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Seatrec’s infiniTE float is an underground ocean profiling platform using new power generation technology. | Source: Seatrec
Today, approximately 80% of the ocean floor remains uncharted, and for good reason. The deep sea is a harsh environment. Between extreme pressure, zero visibility and extremely cold temperatures, individuals and organizations seeking to gain information about the region have enormous challenges to overcome.
Robots are likely to be the main driver of this exploration, but they have their own limitations. Among them, one of the most urgent is power. Batteries in underground sensors often rely on solar energy or other types of renewable energy. That means when the batteries die, they are either left in the water or recharged in a vessel that can cost up to $50,000 per day to operate.
Seatrec Inc. hopes to provide a new kind of power source using technology developed at NASA’s Jet Propulsion Laboratory (JPL) in Southern California and licensed from the California Institute of Technology. The Vista, California-based company said its technology allows robots to work indefinitely at sea without any intervention.
Company founder and CEO Yi Chao studied the ocean from space for 15 years at JPL after earning a doctorate in ocean science. At NASA, he was able to see firsthand how difficult it is to access many of the world’s oceans.
“I had the opportunity to learn about the challenges of underwater robotics, especially energy, and settled on a particular bottleneck that I wanted to solve,” Chao said.
NASA’s Aquarius instrument aboard the joint U.S.-Argentine Satélite de Aplicaciones Científicas spacecraft has mapped the surface salinity of Earth’s oceans. To calibrate the equipment, the JPL team deployed a robotic float. This experience helped inspire Yi Chao to invent an inexhaustible power source. Credit: NASA
Robots driven by the environment
With the help of two JPL colleagues, funding from JPL, and a JPL contract with the U.S. Navy, Chao began looking for a different kind of power source for his undersea robots. The team is using phase-change materials to generate power.
A phase change material is a material that can transition between phases, typically between a solid and a liquid, at a certain desired temperature. The Chao team is producing power by utilizing volume changes due to state changes.
“We use the kinetic energy from the volume expansion to spin the motor and then convert the mechanical energy into electricity, so we can now recharge the battery,” Chao said.
This concept is similar to how a steam engine works, where water expands into steam and rotates the motor. However, the transition from solid to liquid only produces expansion of about 10%. This means that the team must make the most of the small amount of energy generated during the transition. That’s why this method hasn’t been used for a long time.
When used in robots, the temperature of the material changes as the robot rises and falls in the ocean, which is usually what happens anyway. When exploring the deepest parts of the ocean, robots must occasionally surface to determine their location via GPS and transmit the data they collect to satellites.
The team chose a common, industrial-grade, paraffin-based material with a melting point of about 50°F, which lies between the typical ocean temperature of about 40°F and about 70°F at the surface. This material is ideal for average ocean temperatures, but can be interchanged to better suit a variety of environments.
After testing the float prototype at JPL in 2011, Chao and his colleagues tested an underwater glider that operates on the same principles but can also move horizontally. Chao later received an exclusive license for the invention from the California Institute of Technology, which manages JPL. He founded Seatrec in 2016.
Seatrec sees the technology market growing.
Seatrec is now selling its first power modules for diving floats to research labs, universities, government researchers and the military. Chao said he expects a lot of growth in the market. Possible customers include:
- Telecommunications companies interested in laying transoceanic Internet cables
- Companies drilling for oil and gas or building offshore wind farms
- Conservation groups want to know more about where marine habitats are located
- Companies that manage marine operations such as oil wells, wind turbines, and fish farms that require underwater sensors to monitor conditions and equipment.
- This is a company that installs cables on the sea floor or mines rare earth elements. These companies must assess the local environment and wildlife before carrying out work.
In the future, Seatrec plans to commercialize a system that uses solid-liquid phase change technology to power underwater gliders.
The company also plans to develop a power plant to cycle phase change materials from liquid to gas through the ocean depths. This generates significantly more energy, allowing users to charge more robots at sea, he said.
Seatrec received a grant from the Navy to develop a power plant on Arctic ice. This power plant can take advantage of the difference between water temperature and the cold air above the ice.
