A survey of available underwater electric propulsion technologies and implications for platform system safety

The majority of unmanned undersea vehicle (UUV) and autonomous underwater vehicle (AUV) applications are electrically powered, deriving their energy from chemical reactions within a battery. Unlike thermal engines, where chemical energy is metered into a combustion chamber, batteries are unique in the storage of all energy content within a limited material construction. Fuel cells are a logical cross between the concepts of electric storage battery and thermal engine. The requirements for military and some civilian AUVs demand increased battery energy density and volume compared to the overall AUV vehicle. Batteries, like fuel cells. are most cost-effective when they may be recharged and reutilized. The aspects of increased energy density, intrinsic power capability and electrical or mechanical recharging present a significant challenge in designing a power supply system that is safe under all conditions for the AUV and for the deployment platform. This paper will provide an overview of common AUV propulsion systems and discuss aspects of vehicle integration and vehicle and launch platform safety with respect to recharging, refurbishing or refueling an AUV system.