Class 10 Sources of Energy Notes
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Source of Energy
Anything that provides us energy is called a source of energy. We need energy for various purposes. So, we need a source of energy that provides us with this energy. Some sources of energy are more efficient in comparison to others, while some sources of energy are cleaner as they do not contribute to pollution.
Examples of sources of energy are solar energy, wind energy, hydel energy, biofuels, and geothermal energy.
A source of energy can be classified into a renewable and non-renewable source. We will discuss this in detail further.
Sources of Energy – Types of natural resources
(Conventional and Non-Conventional Sources of Energy)
Renewable (non-conventional resources): These are resources that can be used again and again or we can say that these resources will not finish easily and will last for a long time.
For example: solar energy, water, air.
Non-renewable resources (conventional): These are the resources that can not be used again and again because if they get exhausted, they will take a lot of time to form.
For example fossil fuel, etc.
They are formed when dead plants and animals get buried under the earth over millions of years and due to high pressure and temperature, they get transformed into fossil fuels. They are non-renewable resources, so their wise use is recommended.
For example: coal, petroleum and natural gas.
Coal: It is a sedimentary rock that burns. It mainly contains carbon, hydrogen and oxygen. It also has some quantity of nitrogen and sulphur.
Different types of coal:
Peat
Lignite
Bituminous
Anthracite
Destructive distillation is a process when any substance is heated in the absence of air. Products obtained on a destructive distillation of coal are coke, coal tar, coal gas, and ammoniacal liquor.
Coke: it is used as a reducing agent in metallurgy and as a fuel.
Ammoniacal liquor: it is converted into ammonium sulphate by absorbing dilute sulphuric acid and ammonium sulphate is an excellent fertilizer.
Coal tar: it is used for surfacing roads and also as a source of different aromatic compounds.
Coal gas: it is a mixture of hydrogen, methane and carbon monoxide. All these gases provide heat when burnt. It is a good fuel (cooking gas).
Natural gas: it has mixtures of alkanes i.e. 80% methane, 7%ethane, 6% propane and 4%butane.
It occurs deep in the earth’s crust with petroleum deposits.
Propane and butane are separated from natural gas and are liquefied under pressure to form LPG (used as a domestic and industrial fuel).
CNG (Compressed Natural Gas ) having main constituent methane is also used as a fuel in vehicles and in industries.
Energy and environment:
Increasing rate of industrialization.
Increasing demand for luxurious items.
Increase in demand for entertainment facilities.
Increase in demand for various modern techniques of agriculture and also the use of chemicals like pesticides, fertilizers, etc.
Petroleum: the name ‘petroleum’ means rock oil (petra: rocks; oleum:oil). It is called petroleum because it is found in the crust of the earth, trapped in rocks. A range of fossil hydrocarbons that are found as gasses, liquids and solids beneath the earth’s surface. The two common forms of petroleum are crude oil and natural gas.
Crude oil: It is a complex mixture of alkane hydrocarbons with water and earth particles. The final stage of refining involves the removal of impurities such as sulphur compounds.
When a fuel containing sulphur is burnt, the sulphur in it turns into sulphur dioxide which is an acidic gas. So, it is to be purified or refined before it can be used for specific purposes. The process of separating crude petroleum oil into more useful fractions is called refining.The refining of petrol is done by the process of fractional distillation. Refining is needed to make sure that all the oil is turned into useful products.
Cracking also occurs during the refining process of petroleum. The process of breaking bigger hydrocarbon molecules into smaller hydrocarbon molecules by heating in the presence of a catalyst is called cracking. The refining of petroleum or separation of petroleum into different components is based on the fact that the different compounds of crude oil have different boiling point ranges.
The fraction of petroleum having highest boiling point range is collected in the lowest part of the fractionating tower. The fraction having the lowest boiling point range is collected in the topmost part of the tower. Such a process of separation of different fractions of petroleum from crude oil is called fractional distillation. Otherwise, if we discuss about fuels we can define them as:
Fuels: anything that provides us energy is called fuel. Fuels can be solid, liquid and gases.
Solid fuel example : coal
liquid fuel example : kerosene
Gas fuel example : LPG
Characteristics of an ideal fuel are as follows:
It should be cheap.
It should be easily stored.
It should have high calorific value.
It should have proper ignition temperature.
It should not leave any residue.
Uses of fossil fuels:
They are used in generating electric energy in thermal power plants.
Natural gas is also used in thermal power plant.
Petroleum byproducts like paraffin wax, lubricating oil, etc are used for different purposes.
Disadvantage of fossil fuels :
They are non renewable.
They produce a lot of carbon dioxide that causes the greenhouse effect.
They produce a lot of smoke.
