Nearly everything requires energy and a way to use energy is by transferring it from one energy store to another. Systems that can store large amounts of energy are called energy resources. The major energy resources available to produce electricity are fossil fuels, nuclear fuel, biofuel, wind, hydroelectricity, geothermal, tidal, water waves and the Sun. Ultimately, all the energy on Earth originally comes from the Sun but has been stored as different energy resources.
Energy is needed in:
However, producing and distributing electricity can cause damage to the environment. Releasing energy from some stores causes pollution and harmful waste products. Burning fossil fuels releases carbon dioxide, adding to the greenhouse effect, and sulphur dioxide which causes acid rain.
During the Industrial Revolution, advances in automation and transport caused a significant increase in the amount of fossil fuels extracted and burnt.
In the 20th century, electricity became a convenient way of distributing energy that can be used for a wide range of devices and applications such as lighting, heating, computing technologies and operating machinery.
Demand for energy varies with the time of year and the time of day. During early evenings, a lot of energy is needed for heating, lighting and cooking but overnight there is very little needed while people sleep. During winter, there is more heating and lighting required than in summertime.
Most of the electricity generated globally is still produced by fossil fuels. This is partly due to:
The recognised impact on the environment of burning fossil fuels has caused science and society to develop the use of renewable energy resources and make machines more efficient.
In some developed countries, nuclear power stations are a growing form of electricity generation. Nuclear fuel can release large amounts of energy compared to fossil fuels and does not emit carbon dioxide. However, the radioactive waste that is produced is difficult to store and dispose of.
Other factors that could influence governments' decisions about the use of energy resources are political and economic pressures. For example, countries where the economy is heavily based on extracting and exporting oil, have a strong interest in fossil fuels to be largely used in electricity generation. In order to compete with more developed countries, growing countries like China need a large power output to keep growing their industry. This means they are likely to continue using fossil fuels and developing the use of nuclear power, alongside increasing supply from renewable sources of energy.