OpenWater Power developing new fuel cells to give ocean-going robots more time to roam

By Scott Kirsner, Globe Columnist

Last September, a torpedo-shaped unmanned underwater vehicle was lowered into Boston Harbor. Three hundred miles and four-and-a-half days later, near New York City, it had set a record: the longest-ever trip for a battery-powered undersea craft.

But given the size of the world's oceans, 315 miles is a mere pebble skip. And the founders of OpenWater Power, an MIT spin-out based in Somerville, see that as a huge opportunity. They're designing new kinds of energy storage systems for underwater vehicles that they believe will enable much longer voyages. If the 20th century Navy wanted its subs to "run silent, run deep," in the 21st century, they want them to "run autonomously, run long." OpenWater moved off campus last October, and is being funded by a $450,000 grant from the US Navy's Naval Air Systems Command and the Department of Defense's Rapid Reaction Technology Office.

CEO Tom Milnes says the company is working on two different kinds of battery designs: an aluminum-seawater version that needs seawater to operate and must be vented; and an aluminum-permanganate version that is completely sealed. The former, Milnes says, could store as much as 10 times the energy of a lithium ion battery of a similar size. The latter would be able to store three to five times as much energy. (Milnes is on the right in the photo, with co-founder Ian McKay and a prototype battery. )

"The Navy wants to transition from manned ships and submersibles to autonomous vehicles," says Milnes. "But one hurdle they can't get over is energy storage. You just can't get very far if your vehicle can run for a day and travel at three miles an hour." Milnes says that OpenWater's new battery chemistry will be less volatile than lithium ion batteries. It uses an aluminum alloy as an anode, and platinum-coated titanium as a cathode. "We're engineering these especially for the environment of being under water, and under pressure," he says. Milnes says that OpenWater will likely look for partners to manufacture its batteries. (At left is the Reliant underwater vehicle that set the endurance record last year, made by Bluefin Robotics of Quincy.)

Milnes and McKay says the company's products will be useful not just for underwater robots like the Navy's future LDUUV craft, but also for other ocean-going equipment, like floating sensors or communications devices. "Eventually, we think becomes a pretty large-scale business, like aircraft engines at GE," Milnes says. "It may be less flashy than Instagram or Twitter, but it suits us well."

OpenWater's founders initially met in an MIT course Milnes taught called Naval Underwater System Design. "Ian and Ruaridh both got A's," Milnes says. (Ruaridh Macdonald, the company's third founder, remains a student, finishing up his PhD.)

If OpenWater's prototypes hit certain technical milestones, Milnes says it could "unlock another $3 million in [Navy] funding by March." The startup works out of the Greentown Labs shared space in Somerville.

Milnes was involved with two previous startups, both in the 3D scanning and printing arena. Brontes Technologies made scanning equipment for dentists, and was sold to 3M for $95 million. Viztu Technologies was acquired for an undisclosed amount by 3D Systems; it developed software to let consumers turn pictures and videos into printable objects.