1. Field of the Invention
The present invention relates to apparatus for producing useful work from wave motion in a body of water, and more specifically, for converting wave motions of varying periods to continuous kinetic rotational energy.
2. Description of the Prior Art
Waves in large bodies of water, for example in the oceans, extract momentum from the winds in the planetary boundary layer and store energy in the form of kinetic and potential energy. The energy and power in ocean wind waves can be quite considerable. It has been calculated that waves in an average sea having an approximate 1.5 meter wave height occurring with a period of eight seconds will produce a mean flux of wave power across a section of the ocean of about ten kilowatts per meter. These waves vary in several ways. The waves experience short term fluctuations of period and wave length, and height varies with conditions. The long term variations depend primarily on location. There have been many different methods and apparatus developed over the years in an attempt to extract the energy from the wave motion and to convert it into either mechanical or electrical power. Many of these attempts have utilized the pressure head represented by the wave heights. These schemes using pressure chambers, bellows, floats and the like which attempt to directly convert the wave head to usable work have proven relatively ineffective because of the low mean ocean wave heights. Other devices have used seesaw type floats which are dependent on the period of the wave and therefore represent narrow band pass filters which are efficient only at one frequency.
To be efficient, a wave powered machine must be able to extract the energy from the relatively low water head associated with wave height, and it must have a very broad band response for both amplitude and frequency of the waves since these parameters vary widely.