Reviews of fuel cells and energy storage systems for unmanned undersea vehicles.

The world has a growing need for advanced Unmanned Undersea Vehicles (UUVs) that can complete various types of missions autonomously. Power and energy systems that maximize vehicles’ range and endurance are critical to the success of these missions. The current fleet of UUVs is usually powered by lithium batteries, which have relatively low energy density and thus limit the range and endurance of UUVs. On the other hand, high energy conversion efficiency of fuel cells as well as energy-dense reactant storage may provide much longer range and endurance for UUVs. The aim of this study is to review recent progress on fuel cells and energy storage technologies for UUVs. Due to pure oxygen supply and closed-cycle operation, underwater fuel cells require adaption to existing fuel cells in terms of membrane electrode assembly (MEA), bipolar and safety measures, as evidenced by this review. For energy storage, the key issue concerned is to store fuel and oxidizer in high energy density format. From this perspective, a comparative assessment of potential fuel and oxidizer storage technologies is conducted in this study. The results indicate that aluminum fuel is the most promising candidate among hydrogen sources, whereas lithium perchlorate is the best option among oxygen sources. [ABSTRACT FROM AUTHOR]