Yakutat Wave Energy Resource Assessment
Yakutat is a remote community located on the “Lost Coast” along the northeastern Gulf of Alaska. Their current power generation is 100% from diesel fuel which must be barged in, resulting in a high cost of electricity that averages $.60 per kilowatt hour. The City and Borough of Yakutat along with tribal leaders have been proactive in identifying other options to meet their energy needs that are less expensive and more sustainable, including wave energy. Because the majority of wave energy devices are still in development or prototype stages and since the energy potential of specific locations in the region is well understood, assessments of the available wave energy and environmental factors are necessary to determine if the community would like to move forward with this emerging technology.
The first step in this assessment is to determine Yakutat’s wave energy resource. In this phase, ACEP, funded by the City and Borough of Yakutat, will deploy a bottom-mounted mooring offshore of Yakutat to measure key parameters relevant to the placement of an array of wave energy devices called Wave Energy Converter power generation or WEC units.
An Acoustic Doppler Current Profiler (ADCP) will record surface wave statistics such as wave height, time between wave crests, direction, and speed. Another sensor measuring conductivity, temperature and depth (CTD) will be co-located on the mooring and will provide data necessary for quality control of the ADCP information. The CTD observations will also inform the environmental conditions that accompany different wave and current patterns as well as concurrent studies of area marine mammal populations and fisheries.
Data gleaned from Phase I will inform Phase II of the project - a modeling effort funded by the Alaska Energy Authority to support the installation and operation of the WEC units. To pinpoint the best location and configuration for an array of multiple WEC’s, ACEP researchers will utilize the in-situ wave data collected during Phase I to calculate nearshore wave statistics for the year-long period of measurement. As part of the modeling effort, information from the single measurement location will be extrapolated to water depths shallower than the mooring and taking into account non-linear wave effects. The goal of Phase II is to optimize power generation while taking other factors like ocean currents, sediment, marine mammal, fisheries, transmission costs and other users into account. Further, the modeling results will contribute to Resolute Marine Inc.’s ‘wave to wire’ control system for the WEC array.
AEA funding will also support the development of wave climatology for the greater Yakutat area as a key component in properly sizing the array. Additionally, the project funding will be utilized to establish the wave to wire model necessary to ensure the successful integration of the time-varying wave resources into Yakutat’s existing small, isolated diesel power based grid. The wave to wire model will provide advanced notice to the local utility, Yakutat Power, of the expected wave energy.
While this project is solely focused on the Yakutat area, researchers anticipate this study will establish methods and protocols that can be employed in future wave energy site resource assessments around Alaska. See more information on the mooring at the Alaska Ocean Observing System.
Photo 1: Mooring top float with ADCP visible in the center of the float. The float is tethered to an 800 lb weight (a train wheel) that sits on the seafloor. A small “acoustic release” (the yellow cylinder to the right of the float) between the float and the weight, allows for the retrieval of the float when the mooring is recovered for data download. The train wheel remains on the seafloor. This arrangement allows the sensitive instrumentation to remain far removed from the surface where large breaking waves could cause damage while at the same time keeping the instruments above the seafloor where constantly moving waves of sand would likely bury anything on the ocean bottom. Photo courtesy of J. Kasper, UAF.
Photo 2: City and Borough of Yakutat website logo.
Photo 3: Yakutat Shoreline, March 12, 2013. Photo Courtesy ACEP, UAF.