Sources of Energy: An Overview

Broad Classification of Energy Sources

All energy sources can be broadly classified into Conventional and Non-Conventional sources.

Conventional Sources of Energy

These are the traditionally used energy sources that have supported human civilization for centuries.

They are further divided into:

(a) Conventional Non-Renewable Sources

These are mostly fossil fuels, formed over millions of years and found below the ground:

• Coal
• Oil
• Natural Gas
• Coalbed Methane

👉 Key issue: Limited availability and high environmental pollution.

These non-renewable energy sources have already been examined in detail under the “Energy Resources” section of Economic Geography.

(b) Conventional Renewable Sources

These are non-fossil, naturally replenished sources, mostly found above the ground:
→ Firewood
→ Cattle dung
→ Vegetable waste
→ Wood charcoal

👉 Though renewable, overuse leads to deforestation and pollution, so they are not fully sustainable.

Non-Conventional (Renewable) Sources of Energy

These are modern, alternative energy sources developed mainly to reduce dependence on fossil fuels and mitigate climate change.

Examples include:

• Solar Energy
• Hydropower
• Wind Energy
• Nuclear Energy
• Hydrogen Energy
• Geothermal Energy
• Biogas
• Tidal Energy
• Biofuels

👉 These are cleaner, sustainable, and increasingly important for India’s energy transition.

Major Energy Sources: Mechanism, Advantages & Limitations

Let us now analyze the important energy sources one by one:

Nuclear Energy

🔸 How is energy produced?

• Through Nuclear Fission (splitting of heavy atoms like Uranium)
• Nuclear Fusion (joining of light atoms – still experimental)

✅ Advantages

• No air pollution
• Very high energy output from small fuel quantity
• Nuclear fusion reactors theoretically produce no nuclear waste

❌ Limitations

• Very high construction cost
• Risk of nuclear accidents and security threats
• Safe disposal of nuclear waste (especially in fission)
• Nuclear fusion technology is technologically very challenging

Hydropower

🔸 How is energy produced?

• Dams are built on rivers to convert kinetic energy of flowing water into electricity.

✅ Advantages

• Huge global potential
• Relatively cheap and clean energy source

❌ Limitations

• Submergence of forests and fertile farmland
• Displacement of human settlements
• Habitat loss and biodiversity destruction
• Reduced flow of nutrient-rich silt downstream
• Very high initial development cost

Solar Energy

🔸 How is energy produced?

• From natural sunlight, using photovoltaic cells or solar thermal systems.

✅ Advantages

• Environment friendly
• Unlimited and inexhaustible

❌ Limitations

• Storage of sunlight is limited
• Diurnal and seasonal variation
• Grid management challenges

Wind Energy

🔸 How is energy produced?

• Windmills convert wind’s kinetic energy into electricity
• Traditionally used for irrigation and grinding grains

✅ Advantages

• No pollution
• Freely available

❌ Limitations

• Intermittent availability
• Windmill blades are visual hazards for birds and aircraft
• Causes visual pollution

Tidal Energy

🔸 How is energy produced?

• A dam is built across a bay or estuary
• Electricity is generated during both flood tide and ebb tide using reversible turbines

✅ Advantages

• Free and clean source

❌ Limitations

• Very expensive structures
• Disrupts natural estuarine flow
• Pollutants get concentrated in the estuary

Geothermal Energy

🔸 How is energy produced?

• Steam from hot springs and geysers is trapped by drilling wells
• Steam runs turbines to generate electricity

✅ Advantages

• Environment friendly
• Reliable base-load energy

❌ Limitations

• Steam contains Hydrogen Sulphide (H₂S) causing air pollution
• Minerals are corrosive → high maintenance
• Toxic minerals harm aquatic life

Biomass Energy

🔸 What is Biomass?

• Biomass is a renewable energy resource derived from plant and animal waste
• Energy is released by breaking chemical bonds formed during photosynthesis

🔹 Traditional Biomass Use

• Burning firewood directly

Advantages

• Cheap and easily available
• Popular in developing countries

Limitations

• Low energy efficiency
• Bulky and difficult to transport
• Causes air pollution and fly ash
• Leads to deforestation and desertification

Biomass Conversion (Modern Use)

🔸 How is energy produced?

• Biomass converted into:
  • Ethanol
  • Methane (biogas)
• Used for cooking or electricity generation

✅ Advantages

• Renewable energy source

❌ Limitations

• Nutrients are not returned to soil → soil degradation
• Ethanol from maize often consumes more energy than it produces
• Agricultural land diverted from food production

Solid Waste as Energy

🔸 How is energy produced?

• Waste is sorted; combustible material is separated and burned

✅ Advantages

• Reduces landfill requirement
• Lowers disposal costs

❌ Limitations

• Causes air pollution
• Plastics and bleached paper release dioxins (carcinogenic)

Petro Crops (Energy Plants)

🔸 What are Petro Crops?

• Hydrocarbon-producing plants grown on non-agricultural land

🔹 Example

• Jatropha curcas
  • Produces biocrude from latex
  • Can be hydrocracked into petrol, diesel, kerosene

👉 Other petro-crops belong to Asclepiadaceae and Euphorbiaceae families.

Geothermal Energy in India

• Promising regions:
  • North-Western Himalayas
  • Western coastal belt
• Puga Valley (Ladakh) is India’s most promising geothermal field

Environmental Impact

• H₂S causes air pollution
• Toxic minerals affect fish
• Corrosive nature damages pipelines

Tidal Energy: Working Explained Simply

1. A dam is built across a bay or estuary
2. During high tide, water is allowed to enter and turbines rotate
3. The dam is closed when the reservoir is full
4. During low tide, stored water flows back, again rotating turbines
5. Electricity is produced in both directions