Similar work continues at Kerr Powerhouse, located on the Roanoke River in Virginia, near the North Carolina-Virginia border. “The new equipment will increase power output by more than 30 percent and feature the latest environmental technology, keeping the powerhouse operating for years to come,” said Penny Schmidt, Wilmington District public affairs chief.
In addition to increasing power output, the new system being installed at Kerr aerates the water after it passes the turbines. “One issue facing Kerr Reservoir is decreased oxygen at lower levels. The new system adds oxygen back into the water before releasing it downstream, making sure it’s safer for fish,” Sadiki said.
When USACE dams were constructed, there was less emphasis on environmental sustainability, Sadiki said. “Today, environmental sustainability is as important as any element of our operations. Whether it’s fish passage or sustainable habitat, designs for improvements to hydropower facilities must satisfy important environmental benchmarks.”
The newly designed turbines in place at Bonneville and Kerr are the next generation in environmental sustainability. “The old turbines at Bonneville had a gap between the blade and the turbine shaft, which proved damaging to fish passing through the turbines,” Sadiki said. “With the new minimum gap runner blades, there’s almost no space at all between the shaft and the blade, so fish can’t pass through the gaps and aren’t exposed to extreme pressure differentials that are harmful to fish.”
In addition to redesigning turbines, USACE is looking at how to improve the power system as a whole to make fish passage safer. “USACE, as an agency, is making fish a part of the equation when designing hydropower systems,” said John Etzel, Hydroelectric Design Center (HDC) deputy director. “In the past, fish passage elements were usually tacked onto a mostly completed design. Now we start the design process with fish passage criteria and ask, ‘How do we design a hydropower system – intakes, turbine runners, and draft tubes – that will safely pass fish downstream without diminishing its efficiency?’”
Environmental sustainability questions like this are being answered in innovative ways, like the new turbine prototype being developed in a partnership between USACE and private industry.
“The new turbine is being designed cooperatively between Voith Hydro and USACE,” said Etzel. “It will be tested at the Engineer Research and Development Center and after our engineers confirm it performs according to specs, the prototype will be tested in place at a hydropower generating dam.”
The design process and design criteria are a standard that USACE expects to use in years to come while replacing an aging hydropower infrastructure, Sadiki said. “It may not fit at every powerhouse, but turbines designed for improved fish passage will always be part of the conversation as our dams are rehabilitated,” he said.