School of Civil and Environmental Engineering

Ph.D. Thesis Defense Announcement

Wave Energy Resource Characterization and Classification for the United States & Numerical Simulation of Coastal Circulation near Point Sal, California

By

Seongho Ahn

Advisor:

Dr. Kevin A. Haas (CEE)

Committee Members:

Dr. Hermann M. Fritz (CEE), Dr. Donald R. Webster (CEE), Dr. Emanuele Di Lorenzo (EAS), Dr. Vincent S. Neary (Sandia National Laboratories)

Date & Time: Monday, July 22, 2019 – 9am

Location: SEB 122

ABSTRACT
Although ocean waves have significant energy potential, the technology is in early stages of development due to high costs from lower conversion efficiencies as well as risks to operations, maintenance and survival. This study characterizes and classifies the wave energy resource by performing a comprehensive resource assessment of the wave energy for the US. The work for this portion includes three parts. The first part focuses on describing the wave energy resource parameters or metrics for characterization, e.g., wave energy potential, dominant frequency, directional and temporal variability. The second part uses these parameters to delineate and describe eleven distinct US wave climates or wave energy resource regions. In order to gain a high-level wave resource characteristics, marginal and joint energy distributions of the wave energy in terms of the peak period, wave direction, month, and year and corresponding resource attributes are provided. In the third part, wave energy resource classification systems for the US is developed based on wave power and its distribution with peak period. The classification systems, comprised of four power classes and three peak period band classes, are based on the total wave power or the partitioned wave power in the dominant peak period band. This work establishes a framework for investigating the feasibility of a compatible wave climate conditions and WEC technology classification system to reduce design and manufacturing costs.
The second portion of the research focuses on circulation on the inner shelf. The coastal circulations during upwelling favorable wind periods near Pt. Sal, CA, is considered complex. The wind stresses and alongshore flows creates geostrophic flows and Ekman transport simultaneously and alongshore variabilities of the coastline orientation and a bathymetric promontory complicate the circulation. In order to understand the coastal circulations at Pt. Sal, a numerical model, Regional Ocean Modeling System (ROMS) is used to produce a hindcast for the upwelling favorable wind periods. As a result, characteristics of the coastal circulations, circulation boundary, upwelling front, convergence/divergence, and stratifications, are described. Basic forcing mechanisms influencing the circulation during the selected period are discussed and the circulation patterns are diagnosed by linking these mechanisms and three-dimensional momentum balances at different locations.