The Water Power Program has released reports and maps that assess the resource potential of the nation's waves, tidal, ocean, and river currents, and ocean thermal gradients. These resource assessments are pivotal to understanding water power's potential for future electricity production. With more than 50% of the population living within 50 miles of coastlines, there is vast potential to provide clean, renewable electricity to communities and cities across the United States using marine and hydrokinetic technologies.
There are three levels of resource assessments performed by the water power industry. Theoretical potential is the annual average amount of physical energy that is hypothetically available. Technical resource potential is the portion of a theoretical resource that can be captured using a specific technology. Practical resource potential is the portion of the technical resource that is available when other constraints—such as economic, environmental, and regulatory considerations—are factored in. There are many different ways that we can sustainably develop our water resources for energy. The Water Power Program is committed to helping identify new opportunities for developing renewable energy resources at a high level. Additional research by industry stakeholders is needed to identify the practical resource potential at specific sites of interest to achieve commercial development of these resources.
Wave and Ocean Thermal Resource Assessments
The Mapping and Assessment of the United States Ocean Wave Energy Resource report, created by the Electric Power Research Institute (EPRI), assesses ocean wave energy potential along the U.S. coasts. The report finds that the technically recoverable resource for electric generation from waves is approximately 1,170 terawatt-hours per year (TWh/year), which is almost one third of the 4,000 TWh of electricity uses in the United States each year. Developing just a small fraction of the available wave energy resource could allow for millions of American homes to be powered with this clean, reliable form of energy. For context, approximately 85,000 homes can be powered by 1 TWh/year.
The Ocean Thermal Extractable Energy Visualization report, authored by a team led by Lockheed Martin, assesses the maximum amount of energy that can be practicably extracted from the world's ocean thermal resources. Ocean thermal energy uses the temperature difference between the cooler water at the ocean's depths and the warmer, surface water to power an engine that can generate electricity. The technical resource potential for electric generation from ocean thermal resources is estimated at 576 TWh/year in U.S. coastal waters (including all 50 states, Puerto Rico, and the Virgin Islands).
The MHK atlas depicts and maps U.S. wave energy and ocean thermal resources, as well as tidal, ocean, and riverine current resources, which are described in more detail below.
Tidal Streams Resource Assessment
The Assessment of the Energy Production from Tidal Streams in the United States report, created by Georgia Tech, assesses the theoretically available energy in the nation's tidal streams. Based on DOE analysis of the data contained in the final report, the technical resource potential for tidal generation is estimated to be 250 TWh/year. Alaska contains the largest number of locations with high kinetic power density, followed by Maine, Washington, Oregon, California, New Hampshire, Massachusetts, New York, New Jersey, North and South Carolina, Georgia, and Florida. The average tidal stream power density at a number of these locations exceeds 8,000 watts per square meter, which provides strong signals to tidal energy developers looking to test and deploy their devices.
The corresponding database and resource mapping tool provide researchers insight into the potential of the tidal energy resource.
Ocean Currents Resource Assessment
The Assessment of Energy Production Potential from Ocean Currents along the United States Coastline report, created by Georgia Tech, assesses the maximum theoretical power resource contained in the ocean currents. The potential power available for extraction in the Florida Current region of the Gulf Stream is approximately 5.1 GW (corresponding to approximately 45 TWh/year of generation). Considering a larger region of the Gulf Stream—within 200 miles of the U.S. coastline from Florida to North Carolina—the potential power available for extraction is approximately 18.6 GW (or roughly 163 TWh/year of energy).
The corresponding database, available through the pictured online resource mapping tool, provides researchers insight into the potential of the ocean current energy resource.
Riverine Hydrokinetic Resource Assessments
The Assessment and Mapping of the Riverine Hydrokinetic Resource in the Continental United States report, authored by EPRI, assesses the theoretical and technically recoverable riverine hydrokinetic energy resource—energy extractable from the natural flow of a river without the use of a dam—in the contiguous 48 states and Alaska, excluding tidal waters. Eighty percent of the potential comes from four hydrologic regions: the lower Mississippi (48%), Alaska (17%), the Pacific Northwest (9%), and the Ohio River (6%). The theoretical resource potential for generation from riverine hydrokinetic resources in the continental United States is 1,381 TWh/year, and the technically recoverable resource is 120 TWh/year.
The atlas, shown in the map, depicts the generation potential of rivers in the continental United States, showing both their theoretical and technically recoverable potential. EPRI, NREL, the University of Alaska-Fairbanks, and the University of Alaska-Anchorage assembled the dataset and performed the resource potential assessments.