Generating Electricity (GCSE Physics)


Uploaded by freeeschool on 04.09.2012

Transcript:
GCSE Physics – Generating Electricity
Hello! Welcome to a short video on Generating Electricity. We are going to take a look at
how electricity can be generated using fossil fuels and using nuclear fuel. We will do a
brief comparison of the two methods.
To start us off, we have a very basic level here. I’ve got a rough diagram of a turbine
and a generator. This is a set of equipment that produces electricity. Down this end,
we have the turbine and the turbine is just basically a set of fans or blades that can
turn a shaft and that shaft will turn a mechanism inside this part which is called the generator.
In this generator, we have coils of wires and magnets which actually create the electricity.
Now, anything that can turn this turbine will turn the coils of wire and will generate electricity.
So any method that we can use to turn that would be a good generator of electricity.
If you wanted to, you can actually have people standing there turning it. Obviously, it wouldn’t
be a very good idea, but it would work.
How is it done? How do those turbines turn? Well, here’s a very simple diagram of how
it works. What we use is a system that looks like this. We have some water that can be
channeled through a system and that water, when heated, will turn into steam and that
can turn the turbines. But what we have here in order to heat the water is some fuel. In
actual fact, in this example, we are talking about fossil fuels. By fossil fuels, you should
know that we are talking about coal, oil and natural gas. These three or either one of
this could be burned in order to create that heat energy.
In this example here is I got some coal and that’s being burned to create it’s heat
energy and that heat energy will heat water in a boiler and that water will turn into
steam. That steam is under high pressure and it flows down some piping and that can be
passed over your turbine and that turbine can then spin and turn the generator which
will then give you your electricity which can be distributed around and about the place.
A very simple idea: water is heated, turns into steam, steam then turns the turbine.
Actually, when the steam has turned the turbine, it does begin to cool again, but it is specifically
cooled so it turns back into water again and that is done via a condenser. So that condenses
the steam back into water again, which again is heated and then that process continues
to produce that electricity.
That’s a very simple way of our simple method of producing electricity. Another way of doing
it is you can use nuclear fuel. By nuclear fuel, we mean something like plutonium or
uranium and these are radioactive materials and when they decay, when they break down
radioactively, they generate heat. So the radioactive breakdown is controlled and that
generates a lot of heat and that heat can be, like in the last example, be used to heat
water to make steam to turn your turbines.
Now, if we are to do a quick passing of the two methods, using nuclear fuel to create
electricity have advantages and disadvantages. In order of advantages, it doesn’t produce
any polluting gasses and it generates a very large amount of electricity from a small amount
of fuel. That’s two major advantages of this system. But the disadvantage side, you
have radioactive waste. Once plutonium and uranium has reached the end of its useful
life, you have to get rid of it and it is still radioactive, so you have to get rid
of it very carefully. If you don’t do that, it could cause problems in the environment.
This process or method also has high decommissioning cost. By high decommissioning cost, we mean
that it costs a lot of money in order to take down a nuclear power station once you’ve
built it. It is very expensive not only to build, but also to take apart when its lifetime
has reached the end.
Now, if you compare that to using fossil fuels as an example that we saw before. It is a
little bit cheaper to run through this method. Fuel is a bit cheaper. We got coal, oil and
gas. There is no radioactive waste in this process and you do have a fast startup time
for gas, if you are using gas, you can get generator or the power station producing a
lot of electricity very quickly.
But the downside, we’ve got global warming as caused by CO2; something that we looked
at in a previous video. We’ve got acid rain caused by sulfur dioxide and nitrogen oxides
which we also looked at a previous video.
So you have there the plusses and minuses and you should be aware of how the methods
work and what the advantages and disadvantages of each are.
[end of audio – 05:23] GCSE Physics – Generating Electricity
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