Wave power

Wave power is a method of electricity generation where energy from (ocean) waves is transferred into an electrical current. The electricity produced by wave power is renewable energy. Wave energy is a distinct energy source from tidal power but the two are often confused. Wave power generation is not a widely employed technology with only a few experimental sites in existence.

Many different system designs are currently being developed, although numerous practical problems have frustrated progress, particularly storm damage and corrosion. Systems which rely on complex generation equipment in offshore locations have the most difficulties. Systems which locate complex equipment on-shore appear to have more promise, but are less well developed.

Some types of wave power systems:

• In one system, pontoons lying in the water are driven by wave action to push or pull a generator.
• With another method, wave action compresses air in a tunnel which drives the vanes of the generator. The bigger the difference between wave top and wave valley, the more power potential there is.
• A device called CETO, currently being tested off Fremantle, Western Australia consists of a rubber membrane pump mechanism driven by the pressure of passing waves, which pumps water to shore to drive generators and can also be forced through a reverse osmosis filter to provide delsalinated water.
• In yet another design, the overtopping of the waves are being led to a reservoir, the water, being pulled downwards through a tube by gravity, drives a generator.

Harnessing power from wave motion is a possibility which might yield much more energy than tides. The feasibility of this has been investigated, particularly in the UK. A 100–400 kW prototype shore based wave power generator is being constructed at Port Kembla in Australia, due for completion in January, 2005. The energy of waves crashing against the shore is absorbed by an air driven generator and converted to electricity. For countries with large coastlines and rough sea conditions the energy density of breaking waves offers the possibility of generating electricity in utility volumes. Excess capacity in periods of rough sea could be used to generate hydrogen.

See also

• Water power
• Tidal power

Patents

• U.S. Patent 3928967 — Apparatus and metod of extracting wave energy
• U.S. Patent 4134023 — Apparatus for use in the extraction of energy from waves on water