The X-SPAR is a floating spar buoy designed for oceanographic measurements, particularly air-sea interactions, developed by Woods Hole Oceanographic Institution. The low-cost buoy is meant to be expandible. Sandia is working with Woods Hole and Johns Hopkins University to augment the X-SPAR with a wave energy converter (the “WEC-SPAR”). After an initial scoping study (Gaebele et al., 2025), the team is now performing de-risk testing on a oscillating water column (OWC) drive-train.
Images of X-SPAR, courtesy of Woods Hole Oceanographic Institution.
References
2025
Powering the Woods Hole X-Spar Buoy with Ocean Wave Energy—A Control Co-Design Feasibility Study
Despite its success in measuring air–sea exchange, the Woods Hole Oceanographic Institution’s (WHOI) X-Spar Buoy faces operational limitations due to energy constraints, motivating the integration of an energy harvesting apparatus to improve its deployment duration and capabilities. This work explores the feasibility of an augmented, self-powered system in two parts. Part 1 presents the collaborative design between X-Spar developers and wave energy researchers translating user needs into specific functional requirements. Based on requirements like desired power levels, deployability, survivability, and minimal interference with environmental data collection, unsuitable concepts are pre-eliminated from further feasibility study consideration. In part 2, we focus on one of the promising concepts: an internal rigid body wave energy converter. We apply control co-design methods to consider commercial of the shelf hardware components in the dynamic models and investigate the concept’s power conversion capabilities using linear 2-port wave-to-wire models with concurrently optimized control algorithms that are distinct for every considered hardware configuration. During this feasibility study we utilize two different control algorithms, the numerically optimal (but acausal) benchmark and the optimized damping feedback. We assess the sensitivity of average power to variations in drive-train friction, a parameter with high uncertainty, and analyze stroke limitations to ensure operational constraints are met. Our results indicate that a well-designed power take-off (PTO) system could significantly extend the WEC-Spar’s mission by providing additional electrical power without compromising data quality.
@article{Gaebele:2025aa,article-number={4442},author={Gaebele, Daniel T. and Coe, Ryan G. and Bacelli, Giorgio and Lanagan, Thomas and Fucile, Paul and Korde, Umesh A. and Toole, John},bibtex_show=true,date-added={2024-11-11 11:24:08 -0700},date-modified={2025-09-26 09:11:10 -0600},doi={10.3390/en18164442},issn={1996-1073},journal={Energies},number={16},title={Powering the {Woods Hole X-Spar} Buoy with Ocean Wave Energy---A Control Co-Design Feasibility Study},url={https://www.mdpi.com/1996-1073/18/16/4442},volume={18},year={2025},bdsk-url-1={https://www.preprints.org/manuscript/202507.0985/v1}}
