It has been estimated that oceans waves have a total power of around 90 million gigawatts (to put this into context, the output of the UK national grid ranges from between 30-50 gigawatts per hour depending on demand). In some places, a potential energy of 70MW per square kilometre are experienced.
Consequently, ocean waves can potentially provide an unlimited supply of renewable energy. Unfortunately, wave power suffers in the same way that wind and solar power suffers in that it is not consistent, making it difficult to match supply with demand. Unlike wind and solar, wave systems can usually generate some power all of the time.
Around the world there are hundreds of research projects investigating wave power and testing various designs of wave power generator to find out the best solutions, with research being carried out with shore-based, near-shore and off-shore systems. Wave generators tend to use a variant of one of four main designs: