Aluminum Fueled Buoyancy Engine

A buoyancy engine design is presented that utilizes an aluminum/oil fuel paste which is reacted with a 30% ammonia solution to produce ammonia and hydrogen gases, aluminum oxyhydroxide (boehmite) and steam. Buoyancy is achieved by using the generated gases to inflate two bladders; one for primary buoyancy control and the other for vehicle moment control. Although the use of a compressible gas for buoyancy is highly inefficient, the aluminum fuel used by this system is more than forty times as energy dense as lithium batteries, resulting in a three-fold reduction in overall weight and volume compared to conventional hydraulic buoyancy engines. Moreover, since the fuel paste is incompressible and reacts with the ammonia solution on contact, the engine can be entirely housed within a small flooded hull section while remaining mechanically simple and robust.