Where does energy come from?
There are different Useful supply or store of energy. in the world and the amount of The capacity for doing work. stored by them varies greatly. For example, the nuclear energy within 1 kg of uranium contains a very large amount of energy, but the The energy stored by an object lifted up against the force of gravity. Also known as GPE. stored by many thousands of tonnes of water held back by a dam contains less.
Renewable or non-renewable?
Renewable resources are replenished either by:
- human action, eg trees cut down for bio-fuel are replaced by planting new trees
- natural processes, eg water let through a dam for Electricity that is generated by the movement of water. is replaced through the The continuous movement of water on, above and below the Earth.
A non-renewable energy resource is one with a Something that has a limited number of uses before it is depleted. For example, oil is a finite resource. amount. It will eventually run out when all reserves have been used up.
Different energy resources
The table below shows the main features of the most common energy resources used today.
| Energy resource | Energy store | Renewable? | Uses | Power output | Environmental impact |
| Fossil fuels (oil, coal and natural gases) | Chemical | Non-renewable | Transport, heating, electricity generation | High | Releases CO2 (causes global warming) |
| Nuclear fuels | Nuclear | Non-renewable | Electricity generation | Very high | Radioactive waste (needs to be disposed of safely) |
| Bio-fuel | Chemical | Renewable | Transport, heating, electricity generation | Medium | 'Carbon neutral', so low impact |
| Wind | Kinetic | Renewable | Electricity generation | Very low | Takes up large areas that could be used for farming, some people say windmills spoil the view |
| Hydroelectricity | Gravitational potential | Renewable | Electricity generation | Medium | Local habitats are affected by the large areas that need to be flooded to build dams |
| Geothermal | Internal (thermal) | Renewable | Electricity generation, heating | Medium | Very low |
| Tides | Kinetic | Renewable | Electricity generation | Potentially very high, but hard to harness | Tidal barrages can block sewage which needs to go out to sea |
| Sun | Nuclear | Renewable | Electricity generation, heating | Dependent on the weather and only available during daylight | Very little |
| Water waves | Kinetic | Renewable | Electricity generation | Low | Very low |
| Energy resource | Fossil fuels (oil, coal and natural gases) |
|---|---|
| Energy store | Chemical |
| Renewable? | Non-renewable |
| Uses | Transport, heating, electricity generation |
| Power output | High |
| Environmental impact | Releases CO2 (causes global warming) |
| Energy resource | Nuclear fuels |
|---|---|
| Energy store | Nuclear |
| Renewable? | Non-renewable |
| Uses | Electricity generation |
| Power output | Very high |
| Environmental impact | Radioactive waste (needs to be disposed of safely) |
| Energy resource | Bio-fuel |
|---|---|
| Energy store | Chemical |
| Renewable? | Renewable |
| Uses | Transport, heating, electricity generation |
| Power output | Medium |
| Environmental impact | 'Carbon neutral', so low impact |
| Energy resource | Wind |
|---|---|
| Energy store | Kinetic |
| Renewable? | Renewable |
| Uses | Electricity generation |
| Power output | Very low |
| Environmental impact | Takes up large areas that could be used for farming, some people say windmills spoil the view |
| Energy resource | Hydroelectricity |
|---|---|
| Energy store | Gravitational potential |
| Renewable? | Renewable |
| Uses | Electricity generation |
| Power output | Medium |
| Environmental impact | Local habitats are affected by the large areas that need to be flooded to build dams |
| Energy resource | Geothermal |
|---|---|
| Energy store | Internal (thermal) |
| Renewable? | Renewable |
| Uses | Electricity generation, heating |
| Power output | Medium |
| Environmental impact | Very low |
| Energy resource | Tides |
|---|---|
| Energy store | Kinetic |
| Renewable? | Renewable |
| Uses | Electricity generation |
| Power output | Potentially very high, but hard to harness |
| Environmental impact | Tidal barrages can block sewage which needs to go out to sea |
| Energy resource | Sun |
|---|---|
| Energy store | Nuclear |
| Renewable? | Renewable |
| Uses | Electricity generation, heating |
| Power output | Dependent on the weather and only available during daylight |
| Environmental impact | Very little |
| Energy resource | Water waves |
|---|---|
| Energy store | Kinetic |
| Renewable? | Renewable |
| Uses | Electricity generation |
| Power output | Low |
| Environmental impact | Very low |
Comparing resources
Power stations that use Natural, finite fuel formed from the remains of living organisms, eg oil, coal and natural gas. or nuclear fuel are very reliable sources of energy. These two types of station provide much of the country’s electricity. They operate almost continuously. When additional power is needed, gas power stations are usually used because they will come on very quickly and start generating electricity almost immediately.
The fuel for nuclear power stations is relatively cheap, but the power stations themselves are expensive to build. It is also very expensive to dismantle, or To deactivate or remove in a safe manner., old nuclear power stations at the end of their useful life and the highly When unstable atoms give off particles that can be harmful to humans. waste needs to be stored for millions of years before the natural The number of decays of a radioactive element per second. Measured in Becquerels (Bq). will reduce to a safe level.
Water power, eg tidal and Electricity that is generated by the movement of water. , is reliable and predictable because of the Moon causing the tides and rainfall filling reservoirs. They can also be used to supply additional demand. But many of the renewable sources are unreliable, including wind and solar energy, and cannot respond to increased demand - sunny and windy weather cannot be guaranteed.
Renewable resources have no fuel costs, but the equipment used is expensive to build.