Abstract
A tidal energy test site was established by the Atlantic Marine Energy Center (AMEC) to help progress the field of tidal energy conversion towards commercial feasibility and to lower the barrier of entry for turbine developers. AMEC’s Tidal Energy Test Site is located at Memorial Bridge in Portsmouth, NH, in the Piscatatqua River of the Great Bay Estuarine System which is one of the most energetic estuarine systems on the East Coast. The site will allow researchers and developers to test their tidal energy converters (TEC) in a real, energetic tidal flow. There is a need for a comprehensive tidal energy resource and turbulent conditions characterization at AMEC’s site to guide test plans and to aid in TEC design. Performing this characterization in accordance with the International Electrical Commission (IEC) marine energy standards provides a way to compare this site to other US TEC test sites. This work was done in preparation for the deployment of the Open-Source Tidal Energy Converter (OSTEC) axial flow tidal turbine.
The mean inflow current velocity was measured with two 4-beam Acoustic Doppler Current Profilers (ADCPs). The ACDPs were both downward-facing and deployed ~6 meters up- and down-stream of the energy extraction plane (EEP) at approximately 0.4 meters depth. The turbulent characteristics of the flow were measured concurrently using three Acoustic Doppler Velocimeters (ADVs). The ADVs were downward-facing and deployed less than 1 meter away for the EEP with sampling volumes at a depth of approximately 2 meters, which is the hub height of the OSTEC turbine. They were deployed evenly spaced in the cross-stream direction at the EEP. The instantaneous velocity was measured with a sampling rate of 64 Hz to fully resolve the relevant-scale turbulent structures for energy capture and hydrodynamic loading. A follow-on study examined the quality of turbulence measurements taken by a 5-beam ADCP and compared them to that of a (nearly) collocated ADV.
A summary of the energy resource and turbulent metrics, including Reynolds stresses captured by a 5-beam ADCP, at AMEC’s tidal energy test site will be provided, along with a summary of design considerations for future TECs deployed at this site.
This work is supported by the U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy (EERE) through the Water Power Technologies Office (WPTO). Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525. This abstract describes objective technical results and analysis. Any subjective views or opinions that might be expressed in the paper do not necessarily represent the views of the U.S. Department of Energy or the United States Government.