On Thursday, Detroit automaker General Motors and the US Navy announced a partnership in which the Navy would be able to take advantage of hydrogen fuel cell research from GM to develop a long-endurance unmanned undersea vehicle (UUV).

According to Karen Swider-Lyons, the head of the Naval Research Laboratory’s (NRL) Chemistry Division of its Alternative Energy Section, the Navy is looking for “weeks if not months of endurance” from a UUV. She stressed that research and testing is still in early stages and that the Navy had not yet pinpointed a single application it wanted to apply fuel-cell powered underwater drones to. “As the technology becomes available, we’ll see,” Swider-Lyons said on a conference call this morning. “You can look at the history of unmanned air vehicles and guess.”

Fuel cell technology has been lauded as a potentially revolutionary energy source for zero-emissions vehicles, using hydrogen to create electricity and emitting H 2 O as waste. While fuel-cells are more energy dense than batteries, batteries have generally won out when it comes to building zero-emissions cars because hydrogen refueling centers are scarce, and storing hydrogen itself can require a high-pressure container or very cold temperatures.

That hasn’t stopped automakers from developing concept cars to take advantage of fuel cell ideas. GM, Toyota, Nissan, Audi, Hyundai, and Volkswagen have all experimented with building fuel-cell cars. USA Today also notes that “Last November, GM and the US Army signed a contract to build and demonstrate a fuel-cell reconnaissance vehicle for the US Army Tank Automotive Research, Development and Engineering Center (TARDEC) in Warren, Mich.”

The US Navy has turned to fuel cells in lieu of batteries as UUVs have grown larger and larger. Fuel cells also have the advantage of being reliable and are quickly refilled, unlike batteries that can take hours to charge up again. A press release from GM claims its fuel cells "are compact and lightweight, and have high reliability and performance."

"Lower cost is achievable through volume production," the company claimed.

GM and Navy representatives praised their continued partnership on today’s conference call, highlighting how many parallels exist between engineering a car and engineering a UUV. Still, Swider-Lyons said that “information comes one way from General Motors to NRL, it does not go back,” suggesting that more confidential aspects of NRL’s research would not be shared with General Motors.

NRL has already run prototype tests of UUVs at the Naval Surface Warfare Center in Carderock, Maryland, using General Motor’s fuel cells. Now, the Navy wants to improve upon its prototypes. “We’re trying to develop a powertrain that’s very, very efficient,” Swider-Lyons said today. “We try to carry hydrogen efficiently too... it’s a little tricky underwater because it’s not just weight or volume, but buoyancy as well” that the Navy has to account for.

“Part of the research program is determining how much power we need,” Swider-Lyons added.

The Detroit News notes that the Department of Defense budgeted $600 million for UUV development over five years starting in 2017.