Variable Speed and Energy Efficient Depth Changing Buoys

DARPA challenges the community to develop a long endurance and fast profiling float that can dive to 1000m at 1 m/s speed for more than 100 dive cycles. Today’s buoyancy engine used by floats and gliders is too small to support this fast profiling requirement. To increase the size of buoyancy engine and add propeller can achieve 1 m/s speed but require a significantly larger battery in order to maintain long endurance. Innovations of new propulsion and energy harvesting are therefore required to meet this DARPA challenge. This proposal has assembled a multi-disciplinary team of scientists and engineers with demonstrated abilities to accomplish the proposed objective on schedule and within budget. Using a commercially available profiling float, we will develop three innovative technologies: 1) a chemical reactor using fluidized aluminum to react with water to produce pressurized hydrogen for rapid buoyancy change, 2) a hydraulic buoyancy engine with larger size and faster pumping for precise depth control, and 3) an energy harvesting system to convert ocean thermal energy into electricity to enable long endurance. An optimal combination of these three technologies will push the envelope of persistent monitoring and extend the mission endurance from 100 dive cycles towards infinite.