In the U.S. we hear a lot of talk about wind and solar power, but considerably less about wave power. Wave power is simply using the power of the ocean to generate electricity. Well, it’s not quite that simple…

Professor Stephen Salter at the University of Edinburgh, Scotland, began the first modern experiments with wave energy in the 1970s. His invention, called Salter’s Duck is still considered to be the most efficient wave energy technology (able to stop 90 percent of wave motion and convert 90 percent of that to electricity). But the machine never got to sea, primarily because its complex hydraulic system isn’t well-suited to incremental implementation, and the costs and risks of a full-scale test are prohibitive.

Today’s technologies are competing to be the most cost-effective and efficient at capturing wave power. Here are two popular systems:

• Limpet (Land Installed Marine Powered Energy Transformer): Power is generated as waves enter its open cavity and force air through a chamber on the top (or rear, on some designs) of the installation. The forced air turns a turbine that then turns a generator. The Isle of Islay off the coast of Scotland gets a third of its energy from one of these shoreline devices. Greenpeace has a video demonstrating the Limpet technology.
• Pelamis: This long, hinged tube (about 525 feet long) sits in around 165-200 feet of water and bobs up and down in the waves. The hinges bend and pump hydraulic fluid, which drives generators.

The north and south temperate zones of the world are the best spots for wave power. The prevailing westerlies blow the strongest here in the winter.

Wave power still faces some big challenges, including:

• Efficiently converting wave motion into electricity
• Constructing devices strong enough to withstand saltwater corrosion and the power of waves.
• Lowering both the costs of the equipment construction and the costs of the electricity
• Getting the power back to land

If these challenges are met, the benefits would be:

• When located properly, a more consistent power source than wind or solar
• Inexpensive maintenance
• A potentially highly efficient wave-to-electricity conversion ratio, requiring far fewer generators compared with wind turbines
• Low negative impact on ecosystems

The world’s first commercial wave power station went online in Scotland in 2000, and the nation continues to be at the forefront of this technology. In February, ScottishPower announced it was building the world’s biggest commercial wave power project. Four floating Pelamis generators will be stationed off the European Marine Test Centre (EMTC) in Orkney. It’s expected to provide enough power for about 2,000 homes by 2008.

BBC News
Celsias
Inside Greentech
Ocean Power Delivery
Wikipedia