Small Hydro: Power of the Dammed: How Small Hydro Could Rescue America’s Dumb Dams

Fitting the tens of thousands of non-powered dams in the U.S. with hydroelectric generating equipment could provide a valuable source of reliable, emissions-free energy. But this can only happen if developers find ways to overcome the biggest obstacle: government paperwork.

By David Ferris

When early 20th century engineers designed America’s dams, they only imagined a few key uses, such as boat navigation, capturing water for crops or creating a great place to catch bass. Nary a thought was given to how desperately future generations might need all the clean hydropower these dams are capable of producing. In fact, of the 80,000 dams in the U.S., only 3% currently create electricity.

Call it America’s dumb dam epidemic.

Now a host of companies are scheming to retrofit old dams and levees with turbines and plug them in to the power grid. The potential is substantial: Oak Ridge National Laboratory, a multiprogram science and technology laboratory managed for the U.S. Department of Energy, estimates that 54,000 non-powered dams in the U.S. could provide a total capacity of 12.6 GW, which is enough juice to electrify about 12.6 million homes.

The prospect has initiated something of a gold rush for the rights to the best sites and has even received a cautious nod from advocates for healthy rivers.

“There’s no reason these dams shouldn’t have hydro on them,” says Mark Stover, an executive at Hydro Green Energy, a developer that hopes to electrify dozens of dams across the Midwest and South. “That is just wasted renewable energy.”1

Reality check

There are many reasons to believe that smart dams are not just a pipe dream. First among them is that hydropower has a record more than a century long as a producer of reliable, emissions-free, baseload energy. This resume has made it easier for small-hydro entrepreneurs to find investors than their colleagues in the wind or solar industries.

Second, many of the best non-powered dams are located along powerful rivers, from the Mississippi to the Monongahela, that are close by cities and easy to connect to the power grid of the Midwest and industrial Northeast. Coincidentally, these regions are not the strongest candidates for wind or solar.

“People have moved or settled near water, but they haven’t necessarily settled near plains of grass, where the wind blows well,” said Jon Guidroz, director of development for small hydro developer Free Flow Power.

Finally, making better use of existing dams avoids the monumental unpopularity of building new dams, which are subject to years of review and protest for their impact on fish and landscapes.

Not that plugging in dumb dams will be especially easy.

How it works

The tricky part of adding electricity generation to non-powered dams is that the dams themselves vary in shape and size. Everyone wants to capture the energy of the spillway – where the excess water flows – and use it to spin turbines and create electricity. But this water might drop 5 feet or 30 feet, through a channel that’s wide or narrow, into a pool that’s deep or shallow. It’s hard to find an inexpensive, plug-and-play solution.

What many of these untapped dams have in common is that they’re small, or as the hydro industry calls them, “low head.”

More than half of U.S. dams are no more than 25 feet tall, which is laughably small for a hydro industry more accustomed to big, monumental projects. But a swarm of low-head projects, with a capacity anywhere from a few dozen kilowatts to 50 MW, could collectively create lots of clean energy and serious returns for the companies that get there first.

That prospect has nudged some large hydropower manufacturers, such as Andritz Hydro and Voith Hydro, to invest in nimble little turbines, while startups like Cold Water Hydro, Mavel and Natel Energy are developing niche hydropower devices that can operate in water flows just a few feet high.

Other companies, like Hydro Green Energy, are going for a one-size-fits-all approach with what President Michael Maley calls a “power wall.” This wall is equipped with turbine modules and designed to be towed upstream and virtually snapped into place across a sluice of any size.

This energy revolution is likely to have a subtle effect on the landscape. An example can be found at the Buckeye Water Conservation & Drainage District, which provides irrigation water to farmland southwest of Phoenix. In 2010, the district equipped a 10-foot-high outfall near the Gila River with several turbines manufactured by Natel Energy. In place of splashing water is what Ed Gerak, general manager of the district, calls “a giant concrete shoebox” that provides a capacity of up to 23 kW and operates with a low hum.

“The turbines sit inside the vault so they’re protected against the environment and anyone who’d want to put a bullet through it,” Gerak says.

What’s the holdup?

Small hydro entrepreneurs name one towering obstacle to building the smart dam: government paperwork. Building a hydropower project of any size requires approval from overlapping state and federal agencies that represent the electric grid, waterway or environment, or that own the dam itself.

In essence, small hydro projects that involve tinkering with existing dams are held to standards developed for the massive, landscape-altering dams of the 20th century and their tendency to destroy fish migrations.

Green-lighting even a small hydropower project can take up to five years – although change is coming. For example, in September 2011, the Federal Energy Regulatory Commission announced it had approved a small hydroelectric project in Colorado in a breathtakingly fast two months.

Environmental groups are guardedly optimistic that small hydropower, if managed well, could have little impact on fish and perhaps even improve a river’s health by fine-tuning its flow. Low-head dams involve small drops and slow-spinning turbines, and those pose less danger to fish.

“Oftentimes it does make sense,” said Kevin Colburn, national stewardship director for the environmental group American Whitewater.

Meanwhile, small hydro developers slog through one dam permit after another as they confront a looming deadline. To take advantage of a federal production tax credit, projects have to be up and running by the end of 2013. So companies have filed a blizzard of permits in hopes that a few bust through in time.

Free Flow Power, for example, indicates 52 projects under development from the Yakima River in Washington State to the Black River in northern New York State, while Hydro Green Energy has 28 projects in a belt across the Midwest from Minnesota to Louisiana.

But in May, Free Flow Power shelved plans to create five hydroelectric plants on the Mississippi River between Red Wing, Minn., and Lynxville, Wis. The company surrendered its preliminary permits for these five plants at existing locks and dams that would have had a capacity of 8 to 15 MW, citing lower-than-estimated water flows and other “market forces,” as well as uncertainty surrounding renewable energy tax credits.

Reinforcing the company’s existing development plans, in June FERC rejected a challenge by Northland Power Mississippi River LLC to the issuance of preliminary permits to Free Flow Power for projects on the lower Mississippi River.

And in March 2012, the Federal Energy Regulatory Commission ordered Hydro Green Energy to submit a plan to resume hydrokinetic generation at the 4.47-MW Mississippi Lock and Dam No. 2, the nation’s first hydrokinetic project, or to seek a license amendment deleting the hydrokinetic units from the project license. The 35-kW hydrokinetic unit at the 4.4-MW conventional hydro plant has not operated since March 2010, when it was removed from the river due to looming flood waters and placed in storage.

In March 2012, the developers (which includes the city of Hastings, Minn.) said they plan to move the unit back to the river but have cancelled plans to install a second unit. Instead, Hydro Green Energy has turned its focus to low-head hydropower development using a modified version of the technology installed at this dam.

Hydro Green Energy explains its strategy to pursue so many different projects at one time: “You can’t just pick a project and decide this is the one that’s going to be successful,” said Maley. “You keep everything moving – and then one pops.”


1Ray, Russell W., “Viewpoints from the Board Room: Hydro Green Energy, LLC,” Hydro Review, Volume 30, No. 8, December 2011, pages 50-52.

David Ferris is editor of the Matter Network and author of Innovate, a column in Sierra magazine about clean technology and the people who produce it. This article was previously posted on ecomagination, a GE website.

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