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P6 generating-electricity

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P6 generating-electricity

  1. 1. Lesson 8: Generating electricityWhat you need to know: 1. Different energy sources can be used to generate electricity. 2. There are different types of power stations. 3. How to use a Sankey diagram. Electricity is a secondary energy source, this is an energy source which does not exist in nature but is produced from a primary energy source such as fossil fuels. There are a number of primary energy sources that can be used to generate electricity:  Fossil fuels: Coal and gas are examples of fossil fuels, but they will eventually run out. When a fossil fuel is burned in a power station it will release carbon dioxide (CO2) into the atmosphere, adding to the problem of global warming.  Nuclear fuel: Uranium is used as fuel in nuclear power stations. Nuclear power stations do not produce CO 2 but do produce nuclear waste, which is very dangerous.  Renewable energy sources: Solar, wind, tidal and geothermal power can be used to generate electricity. These sources will never run out and do not produce CO2. In your exam you may be asked to identify different primary energy sources that can be used to generate electricity. There are advantages and disadvantages of using these different primary energy sources to produce electricity. Energy source Advantages Disadvantages Coal  Coal is cheap and easy to  Produces lots of CO2 which obtain. contributes to global warming.  High efficiency  Produces acid rain.  High power output.  Need to mine coal, which  Cheap electricity. can damage the environment. © Studydoctor 2009
  2. 2.  Technology is easily  Some countries need to available to build coal import coal, meaning they fuelled power stations. are reliant on other countries. This means they are not secure for their energy generation.  Coal will eventually run out.Gas  Efficient at producing  Produces CO2 which electricity. contributes to global warming.  Cheap electricity.  Difficult to transport.  Technology is easily available to build coal  Some countries need to fuelled power stations. import gas, meaning they are reliant on other countries. This means they are not secure for their energy generation.  Gas will eventually run out.Nuclear  Very cheap electricity.  Produces nuclear waste.  Low levels of CO2  Building and produced. decommissioning power stations is difficult and  Very high efficiency. costs are high.Solar power  No CO2 produced.  Low efficiency.  Easy to build power  Small amounts of stations. electricity produced.  Source not constant.Wind  No CO2 produced.  Need lots of turbines to produce electricity.  Easy to build power stations.  Wind is not constant.  Cheap electricity.  Visual pollution. In your exam you may be asked for some advantages and disadvantages of these different energy sources. © Studydoctor 2009
  3. 3. Power stations use the heat generated from burning fossil fuels and the fission of nuclear fuels to boil water, making steam. This steam drives a turbine which produces electricity. The efficiency of a power station can be described in a Sankey diagram, which shows where the energy created from a fuel source is going. 25% 30% Cooling steam Exhaust gases Electricity 45% As you can see, not all the energy generated from a fossil fuel actually goes into making electricity, lots of the energy is wasted. In your exam you may be asked to use a Sankey diagram to work out the efficiency of a primary energy source used to generate electricity.Recap: 1. Electricity is a secondary energy source that is generated from a primary energy source. 2. Each energy source has its advantages and disadvantages. 3. A Sankey diagram can be used to show the efficiency of energy sources in generating electricity. © Studydoctor 2009

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