ABSTRACT
Very large energy fluxes can occur in deep water sea waves. The power in the wave is proportional to the square of the amplitude and to the period of the motion. Therefore the long period ∼10s, large amplitude ∼2m waves have considerable interest for power generation, with energy fluxes commonly averaging between 50 and 70kWm−1 width of oncoming wave. The possibility of generating electrical power from these deep water
waves has been recognised for many years, and there are countless ideas for machines to extract the power. For example, a wave power system was used in California in 1909 for harbour lighting. Modern interest has revived, particularly in Japan, the UK, Scandinavia and India, so research and development has progressed to commercial construction for meaningful power extraction. Very small scale autonomous systems are used for marine warning lights on buoys and much larger devices for grid power generation. The provision of power for marine desalination is an obvious attraction. As with all renewable energy supplies, the scale of operation has to be determined, and present trends support moderate power generation at about 100 kW-1MW from modular devices each capturing energy from about 5 to 25m of wavefront. Initial designs are for operation at shore-line or near to shore to give access and to lessen, hopefully, storm damage. It is important to appreciate the many difficulties facing wave power
developments. These will be analysed in later sections, but may be summarised here:
1 Wave patterns are irregular in amplitude, phase and direction. It is difficult to design devices to extract power efficiently over the wide range of variables.
