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 (MHK) technologies. In order to understand the full potential for future electricity production that can be harnessed through our nation’s water resources, the Water Power Program has conducted resource assessments for the following:
There are three levels of resource assessments:
- Theoretical resource potential: annual average amount of physical energy that is hypothetically available
- Technical resource potential: portion of a theoretical resource that can be captured using a specific technology
- Practical resource potential: portion of the technical resource that is available when other constraints—such as economic, environmental, and regulatory considerations—are factored in.
The following chart serves as a reference for the technical resource potential found from the resource assessments outlined below.
U.S. MHK Resource Potentials
| Resource Assessment | Resource Potential1 |
|---|---|
| Waves2 |
Theoretical: 1,594–2,640 TWh/year3 |
| Tidal streams |
Theoretical: 445 TWh/year |
| Ocean currents |
Theoretical: 200 TWh/year |
| River currents |
Theoretical: 1,381 TWh/year |
While each of these resource assessments was performed independently with slightly different methodology, comparison among these assessments reveals which resources have the most potential for development. The Water Power Program is committed to identifying resource potential and continuing to refine these assessments as renewable MHK energy resources are further developed. Creating and using the following resource assessments allows the MHK community to identify the resource potential in order to achieve commercial development at specific sites.
1Values for waves, tidal streams, ocean currents, and river currents are from the 2015 Quadrennial Technology Review. The resource potential value for ocean thermal gradients is taken from the Ocean Thermal Extractable Energy Visualization Final Technical Report.
2The wave resource varies as a function of water depth. The wave resource is larger in deeper water further from shore. Ranges reflect distance from shore (50 miles) and 20m; or depth contours (200m or 50m) depending on location; Based on a wave device installation packing density of 15 MW per km of wave front.
3TWh/year is the potential electricity generation in terawatt-hours per year (Approximately 90,000 homes can be powered by 1 TWh/year).
Wave Resource Assessment
The Mapping and Assessment of the United States Ocean Wave Energy Resource report (Electric Power Research Institute (EPRI)) assesses ocean wave energy potential along the U.S. coasts. The theoretical resource potential for generation from wave resources is estimated to range between 1,594–2,640 TWh/year. The technical resource potential for generation from wave resources is estimated to range between 898–1,229 TWh/year. Developing just a small fraction of this resource could allow for millions of American homes to be powered with clean, reliable wave energy.
Tidal Streams Resource Assessment
The Assessment of the Energy Production from Tidal Streams in the United States report (Georgia Tech) assesses the theoretically available energy in the nation's tidal streams. The theoretical resource potential for generation from tidal resources is estimated to be 445 TWh/year. The technical resource potential for generation is estimated to range between 222–334 TWh/year. Alaska contains the largest number of locations with high kinetic power density. Twelve other states, including all of the West coast and a large portion of the East coast, contain a number of locations with significant kinetic power density. The average tidal stream power density at these locations provides strong signals to tidal energy developers looking to test and deploy their devices.
Ocean Currents Resource Assessment
The Assessment of Energy Production Potential from Ocean Currents along the United States Coastline report (Georgia Tech) assesses the maximum theoretical power resource contained in the ocean currents. The theoretical resource potential for generation from ocean currents resources is estimated to be 200 TWh/year. The technical resource potential for generation is estimated to range between 45–163 TWh/year. The technical resource potential available for extraction in the Florida Current region of the Gulf Stream is approximately 45 TWh/year of generation. A larger region of the Gulf Stream—within 200 miles of the U.S. coastline from Florida to North Carolina—creates more than 3.5 times the amount of technical resource potential available for extraction (approximately 163 TWh/year of generation).
Riverine Hydrokinetic Resource Assessment
The Assessment and Mapping of the Riverine Hydrokinetic Resource in the Continental United States report (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 (tidal waters excluded). 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. The technical resource potential is 120 TWh/year.
OCEAN THERMAL RESOURCE ASSESSMENT
The Ocean Thermal Extractable Energy Visualization report (Lockheed Martin) assesses the maximum amount of energy that can be practicably extracted from the world's ocean thermal resources. This energy uses the temperature difference between the cooler water at the ocean's depths and the warmer, surface water to power an engine that generates 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).