PNNL

Pacific Northwest National Laboratory (PNNL)-Sequim facilitated the deployment and testing of the first tidal turbine operated for an extended period on the seafloor in the Pacific Northwest. It highlights PNNL-Sequim’s key role as the only facility on the U.S. West Coast to provide the necessary access to power and data connections, monitoring, and in-water support to test marine energy devices in a tidal channel.  

“This deployment showcases how PNNL-Sequim’s underwater testbed and expert staff are helping move new marine energy technologies from the laboratory to the real world—or as we refer to it, from the bench to the bay,” explained PNNL mechanical engineer and project lead Robert Cavagnaro. 

The novel tidal turbine was designed and built by the University of Washington’s Applied Physics Laboratory (UW-APL) to be deployed off the back of a small ship—an impossible feat for larger turbines—and generate enough renewable energy to indefinitely power technologies like sensors or cameras in hard-to-reach locations. The Naval Facilities Engineering and Expeditionary Warfare Center (NAVFAC EXWC) Marine Energy Development team supported UW-APL in the development and testing of the turbine.  UW-APL partnered with PNNL-Sequim to test the long-term performance of the turbine in Sequim Bay.  This partnership between the UW-APL, the Navy, and PNNL-Sequim enhanced collaboration and efficiency of efforts to accomplish field testing.

“With the Department of Energy’s recent investments in PNNL-Sequim’s underwater and onshore infrastructure, we are growing our ability to provide ocean-based solutions to the climate crisis,” said Chris Meinig, PNNL Coastal Sciences division director. “This turbine deployment is the first of many to come.”

A long road to the ocean

Deployed in Sequim Bay from October 2023 to March 2024, the turbine was the culmination of years of work by Cavagnaro and colleagues at both PNNL and UW affiliated with the Pacific Marine Energy Center. 

“I began working on the basic science behind this cross-flow turbine back in 2012 as a graduate student at UW,” said Cavagnaro. “It’s exciting to be putting it in the water after so many years of work.”

It’s an example of how much time it can take to move new energy technologies from the lab to the real world. This process can be even slower in emerging sectors like marine energy, where there are limited facilities for ocean testing and permitting is a challenge. 

“Having collaborated with PNNL-Sequim for over a decade, it’s difficult to overstate the benefits of working with the Lab on technology development. The in-water turbine deployment is a major milestone for that system and a credit to the entire team,” said Brian Polagye, professor of Mechanical Engineering at UW. 

Location, location, location 

To test how the compact 3-foot by 4-foot turbine would handle long-term tidal forces, the team had to determine exactly where to place the turbine in PNNL-Sequim’s underwater testbed. 

“For a turbine of this size, small-scale ocean dynamics really make a difference. Being off by a few meters—maybe due to a small dip or rise in the seafloor—could have a really big impact on the actual current speeds at the turbine and how well we could test its long-term performance,” explained Cavagnaro.

Models used to simulate tidal energy are helpful for selecting a general testing area but don’t provide information about current speeds on such a small scale. Leveraging PNNL’s expertise and capabilities, the team was able to “microsite” the testbed by measuring current speeds while onboard a research vessel. This was the best way to pinpoint an ideal testing site with the most consistent current speeds.

“While shallow and relatively accessible, the conditions still presented numerous hurdles and the local knowledge of PNNL was critical in establishing our plans for deployment, operations, and recovery,” said Christopher Bassett, senior mechanical engineer at UW-APL.  

More testing in Sequim’s future

Along with the turbine, the team deployed and tested a custom environmental monitoring package designed to support wildlife monitoring efforts in remote ocean locations and inform future marine energy use. Emma Cotter, PNNL environmental engineer and joint appointee at UW, is another UW alum whose graduate research directly contributed to the development of the Adaptable Monitoring Package (AMP). 

With support from DOE’s Water Power Technologies Office through the Testing Expertise and Access for Marine Energy Research (TEAMER) program, PNNL and UW are also collaborating with MarineSitu, Inc., to analyze the data they gathered on turbine performance and environmental interactions monitored by the AMP. 

“Working with PNNL through TEAMER to support the UW deployment of the Turbine Lander allowed us to showcase our capabilities for providing marine environmental monitoring services while continuing to advance the state of the art,” said James Joslin, founder and president of MarineSitu, “Data and lessons learned from this deployment have already helped us to provide better monitoring solutions to our customers. We are hopeful that the results from this project will help advance the greater marine energy industry and are looking forward to our next collaboration.”

Another turbine deployment is already on the docket—representative of PNNL-Sequim’s growing role as a regional center for marine energy testing and development.

The tidal turbine deployment and testing was sponsored by the Naval Facilities Engineering and Expeditionary Warfare Center and represents an enduring partnership with UW-APL and the Navy to advance marine energy technologies.