Profiling floats and gliders/AUVs powered by ocean temperature differential

Development, implementation and testing of a profiling float powered by ocean temperature differentials are described. The current generation profiling floats are all powered by primary battery and therefore have limited lifetime. After a few hundreds dives, the floats have to be disposed in the ocean. To maintain a float array of 3000 units in support of the international Argo program, several hundreds of new floats have to be deployed every year, implying a significant cost for deployment. The limited power from the primary battery also restricts a relatively long (i.e., 10 days) sampling interval and new sensors (e.g., biogeochemical, acoustic and optical) to be attached. Harvesting the ocean thermal energy associated with the vertical temperature differentials has the potential to power profiling floats with fast sampling (e.g., 1 day or 6 hours) while still maintaining a multi-year mission as well as more sensors. The concept of a thermally powered glider will be presented. The design of a thermal recharging station that can be used to dock and charge AUVs will also be discussed.