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Powered Up for Oceans Protection

How a NASA scientist invented a renewable energy underwater battery that will change our ability to protect our oceans

By Ariella Knight

If you had asked Dr. Yi Chao ten years ago if a battery would change his career, he would have chuckled and moved on. At the time, Chao was a NASA scientist working at the Jet Propulsion Laboratory at the California Institute of Technology (CalTech) using satellites to study the health of the world’s oceans. As time passed, however, Chao spent more and more time worrying about battery life. His team was placing battery-powered sensors in the ocean to cross check the data received by the satellites. His problem was that good old-fashioned lithium batteries – the stuff that powers smoke alarms, flashlights and Xboxes – ran out of juice too quickly, resulting in thousands of sensors sinking to their final resting place at the bottom reaches of the ocean. The irony of studying ocean health and science, while littering the ocean in the process, was just too much for Chao. So he took matters into his own hands.

ENRIC SALA/Courtesy of National Geographic Society
The irony of studying ocean health and science, while littering the ocean in the process, was just too much for Chao. So he took matters into his own hands.

Like Something from Science Fiction

Like many a scientist, Chao enjoys a good piece of science fiction, though bringing science fiction to life is quite another story. As early as 1989, oceanographer Henry Stommel envisioned a future of ocean exploration done by hordes of underwater robots powered by renewable energy. Unimaginable in Stommel’s day, Chao spent ten laborious years bringing the second element of Stommel’s vision to life: renewable energy underwater. 

The Thermal Recharging, or TREC, battery is a battery designed to power underwater technology that recharges itself by converting thermal energy (temperature differences) in the ocean. Ask anyone who has scuba dived, ocean temperature changes rapidly with depth– it’s cold down there! The TREC battery takes advantage of this naturally occurring phenomenon by converting these temperature differences into energy. Like an AA battery, the TREC battery is designed to power any underwater device or platform – from a buoy to an underwater drone. The only requirement is that it needs to be able to move up and down to access changes in ocean temperature.

To understand this at a deeper level truly does require a NASA science background. To witness the results, however, does not.

ENRIC SALA/Courtesy of National Geographic Society
The goal was for the vehicle to continue working for three straight months while being powered by the TREC battery. The TREC battery did not last three months. It lasted 18, surfacing only to communicate its discoveries with the team back on shore.
The path of the SOLO-TREC testing off the coast of Hawaii. Photo courtesy of NASA.

From the Napkin to the Seas

“Taking the idea from the back of a napkin to a real device that has been tested in the ocean is the real challenge,” explained Chao. In 2009, Chao and his team at CalTech needed to prove that their four years of work on a TREC battery prototype were not wasted. With support from the U.S. Navy and Scripps Institution of Oceanography at University of California San Diego, the TREC team rented a boat in Hawaii, attached the TREC battery to an underwater drone and held their breath. The goal for the test, dubbed "SOLO TREC," was for the vehicle to continue working for three straight months while being powered solely by the TREC battery. 

The TREC battery did not last three months. It lasted 18, surfacing only to communicate its discoveries with the team back on shore. “We just let it keep going,” said Chao, describing the state of shock among the team as the battery lasted six times longer than hoped for. “It far exceeded our expectations,” he said. This trial marked the moment when the TREC team, now collectively known as Seatrec, realized the true potential this tool held for bringing energy underwater. 

ENRIC SALA/Courtesy of National Geographic Society
Everybody needs a battery” says Chao, and this is particularly true for long term surveillance and enforcement efforts needed to protect MPAs and combat illegal fishing.

Possibilities for Protected Areas

“Everybody needs a battery” says Chao, and this is particularly true for long term surveillance and enforcement efforts needed to protect MPAs and combat illegal fishing. Nearly every solution proposed to reduce costs for MPA enforcement systems includes autonomous systems – whether that be buoys equipped with underwater microphones to listen for approaching trawlers, or underwater drones with cameras to patrol EEZs and spot intruders. 

The vast majority of these systems depend on battery power. SeaTrec’s ocean-friendly batteries are truly a game changer, promising to out-power their lithium counterparts ten times over and mitigate environmental damage by making sure our ocean floors will no longer serve as a cemetery for discarded lithium batteries and powered out sensors. The TREC battery would also breathe new life into existing technology, rather than requiring a new line of gadgets made special for them. 

ENRIC SALA/Courtesy of National Geographic Society
He imagines a future in which Seatrec's technology makes it possible for unmanned underwater vessels to chart the world’s oceans wholly unconcerned with the limitations of power.

Underwater Non-Fat Latte, Please

Seatrec launched as an independent startup in 2012 and is currently working to bring the TREC battery to market early 2017. The sky is the limit for the TREC battery as far as the Seatrec team is concerned. “We hope to become the Starbucks of the oceans,” says Chao. He imagines a future with a network of underwater “outlets” that allow drones to recharge after a long day at work, without needing to come to the surface. A future in which Seatrec's technology makes it possible for unmanned underwater vessels to chart the world’s oceans wholly unconcerned with the limitations of power. While this sounds like complete science fiction now, Seatrec may very well be the team to bring it to life. 

ENRIC SALA/Courtesy of National Geographic Society

Technologies Used

// MISCELLANEOUS

The TREC Battery

The TREC battery is an alternative power source to other battery types, such as a lithium battery, that uses sea temperature changes to keep its charge. The TREC battery lasts significantly longer than its counterpart charging sources, allowing for extended missions out at sea.

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