Generating electricity

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Key points

  • Much of the energy that is transferred in our homes is supplied by electricity.

  • Energy resources are used to generate electricity.

  • Some energy resources are and some are .

Generating electricity

Much of the energy that is transferred in our homes is supplied by electricity. There are a wide range of energy resources used to generate electricity.

Energy resources are systems that can store large amounts of energy. Energy resources can be divided into two categories:

  1. Renewable resources - energy resources that can be replenished. They do not run out although we are using them.

  2. Non-renewable resources - energy resources that cannot be replenished. These resources will eventually run out because we are using them.

Not all energy resources are available everywhere and each one has its own advantages and disadvantages.

Graphic showing different renewable and non-renewable energy types.
Renewable and non-renewable energy types

Renewable energy - wind

Wind is an example of a resource. Wind is caused by the movement of air. The wind turns a wind which generates the electricity.

The wind turns a wind turbine which generates the electricity.
The wind turns a wind turbine which generates the electricity

Advantages and disadvantages of wind

Advantages

  • Wind is a renewable energy resource.

  • Wind does not release any harmful gases.

  • There are no fuel costs involved in running a wind turbine.

Disadvantages

  • Wind turbines can make a lot of noise and some people do not like to live near them because of this.

  • Some people think that wind turbines spoil the landscape.

  • Wind is an unreliable energy resource - the amount of electricity that is generated is dependent on how windy it is.

Wind turbines can be used to generate electricty

Renewable energy - water

Water is an example of a energy resource.

Like wind, moving water can also be used to turn a . The turbine can then turn a .

There are several different energy resources involving water:

  • tidal

  • wave

  • hydroelectric

Tidal

Huge amounts of water move in and out of river mouths each day because of the tides.

A tidal barrage is a barrier built across a river estuary. The barrage contains electricity , which are driven by the water rushing through tubes in the barrage.

A tidal barrage is a barrier built across a river estuary. The barrage contains electricity generators, which are driven by the water rushing through tubes in the barrage.
Tidal barrage

Wave

The water in the sea rises and falls because of waves on the surface.

Wave machines move with the waves to drive generators.

A wave power station showing incoming waves forcing air to be compressed in a chamber which turns a turbine to generate power.
Wave power can be used to generate electricity

Hydroelectric

Like tidal barrages, hydroelectric power stations use moving water. Water is held behind a dam built across a river.

The water high up behind the dam has a lot of energy in the gravitational potential energy store. This is transferred to the kinetic energy store as the water rushes down through tubes inside the dam. The moving water turns a that drive generators.

A hydroelectric power station showing a dam and water flowing through a turbine to turn a generator and produce energy.
Hydroelectric power can be used to generate electricity

Advantages and disadvantages of using water as an energy resource

Advantages

  • There are no fuel costs.

  • No harmful gases are released.

  • Hydroelectric and tidal are reliable sources of power.

Disadvantages

  • Waves are not a reliable source of power. Waves are not consistent and a calm period means there are not waves to generate power.

  • Building dams and tidal barrages can harm habitats and displace people from their homes.

Renewable energy - geothermal

Geothermal energy resources are an example of energy resources.

Hot water and steam from deep underground can be used to turn a which turns a to generate electricity.

Video

Watch the video to understand more about geothermal energy.

Find out how the heat of the Earth can be used to generate clean electricity

A diagram of geothermal energy generating station. Cold water is pumped down and steam and hot water rise.
Geothermal energy can be used to generate electricity

Geothermal resources come from either volcanic areas or hot rocks.

Volcanic areas

Several types of rock contain radioactive substances such as uranium. During nuclear or radioactive , energy in the nuclear store is transferred to the thermal store so the temperature of the rocks increase.

In volcanic areas, energy is transferred by heating. Hot water and steam may rise naturally to the surface. Here the steam can be used to drive turbines and generators.

Hot rocks

In some places, the rocks are hot, but no hot water or steam rises to the surface. In this case, deep wells can be drilled down to the hot rocks and cold water pumped down.

The water runs through cracks in the rocks and energy is transferred by heating. It returns to the surface as hot water and steam.

Advantages and disadvantages of using geothermal as an energy resource

Advantages

  • Geothermal is a reliable energy resource.

  • There are no fuel costs.

