Pioneer WEC

wave energy for ocean observing

The National Science Foundation’s Ocean Observatories Initiative (OOI) fields a large set of oceanographic instruments as part of the Pioneer Array, which is operated by Woods Hole Oceanographic Institution. Within the Pioneer Array, a series of Surface Moorings collect data at surface, within the water column, and at the sea floor. These moorings currently rely on solar and wind power, and achieve full operability approximately 70% of the time during their deployments. Low power periods, due to lulls in wind/solar energy and/or damage to generation systems, require duty-cycling of instruments.

OOI Pioneer Array Coastal Surface Mooring buoys on ship deck

OOI Pioneer Array Coastal Surface Mooring buoy at sea

OOI Pioneer Array Coastal Surface Mooring buoy with R/V Armstrong

Images of Pioneer Array Coastal Surface Mooring buoys, courtesy of Ocean Observatories Initiative (OOI).

Sandia, in partnership with Woods Hole Oceanographic Institution, NREL, Evergreen Innovations, Johns Hopkins University, Monterey Bay Aquarium Research Institute, and East Carolina University Coastal Studies Institute, was tasked with developing a wave energy converter to supplement the Pioneer Array’s Central Surface Moorings with additional power (Coe et al., 2023). The deployment site for the Pioneer Array off the coast of Cape Hatteras, NC experiences relatively modest waves, except during hurricanes (Grasberger et al., 2025). Based on a need to minimize the impact of the wave energy converter on the existing system design and maximize modularity, an innovative “pitch resonator” concept was developed (Devin et al., 2024; Keow et al., 2025). A series of bench testing campaigns have helped to refine numerical models for performance prediction, control tuning, and future design improvements (Coe et al., 2024; Lee et al., 2025).

Pioneer WEC v0 prototype on motion platform

Bench testing of the Pioneer WEC v0 prototype.

Based on testing and analysis of the v0 design, an inverted pendulum variant was selected for the v1 prototype. This system uses a magnetic spring designed by researchers from Portland State University to couple the inverted pendulum to the buoy. The Pioneer WEC v1 prototype was deployed on November 2nd, 2025 on the Central Surface Mooring within the Pioneer Array MAB and is slated to be recovered in May, 2026.

OOI Pioneer Array Coastal Surface Mooring buoy containing Pioneer WEC with R/V Armstrong

Images of Pioneer WEC v1 prototype leading up to and during deployment. (credit: Taylor Mankle & Josh Bauer / NREL)

Other resources

References

2025

Hydrodynamic characterization of the Coastal Pioneer Array ocean observing system

Jeff T. Grasberger, Dominic D. Forbush, Johannes Spinneken, Mark Bruggemann, Jantzen Lee, Alex Franks, John Reine, Giorgio Bacelli, Albert J. Plueddemann, and Ryan G. Coe

