Green Tech

There are a growing number of designs being floated to make electricity from the sea. But the Seadog Pump may get the prize for the simplest.

Wave- or tidal-power devices use underwater turbines or buoys to convert the motion of the ocean's water into electricity.

A source of electricity? Click on the image to see installation of the Seadog Pump in the Gulf of Mexico last year.

(Credit: Independent Natural Resources)

The Seadog Pump from Independent Natural Resources in Minnesota just focuses on pumping water.

A floating station uses wave motion to drive a piston that pumps water through an exhaust pipe. That water is collected and then passed through standard turbines to make electricity when needed, returning the water to its source.

A schematic of how the Seadog Pump works to pump water, which is stored and then passed through a turbine to make electricity.

(Credit: Independent Natural Resources)

The company last week said that Texas A&M University at Galveston's Marine Engineering Technology Department had evaluated a demonstration machine in the Gulf of Mexico. The university found that the Seadog Pump was able to convert 22 percent of ocean wave energy into usable energy.

Independent Natural Resources is looking to test the system for generating power for electrical utilities or for desalination. Water treatment and pumping are very energy-intensive.

The company says the simplicity of design will make it cheaper to scale up.

It uses readily available parts and no electronics, making it more durable in salt water.

"We are planning our first commercial demonstration facility by year-end 2008 or first-quarter 2009, and have already applied for permitting through the required regulatory agencies," said Doug Sandberg, a company vice president.

Independent Natural Resources plans to have an 18-pump field in the Gulf of Mexico used to desalinate seawater.

Ocean power is, for the most part, experimental technology. One company called Marine Current Technologies is expecting to commission a 1.2-megawatt installation in Ireland in the coming months.

There are a number of other tests taking place. But there's a great deal of potential: experts estimate that wave and tidal power could generate gigawatts of electricity within 10 years, enough to power millions of U.S. homes.