On April 17th, US DOE released a report titled An Assessment of Energy Potential at Non-Powered Dams in the United States. The report analyzes the hydroelectric power generating capacity at 54,000 existing dams across the United States, and indicates that fully developing non-powered dams (NPDs) could result in additional generating capacity of more than 12 gigawatts (GW). This would increase current US hydropower capacity by 15% and provide enough energy to power four million households. The report concludes that of the 12 GW of potential capacity, “a majority is concentrated in just 100 NPDs, which could contribute approximately 8 GW of clean, reliable hydropower and the top 10 facilities alone could add up to 3 GW of new hydropower.”

The report stresses the economic and environmental value of converting existing dams. “Importantly, many of the monetary costs and environmental impacts of dam construction have already been incurred at NPDs, so adding power to the existing dam structure can often be achieved at lower cost, with less risk, and in a shorter timeframe than development requiring new dam construction.  The abundance, cost, and environmental favorability of NPDs, combined with the reliability and predictability of hydropower, make these dams a highly attractive source for expanding the nation’s renewable energy supply.”

What should be the role of hydropower in the US energy supply portfolio? What trade-offs accompany expanded hydroelectric power? Is pursuing these resources the domain of the federal government, states, or the private sector?