Sources of Energy

• Introduction to Energy

  • Law of Conservation of Energy: Energy can neither be created nor destroyed, only transformed.
  • Characteristics of a Good Source:
    • Accessible and easy to store/transport.
    • Economical (affordable).
    • High calorific value (amount of work per unit mass/volume).
    • Less polluting (eco-friendly).
  • Classification:
    • Renewable (Non-conventional): Inexhaustible, replenishable.
    • Non-Renewable (Conventional): Exhaustible, finite reserves.

• Conventional Sources of Energy

  • Fossil Fuels
    • Formed from ancient biomass over millions of years.
    • Examples: Coal, Petroleum, Natural Gas.
    • Disadvantages: Causes air pollution, releases greenhouse gases (Carbon Dioxide), leads to acid rain, non-renewable.
  • Thermal Power Plants
    • Uses burning of fossil fuels to boil water, producing steam to run turbines and generate electricity.
  • Hydropower Plants
    • Converts potential energy of falling water into electricity.
    • Advantages: Renewable, no direct pollution.
    • Disadvantages: Submerges ecosystems, displaces communities, constructs large dams.
  • Biomass
    • Plant and animal waste used as fuel.
    • Wood: Traditional use, causes smoke and low heat efficiency.
    • Charcoal: Formed by burning wood in limited oxygen (burns without flame/smoke).
    • Biogas Plant (Gobar Gas):
      • Anaerobic degradation of animal dung/plant waste.
      • Produces Biogas (75% Methane as main constituent) and rich manure residue.
  • Wind Energy
    • Harnesses kinetic energy of blowing wind via windmills to turn turbines.
    • Requirement: Minimum wind speed of 15 km/h.
    • Advantages: Pollution-free, renewable.
    • Disadvantages: High setup cost, requires vast land, dependent on wind availability.

• Non-Conventional / Alternative Sources of Energy

  • Solar Energy
    • Harnesses heat and light from the sun.
    • Solar Cooker: Uses reflectors to trap heat (box-type or concave mirror type).
    • Solar Water Heater: Uses black painted surfaces to absorb heat.
    • Solar Cell (Photovoltaic Cell):
      • Converts solar energy directly into electricity.
      • Made of silicon.
      • Used in calculators, artificial satellites, and street lights.
  • Energy from the Sea
    • Tidal Energy: Uses gravitational pull of the moon to harness energy from high and low tides using tidal barrage dams.
    • Wave Energy: Harnesses kinetic energy of strong sea waves to generate electricity.
    • Ocean Thermal Energy Conversion (OTEC):
      • Uses temperature difference between surface warm water (20°C+) and deep cold water.
      • Used to boil volatile liquids like ammonia to run turbine generators.
  • Geothermal Energy
    • Heat energy from deep underground hotspots.
    • Underground water turns to steam when it contacts hot rocks, which is used to drive turbines.
  • Nuclear Energy
    • Energy released during nuclear fission or nuclear fusion.
    • Nuclear Fission: Splitting of a heavy nucleus (e.g., Uranium, Plutonium, or Thorium) by neutrons.
    • Applications: Power generation in nuclear reactors.
    • Hazards: Accidental radiation leakage, safe disposal of spent nuclear waste.

• Environmental Consequences

  • Burning of fossil fuels increases greenhouse effect and global warming.
  • Construction of dams disrupts flora, fauna, and human settlements.
  • Nuclear waste poses severe long-term radiation hazards.

• Energy Availability and Conservation

  • Non-renewable sources will eventually deplete.
  • Need to switch to renewable and sustainable sources.
  • Practice energy conservation in daily life (e.g., turning off lights, using public transport).