Browsing by Author "Colby, Jonathan"

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    Determining the Spatial Coherence of Turbulence at MHK Sites
    Kilcher, Levi F.; Thomson, Jim; Colby, Jonathan (2014-04)
    Although turbulence is thought to be a key variable in the performance and survivability of Marine Hydrokinetic turbines, it has not been fully characterized at sites where they will be deployed. In particular, the conventional metrics of turbulence intensity and turbulent kinetic energy spectra only describe the turbulence at a point. Spatial information is required to estimate the loading across a rotor, for example, and to understand the short-term evolution of turbulence in the vicinity of a device (for potential use in feed-forward control algorithms). Here, we describe a method to collect and analyze data for determining the spatial coherence of turbulence at marine hydrokinetic turbine deployment sites. The approach uses multiple compliant moorings equipped with acoustic Doppler velocimeters and inertial motion units. Analysis of data from previous deployments of a single mooring is used to demonstrate the method, and future deployments are discussed. It is expected that coherence will be highly dependent on scale, with high coherence for large-scale eddies, and low coherence for the smaller, inertial-scale eddies.
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    Superstorm Sandy and the Verdant Power Rite Project
    Corren, Dean; Colby, Jonathan; Adonizio, Mary Ann (2014-04)
    On October 29, 2012 Superstorm Sandy (formerly Hurricane Sandy) made landfall in New Jersey. With unprecedented size, extreme central low pressure, and full-moon timing , it created a storm surge that inundated New York City with record-breaking water levels, resulting in tremendous destruction of buildings and infrastructure. All along the East River, large areas of the adjacent boroughs were impacted by Sandy, including flooding of the subway tunnels under the river. When Sandy struck, Verdant Power was operating two acoustic Doppler current profilers (ADCPs) at its Roosevelt Island Tidal Energy (RITE) Project in New York City's East River, measuring water velocities and depth. The East River water speed and level data acquired during Sandy is revelatory, not only indicating the extent and timing of the extraordinarily high levels, but also significant changes to the very sense of the tidal flows. As a Federal Energy Regulatory Commission (FERC) licensee for a commercial pilot project to install up to 30 turbines in the East River, Verdant is keenly interested in the effects such an extreme storm could have on turbines, instruments and navigational aids. This unique observational data provides a valuable insight for Verdant Power and the marine and hydrokinetic (MHK) industry.In this paper, Verdant first presents the East River data collected during Superstorm Sandy, indicating what actually happened during the storm. The potential for yet more extreme water levels with a different storm timing relative to the astronomical tides is then examined. Finally, of interest to a kinetic hydropower developer, the data is analyzed to estimate how a different storm timing could affect the water velocities through the river. These findings are related to the design criteria for Verdant's equipment and the potential impact of an extreme storm on a commercial array of kinetic hydropower turbines.
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    Tagged Species Detection: Approach to Monitoring Marine Species at Marine Hydrokinetic Projects
    Tomichek, Chris; Colby, Jonathan; Adonizio, Mary Ann; Firsk, Michael; Dunton, Keith; Fox, Dewayne; Jordaan, Adrian (2014-04)
    Verdant Power, LLC (Verdant) is licensed to operate an array of up to 30 kinetic hydropower turbines in East River, NY. During the licensing process, National Marine Fisheries Service (NMFS), the federal regulatory agency responsible for protecting Endangered Species Act (ESA)‐listed Atlantic and shortnose sturgeons, expressed concern regarding the potential interaction of these species with the turbines. To advance understanding of potential interactions, Verdant, partnering with the marine fishery community through the Atlantic Cooperative Telemetry (ACT) Network, installed 3 VEMCO fixed detection devices near the Project to collect presence and distribution data on sturgeon tagged by the ACT researchers. During the 25 months that the receivers have been deployed, 22 tagged fish ranging in size from <50 cm to >150 cm have been detected including 15 Atlantic sturgeon. These data have provided valuable spatial and temporal distribution information and represent the first documented proof that sturgeon migrate through the East River.