As many as 32 dams that currently do not generate electricity are planned to be converted to hydroelectric dams, adding more than 330 megawatts (MW) of electric generating capacity to the grid over the next several years.

The Energy Department's Energy Information Administration (EIA) said that the United States has more than 90,000 dams, with around 3% of those currently supporting hydroelectric generators. Those generators had a total hydroelectric capacity of nearly 80,000 MW as of February 2019.

The Smithland hydroelectric project under construction in November 2015. Credit: AMP-OhioAlthough many non-powered dams (NPDs) lack the hydrological attributes to support electric power generation, a 2012 U.S Department of Energy report estimated that NPDs have 12,000 MW of potential capacity that could be used to increase U.S. hydroelectric generation. The U.S. Congress passed the America’s Water Infrastructure Act of 2018, which, among other provisions, supported the development of new hydroelectric resources.

Recent growth in NPD projects is notable, EIA said, because conventional hydroelectric generation capacity growth has been relatively modest across the United States. Incremental capacity changes—either from adding generators to NPDs or from uprating existing units—may be small on a national level but can be more meaningful on a state and watershed level.

Ohio River hotbed

For example, EIA said that if these projects are realized, the Ohio River will gain 66 MW and reach a total operational capacity of 750 MW, an increase of nearly 10%.

The Ohio River has been the scene in recent years of three run-of-the-river hydroelectric generation facilities located on United States Army Corps of Engineers dams. These were developed by American Municipal Power (AMP) and its members. The projects include:

• The Cannelton Project uses three 29.3 MW turbines and has a total rated capacity of 88 MW. The first unit entered commercial operation in January 2016, the second in March 2016 and the third in June 2016.
• The Smithland Project uses three 25.3 MW turbines and has a total rated capacity at 76 MW. The first and second units entered commercial operation in July 2017 and the third unit in September 2017.
• The Willow Island Project uses two 22 MW turbines and has a total rated capacity of 44 MW. The first unit entered commercial operation in January 2016 and the second in February 2016.

EIA said that other rivers such as the Red River in Louisiana and the Allegheny River in Pennsylvania will also increase their hydroelectric capacity by 49 MW (a nearly 50% increase) and 9 MW (nearly 20%), respectively. And the Muskingum River in southeastern Ohio, which currently has no hydroelectric capacity, would gain 23 MW.

Proposed NPD projects would add 121.3 MW of hydroelectric generation capacity in Pennsylvania, 48.6 MW in Louisiana and 36 MW in Iowa. As a result of these capacity additions, Pennsylvania, Louisiana, and Ohio will increase their hydroelectric capacity by about 12%, 20%, and 22%, respectively. Mississippi would gain its first hydroelectric capacity with the conversion of four dams in the state’s northwest totaling 35 MW.

Rye and water

Of the 330 MW of NPD projects proposed, Rye Development is developing more than half (236 MW) at 22 NPDs in Kentucky, Louisiana, Mississippi, Ohio, Pennsylvania and West Virginia.

In early May, the U.S. Federal Energy Regulatory Commission issued a 50-year license for a 393.3-MW pumped storage hydroelectric project in Klamath County, Oregon.

The project is not a dam-powering venture, but is being developed by a unit of Rye Development called Swan Lake North Hydro LLC.

The project would consist of a new upper and lower reservoir, a steel penstock connecting the upper reservoir to the powerhouse, a partially buried powerhouse containing three 131.1-MW variable speed reversible pump-turbine units, three steel penstocks connecting the powerhouse to the lower reservoir, a transmission line and substation and access roads to the lower and upper reservoirs.

The upper reservoir will have a storage capacity of 2,568 acre-feet (ae-ft). The lower reservoir will have a storage capacity of 2,581 ae-ft.