When early 20th century engineers designed America's dams, they only imagined a few key uses like 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 that dams are capable of producing. In fact, of the 80,000 dams in the country, only three percent 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 estimates that 54,000 non-powered dams could produce 12.6 gigawatts, or enough juice to electrify 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,” said 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.”

Reality Check

There are many reasons to believe that smart dams aren’t just a pipe dream. First among them is that hydropower has a century-long record 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 aren’t 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 the water might drop five feet or 30, 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 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 accustomed to big, monumental projects. But a swarm of low head projects, yielding anywhere from a few dozen kilowatts to 50 megawatts, 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 like Andritz Hydro and Voith 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 tall.

Other companies, like Hydro Green Energy, are going for a one-size-fits-all approach with what President Michael Maley calls a “power wall” equipped with turbine modules designed to be towed upstream and 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, Arizona.

Last year, the district equipped a 10-foot-high outfall near the Gila River with several Natel turbines. In place of splashing water is what Ed Gerak, general manager of the district, calls “a giant concrete shoebox” that generates up to 23 kilowatts 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 said.

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, the waterway or the environment, or that own the dam itself.

In essence, small hydro projects that tinker 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—though change is coming. In September, the Federal Energy Regulatory Commission announced that it had approved a small hydro project in Colorado in a breathtakingly fast two months.

Environmental groups are guardedly optimistic that small hydro, 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. In order 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, lists 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. Neither yet has a turbine in the water.

“You can’t just pick a project and decide this is the one that’s going to be successful,” said Maley of Hydro Green Energy. “You keep everything moving — and then one pops.”

Illustration by Travis Barteaux

This article was originally published on ecomagination and was republished with permission.