Only
about 1% of electricity generated in the UK (i.e.
about 4,000 GWh out of a total of 350,000 GWh - source DTI) is produced by conventional hydro power
stations (i.e. not including pumped storage). The
great majority is generated from fossil fuels.
Pitlochry Dam (right) only produces about 0.02%
of the UK’s electricity.
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Though hardly apparent from a glance at their website, even most of
the electricity supplied by Scottish “Hydro” Electric (a
trading arm of Scottish & Southern
Energy plc ) is
actually generated from fossil fuels. Their gas power
station at Peterhead (right) alone produces almost
twice as much energy as all of SSE's conventional hydro
power stations put together. |
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Hydro electricity
is expensive in relation to the amount of energy
produced. For example it recently cost SSE about as
much just to refurbish their power station
on the River Gaur (right) as it would to build
a similar
capacity
windfarm from scratch. And that does not include
the vast cost of constructing the dam and all the
associated infrastructure. This power station only
has an installed capacity of about 7MW, equivalent
to about three modern land wind turbines, or little
more than one of the new type of wind turbines
being trialled in the Beatrice
Field
in the Moray Firth. |
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The potential
hydro resource, even in Scotland, is small and expensive
to exploit. A recent study commissioned by the Scottish Executive estimated
that in 2010 Scotland’s exploitable “small” hydro
resource, accepting production costs of 7 pence per KWh, would only be as high as 1,000 GWh.
By comparison
land based windturbines might produce 45,000 GWh for a cost of less than 3 pence per KWh.
At a time when the real price of electricity was much higher than today, the Cooper Report (1942) which gave rise to the Hydro Board, estimated that there was then an economically exploitable resource of only about 6,000 GWh in Scotland. Scotland simply does not have a big enough nor high enough land mass.
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The paltry nature
of hydro can be illustrated by way of the following
example.
The River Tay has as much flow as the Thames
and Severn combined. Lets use it to generate electricity.
Let's build a dam across the Tay at the
tidal limit at
Perth.
For
it to produce as much energy per year as Scotland’s
biggest coal burning
Longannet
power station in Fife (right), the dam
at Perth would need to be 500 metres high! That means the dam
would have to be twice the height of Kinnoull Hill at Perth flooding everything from Crianlarich to Kirriemuir, Pitlochry, Dunkeld and Perth itself.
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It
would have to be a phenomenal construction, higher
than Drumochter pass which separates the Garry
from Strathspey! It would even tower above the Three Gorges Dam in
China, a mere dwarf at 181 metres! |
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