The dank, dark tunnel deep inside the Cowans Ford Dam—about 100 feet or so below the water line of Lake Norman north of Charlotte—is where I learn a little-known fact.
All dams leak.
Jeff Lineberger, Duke Energy’s director of Hydro Strategy and Licensing, and Mike Williams, the Cowans Ford facility director, smile and patiently explain to a novice the small waterfalls cascading down a staircase and into a trough alongside the tunnel.
“These are just pressure relief points to help with uplift on the dam itself,” says Williams. “So it relieves the pressure. We do have to keep an eye on it.”
Cowans Ford is Duke Energy’s largest hydroelectric power plant in North Carolina, capable of producing enough electricity for 240,000 homes. The amount of concrete used to build this facility is enough to construct a sidewalk from here to California.
The hydropower produced here is renewable, reliable, and available immediately when electricity is needed.
“We have to match the energy production with the load at all times and hydro is so flexible and so fast,” explains Lineberger. “Even this big Cowans Ford Hydro Station, we can take from fully shut down to fully operational in less than ten minutes. We don’t have anything else that’s that flexible.”
At least one of the four Cowans Ford turbines runs once a day, by rule, and is run by remote from Duke Energy’s downtown Charlotte headquarters. But it almost never runs at full capacity, because the dam’s other main job is water management—and releasing too much water would overwhelm Mountain Island Lake downstream.
The Catawba River basin, infact, is now almost entirely a series of man-made lakes, from the mountains into South Carolina.
But it wasn’t always this way. The Dukes began the process of damming the Catawba River in 1899 to power textile factories.
“This was actually the first river in the United States that was comprehensively planned and developed for electricity generation,” says Lineberger.
Hydro-electricity has since given way to coal, nuclear, and natural gas as the main sources of power generation.
And now renewable energy is growing faster than any of those. A massive wind farm is underway in northeastern North Carolina, and the state is fourth in the country in installed solar capacity.
But environmental advocates never mention hydropower as a preferred renewable source, despite the fact it generates more electricity in North Carolina than any other single renewable source, and does it with no carbon emissions.
And there’s a reason why.
“It’s perhaps one of the most damaging power sources that we have, actually,” says Gerritt Jobsis, the senior director of Rivers of Appalachia and the Carolinas at American Rivers, a conservation organization.
“Building dams totally changes the way a river functions naturally. It reduces or eliminates habitat for a number of species that causes them to go extinct or at least be severely diminished.”
In the southeast, mussels, snails, and fish have all been negatively affected by dams.
But despite the relatively small amount of power it generates and the harm it does, hydroelectricity is still big business. That’s because all of the rivers in North Carolina that have the potential to make utility-scale electricity have already been dammed up.
That’s one explanation for the ongoing multi-billion dollar fight over Alcoa’s rights to hydropower on the Yadkin River.
Even environmentalists say that once a large river is dammed up, it makes sense to get as much renewable energy from it as possible. And Duke Energy says hydropower isn’t going anywhere.
“It’s been a significant part of our portfolio for over a hundred years,” says Lineberger. “I really think a hundred years from now it will still be a significant part of our portfolio.”
Duke Energy is investing $75 million in the Cowans Ford Dam. The renovations will improve efficiency and safety—but it still won’t plug all the little leaks.