Abstract
In spring 2022 R/V Russell Davis Light was moored in Agate Pass, Washington, to perform the first saltwater test of a university-developed tidal turbine designed for sustained deployment as a bottom lander to power oceanographic sensors. The system, as deployed, was self-contained in that all system components associated with a hypothetical bottom-lander configuration were present. Potential benefits of the deployment in a moored configuration were the ability to intervene rapidly in the event of a critical system failure and the ability to regularly inspect the system for signs of premature failure. The Adaptable Monitoring Package (AMP), a custom environmental monitoring system, was also used throughout the deployment. The AMP was equipped with an acoustic Doppler current profiler ADCP that passed current velocities to the tidal turbine for control purposes. In addition, the AMP was equipped with a pair of stereo optical cameras with triggered LEDs for artificial illumination and two high-frequency imaging sonars with combined fields of view covering the rotor and areas up to 10 m up and downstream of the rotor. Both the tidal turbine and AMP systems sampled with greater than 95% up-time, with downtime being driven primarily by user-interventions to modify settings.
Prior to testing at Agate Pass the tidal turbine system had undergone extensive vessel-based tow testing in a freshwater lake (Lake Washington, Seattle, WA) and laboratory dynamometry testing. As such, a priori expectations for system performance in Agate Pass were used in deployment planning and contrasted with post-deployment analysis. I will present descriptions of the system architecture and turbine performance. I will also present snapshots of observed biological interactions with the turbine and co-registration and tracking of targets with the acoustic and optical cameras. Topics including planning, site selection, mooring design, operations/logistics, personnel requirement, and costs inform a personal assessment of whether the benefits of a moored vessel deployment outweigh the costs.
I gratefully acknowledge the support (in alphabetic order) of the following individuals that were critical in the design, fabrication, deployment, and operations at Agate Pass: Paul Aguilar, Eric Boget, Ben Cunningham, Cameron Fisher, James Joslin Derek Martin, Tim McGinnis, Nick Michel-Hart, Jennie Moufat, Brian Polagye, Andy Reay-Ellers, Cassie Riel, Mitchell Scott, Harlin Wood, Kevin Zack. Of particular note are the contributions of three additional people without whom the Agate Pass test would not have been successful: Jesse Dosher (software), Paul Gibbs (mechanical design lead), Paul Murphy (AMP).