We’ve covered a few underwater autonomous robots designed to make exploring the murky depths easier here on Gizmag, such as Snookie and the Talisman, but none that can generate its own power – until now. NASA, US Navy and university researchers have successfully demonstrated the first underwater vehicle to be powered entirely by natural, renewable, ocean thermal energy. Scalable for use on most robotic oceanographic vehicles, this technological breakthrough could usher in a new generation of autonomous underwater vehicles capable of virtually indefinite ocean monitoring for climate and marine animal studies, exploration and surveillance.
The Sounding Oceanographic Lagrangrian Observer Thermal RECharging (SOLO-TREC) autonomous underwater vehicle uses a novel thermal recharging engine powered by the natural temperature differences found at different ocean depths.
How it works
SOLO-TREC draws upon the ocean’s thermal energy as it alternately encounters warm surface water and colder conditions at depth. Keys to its operation are the carefully selected waxy substances known as phase-change materials that are contained in ten external tubes, which house enough material to allow net power generation. As the vehicle surfaces and encounters warm temperatures, the material melts and expands; when it dives and enters cooler waters, the material solidifies and contracts.
The expansion of the wax pressurizes oil stored inside the float. This oil periodically drives a hydraulic motor that generates electricity and recharges the vehicle’s batteries. Energy from the rechargeable batteries powers the float’s hydraulic system, which changes the float’s volume (and hence buoyancy), allowing it to move vertically.
The 84kg (183lbs) SOLO-TREC prototype was tested and deployed by researchers at NASA’s Jet Propulsion Laboratory, Pasadena, California; and the Scripps Institution of Oceanography, University of California, San Diego on November 30, 2009, about 161km (100 miles) southwest of Honolulu. They completed the first three months of an ocean endurance test of the prototype vehicle off the coast of Hawaii in March
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