Assessment of hydrokinetic energy near Rose Dhu Island, Georgia

Abstract

The presented study reports on numerical simulations of flows in tidal channels near Rose Dhu Island, GA, which is used to identify hotspots of hydrokinetic energy and to assess the tidal stream energy potential at this site. The numerical simulations are complemented with field measurements of local current velocities and water surface heights, which are used to validate the simulations. Both velocity distributions and water surface heights as predicted by the numerical model are in good agreement with observed data. The simulations reveal a tidal asymmetry in the encompassing Ogeechee estuary with the ebb tide currents dominating over the flood tide ones. The model is able to successfully predict the distribution of discharge into the smaller creeks around Rose Dhu Island and thereby capturing the location of local hotspots of hydrokinetic energy. It is found that local hotspots do exist near the island, and the analysis suggests the maximum available annual power of 4.75 MW, with a peak estimated extraction surpassing 4 KW during Spring tides.

Modeling tidal distortion in the Ogeechee Estuary

“…1. This domain slightly differs from that of Bomminayuni et al (2012) with the inshore boundary extended further inland to provide a better representation of the smaller creeks upstream of the Little Ogeechee River. Specifying marsh zones as any location with elevation above mean tidal level, 49.3% of the inland wetted surface area is classified as wetland.…”

“…The horizontal grid spacing is $300 m at the open boundary (located in the ocean) and varies between 20 and 100 m in the tidal channels of the estuary. The model utilizes 10 layers in the vertical direction; for the deepest channel in the estuary with water depth of $10 m, this corresponds to a vertical resolution of $1 m. This numerical grid is finer than that of Bomminayuni et al (2012) in both the horizontal (by a factor of 1.5) and vertical directions (by a factor 2.0). The mean water depth at each of the numerical grid points is calculated through an interpolation of bathymetric data consisting of field measurements and survey data from the National Oceanic and Atmospheric Administration (NOAA) database.…”

“…Further details and specifics of the field campaign, originally charted for a tidal energy assessment, can be found in Bomminayuni et al (2012). Measurements were acquired in the upper portion of the Ogeechee Estuary along the cross section labeled 'Measured Transect' in Fig.…”

“…1, is a tidally driven coastal plain system described by little freshwater flow, well mixed saline zones, branching shallow channel networks, and extensive wetlands (Dame et al, 2000). Previous studies have characterized the estuary as heavily distorted or asymmetric (Bomminayuni et al, 2012). For the Ogeechee and similar systems, such distortion has been attributed to the extensive intertidal storage provided by the wetlands Huang et al, 2008;Zheng et al, 2003).…”

A review of tidal energy—Resource, feedbacks, and environmental interactions

“…Another study by Ramos et al53 coupled several structured grids with varying grid resolutions in a relatively simple estuary. In another example, Bomminayuni et al54 used a model with an unstructured grid and therefore higher resolution in the region of interest to simulate the flows in tidal channels near Rose Dhu Island, Georgia. Recently, Lewis et al55 simulated the Irish Sea with a structured grid model and determined that model resolution had a significant effect on the local resource assessment.…”