A small-scale wave energy converter developed by the National Laboratory of the Rockies (NLR) and the University of Hawaii (UH) at Manoa has begun generating power during an open-water deployment off Oahu, Hawaii.
The Small Underwater Research Flap Wave Energy Converter (SURF-WEC) has been installed near Makai Research Pier, where it is expected to remain in operation for up to a year. Researchers will use the deployment to collect real-world performance data and compare active and passive approaches to wave energy capture.
The project is intended to address a shortage of accessible data from open-water marine energy trials. Its design, operational data and lessons learned will be made publicly available to support further technology development.
“The marine energy community is so data starved,” said Bri Friedman, an NLR researcher working on the project. “There’s just so few deployments that have occurred. And on top of that, a lot of those deployments don’t have accessible or shared data.”
SURF-WEC incorporates a buoyant flap anchored close to shore that oscillates as waves pass. This movement drives a hydraulic system, pumping fluid through a sealed circuit and building pressure. Once a specified pressure is reached, the system drives a motor connected to a generator.
The device can be controlled remotely, allowing researchers to adjust its response to waves and switch between active and passive operating modes.
Passive wave energy systems operate without adapting to incoming conditions, while active systems use controls and mechanical adjustments to respond to changing waves. Although modelling indicates that active systems can capture more energy, they also require power for sensors, controls and mechanical functions.
“Active systems generally outperform passive systems in models, but reality is a different story. Active systems also introduce more losses,” Friedman said. “What’s exciting here is that, from my desk in Colorado, I can push a button and switch the SURF-WEC between active and passive modes.”
NLR led much of the power take-off engineering, while UH Manoa contributed wave modelling, anchoring, deployment and testing expertise.
“Projects like SURF-WEC work because different teams bring different expertise,” said Pat Cross, programme manager for marine energy at the Hawaii Natural Energy Institute in the UH Manoa School of Ocean and Earth Science and Technology.
“NLR led much of the power take-off engineering, while we helped ensure a robust anchoring and deployment approach and supported testing here in Hawaii. We learn from each other—and that collaboration is what makes projects like this successful.”
Laboratory testing informs design
The open-water trial follows two years of modelling, construction and laboratory testing at NLR. Researchers combined hydrodynamic models developed with UH Manoa, using the WEC-Sim modelling tool, with detailed simulations of the power take-off system.
The hydraulic equipment was assembled and tested at NLR’s Flatirons Campus in Colorado. An electric actuator was used to reproduce the movement of the flap under wave loading, enabling researchers to assess performance, quantify efficiency losses and test the system under extreme conditions.
The team also developed MODAQ 2.0, a data acquisition and control platform that monitors performance, controls system functions and collects operational information. The platform allows data from the Hawaii deployment to be viewed through a live interface.
Following laboratory validation, the system was sealed, protected and reinforced for operation in the marine environment before being shipped to Hawaii.
Deployment was temporarily interrupted by an approaching Kona storm, which was expected to bring stronger winds and waves than indicated by historical data. The team initially installed and secured only the supporting frame.
Researchers subsequently used real-time information from nearby spotter buoys to update their simulations and reassess the system’s expected response. The remaining components were installed two days later, after conditions had improved.
The submerged flap and offshore power take-off system were anchored to the seabed and connected by cables to the shore-based MODAQ equipment. The converter began generating its first power shortly after installation.
More than five months of operation have now been completed, with researchers beginning to assess the resulting data. A final report will be published following the trial.
“The whole point of research is to learn,” said Senu Sirnivas, NLR principal investigator. “It will be great if SURF-WEC stays in the water for a year. But even if it doesn’t, it’s still a success. We learn—and those lessons will be shared with the community.”
The project was funded by the US Department of Energy’s Hydropower and Hydrokinetic Office.
