Wasted Energy

• Wasted Energy

  • In practice, most systems tend to be open systems
  • When energy transfers occur that are not useful, these are described as energy being dissipated to the surroundings 
  • Dissipated just means spread out
  • This is considered to be wasted energy
• Wasted Energy

  • Often these less useful energy transfers often involve heating, light and sound
  • When energy is transferred to the thermal stores of the objects, the temperature of the objects increases
  • The particles that make up the objects vibrate more, hence the transfer pathway is by heating (of the particles)
  • Visible light is electromagnetic radiation
  • Therefore, when light is produced, energy is transferred by radiation
• Wasted Energy

  • When sound is produced, the sound waves make the air particles vibrate as the wave carries energy away 
  • This increases the energy in the thermal store of the air, hence the transfer pathway is by heating (of the particles)

    

  • Useful energy can be defined as:The energy that is transferred from store to store and used for an intended purpose
  • Wasted energy can be defined as:The energy that is not useful for the intended purpose and is dissipated to the surroundings 
• Reducing Energy Loss

  • Mechanical processes can become wasteful when they cause a rise in temperature
  • These processes often involve friction
  • When friction acts, it has the effect of transferring energy from the kinetic store by heating to the objects and the surroundings
  • This energy cannot be used in a useful way, therefore it is called wasted energy
  • Energy that is transferred to the surrounding is said to be dissipated (spread out) to the surroundings
• Lubrication

  • Friction is a major cause of wasted energy in machines
  • For example, the gears on a bike can become hot if the rider has been cycling for a long time
  • Energy is wasted as it is transferred from the kinetic energy store of the bike to the thermal energy store of the gears and the chain
  • This friction makes them become hot and transfers energy by heating to the thermal energy store of the surrounding air
  • This wasted energy can be reduced if the amount of friction can be reduced
  • This can be achieved by lubricating the parts that rub together
• Lubrication helps reduce friction in the parts of a cycle

  
• Insulation

  • In many situations, the energy transferred by heating is wanted. For example:
  • When heating a home
  • When boiling a kettle
  • If this energy can be prevented from dissipating, then less energy will be needed to replace the wasted energy
  • This can be achieved by surrounding the appliance with insulation
  • The effectiveness of insulation depends upon:
  • How well the insulation conducts heat
  • How thick the insulation is