It is also important to note the difference between utility-scale and small scale developments, as these terms are mentioned throughout the report. Utility-scale MHK developments would produce from tens to hundreds of megawatts and would require significant infrastructure and fully-proven MHK devices rather than prototypes. Utility-scale MHK deployment has the greatest potential for substantial environmental impacts as well as conflicts with other ocean and freshwater uses. In comparison, smaller-scale developments would typically produce less than 10 MW and potentially have fewer conflicts and adverse impacts. Small MHK developments could be deployed in locations with high local resource availability and low electricity demands (such as remote villages or small islands) or in locations that lack interconnection to a utility-scale electricity system. Additionally, a project developer would need to prove the feasibility of a smaller-scale pilot application before a utility would invest in building a utility-scale system. The regional- to global-scale approach used by the resource assessment groups was a top-down evaluation that is most useful in understanding the utility-scale potential for MHK.

THE “SINGLE NUMBER” ESTIMATE FOR RESOURCE ASSESSMENTS

Although each of the five MHK resource assessments is evaluated in detail in Chapters 2 through 6, here the committee draws attention to an important point that applies to the assessments both individually and for the project as a whole. The committee is concerned about the appropriateness of aggregating the results of individual MHK resource assessments to produce a national or regional single-number estimate of the theoretical and/or technical resource for any one of these energy sources. It finds that the theoretical resource assessments, especially when examined at a regional or national scale, have limited utility for developers and stakeholders and also have potential for misuse. As an example, the numbers associated with the wave and tide assessments do not accurately convey how the theoretical resources are concentrated along the coast, nor do they explain how much power would be practically available once devices are deployed. Although such estimates provide a broad order-of-magnitude idea of potential energy resources, many extraction filters are needed to determine the technical resource, and at this time the assessment groups can rigorously evaluate only a few of these filters. Most of the extraction filters require assumptions about which particular MHK technologies will be used and what their technical specifications will be; moreover, the technologies are likely to vary by resource and location—for instance, wave energy off the coast of Oregon



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