P1.4 Generating Electricity

  • Created by: Fiona S
  • Created on: 19-02-15 23:28

Power Stations

The majority of the electricity we use is generated in power stations.


1. Burning fuel which give off heat energy. The heat energy is used to heat water in the boiler. This produces steam
2.The steam turns a turbine
3. The turbine drives a generator
4. The generator generates electricity


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Most fuels used in power stations are non-renewable, these include: Coal, Oil, Gas and Nuclear

One renewable fuel which can be used in power stations is biofuel. Examples include: methane (manure), ethanol (fermented sugar cane), straw and woodchip.

Biofuels are carbon-neutral. This is because the CO2 released when burnt is equal to the amount taken in while growing.
When coal, oil and gas are burnt they produce CO2. This is a greenhouse gas, contributes to global warming and climate change. One possible solution to this problem is Carbon Capture and Storage.

When Coal is burnt it produces sulphur dioxide (SO2) which causes acid rain.
Gas fired power stations have an advantage over oil and coal in that they have a very quick start up time.

Carbon Capture and Storage is a way to prevent carbon dioxide building up in the atmosphere. It is a rapidly evolving technology that involves separating carbon dioxide from waste gases. The carbon dioxide is the stored underground, for example, in old oil fields or gas fields such as those found in the North Sea.
This technology traps some carbon dioxide emitted by power stations and stops it from entering the atmosphere. It is carbon negative.

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Nuclear Power Stations

How do we get energy from the nucleus?

The fuel used is either Uranium or Plutonium. The nucleus is unstable because it is extremely large. When a slow moving neutron is absorbed by the nucleus it causes the nucleus to split into two smaller nuclei. This is called nuclear fission.

(http://www.bbc.co.uk/staticarchive/449eebc0398b330e0b9d9ca0cf88edeb8fcd2ba3.gif)These neutrons will repeat the process


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Inside a Nuclear Reactor

Nuclear reactors use Uranium or Plutonium to generate heat and turn water into steam. The Uranium is stored in sealed cans in the reactor core. Uranium has an unstable nucleus which can split into two smaller nuclei releasing energy, this is nuclear fission.

  • The core of the reactor becomes very hot and this heat energy is transferred to a fluid (the 'coolant') which is pumped through the core 
  • The coolant is very hot when it leaves the core and flow to a heat exchanger.
  • In the heat exchanger, the heat energy from the coolant is used to turn water into steam
  • The steam drives turbines that turn electricity generators


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Fossil Fuels vs. Nuclear Power

Fossil Fuels

Fuel: Oil, Coal, Natural Gas
Energy released per kg of fuel: 100 kWh
Waste: Non-Radioactive Waste
Pollution: CO2 given off causes global warming. SO2 given off by Coal causes Acid Rain
Reliability: Yes

Nuclear Power

Fuel: Uranium, Plutonium
Energy released per kg of fuel:
 1,000,000 kWh
Waste: Radioactive Waste - needs storing safely for many years
Pollution: None - energy released without any burning
Reliability: Yes

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The National Grid

1. Fossil fuels are burnt to heat water
2. Steam passes through turbines making them turn
3. The turbine is attached to a generator which turns to generate electricity
4. Step up transformer increase the voltage to 400,000V
5. Electricity is transported across the country by a vast network of pylons and cable
6. Near houses and factories, the voltage is stepped down to 30,000V
7. At local transformer substations, the voltage is stepped down to 230V, for use in the home
8. Electricity in the home comes in through the meter to all plug sockets


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The National Grid

The National Grid is a network of power stations and cabling that carries electricity around the country.

Why do we use step up transformers?

Step up transformers increase the voltage which means the current can be low. This means that less heat is lost as the current passes through the cable making the National Grid more efficient.

Why do we use step down transformers?

Step down transformers decrease the voltage so that it's safe to use in homes.

Cables - Underground vs. Overhead

Underground - hard to fix, can conduct underground minerals, may harm animals that live underground.

Overhead - spoiling the landscape

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Types of Energy

Fossil Fuels
Initial Energy:
Advantages: Reliable, proven technology, no radioactive waste
Disadvantages: produces greenhouse gases, coal causes acid rain, non-renewable, when burned causes global warming

Initial Energy: Nuclear
Advantages: No greenhouse gases, produces more energy, reliable, lasts longer than fossil fuels
Disadvantages: Non-renewable, expensive to get rid of waste, produces Radio-Active waste, stored underground in geologically stable sights

Initial Energy: Kinetic
Renewable, no fuel costs, no greenhouse gases, put in isolated places
Not always windy

Initial Energy: Kinetic
Advantages: Renewable, free fuel, no greenhouse gases, there are always waves
Disadvantages: damaged by stormy seas, hard to repair, unreliable, effects boats and marine life

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Types of Energy continued...

Initial Energy: Light
Renewable, no greenhouse gases, free fuel
Not always sunny and large areas needed, unreliable, expensive

Initial Energy: Gravitational Potential
Renewable, no greenhouse gases, free fuel, reliable
Disadvantages: Tide only comes in twice a day, damage sea life, eyesore, stops boats and shipping

Initial Energy: Gravitational Potential
Renewable, reliable, no greenhouse gases, free fuel, quick start up time, can store energy until needed, no CO2 produced
damages environment, disrupt river life, flood reservoir, impact of environment and local community

Initial Energy: Chemical
Renewable, no greenhouse gases, free fuel, carbon neutral
only small scale, takes up land, smell

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Types of Energy continued...

Initial Energy: Nuclear
Renewable, no greenhouse gases, free fuel
Only works in certain places

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