Non-powered Dams: An Untapped Source of Electricity?
Robert Springer | September 08, 2016More than 90% of the United States’ 80,000 dams do not produce electricity, yet many could, potentially providing a source of renewable energy. The country’s non-powered dams (NPDs) could produce 12 GW of electricity, according to the Department of Energy, with the majority of potential dam conversion sites in the Midwest and South.
In Hydropower Vision, a recent report by the Department of Energy, experts forecast U.S. hydropower to grow from 101 GW of capacity to near 150 GW by 2050. The growth would result from NPD conversions, irrigation canals and pumped hydro storage.
Several NPDs have either been converted or will be converted in the near future. In the Midwest, several run-of-the-river dams (dams that have little or no water storage) have been powered, yet permitting issues continue to frustrate both industry and regulatory agencies.
Cannelton
Inspecting the Unit 3 water passage before closing the discharge ring. Image source: AMP-Ohio.The Cannelton Locks and Dam was constructed in 1966 to facilitate barge traffic and manage floods on the Ohio River. Building a power plant at the site beginning in 2009 turned out to be challenging as the dam was built on a sandy river bottom. With the bedrock inaccessible, the engineering team supported the power plant with stone columns.
“The stone columns were drilled in a pattern all over the job site in 10-foot increments, and each of them went to different depths because it’s based on the founding of the equipment as they’re going down,” says Pete Crusse, vice president of hydro construction for American Municipal Power of Ohio, which was behind the power plant’s construction. “The stone columns were built up to grade, and then they built the powerhouse foundation on top of the stone columns.”
The Cannelton hydro facility came online in June 2016 and could generate an average annual output of about 458 million kilowatt-hours (kWh), according to AMP. Cannelton is one of four run-of-the-river NPD conversions that AMP has simultaneously undertaken on the Ohio.
An “Arduous” Process
Building the hydro power plant often takes less time than obtaining the permit for an NPD conversion. “The licensure and permitting process is arduous,” says Carson. It can take years to accomplish and involves multiple governmental agencies.
For the Cannelton project, AMP started with a license it obtained from a third party. Even so, it took eight years to get the Cannelton project fully approved and constructed. Carson says that the process starts with the Federal Energy Regulatory Commission (FERC), which grants a preliminary license, and, if all goes well, eventually a full operating license.
“Before you can even start construction you have to go through a process with the U.S. Army Corps of Engineers, which is the permit. That permitting process dragged on [with Cannelton],” Carson says.
It was frustrating for AMP to have to “start over again” with the Corps and go through “some of the same review” after submitting some of the identical information to FERC, says Carson.
“It’s really our thought that (the) process can be streamlined and still offer the same protection through some of the redundancies,” he says.
The Corps of Engineers and Energy Department have heard these concerns and have worked to streamline the permit process, says Patrick Duyck, project manager for the Corps’ Portland District. Duyck, who has reviewed and approved NPD conversions, says that the Corps and FERC approach the approval process from different viewpoints. “FERC’s kind of looking at what is the impact of actually installing the facility, whereas the Corps is looking at what’s the impact of constructing that facility,” Duyck says.
And the Corps has a lot to consider when deciding upon an NPD project conversion’s merit. “We’ve owned and operated dams for hundreds of years and you have a private developer that’s looking to basically make a profit and make money, right?” he says. “And to balance protection of life and dam safety with being able to turn a profit is sometimes a challenge.”
The Tradeoffs of Hydropower
Like any form of energy generation, producing electricity from moving water has its challenges, with one of the chief ones being the up-front cost. Although no new hydropower dams are being constructed in the U.S., the cost of converting an existing NPD can be prohibitive.
Hydropower is “going to be more expensive upfront on a per megawatt basis than a coal or a gas plant,” says Carson. A former AMP board chair used to say that “you don’t do hydro as a short-term investment.”
While hydro power plants cost more up front, “the fuel’s free, it doesn’t take a lot of operators to operate it, so labor and fuel costs are zero or minimal, and there’s no waste to deal with on the backend. So operationally they are cheaper to operate,” Carson says.
Other benefits include a long life as the plants will generate electricity for 80 to 100 years. Coal and gas-fired plants may be less expensive to build, but they don’t have a hydropower plant’s longevity and may face an uncertain regulatory future due to carbon emissions.
Another issue with NPD conversions concerns the amount of electricity it will produce. While a river’s flow may support generating 300 MW, the reality of retrofitting a dam for hydropower means that the new hydro facility may produce only 100 MW.
“Sometimes you don’t take the whole flow; you take just a fraction of that flow and run it through turbines and put it back in the river,” says Boualem Hadjerioua, deputy water power manager and senior research engineer at Oak Ridge National Laboratory. “Sometimes there is not enough space to put all these big turbines in the middle of the dam in the river.”
A Smaller, Easier Alternative?
With new hydropower projects on the wane and licensure issues dogging NPD conversions, other solutions are gaining traction. Irrigation canals, for example, can produce electricity 24 hours a day for the 6 months or so they operate.
Permitting for canals is usually quick and uneventful, says Hadjerioua. “Especially if it’s small hydro, it’s very easy to get a permit if you have clean water,” he says. He helped EBD Hydro obtain funding from the Department of Energy for a three megawatt project on an irrigation canal in Jefferson County, Ore.
“They were done within two years,” Hadjerioua says. “We started paperwork in 2011-12; the permitting took less than six months. And then the construction was very, very quick.”
The project went online in 2015 and is now owned by Apple, which uses the power for its data center in nearby Prineville.