• Oceanic research using data-gathering floats is vital to help combat climate change.
  • But each year, thousands of these lithium-ion-powered floats lose power and pollute the ocean bed.
  • Seatrec’s technology harnesses the ocean’s thermal energy to make the floats rechargeable - and sustainable.

In 2011, a marine biologist told his audience at a TED conference that “we know more about the surface of the moon and about Mars” than we do of our own planet’s ocean floor.

While much progress has been made since then to narrow the gap in our oceanographic knowledge, the gulf remains considerable. And the pressure to make sea exploration a much cleaner affair increases.

Seatrec, a five-year-old ‘blue tech’ start-up based in Vista, California is one company rising to that challenge, with power generating technology that it hopes will bring a level of sustainability to oceanographic exploration not possible until recently.

Dead batteries on the seabed

‘Profiling floats’ – unmanned, robotic data gathering devices that monitor the sea’s physical, chemical and geological characteristics – is an established approach. The Argo international research project, for example, has more than 3,000 active floats dotted around the world.

Laden with sensors, these battery-fuelled floats dive to predetermined depths to carry out their programmed tasks, re-emerge on completion and transmit their data harvest to the research stations via satellite.

Well, that’s the theory anyway. Sometimes the floats never make it back from the deep and run out of power mid-mission.

Consequently, countless robotic probes scattered around the globe remain adrift on the seabed forever, considered too expensive to retrieve and cheaper to replace with fresh devices.

Seatrec estimates that up to a thousand floats expire each year, dropping to the ocean floor tethered to dead lithium-ion batteries.

Seatrec’s floats harness the ocean’s thermal energy to recharge, meaning they can transmit data without polluting the water.
Seatrec’s floats harness the ocean’s thermal energy to recharge, meaning they can transmit data without polluting the water.
Image: Seatrec

Harnessing the ocean’s own energy

Seatrec has designed a sustainable alternative: a generator system for profile floats that harnesses the ocean’s own thermal energy to recharge itself.

The generator essentially exploits the temperature differentials within the ocean itself, to create renewable electrical energy which it stores for ongoing and future use.

The SL1, about 1.5 metres high and weighing around 30kg, uses specially designed wax known as Phase Change Material (PCM) which solidifies in cold temperatures lower down in the ocean and liquifies in warmer waters closer to the surface.

Seatrec floats generate electricity from ocean temperature changes.
Seatrec floats generate electricity from ocean temperature changes.
Image: Seatrec

These temperature changes cause the PCM to respectively contract and expand: on expansion, it exerts upward pressure inside the generator, which in turn is converted into electrical energy.

To maintain the ability to replenish power to the attached profile float, the SL1 merely has to ‘dive’ down to colder waters to contract the PCM and ‘rise’ again to the warmer surface to generate more energy. This is achieved by an internal flotation device that inflates and deflates accordingly.

Seatrec founder Dr Yi Chao says the harvesting technology enables floats to last indefinitely, sample more frequently and with more sensors. Such capability allows for more comprehensive data gathering that can be deployed to better predict hurricanes, for example, protecting both the ocean and adjacent lands.

Crowdsourcing for a healthy ocean

Seatrec is one of multiple start-ups championing the ocean’s health through sustainable resource use.

The World Economic Forum has provided an environment for entrepreneurs to present and seek funding for ideas driven by the need to reverse climate change. Called UpLink, the digital platform seeks to foster innovation that addresses the world’s most pressing environmental challenges, particularly in the wake of the pandemic.