World’s first tidal-powered island
New plans for tidal turbines in Scotland mean island
could get all of its energy from the sea
Islay could become the first island in the world to be powered
by the sea.
It was announced yesterday that a new kind of tidal power
turbine will be built and installed in Scotland. The hope is
that by 2013, ten of these turbines will be placed in the sea
around Islay so that the island can get all of its energy from the
tides.
The turbine, which was created by a Norwegian energy company,
will be made by workers in Stornaway, on the isle of Lewis.
After it is built, the device will be installed around 50 metres
under the sea in Orkney - you won't see a thing from above the
water, even though the machine is around 20 metres high, with 10
metre-long blades.
By 2017, almost 100 turbines could be fitted in Ness of
Duncansby in the Pentland Firth. This will help Scotland to
produce six times more electricity than we need. The extra
power could be sold to other countries, to make a profit.
Each turbine captures enough energy from the ebb and flow of the
tide to power 1,000 homes.
Scotland's First Minister, Alex Salmond, announced the plans
yesterday, saying that Scotland has the best energy resources off
our coast, and that a range of wave, tidal and offshore wind
projects were already underway.
"Scotland leads the way in generating power offshore," the
leader said.
Tidal energy is created when the moon and the sun cause the
water in the oceans to move as the earth turns.
In the UK high and low tides occur twice a day and the height of
the tide changes in two-week cycles.
The flow of the water caused by the tides is called a tidal
stream. This can be used to turn turbines that generate
electricity.
The boss of the Norwegian company making the turbine said it was
an obvious choice to build the machine here, because Scotland has
strong tidal flows and is dedicated to renewable energy. "The
kettle is boiling there (in Scotland) and we want to be part of
that."
While in Norway, Mr Salmond will talk to other Norwegian experts
about more renewable energy sources and climate change.
Another possible plan is to make floating wind turbines that
will generate electricity and send it to the mainland.
All this will help the UK to meet its target of cutting carbon
dioxide emissions by 80% by 2050. Scotland is pretty advanced
- renewable energy already meets more than 20% of the electricity
we use.
Teaching ideas and suggestions
World’s first tidal-powered island
As a Scottish company is told it will get more than £2
million to develop tidal turbines, the Daily What News investigates
the science behind the scheme
Scotland could have more than 100 tidal turbines spinning away
under the sea by 2017. Together, they could generate almost
enough energy to power a city the size of Dundee!
But what is tidal power and why has Scotland's First Minister,
Alex Salmond, gone all the way to Norway to secure a deal with an
energy firm to produce these futuristic machines?
One major advantage of tidal power as a renewable energy source
is that it is reliable and predictable. Whereas wind turbines
stand idle on still days, and solar panels become pretty useless
when it's cloudy, you can always rely on the tides.
Tides are caused by the gravitational pull of the sun and the
moon on the earth as it turns. Our oceans literally bulge
towards these celestial objects, particularly the moon.
Although the moon is a lot smaller than the sun, it is far closer
and so exerts a greater force. Tides rise and fall every day,
around a two-week cycle.
In some places, the height of the tide can vary hugely.
The Bay of Fundy in Nova Scotia, Canada, has the most extreme tides
in the world. High tide can be 15 metres higher than low
tide!
As the tides move, they create streams within the seas and
oceans. What energy experts have found is that if they put
giant turbines in the middle of these streams, they can harness the
energy of the water's movement and turn it into electricity.
But how?
Imagine an electric fan with three blades. Now imagine it
underwater. That's pretty much what a tidal turbine looks
like. But instead of the blades turning because it's plugged
into a socket, they turn because they are pushed by the
water. When tides are moving quickly, the blades can rotate
around 10 times a minute. This is slower than the blades of a
wind turbine, because water is 800 times denser than air.
As the turbine blades revolve, they in turn rotate an
electricity-producing generator. In this way, kinetic energy
- the movement of the water- is harnessed and turned first into
mechanical energy - the movement of the turbine blades - and
finally into usable energy - electricity.
Tidal turbines are expensive to build and there are not many of
them around, but there are loads of reasons for wanting to develop
this technology and make it more widely useable.
The machinery is invisible above water. This gives it an
immediate advantage over wind power, which has been criticised by
some people who think wind turbines are ugly and scar the
countryside.
Turbines will be stuck to the bottom of the ocean, around 50
metres deep. This means that nearly all kinds of boats will
be able to use the same areas without any danger.
As the blades of the turbines will turn slowly, it is not
expected that sea life will come to any harm because of them,
though this is an area that environmental experts are still
investigating.
So far so good - perhaps Alex Salmond is justified in his
claim:
"We see today a significant step forward to bring into
commercial reality one of the most significant resources on the
face of the earth and that is the power of gravity, exemplified by
the tidal flow in this part of the world."
Teaching ideas and suggestions