The Cantick
Head Tidal Development Ltd renewable energy site has been awarded to a
joint
venture company owned by OpenHydro and Scottish and Southern Energy
(SSE). The site is a three mile stretch along the
south coast of South Walls
(Hoy) and lies within the Pentland Firth
which is considered to be one of the world’s largest
single tidal sites. It is claimed that the site will be a major first
step in
delivering, by means of undersea turbines, large scale tidal energy to
the UK;
with this one project having the potential to
provide enough energy to power over 130,000 homes. Extrapolated from
their own
published data this would mean that between 850-900 turbines [of the
size
tested] were required to meet this target
Over
the next few years, the joint venture company says that it will be
working
closely with statutory bodies, local communities and others to complete
the
required surveys prior to bringing forward an application to deploy
these tidal
undersea “open-centre” turbines.
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Their Open-Centre Turbine
is designed to be deployed directly on the seabed and, it is said, will
be silent and invisible from the surface.
“Farms” of
these turbines will be located at depth and present no navigational
hazard whilst providing, it is said, a significant, predictable and
undetectable supply of clean renewable energy.
The developers
claim that communities that benefit from power supplied by the undersea
turbine technology will never be conscious of the turbines' existence.
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The open-centre
turbine is an example of a simple idea proving to be a most effective
solution to renewable energy generation.
The
functionality and robustness of such equipment in an underwater
environment is crucial. The turbines expect to meet these demands, with
a slow-moving rotor (about seven r.p.m) and a lubricant-free operation
minimising risk to marine life..
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The proposed
turbine has a number of design features intended to avoid any impact on
marine life. The large open centre, about 2 metres in diameter,
provides a safe passage for smaller marine life and the turbine's
hydrodynamic lines should ensure that fish will not become entangled. The minimal underwater
noise may prove sufficient to allow larger mammals to detour around the
turbines
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Currently, no
scientific evidence seems
to exist concerning the impact of such undersea turbine developments on
marine life
or the environment. Nor
does there
appear to by any planned other than a three year research project,
which hopes
to determine whether sea mammals can detect noise from the turbines
and, thus, can
avoid colliding with them.
All we know for sure is that the
introduction of undersea turbines (and exclusion of some types of
fishing) will
bring about some changes for species and habitats, but nobody can say
for sure
at this point what those changes will be.
Present knowledge – based on offshore
windfarms seems to be that there
may be some disruption during the installation stage but no evidence of
damage
to marine life has been witnessed.
The
scientific consensus, therefore, seems
to be to install the turbines and then observe the consequences: early
results
should be available from turbines already installed in the Channel Islands and Canada.
