Nearly 180 years after the invention of the first hydrogen fuel cell, hydrogen power is making a comeback. The Defense Innovation Unit has awarded a contract to Pratt Miller to prototype a hydrogen-powered system for naval vessels. If successful, the Expeditionary Hydrogen On Ship & Shore project, or EHOSS, could help fulfill a long-standing Pentagon goal of eliminating petroleum-based propulsion from military operations.
In a statement viewed by Defense One, DIU described the objective as a tactical “micro hydrogen supply chain.” The concept relies on commercial components to build a hydrogen generation, storage, and dispensing system. It also could charge the batteries of onboard drones or other equipment and provide power for off-ship uses.
The contract involves U.S. Indo-Pacific Command, the Marine Corps Expeditionary Energy Office, and research teams from both the Navy and Army.
Pratt Miller has worked with the Army since 2019 on deploying hydrogen systems in military trucks. In an interview with Defense One, Christopher Archambo, the company’s chief engineer for hydrogen fuel cell technology, said the Navy prototype will use a proton exchange membrane electrolyzer to compress hydrogen gas storage at 10,152 pounds per square inch, or 700 bar. The hydrogen is then stored in conformable tanks. That level of compression is suitable for large trucks or generators used to recharge drone batteries. stored in conformable hydrogen storage tanks, then used to refuel hydrogen vehicles and equipment.
Pratt Miller’s Flexible Power Conversion Module allows EHOSS to use a power from a single source or the multiple power sources commonly used on the battlefield and aboard ships.
Hydrogen fuel cells are used to allow for extended operations and reduced signature power in UAVs, UUVs, ground vehicles, and power generators.
Welsh physicist Sir William Robert Grove invented the hydrogen fuel cell in 1839, which converts hydrogen’s chemical energy into electricity, heat, and water through an electrochemical reaction. Because hydrogen is lightweight, it quickly found applications in early aviation, especially among the makers of steerable balloons, or airships.
But too much enthusiasm too quickly proved to be hydrogen energy’s downfall—literally. In May 1937, the German airship LZ 129 Hindenburg caught fire and crashed, just seven years after the British R101 suffered a similar fate. These high-profile disasters, combined with improvements in internal combustion engines, halted momentum around hydrogen energy for decades.
Interest returned briefly in the early 2000s. In January 2003, just two months before the U.S. launched Operation Iraqi Freedom, President George W. Bush pledged $1.2 billion to support hydrogen fuel cell research for vehicles. That April, General Motors’ president of research and engineering predicted there would be a million hydrogen-powered cars on U.S. roads by 2010.
That milestone has not yet arrived, and public skepticism about hydrogen safety remains widespread. On the 2024 campaign trail, Donald Trump pledged to shut down hydrogen vehicle programs altogether, claiming they “blow up.”
Hydrogen’s economic limitations are also a factor. Producing hydrogen requires electricity, so it is rarely cheaper than just drawing power from the U.S. electric grid. That’s one reason why hydrogen power failed to catch on in the United States for consumer automobiles. However, for the military, condensed hydrogen produced on-site is significantly cheaper than flying in fuel via tanker aircraft, especially over waters monitored by China. And hydrogen fuel systems have improved more quickly than combustion-based systems. With continued investment, hydrogen could become a practical alternative.
Military interest in hydrogen is less about price and more about flexibility. Hydrogen-generation systems developed under DIU’s Hydrogen at the Tactical Edge of Contested Logistics program, or HyTECH, allow forward-deployed forces to produce their own power without relying on fuel convoys. That logistical advantage is especially valuable in the Indo-Pacific, where U.S. forces would be dispersed across vast distances in the event of a conflict.
The Pratt Miller system draws on decades of research aimed at improving hydrogen safety, including the use of conformable storage tanks and small-diameter tubing.
The goal for EHOSS is to produce 20 kilograms of hydrogen in a 24-hour period using 100 kilowatts or less. It still costs more than grid electricity,
Another advantage is stealth. Hydrogen fuel cells generate less heat and noise than diesel engines and have fewer moving parts.
“We’ve done multiple fuel cell variants, side-by-side comparisons, and thermal acoustic inventory testing,” Archambo said. “We took thermal acoustic data even at a [U.S. military] demonstration two weeks ago,” which showed significantly reduced signatures compared to diesel generators.
The work is also advancing solid-state hydrogen storage, which uses nanomaterials to trap hydrogen molecules, Archambo said. This method improves transport safety, a key Navy concern, but requires more material (and holds less hydrogen), which increases weight.
But there have been improvements and advances to overcome those limitations. Pratt Miller expects to begin testing solid-state hydrogen storage in vehicles later this year.
