overestimating the resource. The group used a “unit circle” approach to estimate the total theoretical resource, which summed the wave energy flux across a cylinder of unit diameter along a line of interest, such as a depth contour. This approach has the potential to double-count a portion of the wave energy if the direction of the wave energy flux is not perpendicular to the line of interest or if there is significant wave reflection from the shore. Further, the technical resource assessment is based on optimistic assumptions about the efficiency of conversion devices and wave-device capacity, thus likely overestimating the available technical resource.
Recommendation: Any future site-specific studies in shallow water should be accompanied by a modeling effort that resolves the inner shelf bathymetric variability and accounts for the physical processes that dominate in shallow water (e.g., refraction, diffraction, shoaling, and wave dissipation due to bottom friction and wave breaking) (Chapter 3).
The ocean current resource assessment is valuable because it provides a rough estimate of ocean current power in U.S. coastal waters. However, less time could have been spent looking at the West Coast in order to concentrate more fully on the Florida Strait region of the Gulf Stream, where the ocean current can exceed 2 m/s. This would have also allowed more focus on the effects of meandering and seasonal variability. Additionally, the current maps cannot be used directly to estimate the magnitude of the resource. The deployment of large turbine farms would have a back effect on the currents, reducing them and limiting the potential power.
Recommendation: Any follow-on work for the Florida Current should include a thorough evaluation of back effects related to placing turbine arrays in the strait by using detailed numerical simulations that include the representation of extensive turbine arrays. Such models should also be used to investigate array optimization of device location and spacing. The effects of meandering and seasonal variability within the Florida Current should also be discussed (Chapter 4).
The OTEC assessment group’s GIS database provides a visualization tool to identify sites for optimal OTEC plant placement. However,