Tidal Energy

Tide level. In locations where there is a large difference in ocean levels between low and high tide (16 feet is considered the minimum required difference), a dam with gates is used to seal off a large tidal basin. At the point of the highest tide level, the gates are closed, thus trapping the water in the basin. Where the tide begins to fall, the trapped water is allowed to flow back out to the ocean through turbines that power electricity generators. A large 240 megawatt tidal dam has been in operation in France since 1966 and a 100 megawatt system has been in operation in Canada since 1984.

Tide current. Tidal current systems capture energy from fast moving tidal currents that flow in and out of harbours, or between offshore islands and the mainland. As tides rise and fall, water can flow at speeds of six to nine miles per hour through channels. A set of turnstiles can be installed near the surface of the channel to rotate as the current flows by, thus driving generators and creating electricity. Underwater turbines can also be used to drive a generator.

Wave motion. Wave motion is another type of energy that can be harnessed from the ocean. Wave action can generate electricity by using floating buoys or platforms that move with wave action. That movement can be converted into electricity.