Wave power is the transport of energy by ocean surface waves, and the capture of that energy to do useful work — for example for electricity generation, desalination, or the pumping of water (into reservoirs). Wave power is a renewable energy source.
Though often co-mingled, wave power is distinct from the diurnal flux of tidal power and the steady gyre of ocean currents. Wave power generation is not currently a widely employed commercial technology although there have been attempts at using it since at least 1890. The world's first commercial wave farm is based in Portugal, at the Aguçadora Wave Park, which consists of three 750 kilowatt Pelamis devices.
Physical concepts.
Waves are generated by wind passing over the water: as long as the waves propagate slower than the wind speed just above the waves, there is an energy transfer from the wind to the most energetic waves. Both air pressure differences between the upwind and the lee side of a wave crest, as well as friction on the water surface by the wind shear stress cause the growth of the waves. The wave height increases with increases in ( Ocean surface wave):
wind speed,
time duration of the wind blowing,
fetch — the distance of open water that the wind has blown over, and
water depth (in case of shallow water effects, for water depths less than half the wavelength).
In general, large waves are more powerful. Specifically, wave power is determined by wave height, wave speed, wavelength, and water entity.
Wave size is determined by wind speed and fetch (the distance over which the wind excites the waves) and by the depth and topography of the seafloor (which can focus or disperse the energy of the waves). A given wind speed has a matching practical limit over which time or distance will not produce larger waves. This limit is called a "fully developed sea."
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