Ocean waves are characterized by large variability in height, speed, period and steepness. Variations can occur on timescales of seconds from wave to wave, up to hours and days as dictated by weather systems, and seasons caused by the relative position of the earth to the sun. Therefore, any system which aims to efficiently extract energy from ocean waves has to deal with this large variability.

Despite their large variability, some wave heights are more likely to occur than others. Assuming that waves can be modeled as a stochastic process, a Rayleigh distribution can be used to characterize the likelihood that a specific wave height will occur. The average wave height for oceans is often claimed to be around 3 meters, although the average value is but a fraction of the different wave heights that can occur. For one specific measurement buoy off the West Coast of Ireland, a wave height recording within a period of two years is shown in the figure below. As can be seen, although wave heights between 1 to 6 meters are most likely to occur at this specific location, their variability is, in fact, larger. Although higher waves may occur less frequently, they do contain more energy. Therefore, extracting energy from waves across the spectrum of 1 to 12 meters, instead of being limited to a small range, would be a significant advantage for a wave harvesting device.

The Ocean Grazer’s core technology is able to extract wave energy from waves ranging in height from 1 to 12 meters, thereby covering the entire spectrum of wave heights shown above. At the same time, it is designed to withstand extreme conditions with wave heights as large as 30 meters.

Wave height distribution

Ocean waves are characterized by a large variability.