Video clip: Fossil fuel power station - how it works
The steam that has passed through the
power station's turbines has to be cooled, to condense it back into water before it can be
pumped round again. This is what happens in the huge "cooling
towers" seen at power stations.
Some power stations are built on the
coast, so they can use sea water to cool the steam instead. However,
this warms the sea and can affect the environment, although the
fish seem to like it.
provides around 28% of our energy, and oil provides 40%. Mind you,
this figure is bound to have changed since this page was written,
so check the figures if you want to quote them.
Burning coal produces sulphur dioxide, an acidic
gas that contributes to the formation of acid rain. This can be
largely avoided using "flue gas desulphurisation" to clean
up the gases before they are released into the atmosphere. This
method uses limestone, and produces gypsum for the building industry
as a by-product. However, it uses a lot of limestone.
(called "petroleum") is easier to get out of the ground
than coal, as it can flow along pipes. This also makes it cheaper
I ought to point out that some scientists are
claiming that oil is not a 'fossil' fuel - that it is not the remains
of prehistoric organisms after all. They claim it was made by some
other, non-biological process. Currently this is not accepted by
the majority of scientists.
provides around 20% of the world's consumption of energy, and as
well as being burnt in power stations, is used by many people to
heat their homes.
It is easy to transport along pipes, and gas power stations produce
comparatively little pollution.
What is crude oil?
Other fossil fuels
are being investigated, such as bituminous sands and oil shale. The difficulty
is that they need expensive processing before we can use them; however
Canada has large reserves of 'tar sands' , which makes it economic for
them to produce a great deal of energy this way.
As far as we know, there is still a lot of oil in the ground.
But although oil wells are easy to tap when they're almost full, it's
much more difficult to get the oil up later on when there's less oil down
there. That's one reason why we're increasingly looking at these other
Very large amounts of electricity can be generated
in one place using coal, fairly cheaply.
Transporting oil and gas to the power stations
Gas-fired power stations are very efficient.
A fossil-fuelled power station can be built almost
anywhere, so long as you can get large quantities of fuel to it.
Didcot power station, in Oxfordshire, has a dedicated rail link
to supply the coal.
Basically, the main drawback of fossil
fuels is pollution.
Burning any fossil fuel produces carbon dioxide, which contributes
to the "greenhouse effect", warming the Earth.
Mining coal can be difficult and dangerous.
Strip mining destroys large areas of the landscape.
Coal-fired power stations need huge amounts
of fuel, which means train-loads of coal almost constantly. In order
to cope with changing demands for power, the station needs reserves.
This means covering a large area of countryside next to the power
station with piles of coal.
Is it renewable?
Fossil fuels are not
Once we've burned them all, there isn't any more, and our consumption
of fossil fuels has nearly doubled every 20 years since 1900.
This is a particular problem for oil, because we also use it
to make plastics and many other products.
Ok, you could argue that
fossil fuels are renewable because more coal seams and
oil fields will be formed if we wait long enough.
However that means waiting for many millions of years. That's
a long time - we'd have to wait around for longer than the time
that humans have existed so far!
As far as we today are concerned, we're using it up very fast
and it hardly gets replaced at all - so by any sensible human
definition fossil fuels are not renewable.
What fraction of the
wold's energy do fossil fuels provide?
From this "oilprice.com" widget, add together
the figures for coal, oil and gas, then divide that figure
by the total at the bottom.
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