The U.S. Department of Energy released two reports last week documenting two of the nation's potential ocean energy resources: waves and tidal streams. Hydrokinetic energy resources such as waves, tides, and currents may soon play an increasing role in US energy supply.
Although each of these reports was prepared in 2011, DOE is pointing to the reports as demonstrating the potential of conventional and innovative water power resources to generate electricity. In its statement promoting the reports, the Department of Energy noted that water power, including conventional hydropower and wave, tidal, and other water power resources, can potentially provide 15% of our nation's electricity by 2030 (up from 6% currently). As DOE noted, the United States currently uses about 4,000 terawatt hours (TWh) of electricity per year. Based on these reports, and other studies, DOE estimates that the maximum theoretical electric generation that could theoretically be produced from waves and tidal currents is approximately 1,420 TWh per year, approximately one-third of the nation's total annual electricity usage.
The wave energy assessment report, Mapping and Assessment of the United States Ocean Wave Energy Resource, was prepared by the Electric Power Research Institute (EPRI). That report identified a total available wave energy resource of 2,650 TWh per year. As in previous studies, Alaska's Pacific coast is the wave energy standout, hosting about half of the total available wave energy. The west coast (Washington, Oregon, and California), the northern east coast (from Maine through North Carolina), and Hawaii also host significant wave energy resources.
The tidal stream report, Assessment of Energy Production Potential from Tidal Streams in the United States, was prepared by Georgia Tech Research Corp. It describes the effort to create a national database of tidal stream energy potential. The geographic distribution of the tidal stream resource is similar to that of wave energy: Alaska contains the largest number of locations with "considerably high kinetic power density", followed by Maine, Washington, Oregon, California, New Hampshire, Massachusetts, New York, New Jersey, North and South Carolina, Georgia, and Florida. In total, the report identified 50 GW of tidal stream capacity nationwide, 47 GW of which is in Alaska.
The size of these resources is significant. What remains to be seen is whether hydrokinetic energy can be generated in a cost-effective manner. With significant research and developments ongoing, competitively-priced hydrokinetic power may soon be generated along US coasts.