Abstract
Oyster farming is a growing sector of the blue economy with demand currently exceeding supply. As oyster farms increase their production, their power needs grow. Oyster farms are located in coastal areas where tidal currents deliver nutrients for growth but are not yet being used to generate electricity. Tidal turbines and similar devices are being developed to generate electricity for off-grid applications such as oyster farm operations. Here we present a feasibility study of the use of tidal power at oyster farms. The feasibility study includes acoustic doppler current profiler (ADCP) micro-siting surveys at three oyster farms, an energy usage assessment at each farm, and a field test of a current energy converter device. The power versus current speed curves obtained from the field test will be used to calculate the potential power that would be generated at each of the three farms.
The ADCP micro-siting surveys will take place at three oyster farms. The farms are in Washington, California, and Maine. Three sites will be studied at the farms in WA and ME and two sites will be studied at the farm in CA. The data collection for the micro-siting surveys has been completed at the farm in CA and tidal current speeds above 1.6 m/s were measured.
The farms range in size from a family business to one of the largest oyster farm companies in the U.S. Electricity is needed at the farms to power a hatchery, a floating upwelling system, and oyster tumblers. The farms in WA and CA currently rely on grid connected power sources but the farm in ME has offshore solar panels and batteries. All of the farms expressed interest in decarbonizing their boats.
The current energy converter to be tested (VIVACE) was developed by researchers at the University of Michigan and manufactured by Vortex Hydro Power. VIVACE is not a traditional turbine with blades but instead utilizes flow induced oscillations of cylinders. Cylinders submerged in tidal currents oscillate due to vortex shedding, shear-layer instabilities, or their coexistence resulting in an open-ended response amplitude operator (RAO) starting at very low flow speed. In the laboratory VIVACE generated electricity in currents as slow as 0.19 m/s. It has a passive turbulence control system, can operate in turbulent currents, and its oscillators can generate electricity effectively in variable flow speeds such as tidal currents. VIVACE will be field tested in a tidal channel near PNNL-Sequim.