Run of the river -
A new assessment conducted by Oak Ridge National Laboratory (ORNL) has identified more than 65 gigawatts of untapped hydropower potential in US rivers and streams. The greatest hydropower potential was found in western US states, including Alaska, California, Colorado, Idaho, Montana, Oregon and Washington. Kansas, Missouri, Pennsylvania and Wyoming led the rest of the country in new stream-reach hydropower potential.
The highest potential was identified in the Pacific Northwest Region (32%), followed by the Missouri Region (15%) and the California Region (9%). In total, the undeveloped NSD capacity is 84.7 GW, and the undeveloped NSD generation is estimated to be 460 TWh/year. When areas protected by federal legislation limiting the development of new hydropower (national parks, wild and scenic rivers, and wilderness areas) were excluded from the analysis, the estimated NSD capacity falls to 65.5 GW, slightly lower than the current existing U.S. conventional hydropower nameplate capacity (79.5 GW; NHAAP, 2013).
Undeveloped NSD generation with these areas excluded is estimated to be 347.3 TWh/year, roughly 128% of the average 2002–2011 net annual generation from existing plants (272 TWh/year; EIA, 2013). Since the assessment was designed to identify potential run-of-river projects, NSD stream-reaches have higher capacity factors (53%–71%), especially compared with conventional larger-storage peaking-operation projects that usually have capacity factors of around 30%.
http://www.greencarcongress.com/2014/04/20140430-ornlnsd.htmlConverting existing dams -
In 2007 the US Departments of Interior, Army and Energy released a review of 871 dams on federal land which are not currently used to produce electricity. Of the 871 they found that 195 (22%) had a adequate elevation (head) and were reasonably close to existing power transmission lines. Of that 195 a total of 71 (8% of the original 871) were located outside of protected areas (national parks, wilderness areas, etc.) and had adequate generating capacity (enough year around flow) based on actual hydrological records to make them good candidates for power generation. The 14% which had enough head but not adequate year round flow should be good candidates for pump-up storage.
http://www.usbr.gov/power/data/1834/Sec1834_EPA.pdfIn the US we have approximately 80,000 dams with about 2,400 (3%) used for power generation. We get 6%-7% of all our electricity from those 2,400 dams.
If we use the federal findings as an indicator we might suspect that over 6,300 dams might be available to supply power to the grid and another 10,800 might serve pump-up storage purposes.