogen and sulphur are also present in petroleum. Fractional distillation of petroleum gives rise to petroleum gas petrol, diesel, kerosene and fuel oil.
- Petroleum gas is used as fuel for domestic heating purposes in the form of liquefied petroleum gas (LPG).
- Fuel oil is a better fuel than coal because fuel oil burn completely and does not leave any residue.
- The main constituent for petroleum gas is Butane with small proportion of propane & ethane. A strong smelling agent ethyl mercaptan is added to LPG cylinder to help in detection of gas leakage. Its caloric value is 50kj/g. it is clean fuel, it is easy to handle and store.
When the aquatic plant and animal dies and they sink to the bottom of sea and get buried in the layer of mud and sand. With the passage of time this organic material sank deeper and deeper. Anaerobic reaction and heat of earth help in conservation of material into oil. Oil move upwards and trapped beneath impermeable rocks in the earth crust.
Natural gas: Natural gas is formed under the earth by decomposition of vegetable matter lying under water. It is an important fossil fuel and is usually found underground near an oil source. It is lighter than air and mixture of methane (95%), ethane propane & butane.
- It occurs deep under the earth crust just above the petroleum deposit. It is environment friendly fuel. CNG is a good alternative in comparison of petrol and diesel. Largest reservoir for natural gas is Soviet Union.
Use of natural gas
- It is used as industrial fuel.
- It is used as fuel in thermal power plants to generate electricity.
- It has been a source of hydrogen in the manufacture