Journal of Ocean Engineering and Marine Energy, 2025

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Ocean observation buoys require relatively small amounts of power, yet traditionally necessitate costly resupply trips for battery replacement. With the offshore location of the buoys and small power requirements, wave energy may be an effective solution for providing consistent and reliable power to support the buoy instrumentation. The US National Science Foundation Ocean Observatories Initiative (OOI) includes arrays of point absorber-like buoy systems used for ocean observation that have been deployed at multiple locations including the Southern Mid-Atlantic Bight. A study is currently underway to design a pitch resonator wave energy converter to supplement existing renewable energy generation for powering observation instrumentation. This paper details field measurements from surface moorings of the OOI Coastal Pioneer Array, which informs the subsequent development of a numerical model for the moored observation system. The model is developed in Wave Energy Converter Simulator (WEC-Sim), which leverages the Simscape multibody solver within the MATLAB/Simulink framework and linear potential flow theory to simulate the hydrodynamic interactions and multibody dynamics in 6 degrees of freedom. Multiple tuning variables are considered to produce a model for the system that matches well with empirical data (about 8% error). The WEC-Sim model will serve as a platform for integrating the pitch resonator wave energy converter concept and deployment preparation (detailed design including power take-off and control systems, response evaluation, etc.).
@article{Grasberger:2025ab, author = {Grasberger, Jeff T. and Forbush, Dominic D. and Spinneken, Johannes and Bruggemann, Mark and Lee, Jantzen and Franks, Alex and Reine, John and Bacelli, Giorgio and Plueddemann, Albert J. and Coe, Ryan G.}, bibtex_show = true, date = {2025/04/28}, date-added = {2024-06-28 11:22:15 -0600}, date-modified = {2025-06-25 12:07:26 -0600}, doi = {10.1007/s40722-025-00392-y}, id = {Grasberger2025}, isbn = {2198-6452}, journal = {Journal of Ocean Engineering and Marine Energy}, title = {{Hydrodynamic characterization of the Coastal Pioneer Array ocean observing system}}, url = {https://link.springer.com/article/10.1007/s40722-025-00392-y}, year = {2025}, bdsk-url-1 = {https://link.springer.com/article/10.1007/s40722-025-00392-y}, bdsk-url-2 = {https://doi.org/10.1007/s40722-025-00392-y} }
Design Principles for Resonant Wave Energy Converters: Benchmarking Power Capture and Flow

Alicia Keow, Jantzen Lee, Giorgio Bacelli, and Ryan G. Coe

IEEE Transactions on Energy Conversion, 2025

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Control co-design (CCD) in Wave Energy Converters (WECs) integrates the controller, power take-off (PTO), and buoy models during system design to optimize power output. Using the bi-conjugate impedance matching principle, this study models the PTO as a two-port network, revealing impedance matching conditions at the input and output ports as a function of the buoy, PTO, and controller. This study examines the pairing of a flywheel-type pitch resonator PTO within a given buoy constrained by limited space and ballast capacity. The results show that physical constraints imposed by the buoy affect PTO performance. While controller tuning achieves optimal output impedance matching and flywheel inertia is maximized within the buoy’s limitations, the PTO’s input impedance remains smaller than the complex conjugate of the buoy’s intrinsic impedance. This mismatch limits the PTO’s ability to generate sufficient reaction torque, particularly outside the resonance frequency, resulting in narrow-band power transfer. The findings emphasize the need for PTO design modifications to improve input power transfer. Pendulum-based PTO mechanisms are proposed as alternatives to couple with multiple buoy motion modes and improve wave-to-wire efficiency while respecting system constraints.
@article{Keow:2025aa, author = {Keow, Alicia and Lee, Jantzen and Bacelli, Giorgio and Coe, Ryan G.}, bibtex_show = true, date-added = {2024-11-11 11:22:20 -0700}, date-modified = {2025-08-20 17:55:39 -0600}, doi = {10.1109/TEC.2025.3593152}, issn = {1558-0059}, journal = {IEEE Transactions on Energy Conversion}, keywords = {Impedance;Impedance matching;Torque;Generators;Energy exchange;Seaports;Flywheels;Charge coupled devices;Wave energy conversion;Angular velocity;Wave Energy Converter;Power Take-off Design;Design Methodology;Wave-to-Wire Efficiency;Impedance Matching;Control Co-Design;Energy Conversion}, pages = {1-12}, title = {Design Principles for Resonant Wave Energy Converters: Benchmarking Power Capture and Flow}, year = {2025}, bdsk-url-1 = {https://doi.org/10.1109/TEC.2025.3593152} }

Theory, Analysis, and Testing of an Angular Resonator for Wave Energy Generation

Jantzen Lee, Alicia Keow, Ryan G. Coe, Giorgio Bacelli, Johannes Spinneken, Steven J. Spencer, and Damian Gallegos-Patterson

Journal of Ocean Engineering and Marine Energy, 2025

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This article describes the theory, analysis, and initial bench-top testing of a minimally invasive, rotational resonator designed to produce small amounts of electrical energy for use in oceanic observation buoys. This work details the systems of equations that govern such a resonator, its potential power production, and its predicted effects on the modified motion of the buoy. Finally, a bench-top test apparatus is designed and experimented upon to identify the system and verify the system of equations empirically.

