Physics: Energy and Energy sources
Key points
• Most of the energy on Planet Earth comes originally from the Sun.
• “Law of the Conservation of Energy” = Energy cannot be made or
destroyed, it is just changed from one form to another.
• Energy is measured in Joules (J) or Kilojoules (KJ)
Types of Energy
Types of Energy
Light
Thermal
Sound
Chemical
Kinetic (movement)
Gravitational potential
(GPE)
Electrical
Strain or elastic
Nuclear
Examples
Sun, stars, fire, light bulbs
Fires. Sun, hair dryer, light bulbs
Objects that are vibrating
Food, battery cells, chemicals (e.g. coal)
Moving objects (falling skydiver)
Objects that are high up (e.g. diver at the top
of a cliff)
Current flowing through a complete circuit
Stretched objects (e.g. elastic band)
Obtained from nuclear reactions
Energy transformations
Whenever we use energy, it changes from one form into another.
E.g.
Start energy
Chemical
•
•
Energy changer
Burning candle
Finish energies
Thermal and Light
Concentrated energy: energy that is easy to use, e.g. chemical
energy in coal.
Most energy eventually changes into thermal energy and is lost to
our surroundings – we can no longer easily use it.
P.T.O
Energy Sources
There are two main types of energy sources:
Renewable and Non-renewable
Renewable sources of energy
Renewable sources of energy: these types of energy can be replaced, so
will not run out.
e.g. Wave, tidal, hydroelectric, solar, geothermal, biomass (e.g. wood
– note, although the piece of wood burns away, it is possible to replace by
growing another tree), tidal.
Problems with non-renewable include;
• Expensive to set up projects
• Not always reliable (e.g. the wind does not always blow strong
enough)
Non-renewable sources of energy
• Fossil fuels (e.g. Coal, Gas and Oil) contain chemical energy
• These fuels cannot be replaced – once they are burnt they cannot
be used again.
Note:
The energy in fossil fuels has originally come from the Sun.
e.g. Coal is made from fossilized plants. These plants were once living
and will have carried out photosynthesis changing light energy into
chemical energy.
Energy changes in Power Station to generate electrical energy
Burn fuel to
heat water
Chemical energy
To
Thermal energy
Steam turns
turbine
Turbine turns
generator making
electricity
Thermal energy
To
Kinetic energy
Kinetic energy
To
Electrical energy