Sources of Energy – Complete Notes for SSC & JKSSB General Science
By Home Academy
Energy is the capacity to do work. Every physical, chemical, and biological process on Earth depends on energy. For competitive examinations like SSC and JKSSB, questions are frequently asked about classification of energy sources, renewable vs non-renewable energy, thermal power plants, nuclear energy, and conventional vs non-conventional sources. This article covers the topic from beginner to advanced level with exam-oriented highlights.
1. What is a Source of Energy?
A source of energy is any system or resource from which usable energy can be obtained for performing work such as heating, lighting, transportation, or running machines.
Example: Coal burns to produce heat energy; water stored at height produces hydroelectric energy.
2. Classification of Sources of Energy
Energy sources are classified in different ways:
A. On the Basis of Availability
| Basis | Types | Examples | Exam Focus |
|---|---|---|---|
| Renewable | Can be replenished naturally in a short time | Solar, Wind, Hydropower, Biomass | Environment-friendly, sustainable |
| Non-renewable | Limited and exhaustible | Coal, Petroleum, Natural Gas, Nuclear fuels | High energy output, pollution issues |
B. On the Basis of Usage
| Type | Description | Examples |
|---|---|---|
| Conventional | Traditionally used for long time | Coal, Petroleum, Hydropower |
| Non-Conventional | Recently developed and promoted | Solar, Wind, Tidal, Geothermal |
C. On the Basis of Origin
| Type | Meaning | Example |
|---|---|---|
| Primary Energy | Available directly in nature | Coal, Sunlight, Wind |
| Secondary Energy | Produced from primary sources | Electricity, Hydrogen |
3. Characteristics of a Good Source of Energy
High calorific value
Easily availableEasy to store and transport
Economical
Less pollution
Safe and convenient
Exam Question Example:
Which of the following is not a characteristic of a good fuel?
4. Renewable Sources of Energy (In Detail)
4.1 Solar Energy
The Sun is the ultimate source of energy for most processes on Earth.
Devices Used:
Solar cooker
Solar cell
Solar water heater
Solar panel
India has established the International Solar Alliance, headquartered in Gurugram.
Advantages:
No pollution
Unlimited supply
Low maintenance
Disadvantages:
Dependent on weather
High initial cost
Exam Highlight:
Solar cell works on photovoltaic effect.
4.2 Wind Energy
Wind turbines convert kinetic energy of wind into electrical energy.
Major Wind Power States in India:
Tamil Nadu
Gujarat
Maharashtra
Karnataka
Advantages:
Clean energy
Low operating cost
Limitation:
Requires high wind speed
Exam Question:
Wind energy is converted into electrical energy by wind turbines.
4.3 Hydroelectric Energy
Energy obtained from flowing water.
Major Dam Example:
Bhakra Nangal Dam
Working Principle:
Potential energy of stored water → Kinetic energy → Mechanical energy → Electrical energy.
Advantages:
Renewable
No fuel cost
Disadvantages:
Displacement of people
Ecological imbalance
Exam Highlight:
Largest source of renewable electricity in India.
4.4 Biomass Energy
Energy obtained from plant and animal waste.
Example:
Biogas plant (Gobbar gas)
Biogas mainly contains Methane (CH₄).
Advantages:
Reduces waste
Rural energy solution
Exam Question:
Major component of biogas is methane.
4.5 Geothermal Energy
Energy from heat inside the Earth.
In India, geothermal potential areas include Ladakh and Himachal Pradesh.
Advantage:
Continuous energy supply
Limitation:
Limited geographical availability
4.6 Tidal Energy
Produced from rise and fall of sea tides.
Tidal energy plant requires large difference between high tide and low tide.
Exam Highlight:
Moon's gravitational pull causes tides.
5. Non-Renewable Sources of Energy
5.1 Coal
Major fossil fuel.
Highest use in thermal power plants.
India is one of the largest coal producers.
Advantages:
High calorific value
Cheap
Disadvantages:
Air pollution
Global warming
Exam Highlight:
Coal formed from dead plants millions of years ago.
5.2 Petroleum
Called Black Gold.
Refined in petroleum refineries.
Products:
Petrol
Diesel
Kerosene
LPG
Exam Question:
Petroleum is found between layers of sedimentary rocks.
5.3 Natural Gas
Cleanest fossil fuel.
