The SOLO-TREC (Sounding Oceanographic Lagrangrian Observer Thermal RECharging) is a

profiling float A float (not to be confused with a drifter) is an oceanographic instrument platform used for making subsurface measurements in the ocean without the need for a ship, propeller, or a person operating it. Floats measure the physical and chemical asp ...

that uses a novel thermal recharging engine powered by the natural temperature differences found at different ocean depths to cycle up and down in the ocean. The research and prototype were developed by researchers at the

Jet Propulsion Laboratory The Jet Propulsion Laboratory (JPL) is a federally funded research and development center and NASA field center in the City of La Cañada Flintridge, California, United States. Founded in the 1930s by Caltech researchers, JPL is owned by NASA ...

Pasadena Pasadena ( ) is a city in Los Angeles County, California, northeast of downtown Los Angeles. It is the most populous city and the primary cultural center of the San Gabriel Valley. Old Pasadena is the city's original commercial district. Its ...

, CA, and the

Scripps Institution of Oceanography The Scripps Institution of Oceanography (sometimes referred to as SIO, Scripps Oceanography, or Scripps) in San Diego, California, US founded in 1903, is one of the oldest and largest centers for ocean and Earth science research, public servi ...

San Diego San Diego ( , ; ) is a city on the Pacific Ocean coast of Southern California located immediately adjacent to the Mexico–United States border. With a 2020 population of 1,386,932, it is the eighth most populous city in the United States ...

, CA. The project name stands for "Sounding Oceanographic Lagrangrian Observer Thermal RECharging" vehicle.Vu, Q. "Jet Propulsion Laboratory", July 25, 2011
Nasa Site
Retrieved July 2011

History

Research and technology development for SOLO-TREC began in 2004 with funding provided by JPL Research & Technology Development program (2005–2007) and the

Office of Naval Research The Office of Naval Research (ONR) is an organization within the United States Department of the Navy responsible for the science and technology programs of the U.S. Navy and Marine Corps. Established by Congress in 1946, its mission is to pla ...

(2008–2010). On November 30, 2009, the first SOLO-TREC prototype was deployed 161 kilometers southwest of

Honolulu Honolulu (; ) is the capital and largest city of the U.S. state of Hawaii, which is in the Pacific Ocean. It is an unincorporated county seat of the consolidated City and County of Honolulu, situated along the southeast coast of the islan ...

by a group of scientists and engineers from JPL and Scripps.

Design

The original prototype weighed 84 kilograms, dived autonomously to depths of 500 meters, and generated 1.7 watt-hours of energy per dive. SOLO-TREC draws upon the ocean's thermal energy as it alternately encounters warm surface water and colder conditions at depth.Hambling, D. "Popular Mechanics", April 10, 201
Article
Retrieved July 2011 Key to its operation are the carefully selected waxy substances known as

phase-change material A phase change material (PCM) is a substance which releases/absorbs sufficient energy at phase transition to provide useful heat or cooling. Generally the transition will be from one of the first two fundamental states of matter - solid and li ...

s that are contained in 10 external tubes, which house enough material to allow net power generation.Guevin, J. "CNET", April 5, 2010
News
Retrieved July 2011 As the float 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.

Recent Developments

SOLO-TREC has completed more than 450 dives from the ocean surface to a depth of 500 meters (1,640 feet) and is reporting temperature and salinity profiles three times per day. Designers control the depth to which the instrument dives through its hydraulic system. Its thermal recharging engine produces about 1.7 watt-hours, or 6,100 joules, of energy per dive, enough electricity to operate the vehicle’s science instruments, GPS receiver, communications device and buoyancy-control pump. SOLO-TREC has the potential to replace current ocean monitoring currently done by 3,200 battery-powered Argo floats deployed previously to measure temperature,

salinity Salinity () is the saltiness or amount of salt dissolved in a body of water, called saline water (see also soil salinity). It is usually measured in g/L or g/kg (grams of salt per liter/kilogram of water; the latter is dimensionless and equal ...

, and velocity. The US Navy is also exploring the use of thermal recharging technology for the next generation of autonomous submersible vehicles. Scalable for use on most robotic oceanographic vehicles, this technology 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.

References

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External links

SOLO-TREC Home Page
Submarines Robots of the United States