Although the United States now has about 50 gigawatts of installed wind capacity and roughly 5 GW of solar, one form of renewable power still dwarfs the rest. At last count, the country’s 2,500 dams provided 78 GW of power (and with few of the same intermittency issues). But hydoelectric power often isn’t even included in discussions about renewable energy because it doesn’t have quite the same credentials: building a dam fundamentally alters an ecosystem in a way that building solar panels or wind turbines don’t.
That said, it turns out we could probably generate a lot more hydro-power if we wanted to, without doing any damage: up to 12 GW more, according to a recent Department of Energy report. The study says there are thousands of “non-powered” dams (NPDs)–dams that don’t currently generate electricity–that could be converted.
“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 study says.
It continues: “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.”
The study explored the potential of some 54,391 sites, but found that as few as 100 could generate 8 GW. The DOE found the greatest potential at facilities on the Ohio, Mississippi, Alabama, and Arkansas Rivers. All the facilities are already owned by the Army Corps of Engineers, making them ripe for ready adaption.
Given all the controversy around other forms of renewable energy, developing these hydro facilities would seem a no-brainer––especially if the environmental impacts of new dam projects could be avoided.
The study doesn’t give any indication of the cost relative to solar or wind. But, given hydro’s maturity, it doesn’t seem a stretch to say that it could be cost-competitive. The DOE notes that four projects already being built on the Ohio River have “capacity factors” in the 60% range (meaning the actual output rather than its “nameplate”). By comparison, wind projects have 20-30% capacity factors, according to the non-profit company behind the schemes.
In addition, the DOE report shows that some of the greatest potential happens to be in areas of the country with less than optimal wind and solar resources.
If it works, why knock it?