Analysis and Prototype Testing of a Wave-Powered Oceanographic Profiler
Abstract
The PIs propose to build a new generation of long-duration oceanographic platforms that harvest energy from waves while remaining submerged. The wave energy can be converted to electrical energy and used directly for propulsion and station keeping. Such a vehicle would surface only when necessary for conducting RF communications and gathering GPS fixes. The US Navy is now moving to autonomous robotic platforms for a variety of tasks and many of these will be deployed in areas where long-term unattended operation will be critical. Energy sources are key components for both naval and civilian systems, and current R&D efforts are focused on many technologies such as batteries, fuel cells, and devices that can scavenge energy from the environment. Environmental sources include solar, wind, and waves. Nearly all energy scavenging devices suitable for small robotic systems in remote areas in deep water require a surface expression. We propose to build a new generation of long-duration oceanographic platforms that harvest energy from waves while remaining submerged. The wave energy can be converted to electrical energy and used directly for propulsion and station keeping. Such a vehicle would surface only when necessary for conducting RF communications and gathering GPS fixes. Our candidate design will utilize turbines to extract energy from the rotational energy in the wave field. This new class of wave energy conversion devices to be developed is referred to as rotational field wave energy conversion systems (RF-WECSs), which differentiates the class from the current variety of wave energy convertors such as surface following and surface or subsurface blanket concepts. In our design, the horizontally-oriented blades will resemble vertical-axis wind turbines that are capable of generating power from wind from any direction. Existing wind and water turbine designs will serve as the starting point for our design. Some of these designs perform well in low flows and produce unidirectional motion for flow in any direction. The energy harvesting technique we are pursuing is fundamentally well suited for a profiling device. We will be able to build a device that could charge near the surface, profile or hover at nearly any depth, then return above the wave floor to recharge its batteries. These devices would also surface for communications via satellite or other RF method. The device could be selfcontained with no need to connect to a docking station to recharge. In principal, these technologies could support docking stations that could recharge themselves while submerged. A team of such devices could provide continuous presence at depth, with some members of the team recharging while others remained at depth. We propose a three-year program. Year 1 will feature conceptual design and analysis to determine the best design of the turbines for the range of expected flows, the best form for the profiler body that will provide the inertia against which the turbines react, and sizing the turbines relative to the main profiler. In Year 2, we will construct an engineering prototype and test it in a wave tank to verify power generation performance. In Year 3, we will enhance the prototype and test it offshore.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Nov 23, 2016
- Source ID
- N000141613037
Entities
People
- Dana R. Yoerger
Organizations
- Office of Naval Research
- United States Navy
- Woods Hole Oceanographic Institution