APPENDIX 7
Memorandum submitted by Emeritus Professor
Keith Clayton, School of Environmental Sciences, University of
East Anglia
1. The rapid diffusion of wind energy machines
in much of Europe and the USA contrasts with the very few—and
still essentially experimental—pieces of equipment which
utilise wave or tidal flows. Yet the available wave energy which
might be exploited is immense, and at least in well-chosen locations,
where constriction gives higher velocities in tidal flows, the
same is true. The exploitation of tidal flows has the added advantage
that even in periods of calm sea, tidal movements continue unabated.
Only the long-term shift between Spring and Neap tides limits
the extent to which a relatively continuous level of power can
be exploited.
2. The limited development of wave and tidal
power is, in my view, very largely the result of the difficult
environment in which such equipment must operate, and the problems
involved in making it substantial enough to withstand the worst
conditions that can occur. To the extent that this is overcome
by robust design, this threatens the requirement to build cheaply
enough to make it commercially viable.
3. Wave riders of various types can easily
be brought ashore for periodic maintenance, even if they will
normally be expected to survive the largest waves that occur in
the locality they are deployed. Undersea tidal stream devices
are expensive to move and secure on site, and hence are more likely
to be expected to survive for longer periods without attention.
This will usually involve more sophisticated design and probably
make them more expensive to build. They are, however, less likely
to be damaged during severe storms, provided their anchorage remains
secure.
4. It seems clear from the very limited
progress over several decades that, unless some unforeseen innovation
in design occurs, industry is unlikely to regard this energy source
as an attractive investment. What has been lacking has been the
willingness of government (usually the DTI) to fund the deployment
of experimental machines which have been developed and which have
passed some type of peer review which regards them as promising
(and robust) enough for sea trials. Only by such field trials
will the limitations of existing designs be exposed and the experience
gained to improve whichever aspects have proved the Achilles heel
of any particular machine.
5. As a Committee member has suggested,
the experience that has been acquired by our offshore oil industry
over three decades should find application in particular aspects
of this field, especially perhaps the provision of secure anchorages
or foundations, and the problems of corrosion by sea water and
attrition by moving sediment, as well as the secure placing of
power cables to link the offshore generators to the grid. But
I remain convinced that however optimistic our designers and engineers
may be about new developments, until these have been demonstrated
to work and survive for several seasons at sea, the viability
of the equipment remains unproven.
25 January 2001
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