@article{Lee:2025aa,
  author = {Lee, Jantzen and Keow, Alicia and Coe, Ryan G. and Bacelli, Giorgio and Spinneken, Johannes and Spencer, Steven J. and Gallegos-Patterson, Damian},
  bibtex_show = true,
  date = {2025/02/01},
  date-added = {2024-02-07 13:34:05 -0700},
  date-modified = {2025-06-25 12:01:07 -0600},
  doi = {10.1007/s40722-024-00366-6},
  id = {Lee2025},
  isbn = {2198-6452},
  journal = {Journal of Ocean Engineering and Marine Energy},
  number = {1},
  pages = {97-107},
  title = {Theory, Analysis, and Testing of an Angular Resonator for Wave Energy Generation},
  url = {https://link.springer.com/article/10.1007/s40722-024-00366-6},
  volume = {11},
  year = {2025},
  bdsk-url-1 = {https://link.springer.com/article/10.1007/s40722-024-00366-6},
  bdsk-url-2 = {https://doi.org/10.1007/s40722-024-00366-6}
}

2024

High-dimensional control co-design of a wave energy converter with a novel pitch resonator power takeoff system

Michael C. Devin, Daniel T. Gaebele, Carlos A. Michelén Ströfer, Jeff T. Grasberger, Jantzen Lee, Ryan G. Coe, and Giorgio Bacelli

Ocean Engineering, Sep 2024

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Researchers are exploring adding wave energy converters to existing oceanographic buoys to provide a predictable source of renewable power. A ”pitch resonator” power take-off system has been developed that generates power using a geared flywheel system designed to match resonance with the pitching motion of the buoy. However, the novelty of the concept leaves researchers uncertain about various design aspects of the system. This work presents a novel design study of a pitch resonator to inform design decisions for an upcoming deployment of the system. The assessment uses control co-design via WecOptTool to optimize control trajectories for maximal electrical power production while varying five design parameters of the pitch resonator. Given the large search space of the problem, the control trajectories are optimized within a Monte Carlo analysis to identify optimal designs, followed by parameter sweeps around the optimum to identify trends between the design parameters. The gear ratio between the pitch resonator spring and flywheel are found to be the most sensitive design variables to power performance. The assessment also finds similar power generation for various sizes of resonator components, suggesting that correctly designing for optimal control trajectories at resonance is more critical to the design than component sizing.
@article{Devin:2024aa, author = {Devin, Michael C. and Gaebele, Daniel T. and Str{\"o}fer, Carlos A. Michel{\'e}n and Grasberger, Jeff T. and Lee, Jantzen and Coe, Ryan G. and Bacelli, Giorgio}, bibtex_show = true, date-added = {2024-02-07 13:37:15 -0700}, date-modified = {2024-11-11 11:18:47 -0700}, doi = {10.1016/j.oceaneng.2024.119124}, issn = {0029-8018}, journal = {Ocean Engineering}, keywords = {Wave energy converter, Control co-design, Optimization, Power take-off, Central Pioneer Array, WecOptTool}, month = sep, pages = {119124}, title = {High-dimensional control co-design of a wave energy converter with a novel pitch resonator power takeoff system}, url = {https://www.sciencedirect.com/science/article/pii/S0029801824024624}, volume = {312}, year = {2024}, bdsk-url-1 = {https://www.sciencedirect.com/science/article/pii/S0029801824024624}, bdsk-url-2 = {https://doi.org/10.1016/j.oceaneng.2024.119124} }

Bench testing of an early prototype pitch resonator WEC

Ryan G. Coe, Jantzen Lee, Alicia Keow, Giorgio Bacelli, Steven J. Spencer, Johannes Spinneken, Damian Gallegos-Patterson, Elaine Liu, Kevin Dullea, Robert Crandell, Miles Skinner, Casey Nichols, and Rebecca Fao

Aug 2024

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This report describes a series of tests performed on a "pitch resonator’" concept for a wave energy converter. The overall testing campaign goals centered on risk reduction for the pitch resonator wave energy converter concept and model validation. Two modes of testing are captured in this report: one using a single degree of freedom test rig and one in which a six degree of freedom Stewart platform was employed.

