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