Hydropower Resource Assessment and Characterization

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The Water Power Program has released reports and maps that assess the total technically recoverable energy available in the nation's powered dams, non-powered dams, and untapped stream-reaches. These resource assessments are pivotal to understanding hydropower's potential for future electricity production. Hydropower already provides 6–8% of the nation's electricity, but more potential resides in our flowing waters to provide clean electricity to communities and cities across the United States.

There are three levels of resource assessments performed by the hydropower 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 and converted into electricity using a specific technology. Practical resource potential is the portion of the technical resource that is available when other siting considerations and constraints—including economic, environmental, and regulatory—are factored in. While there are many different ways that we can sustainably develop hydropower resources for energy, other water uses and interests must also be considered. The Water Power Program is committed to helping identify new opportunities for developing renewable energy resources at a theoretical and technical level, while also providing many different types of useful data and information that can be used by developers, regulators and other stakeholders to determine practical potential and make informed siting decisions.

Non-Powered Dams

An Assessment of Energy Potential at Non-powered Dams in the United States, compiled by the Department of Energy's Oak Ridge National Laboratory (ORNL), assesses the ability of existing non-powered dams across the country to generate electricity. The 80,000+ non-powered facilities represent the vast majority of dams in the country; more than 90% of dams are used for services such as regulating water supply and controlling inland navigation, and lack electricity-generating equipment. The study found that the nation has over 50,000 suitable non-powered dams with the technical potential to add about 12 gigawatts (GW) of clean, renewable hydropower capacity. The 100 largest capacity facilities—primarily locks and dams on the Ohio, Mississippi, Alabama, and Arkansas rivers operated by the U.S. Army Corps of Engineers—could provide 8 GW of power combined. Power stations can likely be added to many of these dams at a lower cost than creating new powered dam structures without impacting critical habitats, parks, or wilderness areas. Together, these facilities could power millions of households and avoid millions of metric tons of carbon dioxide emissions each year.

The interactive "Powering Up America's Waterways" map shows the generation potential of the top 600 dams that do not currently produce power, but that could each add potential capacity ranging from 1–500 megawatts. Download the underlying data.

New Stream-Reach Development

An Assessment of Energy Potential from New Stream-reach Development in the United States led by DOE's Oak Ridge National Laboratory (ORNL) provides a national picture of the remaining new hydropower development opportunities in U.S. rivers and streams. This study leverages recent advances in national geospatial data sets to provide the highest fidelity national study yet, including the identification of social, economic, and environmental attributes of the stream reaches in addition to the technical power potential. The assessment concluded that the technical resource potential is 85 GW of capacity. When federally protected lands—national parks, national wild and scenic rivers, and wilderness areas—are excluded, the potential is over 65 GW of capacity or 347 TWh/year of generation. A fact sheet summarizing the study's methodology and findings by state is available for download.

The New Stream-reach Development Potential map shows the new stream reaches by subbasin for the United States. Maps and additional data for all U.S. subbasins are available on ORNL's website.

Existing Hydropower

In addition to looking at new opportunities for hydropower, the Water Power Program also recognizes the importance of cataloguing existing hydropower and where this capacity is distributed geographically. ORNL created a geospatial database of existing hydropower assets so the nation can keep an eye on its largest renewable electricity resource, integrate it with other resource assessments, and run analyses on a number of different datasets to help inform decision-makers.

The National Hydropower Map shows the capacity of the existing fleet of hydropower facilities in the United States by ownership. Background information on the existing fleet assessment can be found on the NHAAP portal. Some of the accumulated data can be accessed by applying for an account on ORNL's HydroGIS service.