Abstract
As the likelihood of flooding and damaging coastal erosion grows, so too does the need for new and expanded coastal defense structures such as sea walls, breakwaters, and harbors. According to the National Oceanic and Atmospheric Administration, 39% of the U.S. population lives in coastal counties that are at risk from coastal erosion and flooding, and 40% of those residents are at elevated coastal hazard risk. While coastal defense infrastructure projects are mature engineering technologies, costs remain high.
One option for reducing lifetime costs and increasing net potential benefits of such coastal defense infrastructure is to incorporate a wave energy converter (WEC) element into them— otherwise known as coastal structure integrated wave energy converters (CSI-WECs). This report investigates the promise and potential of CSI-WECs, which to date have been a largely underexplored application for wave energy in the United States.
Because coastal defense structures are generally deployed in places with significant wave resources, CSI-WECs could generate energy for local communities for a variety of applications while also enhancing their resilience. With an estimated total of 2,640 terawatt-hours per year of wave energy on U.S. coasts and 14% of the U.S. coastline currently hardened with coastal defense structures, this latent energy could benefit coastal communities if even a small percentage of it could be harvested.
Marine energy is considered, in most cases, to be a high-risk, high-reward effort. However, the research team proposes that CSI-WECs are a relatively low-risk, high-reward approach to harvesting marine energy. By deploying the devices on or near the shore and integrating them into coastal structures such as breakwaters or harbors, there is less overall project risk compared to wave energy deployments farther offshore.
CSI-WECs leverage the design and economic advantages of being onshore, such as reduced costs for cabling, operations, and maintenance. Moreover, should challenges arise from the energy-generation element, the shore and coastal communities remain protected, as the coastal infrastructure would remain intact. Because coastal structures are primarily designed for coastal defense and resiliency, integrating a WEC into coastal structures can add untapped value (via energy generation potential) without changing their primary design purpose.
The research team proposes that CSI-WECs are a high-value marine energy application that have been largely overlooked thus far in the United States. CSI-WECs are a unique marine energy technology that can meet a range of end-use applications—both on- and off-grid—as demonstrated by successful international deployments. This suggests that there is substantial potential for their implementation in U.S. coastal communities.
The purpose of this report is to explore the full value proposition of CSI-WECs in the United States. The report provides background information on the state of the art of the technology as well as a summary of important technology developments and a review of devices currently in operation.
We present an end-use, application-focused case study in which four U.S. sites are selected for their high-value CSI-WEC deployment potential: Puerto Rico, Hawaii, the Pribilof Islands of Alaska, and Humboldt Bay, California. For each of these sites, three developers—Eco Wave Power, Wave Swell Energy, and the combined efforts of Professor Diego Vicinanza and Professor Pasquale Contestabile—conducted an energy production analysis of their technologies for the four selected sites.
Initial results indicate significant near-term potential in the development and deployment of these solutions, with annual energy production in a range of tens of megawatt-hours per year for each device under normalized 10-meter (m) deployments. These findings were valid even in areas considered to have lower wave energy density. For areas with higher energy density, however, the potential was found to be hundreds of megawatt-hours per year. All devices included in the analysis are highly scalable, and deployments have the potential of reaching microgrid- or gridscale (multiple gigawatt-hours per year) generation given sufficient linear space.
Additionally, through this work, the research team developed a geographic information system (GIS)-based tool to support efficient and comprehensive site assessment for optimal and highvalue deployments. The parameters and framework of this tool are discussed using Puerto Rico as an example case. The output is a heat map of suitable sites based on the ranking of geospatial data input into the tool, which can be used as a visual for community engagement during the site selection process.
To further support the value proposition investigation of CSI-WECs, the research team performed a techno-economic assessment for a hypothetical CSI-WEC deployment at the Humbolt Bay site, showing that there can be favorable returns on a CSI-WEC investment when coupled with applications or deployments where the value of energy is high. For all developer devices and a dollar-per-kilowatt-hour value of $0.20, the initial capital investment is returned within 5 to 6 years, with potentially millions of dollars’ worth of energy generated over a 20-year time frame. The team also identified possible funding opportunities and pathways that could support the deployment of CSI-WECs in the United States.
CSI-WECs can provide locally generated energy for a multitude of high-value applications, all while increasing community defense through coastal protection and coastal hardening. Though further development, demonstration, and analysis are required, the technology presents an opportunity for the advancement of water power technologies in the United States while adding value to coastal infrastructure projects.