A fuel cell technology used on allied submarines for more than a decade is available for use by the U.S. Navy for its larger unmanned underwater vehicles (UUVs) in development and as a backup propulsion sources for nuclear attack and ballistic missile submarines, according to an official with Siemens Government Technology.

The polymer electrolyte membrane (PEM) fuel cells don’t require a submarine or UUV to surface, they operate quietly, and can be strung together to match power requirements for a particular type of vessel, Dan Wise, director of Federal Marine Programs at SGT, told Defense Daily. SGT is the U.S.-based government business of Germany’s multi-industrial company Siemens [SIEGY].

Wise said that Chief of Naval Operations Adm. John Richardson has stressed the need for force multipliers and bringing autonomous underwater vehicle systems into operations, but that taking full advantage of the technology is energy storage and mission duration. The Navy is currently going down the path of using advanced lithium batteries for its larger UUVs but Wise said that SGT hopes to make the case to the service to consider the PEM technology at some point.

German navy U-31 (S181) submarine includes diesel-electric engine and PEM fuel cells. The boat was commissioned in 2005. Photo. Deutsche Marine.

The PEM technology can provide the increased duration that the Navy seeks for its larger UUVs, Wise said.

The applications for the PEM fuel cells that Wise is pitching include the multi-mission Extra Large UUV, the Large Displacement UUV, the Dry Combat Submersible (DCS) and as backup power system for nuclear attack and ballistic missile submarines, Wise, a retired Navy captain, said in a telephone interview on Feb. 20. Boeing [BA] recently was selected to build four XLUUVs based on the company’s Echo Voyager.

Lockheed Martin [LMT] is making the DCS for U.S. Special Operations Command.

The PEM fuel cells are used with diesel-electric submarines on a number of allied navies, including Germany. The technology can be used as a stand-alone quiet air independent propulsion system for slow cruising and in combination with the diesel electric batteries to increase the propulsion power for short sprints or to meet other requirements.

Last year, SGT worked with Siemens in Germany to demonstrate the PEM technology in the U.S. in a “generic” UUV close in size to an LDUUV. The XLUUV being developed by Boeing is for pier launch and the Navy is examining LDUUVs to be lunched from a submarine or surface ship.

SGT paid for Colorado State Univ. (CSU) to conduct an independent test of the PEM fuel cell to provide power and endurance to a UUV in a land-based demonstrator last August.

“The data recorded in this demonstration support the suitability of the fuel cell module in this application,” the CSU researchers say in the conclusion to their report. “The efficiency of the unit, based on power produced and hydrogen consumed, is consistent with performance data published by the fuel cell manufacturer. The ability of the unit, in the course of a test day, to start up, shut down, and respond to widely varying load demands was demonstrated.”

In its own conclusions based on the CSU report, Siemens said the design and ultimate demonstration, which was completed in seven months, “provides a compelling illustration of the feasibility and maturity of a fuel cell based power module for UUVs as well as of applications of interest to the U.S. Navy.” The company continues that “Significant improvements can be made based on experience gained from this work. The next step in the development of an optimized UUV power application will be to design and build a power module for at-sea demonstration in an actual UUV.”

Wise said that SGT continues to discuss potential prototype efforts with U.S. manufacturers and the Navy.

“Our message to the PEM is that there are no safety problems. There have been no incidents in over a decade of use,” he said. “And the technology is capable and reliable.”