Generating electricity

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Fuel for electricity

Water is heated to produce steam.
Steam is then used to drive a turbine.

This powers an electrical generator that produces the electricity.

Energy can come from burning a fossil fuel. (eg. coal, oil and gas)

Fossil fuels are obtained from long-dead biological material.

In some gas-fired power stations hot gases drive the turbine directly. It can be switched on very quickly.

A biofuel is a fuel obtained from living or recently living organisms - RENEWABLE.

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Nuclear power station

In a nuclear power station, the fuel used is uranium.

The nucleus of a uranium atom can undergo a process called nuclear fission which releases energy.

1. Uranium nucleus hit by a neutron.
2. Nucleus splits into two smaller nuclei.
3. Two/three more neutrons are released.
4. Energy is released and used to heat water, turning it into steam.

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Energy from wind and water

A wind turbine is an electricity generator on top of a tall tower.

At a hydroelectric power station, water is collected and allowed to flow downhill and turn turbines at the bottom of hill.

Wave power uses the movement of waves to drive a turbine which turns a generator.

Tidal power uses the high tide by trapping it. The water drives turbines once released to fall down to lower sea level.

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Power from the sun and earth

Solar energy from the Sun travels through space to Earth as electromagnetic radiation.

Solar cells transfer this energy into electrical energy. These are useful to power small devices. (eg. watches and calculators)

We can join large numbers of solar cells to form a solar panel.

Solar heating panels use the Sun's energy to heat water directly.

A solar panel tower uses thousands of mirrors to reflect sunlight onto a water tank to heat the water and produce steam.

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Power from the earth

Geothermal energy is produced inside the Earth by radioactive processes and this heats the surrounding rock.
Deep holes are drilled and cold water is pumped down to the hot rocks.

The water is heated and comes back to the surface as steam which is used to drive turbines that turn generators so electricity is produced. 

Geothermal energy can only be used in some parts of the world as in many others the hot rocks are too far below the surface to be used.

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Energy and the environment

Burning fossil fuels produces greenhouse gases that cause global warming.

eg. Sulfur dioxide is released by burning coal and causes acid rain.

Nuclear fuels produce radioactive waste.

Using renewable energy resources can affect plant and animal life.

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Energy and the environment

Burning fossil fuels produces greenhouse gases that cause global warming.

eg. Sulfur dioxide is released by burning coal and causes acid rain.

Nuclear fuels produce radioactive waste.

Using renewable energy resources can affect plant and animal life.

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The National Grid

The National Grid distributes electricity from power stations to our homes. 

Step-up and step-down transformers are used in the National Grid.

Step-up transformers increase the voltage so that less energy is wasted through the cables.

Step-down transformers decrease the voltage so that it can be used in homes and offices.

A high grid voltage reduces energy wastage and makes the system more efficient. 

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Big energy issues

A constant amount of electricity is provided by a nuclear, coal-fired and oil-fired power stations. This is called the base load demand.

Gas-fired power stations and pumped-storage stations can meet variations in demand.

Nuclear, coal and oil power stations can meet base load demands.

Nuclear power stations, fossil-fuel power stations using carbon capture and renewable energy are all likely to contribute to future energy supplies.

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