  • No harmful polluting gases are produced.

  • The hot water and steam can also be used for heating buildings directly.

Disadvantages

  • Big investment is needed to set up geothermal energy projects and some countries cannot afford these.

  • Most parts of the world do not have suitable areas where geothermal energy resources can be easily exploited.

Renewable energy - solar

Solar energy resource is an example of a energy resource. Energy is transferred from the sun by radiation. It can generate electricity in solar cells. It can also warm water in solar panels.

In the Northern Hemisphere, solar cells or solar panels are positioned facing south on the roofs of buildings. In the Southern Hemisphere they are placed facing north.

Advantages and disadvantages of solar power

Advantages

  • Solar power is a renewable energy resource.

  • There are no fuel costs.

  • No harmful gases are released.

Disadvantages

  • It is an unreliable energy resource. It is dependent on the weather and how many hours of sunlight there are.

  • Solar panels are expensive to fit.

Renewable energy - biomass

Biomass is an energy resource from animal or plant material, for example wood or food waste. It is a energy source.

The biomass is burnt and this can be used to turn water into steam. The steam turns . The turbines drives electrical .

Biomass can be converted into liquid fuels known as biofuels such as biodiesel and ethanol. These may be used instead of petrol in vehicles.

Biogas plant

Advantages and disadvantages of biomass

Advantages

  • Biomass is a renewable energy resource.

  • Growing more crops takes in carbon dioxide. This can offset what is given out during burning. This is called carbon neutral.

Disadvantages

  • Gases and smoke are released as the biomass fuel is burnt.

  • Lots of land is needed for growing the fuel crop.

Non-renewable energy - fossil fuels

Fossil fuels are an example of a non-renewable energy resource. Fossil fuels take a very long time to form so they are being used up faster than they can be replaced.

Coal, oil and natural gas are all fossil fuels. They are formed over millions of years from the remains of dead organisms.

Fossil fuel power stations generate electricity by burning fuel (coal, oil or natural gas). Energy transferred by heating causes water to boil, turning it into steam. The steam then turns a which turns a .

Coal, oil and natural gas are all all fossil fuels and are non-renewable energy types.
Coal, oil and natural gas are all fossil fuels and non-renewable energy types

Disadvantages and advantages of fossil fuels

Disadvantages

  • are finite and will therefore not last forever.

  • Fossil fuels are a resource. When burnt they release harmful gases including:

    • Carbon dioxide - a greenhouse gas which causes and contributes to climate change.

    • Sulphur dioxide and nitrogen oxides which cause acid rain. This is a significant issue when burning coal.

  • Smoke from burning coal or oil contains lots of fine particles. These can cause smog and result in breathing difficulties.

  • Taking fossil fuels from the ground has a negative impact on the landscape and environment.

Advantages

  • Fossil fuels are a resource.

  • Fossil fuels have a large amount of energy in the chemical energy store per kilogram.

Smoke from burning coal or oil contains lots of fine particles which can cause smog and result in breathing difficulties

Non-renewable energy - nuclear fuel

is an example of a energy resource.

Nuclear power stations generate electricity using nuclear fuels, such as uranium and plutonium.

Energy in the nuclear store is transferred to energy in the thermal store through nuclear reactions. Energy is transferred by heating to boil water, turning it to steam. The steam then turns a which then turns a .

Sellafield Nuclear Plant, Cumbria

Disadvantages and advantages of nuclear fuel

Disadvantages

  • The needed for nuclear power stations will run out. Nuclear fuel is a . This means that nuclear fuels are a non-renewable energy resource.

  • Although a lot of research has been done on how to make nuclear power stations safe, if an accident occurs radioactive material may be released into the environment. This can cause cancers and therefore be hazardous to health.

  • Nuclear power stations also create a lot of nuclear waste. This harmful waste material can be radioactive for many thousands of years. It is important that it is stored correctly so that it is safe.

Advantages

  • Unlike , nuclear fuels are not burnt. They do not cause smoke or release harmful gases which contribute to and climate change.

  • Nuclear fuel has a high power output per kg of fuel. It is much higher than any of the fossil fuels. 1 kg of enriched uranium has the same power output as about 14,000 kg of coal.

A black and yellow symbol indicating radiation warning.
Radiation warning symbol

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