The estimates are limited by sparse data and the assumptions inherent in the WAVEWATCH III model. Most notably, the assessment is limited to deep-water locations (depths greater than 50 m on the U.S. West Coast and 20 m on the East Coast). While there has been a recent trend to envision wave energy extraction in deep water to avoid ecological impacts, there are several potential projects seeking shallow-water siting because it affords closer proximity to transmission lines and other logistical requirements. Devices may be placed in shallow-water areas because such siting also reduces construction and maintenance costs.
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, wave dissipation due to bottom friction and wave breaking).
The technical resource assessment is based on loose assumptions about how much average power is available from each kilometer of installed wave-energy conversion facility, indicating that nearly all of the available wave energy in some sites could be converted to electrical energy if enough wave-energy converters are installed. Since there will always be mechanical and electrical loss mechanisms, this seems unlikely. Conversion percentages from theoretical wave power to electricity on the grid are expected to be dramatically less than the 90 percent values that are reported as the recoverable resource. In addition, estimates of the current state of wave-energy technology are not based on proven devices.
Finally, although the optimal layout of wave farms designed to maximize wave power capture and minimize costs is still an open question, the footprint of the infrastructure required to recover 1 GW cannot be reduced to less than a row of devices more than 100 km long and parallel to the coast, given current levels of technology. Because of the high development and maintenance costs, low efficiency, and large footprint of wave converter technologies, such devices would be a sustainable option only for smaller-scale developments that are considerably less than 1 GW, ideally close to territories with limited demand, such as islands.