It is to be hoped that the lessons learnt in connection with the Turner Gallery will result in greater realism concerning the difficulty and cost of harnessing wave energy.
Ocean waves carry a lot of power, sometimes more than 100kW per metre frontage during a severe Atlantic storm. However waves also carry momentum and a device designed to harness a significant amount of power must also absorb a significant amount of momentum.
Somewhere within the system there will be large forces that ultimately have to be resisted by foundations or moorings.
It is easy to underestimate the forces and pressures exerted by waves. During recent tests on a 1:4 scale model of Admiralty Breakwater, Alderney, wave impact pressures well over 1MN/m 2 were recorded when the incident waves were only 1.7m high. The measurements suggest that pressure heads of over 500m of seawater could be generated at full scale.
No doubt designers of waveenergy converters will attempt to minimise the risk of waveimpact damage. Unfortunately, this is only one of the many problems to be overcome.
Geoff Bullock, professor of coastal & civil engineering, University of Plymouth, G.Bullock@plymouth. ac. uk