Abstract: Wave energy converters (WECs) can advance the global energy transition by harnessing ocean waves to produce clean power for utility grids and offshore activities. This dissertation describes (1) the development of a fast and accurate computational model to simulate the WEC including hydrodynamics, constrained optimal control, and structural survival; (2) the application of the model in a systems optimization framework to understand how WEC shape and size mediate the tradeoff between cost and power; and (3) the extension of this framework to holistically incorporate techno-economic viability and environmental impacts at the grid level.
Guided by a first-principles understanding of frequency-domain dynamics and a geometric interpretation of the constrained optimal control problem, we quasi-linearize the drag and force saturation nonlinearities and solve the resulting low-order quadratic program analytically. The simplified dynamics model achieves runtimes 10-1000x faster than prior state-of-the-art with acceptable accuracy (errors of 1-10%). We combine this quasi-linearized dynamics model with mathematical models for concentric-cylinder hydrodynamics, stiffened-plate structural stress, hydrostatic stability, allowable oscillation amplitude, and material and component cost to form a multidisciplinary WEC simulation. We release the software and corresponding numerical benchmarks open source as
MDOcean and
OpenFLASH.
The subsequent design study leverages the model's efficiency and structure to enable a more comprehensive and thoughtful search of the design space. We synthesize aspects of multidisciplinary design optimization, control co-design, techno-economic analysis, and systems engineering to create an integrated methodology for WEC design optimization that incorporates necessary coupling while remaining computationally efficient and robust to uncertainty. We demonstrate ~50% reduction in the levelized cost of energy, outline the dominant role of powertrain constraints in the power-cost balance, derive sensitivities, and discuss implications for WEC design and future model development. Finally, we revise the framework by integrating life cycle analysis and capacity expansion modeling to maximize more meaningful net value metrics including profitability and avoided carbon emissions. Preliminary results suggest that while seasonal grid variation complicates the power-cost tradeoff, carbon emissions can be considered more simply. The system design process articulated here can generalize to other emerging energy technologies, ultimately advancing the decarbonization of the electricity sector.