
Hydrogen fuel cells convert high-energy hydrogen efficiently into electricity - hence, vehicles are able to achieve greater range and endurance than vehicles with electric motors that are powered with batteries only. Vehicles that are powered by such fuel cells are promised 60 days endurance.
The American Naval Research Laboratory recently completed an evaluation of a prototype UUV equipped with a GM fuel cell and came up with some encouraging results. According to Frank Herr, ONR's department head for Ocean Battlespace Sensing, their in-water experiments with an integrated prototype show that fuel cells can be game changers for autonomous underwater systems, as they offer great reliability, high energy, and cost effectiveness.