Wave Energy Converter Performance- and Cost Optimization Through Novel Controls Strategies

The US Department of Energy (DOE) has reported that the wave energy resource available in the US has the potential to power over 100 million homes each year, and the DOE is currently developing an aggressive strategy to support its vision of providing 15% of our nations electricity needs from water power by 2030. However, in addition to survivability and impact issues, producing cost-competitive energy from ocean waves presents unique challenges, such as extreme seasonal variations of two orders of magnitude (100x), hourly power variations of a factor of four, and stochastic second-by-second variances that exceed the capabilities of conventional energy and control design strategies. Fully accessing the theoretical potential from this instantaneously variant resource is a complex control problem that has yet to be mastered by existing technologies. To this end, Columbia Power is commercializing a survivable, low-impact and cost-competitive wave energy conversion (WEC) system, the StingRAY, which presently demonstrates (numerically and experimentally) the ability to efficiently extract energy from waves. The goal is to design (Phase I) and demonstrate, in an open-ocean experiment (Phase II), a WEC control strategy that enables StingRAY performance to reach theoretical limits 80% higher than the present baseline. This is achieved by researching, designing, numerically validating (with time domain models) and implementing the most promising novel control strategies, while efficiently analyzing, systematically prioritizing, and selecting the extensive matrix of parameters necessary to confirm results. Commercial Applications and Other Benefits Knowledge gained, modeling approaches, and control strategies developed under this project will provide practical paths to numerically optimizing WEC controls. The project will share academic and theoretical findings of significance that benefit most other wave energy technologies and will potentially apply to other industrial controls, such as wind, marine current, and various automation applications. By advancing the Columbia Power WEC through control optimization, a material improvement in annualized power output can make the reduction in levelized cost of energy a practical objective and bring WEC technologies closer to commercialization. The delivery and consumption of wave-generated electricity is beneficial in many ways. In addition to the reduced reliance on legacy base-load resources and foreign energy imports combined with the increased supply of clean, renewable electricity, WEC commercialization will benefit a number of strategically and economically important industries throughout the US, including ship-building, marine construction/operations and heavy equipment manufacturing. Another beneficiary is the US DOD, which is required to procure 25% of its energy from renewable sources by 2025. According to a 2010 announcement by the Secretary of Navy, half of the Navys total energy consumption ashore by 2020 will come from alternative sources; the Navy will make half of its installations net-zero energy consumers, using solar, wind, ocean, and geothermal power generated on base.