@techreport{Coe:2024ab,
  address = {Albuquerque, NM},
  author = {Coe, Ryan G. and Lee, Jantzen and Keow, Alicia and Bacelli, Giorgio and Spencer, Steven J. and Spinneken, Johannes and Gallegos-Patterson, Damian and Liu, Elaine and Dullea, Kevin and Crandell, Robert and Skinner, Miles and Nichols, Casey and Fao, Rebecca},
  bibtex_show = true,
  date-added = {2024-06-14 15:05:02 -0600},
  date-modified = {2025-05-12 18:49:17 -0600},
  doi = {10.2172/2429934},
  institution = {Sandia National Laboratories},
  month = aug,
  number = {SAND2024-10402},
  title = {Bench testing of an early prototype pitch resonator {WEC}},
  url = {https://www.osti.gov/biblio/2429934},
  year = {2024},
  bdsk-url-1 = {https://www.osti.gov/biblio/2429934}
}

2023

Pioneer WEC concept design report

Ryan G. Coe, Jantzen Lee, Giorgio Bacelli, Steven J. Spencer, Kevin Dullea, Albert J. Plueddemann, Derek Buffitt, John Reine, Donald Peters, Johannes Spinneken, Andrew Hamilton, Sahand Sabet, Salman Husain, Dale Jenne, Umesh Korde, Mike Muglia, Trip Taylor, and Eric Wade

Oct 2023

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The “Pioneer WEC” project is targeted at developing a wave energy generator for the Coastal Surface Mooring (CSM) system within the Ocean Observatories Initiative (OOI) Pioneer Array. The CSM utilizes solar photovoltaic and wind generation systems, along with rechargeable batteries, to power multiple sensors on the buoy and along the mooring line. This approach provides continuous power for essential controller functions and a subset of instruments, and meets the full power demand roughly 70% of the time. Sandia has been tasked with designing a wave energy system to provide additional electrical power and bring the CSM up-time for satisfying the full-power demand to 100%. This project is a collaboration between Sandia and Woods Hole Oceanographic Institution (WHOI), along with Evergreen Innovations, Monterey Bay Aquarium Research Institute (MBARI), Eastern Carolina University (ECU), Johns Hopkins University (JHU), and the National Renewable Energy Laboratory (NREL). This report captures Phase I of an expected two phase project and presents project scoping and concept design results. phase project and presents project scoping and concept design results.
@techreport{Coe:2023aa, address = {Albuquerque, NM}, author = {Coe, Ryan G. and Lee, Jantzen and Bacelli, Giorgio and Spencer, Steven J. and Dullea, Kevin and Plueddemann, Albert J. and Buffitt, Derek and Reine, John and Peters, Donald and Spinneken, Johannes and Hamilton, Andrew and Sabet, Sahand and Husain, Salman and Jenne, Dale and Korde, Umesh and Muglia, Mike and Taylor, Trip and Wade, Eric}, bibtex_show = true, date-added = {2024-02-16 13:45:40 -0700}, date-modified = {2024-03-28 12:18:50 -0600}, doi = {10.2172/2280833}, institution = {Sandia National Laboratories}, month = oct, number = {SAND-2023-10861}, title = {{Pioneer WEC concept design report}}, url = {https://www.osti.gov/biblio/2280833}, year = {2023}, bdsk-url-1 = {https://www.osti.gov/biblio/2280833}, bdsk-url-2 = {https://doi.org/10.2172/2280833} }