with one another or comparing the MHK resource base with other renewable resources, a single number is of limited value for understanding the potential contribution of MHK resources to U.S. electricity generation, which must ultimately be assessed from the bottom up on a site-by-site basis. The tapping of wide swaths of ocean or coastal straits and embayments for harvesting a significant portion of their tidal and/or wave energy runs into insurmountable barriers of other ocean uses in addition to technology and materials limits. Furthermore, attempting to develop such a national-level assessment requires that the assessment groups expend effort and resources in locations of lower power density that may divert the groups from doing a thorough assessment in locations with high resource potential. However, the committee recognizes that one of the objectives of this study could be not only to advise developers of areas of high energy, but also to inform decision makers, within a common platform, with an understanding of areas in which there is limited resource potential. Therefore, the assessment groups’ confirmation of the spatial variability for wave and tidal resources is useful for a number of interested parties.

The committee’s final report will consider types of information that might be needed and follow-up studies that might be done to help estimate the maximum practicable, extractable resource base. Included might be the detailed assessments of specific sites, including investigations where the deployment of MHK devices might be promising and might possibly serve an additional purpose, as well as where the use of MHK resources might serve remote locations with difficult access to other electricity supplies. The final report will also further consider the source and magnitude of the uncertainties in the resource estimates.

Coordination Among GIS Products

A lesser overarching concern than those summarized above is the inconsistency across the implementation of GIS databases for presenting power density results. Continuing the committee’s warnings on total resource numbers, the local results and spatial distribution of power densities are agreed to be the primary utility of the resource studies. For this reason, it would be best to have the GIS products coordinated and readily able to be integrated across the resource assessment groups. This was not included in the DOE tasking of the groups and has not been done spontaneously by them. Additionally, there is a concern that the databases will not be maintained after the performance period of the DOE contracts. Finally, the committee concludes that caveats and warnings need to accompany the GIS products so that users are not tempted to sum over, or extrapolate from, the power density maps.

Sincerely,

Paul Gaffney, Chair

Committee on Marine and Hydrokinetic Energy Technology Assessment

Attachments

A Statement of Task

B Biographies of the Committee Members



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