1.1.12 Wasted Energy

• Wasted energy

  Energy that is not converted into the desired useful form but instead dissipates into less useful forms, typically as heat or sound
• This energy is not lost; it is just transferred to the surroundings and is often difficult to reclaim
• Inefficiencies in Energy Conversion

  • Not all input energy is converted into useful work
  • Some energy is inevitably converted into less useful forms
• Heat Dissipation

  • Most mechanical and electrical devices generate heat as a byproduct
  • This heat energy is often transferred to the surroundings
• Sound Energy

  • Devices produce sound energy as a byproduct
  • This sound energy disperses into the environment
• Wasted Energy in Light Bulbs

  • Incandescent Bulbs
  • Fluorescent and LED Bulbs
• Incandescent Bulbs


  • Convert only a small fraction of electrical energy into visible light; the rest is dissipated as heat
• Fluorescent and LED Bulbs

  • More efficient because they convert a higher percentage of electrical energy into light and less into heat
• Wasted Energy in Engines and Cars

  • Internal Combustion Engines
• Internal Combustion Engines

  • A significant amount of energy from burning fuel is lost as heat
  • Only a portion of the energy is used for moving the car
• Wasted Energy in Electrical Appliances


  • Toasters
  • Kettles
  • Computers
• Electrical Devices

  • Generate heat as a byproduct
  • Not all electrical energy is used for the intended purpose
• Friction in Mechanical Systems

  • Friction converts some mechanical energy into heat
  • Reduces overall efficiency
• Calculating Wasted Energy

  Compare useful energy output to total energy input
• Efficiency Formula

  Efficiency = Useful Energy Output / Total Energy Input × 100%
• Wasted Energy Calculation

  Wasted Energy = Total Energy Input - Useful Energy Output
• Improving Efficiency

  • Improve insulation
  • Use energy-efficient appliances
  • Reduce friction
  • Optimize designs
• Insulation

  Improve insulation in buildings and appliances to reduce heat loss
• Energy-Efficient Appliances

  Use appliances with higher energy efficiency ratings
• Lubrication

  Reduce friction in mechanical systems using lubricants
• Design Improvements


  Optimize designs to convert energy more effectively