Transcript Physics 2 - The New Bridge Academy

05/04/2016
Generating Electricity
(AQA)
New Bridge AcademyScience Dept.
Fuels
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A “fuel” is something that can be burned to release heat and
light energy. The main examples are:
Coal, oil and gas are called “fossil fuels”. In other words, they
were made from fossils. We say they are NON-RENEWABLE.
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Using non-renewable fuels in power stations
1) A fossil fuel is burned in the boiler
2) Water turns to steam and the steam drives a
turbine
3) The turbine turns a generator
4) The output of the generator is connected to a
transformer
5) The steam is cooled down in a cooling tower and
reused
Nuclear power stations
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These work in a similar way to normal power stations, nuclear is NON RENEWABLE.
The main difference is that the nuclear fuel is NOT
burnt – it is used to boil water in a “heat exchanger”
Start up times
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Different power stations have different start up times:
Gas
Quick
Oil
Coal
Nuclear
Slow
Some definitions…
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A renewable energy source is clearly one that can be
_______ (“renew = make again”), e.g. _____, solar power
etc.
A ___________ energy source is one that when it has
been used it is gone forever. The main examples are
____, oil and gas (which are called ______ ____, as they
are made from fossils), and nuclear fuel, which is nonrenewable but NOT a fossil fuel.
Words – non-renewable, coal, fossil
fuels, wood, renewed
Non-renewable energy sources
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Advantages
Disadvantages
Cheap fuel costs
Costs a lot of
money to
decommission a
nuclear plant
Good for “basic
demand”
Reliable
Coal, oil, gas and
nuclear
Fuel will run
out
Short start-up time for
gas and oil
Nuclear produces little
pollution
Pollution – CO2 leads to
global warming and SO2
leads to acid rain
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Other ways of generating electricity
Can we drive the turbine directly
without burning any fossil fuels?
Wind Power
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Tidal Power
High
tide
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Low
tide
Wave Power
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Hydroelectric Power
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Renewable energy sources summary
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Advantages
Disadvantages
Zero fuel costs
Unreliable
(except for
hydroelectric)
Don’t produce
pollution
Hydroelectric
is good for a
“sudden”
demand
Solar is good for
remote locations
(e.g. satellites)
Wind, tidal,
hydroelectric and solar
Expensive
to build
Tidal barrages destroy the
habitats of wading birds
and hydroelectric schemes
involve flooding farmland
Other renewable options…
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Geothermal energy – water is heated
using heat given off by _________ rocks
underneath the surface of the Earth
Solar energy – using solar panels
______ can be converted straight
into electricity
Although renewable fuels are ____, the energy we get from them is
“_______”. This means that we have to spend a lot of money on
generators to make them worthwhile.
This is why solar panels are only used in small things (like calculators) or
extremely remote locations (like ____________).
Words – dilute, radioactive, free, satellites, light
The National Grid
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Electricity reaches our homes from power stations through the National
Grid:
Power station
Step up
transformer
Step down
transformer
Homes
If electricity companies transmitted electricity at 240 volts through
overhead power lines there would be too much ______ loss by the time
electricity reaches our homes. This is because the current is ___. To
overcome this they use devices called transformers to “step up” the
voltage onto the power lines. They then “____ ____” the voltage at the
end of the power lines before it reaches our homes. This way the voltage
is _____ and the current and power loss are both ____.
Words – step down, high, power, low, high