The Seasteading Institute

This site might be interesting for an Oscillating Water Column (OWC) Generator :

http://www.floatinc.com/Wave%20Energy.html

The quote below is from the page.

“Designing a mechanical device to capture wave energy poses challenging engineering problems. The device must be capable of gathering useful energy from a relatively calm sea with wave heights of a few feet. It must also be able to survive sea conditions where wave heights can exceed 50 feet. In this hostile, salt-laden environment, simplicity and reliability become leading design criteria.The rule of thumb has been, the fewer moving parts the better.

These criteria have caused the Oscillating Water Column (OWC) approach to harvesting wave energy to emerge as a leading candidate. Briefly, the OWC operates similiar to a blow hole. It is a chamber of air closed above the surface and open underwater. As the water rises and falls outside the chamber, the water column inside the chamber oscillates, blowing out and drawing in the trapped air, either directly through a turbine, or rectified through one-way valves. The compressible air acts as a buffer, and the OWC’s design and operation are simple.

One of the main problems the OWC has faced has been where to put it. On shore installations have proved prohibitively expensive. Additionally, waves have generally lost a great deal of their energy by the time they reach the shore. Floating OWCs face two problems: survival and efficiency. Any point absorbing wave energy collector, i.e. a small floating or buoy-like device, has a difficult time surviving everything the ocean is capable of doing to it. Efficiency suffers if the device itself moves because an OWC works when the water moves relative to the collector. Efforts have been made to design the collector to heave out of phase with the waves in order to create that differential, but that really only works well when the wave frequency matches the OWC’s natural resonating frequency. That only occurs some of the time, and most of the time, the ocean is a cacophony of mutiple wave frequencies overlaid.”