generating electricity physics 1 gcse sciencechapter 10
TRANSCRIPT
Generating ElectricityGenerating Electricity
Physics 1Physics 1
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Energy– the problem with using too much
Where do we get most of our energy from?
Oil
Coal Gas
Environmental problems!(Atmospheric pollution and climate change)
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What happens to the Earth?
Global Warming
Earth’s Atmosphere
Sunlight travels as electromagnetic waves through space and the atmosphere, towards the Earth.
A proportion of this energy is absorbed, and a part of it is reflected.
When the Earth radiates the absorbed heat energy back into space, it is in the form of infra-red radiation with a longer wavelength. Some molecules, such as carbon dioxide and methane, absorb some of this longer wavelength radiation, and trap the energy within the atmosphere. Consequently the atmosphere heats up – this is known as the Greenhouse Effect.G
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The Effect of Global WarmingWhat will the effect of a temperature rise of 2°C be?
More deserts – less land to grow crops.
Change in climate – more extreme weather, floods and drought becoming common.
Winters will be warmer
The sea level will rise as a result of polar ice caps melting.
The Gulf stream’s direction could change and as a result, Britain’s temperature would fall.
Our carbon dioxide emissions is responsible Our carbon dioxide emissions is responsible for this, and there is a constant campaign to for this, and there is a constant campaign to get us to burn less coal, oil and gas.get us to burn less coal, oil and gas.
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The Energy Crisis
Coal, oil and gas are examples of non-renewable resources.
Oil
Coal Gas
After using them once, you cannot re-use them – you would have to wait millions of years for them to be produced.
By 2020 we in Britain will have to reduce our dependence on coal, oil and gas and produce electricity by renewable means.
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Thermal Power Stations
turbine generator
Hot water
condenserCold water
Water
Steam
Hot steam
Cooling tower
steam
Cold water
boiler
Coal, oil or gas
Fossil Fuel
1. Burning Fossil Fuels
2. Cold water turned into steam in the boiler.
3. Steam turning the turbine
4. Turbine turning the generator and producing electricity.
Cold steam
5. Part of the energy is lost to the environment at this stage.
It’s possible to use the waste steam to heat the factory or
nearby houses.
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National grid
Condenser
Cold Water
Turbine Generator
Heat
Hot steam
Hot water
The latest power stations use the hot water to heat up the surrounding houses.
Is it possible to improve the design?
It’s possible to use wood as fuel. New trees can be
planted and grow quickly to replace the fuel supply.
These trees absorb CO2 as they grow and release it
when they burn – so no net gain or loss of CO2.
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Thermal Power Station
turbine generator
Hot water
condenserCold water
Water
Steam
Hot steam
Cooling tower
steam
Cold water
Nuclear
3. Steam turning the turbine
4. The turbine turning and generating electricity.
Cold steam
5. At this stage, part of the energy is lost to the environment.
Cooler
core fuel
Steam generator
2. The steam generator turns cold water to steam
1. A nuclear reaction in the core.
One nuclear station is equal to 2400 wind
turbines!
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Start up timeThe different types of power stations have different ‘preparing to start’ times:
Fast
Slow
Gas
Oil
Coal
Nuclear
OilOil
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Non-renewable Energy Sources
Coal, oil, gas and nuclear
Advantages
Disadvantages
Low fuel costs
Good for meeting basic energy requirements
Fuel supplies depleting
Nuclear energy
creates very little pollution
High commissioning and decommissioning
costs in a nuclear power station
Gas and oil have a
low start-up timePollution – CO2 leads to
global warming and SO2 to acid rain
Dependable
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Renewable Energy – Wind Power
Wind turbines are a familiar site in this country. The sites are called ‘wind farms’.
Strong winds in Britain mean that this is a viable source of energy production for us.
However, some are against this . They claim that the wind turbines destroy habitats, that they are noisy and ineffective.
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Renewable Energy – Tidal Power
Low Tide
High Tide
As the tides turn, the movement of the water turns the turbine, and the generator produces electricity.
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Renewable Energy – Wave Power
The movement of the waves causes the float to move up and down. This turns the generator and it produces electricity.
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Renewable Energy – Hydro-Electric Power and Pumped Storage
High resevoir
When electrical energy is needed urgently, this hydro-electric system is used. Water form a high resevoir is released and as it flows, it turns the turbine and produces electricity. It depends on gravity. In a pumped storage scheme, an electrical pump can be used to pump the water back into the resevoir at off-peak rates, and so it can be re-used.
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SourceSource DisadvantageDisadvantage
Wind
Waves
Tide
Hydro-electric
Also, the above have a long start-up time
Weather-dependent; can be perceived as being an eye-sore by some; difficult to store.
Can be harmful to marine life; dependent on the size of the waves; weather-dependent.
Depends on the size of the tide and can affect habitats if mud flats are not uncovered for birds to feed.
Habitats suffer due to flooding of river valleys in some schemes.
Are there disadvantages to using renewable sources?
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Renewable Energy SourcesRenewable Energy Sources
Wind, tide, hydro-electric and solar
AdvantageAdvantagess
DisadvantagDisadvantageses
No pollution
Hydro-electric good
for urgent demand
for electric
ity
Solar is good for remote areas (e.g. satellites)
No fuel costs
Unreliable (except Hydro-electric)
Expensive to build
Tidal barriers destroy bird habitats and hydro-electric depends on flooding farm land
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