Example:
CNG (Compressed Natural Gas)
Exam Highlight:
Less polluting compared to coal and petroleum.
5.4 Nuclear Energy
Produced by nuclear fission.
Example:
Tarapur Atomic Power Station
Fuel Used:
Uranium-235
Advantages:
Huge energy from small fuel
Low carbon emission
Disadvantages:
Radioactive waste
High risk
Exam Question:
Nuclear energy is produced by fission of Uranium.
6. Comparison Table (Very Important for Exams)
| Feature | Renewable | Non-Renewable |
|---|---|---|
| Availability | Unlimited | Limited |
| Pollution | Less | More |
| Cost | High initial | Lower initial |
| Examples | Solar, Wind | Coal, Petroleum |
7. Advanced Concept – Thermal Power Plant Working
Coal → Burned in boiler → Steam produced → Turbine rotates → Generator produces electricity.
Most electricity in India is generated by thermal power plants.
8. Energy Conservation (Frequently Asked)
Energy conservation means using energy efficiently to reduce wastage.
In India, Bureau of Energy Efficiency works under Ministry of Power.
9. Important Exam Highlights (Quick Revision)
Solar energy works on photovoltaic effect.
Wind turbine converts kinetic energy into electrical energy.
Biogas contains methane.
Uranium-235 is used in nuclear reactors.
Coal is fossil fuel formed from plants.
Tides are caused by Moon’s gravity.
10. Previous Year Type MCQs (Practice for SSC & JKSSB)
Which fuel has highest calorific value?
(a) Wood (b) Coal (c) LPG (d) KeroseneThe main component of biogas is
(a) Oxygen (b) Nitrogen (c) Methane (d) Carbon dioxideNuclear energy is obtained by
(a) Fusion (b) Fission (c) Combustion (d) OxidationWhich of the following is non-renewable?
(a) Solar (b) Wind (c) Coal (d) Tidal
Answers:
1 (c), 2 (c), 3 (b), 4 (c)
Sources of energy are essential for development, industry, transportation, and daily life. For SSC and JKSSB exams, focus on classification, advantages and disadvantages, nuclear energy, thermal power plant working, renewable vs non-renewable comparison, and characteristics of good fuel.
Energy conservation and promotion of renewable energy are crucial for sustainable development
MCQ questions on Sources of Energy
Which of the following is a renewable source of energy?
A. Coal
B. Petroleum
C. Solar energy
D. Natural gasThe main component of biogas is
A. Hydrogen
B. Methane
C. Oxygen
D. NitrogenWhich fuel is known as Black Gold?
A. Coal
B. Uranium
C. Petroleum
D. BiomassWind energy is converted into electrical energy by using
A. Transformer
B. Generator
C. Wind turbine
D. InverterThe energy obtained from the heat inside the Earth is called
A. Tidal energy
B. Geothermal energy
C. Solar energy
D. Biomass energyNuclear energy is produced by the process of
A. Combustion
B. Oxidation
C. Nuclear fission
D. DistillationWhich of the following is a non-renewable source of energy?
A. Wind energy
B. Solar energy
C. Hydropower
D. CoalThe device used to convert solar energy directly into electricity is
A. Solar cooker
B. Solar heater
C. Solar cell
D. TurbineThe major source of energy in thermal power plants is
A. Water
B. Coal
C. Wind
D. UraniumTidal energy is mainly caused by the gravitational pull of
A. Sun only
B. Earth
C. Moon
D. MarsWhich of the following has the highest calorific value?
A. Wood
B. Coal
C. LPG
D. Cow dung cakeCNG stands for
A. Compressed Natural Gas
B. Controlled Natural Gas
C. Combined Natural Gas
D. Converted Natural GasHydroelectric power plants convert
A. Chemical energy into electrical energy
B. Potential energy of water into electrical energy
C. Heat energy into light energy
D. Nuclear energy into mechanical energyUranium-235 is used as fuel in
A. Thermal power plants
B. Hydroelectric plants
C. Nuclear reactors
D. Wind turbinesWhich of the following is considered the cleanest fossil fuel?
A. Coal
B. Petroleum
C. Natural gas
D. Wood
Answer Key:
1 C
2 B
3 C
4 C
5 B
6 C
7 D
8 C
9 B
10 C
11 C
12 A
13 B
14 C
15 C