An Assessment of Marine Hydrokinetic (MHK) Energy in the Gulf Stream off Cape Hatteras, North Carolina

The Gulf Stream is the western boundary current of the North Atlantic subtropical gyre, and it flows for part of its course just offshore of the southeastern US coastline. This large-scale ocean current has current velocities reaching approximately 2 m s-1, which distinguish it as a potential source of marine hydrokinetic (MHK) energy. The upper continental slope off Cape Hatteras is a desirable area for development of offshore renewable energy because of the narrowness of the continental shelf and the Stream’s minimal meanderings there. Using current data from a moored 150 kHz acoustic Doppler current profiler (ADCP) and from the Mid-Atlantic Bight and South Atlantic Bight (MABSAB) regional ocean circulation model, MHK power characteristics have been computed for this area. These calculations quantify the Gulf Stream power resource and its temporal and spatial variations. During August 2013 – April 2014 at the moored ADCP site and 75 m below the ocean surface, which was within the Gulf Stream’s cyclonic shear zone, a comparison of the ADCP and MABSAB model currents reveals that the average current speeds from the two sources are nearly identical, with a magnitude of 0.94 m s-1. A comparison for the same time period was made for the current’s power density. The ADCP-observed average was 798 W m-2, and the model average was 641 W m-2, a difference of about 20%. The model has shown to have similar current speeds to the ADCP for slowly varying currents (fluctuations of weeks to months), and lower speeds for higher frequency current variations (fluctuations of several days to a couple of weeks). The model also shows somewhat less variability than the ADCP in directionality of the Stream’s flow. Model data have been used to calculate the annual power density averages for a number of years at various locations within the Gulf Stream over the North Carolina continental slope. These results show the variation of the Stream's position along the North Carolina coastline over 2009-2013, and show that yearly averaged power ...