Underwater drone manufacturers eye new power technologies.

• Author: Tadjdeh, Yasmin

* Underwater drones have been used for everything from environmental research to scouring the ocean floor for wreckage of crashed airplanes. They are able to go where manned vessels historically have been unable to due to crushing depths and dangerous mission sets.

Experts agree that the future of unmanned underwater vehicles is bright, with more investment expected from both the government and commercial sector. However, power generation continues to be a conundrum for engineers.

UUVs need a tremendous amount of juice to complete the various missions for which they are deployed. Many stay under the waves for hours, days and even months at a time, all while carrying a variety of payloads.

Rear Adm. Mathias W. Winter, chief of the Office of Naval Research, noted that the Navy is investing science and technology dollars toward undersea platforms.

While UUVs and unmanned aerial vehicles are very different, the technology underlying both systems is similar, he said at Navy League's Sea-Air-Space Conference in March. More testing is still needed in terms of power generation, sense-and-avoid, persistence and payload capability for both kinds of robots, he noted.

"All of that is underway," he said. ONR is currently working on developing the large-displacement unmanned undersea vehicle-innovative naval prototype, a device that will be able to prowl the littorals for months at a time. The system takes advantage of new energy technologies in order to power it for extended periods.

The program is "develop[ing] new air independent energy systems and core vehicle technologies to extend unmanned undersea vehicle endurance into months of operation time," ONR materials said. "New energy sources for unmanned undersea vehicles will increase the current energy density significantly, allow for quick recharge or refueling, operate at an acceptable cost level and enable pier-to-pier operation with months of endurance."

Air independent systems allow non-nuclear powered subs to stay submerged for long periods of time without having to surface for oxygen.

The vehicle has been in development since 2011. ONR recently announced that it would make a voyage from San Francisco to San Diego in 2016.

Officials hope the UUV will one day work alongside manned assets and unmanned aerial vehicles to give military leaders increased situational awareness, said Rear Adm. Mark W. Darrah, program executive officer for unmanned aviation and strike weapons.

In the future, "we're...