Houston Chronicle. A small Texas company, Renew Blue, will use 18 ocean Seadog pumps from parent Independent Natural Resources Inc. (INRI) to generate electricity to run a 3,000 gallon per day desalination plant. The Seadog is a point absorber wave energy device that uses pressurized hydraulics for power takeoff; the pressurized water drives a turbine.
|Early sketch of the Renew Blue project, with the turbine and desalination plant onshore. Source: INRI. Click to enlarge.|
The 18 Seadog pumps in the project off Freeport will be able to generate up to 60 kilowatts of electricity, depending on wave size. The desalination equipment only requires about 4 kilowatts, leaving power to run lighting on the platform, said Sandberg.
Renew Blue has a lease from the state of Texas to place the facility in 25 feet of water about a mile off the coast from Freeport.
The desalinated water will be stored in a 30,000-gallon tank on the platform and then transported to shore, where it will be put in bottles made from corn-based plastic and marketed under the Renew Blue brand.
The Seadog pump. The Seadog Pump, which is seated on the ocean floor, uses buoyancy to convert wave energy to mechanical energy. The main components of the pump include a buoyancy chamber, buoyancy block, piston assembly, piston shaft, piston cylinder, and intake and exhaust valves. When positioned in the water the buoyancy block (filled with air) floats within the buoyancy chamber, moving up and down in relation to the ocean waves and swells. The buoyancy block is connected to the piston shaft which in-turn moves the piston assembly through the piston cylinder.
|Loading the Seadog pump for trials in the Gulf of Mexico. Source: INRI. Click to enlarge.|
As the buoyancy block moves down in the trough of a wave it draws the piston downward through the piston cylinder. The downward movement draws water into the piston cylinder through the intake valve filling the piston cylinder chamber. As the next wave lifts the buoyancy block the water within the piston cylinder is under pressure and is expelled through the exhaust valve. Each stroke of the piston causes the water to be pumped from the piston cylinder in a regular manner.
INRI has performed prototype performance testing in its internal development lab, in the Texas A&M Offshore Technology Research Center’s wave tank, and most recently, in actual ocean trials conducted off the coast of Freeport, TX.
Ocean Energy: Global Technology Development Status (IEA, March 2009)