On March 2, 2023, the Department of Energy (DOE) announced a plan to invest $3.7 million to expand collaboration on the sometimes competing goals of maintaining hydropower as a key source of renewable energy while supporting communities and protecting the environment. The project will be led by the nonprofit organization American Rivers. Those of us more accustomed to reading about solar or wind-generated renewable energy projects, may have questions: Why hydropower? Why social engagement? Why now?
Over 90,000 dams exist in the United States. According to the Army Corps of Engineers, 98 percent of these were designed for flood control, irrigation, direct-drive power for historic manufacturing processes (such as weaving or spinning) and recreation. The remaining two percent were built for electricity generation. These large scale facilities, such as the Hoover or Grand Coulee dam projects, generate 6.3 percent of total U.S. electricity. Hydropower plants flow water through a large pipe, or penstock, that pushes against blades of a turbine, which spins a generator to produce electricity.
Hydropower provides approximately one-third of all renewables-generated power. Alejandro Moreno, Acting Assistant Secretary for Energy Efficiency and Renewable Energy, says, “Incredible work is underway across the U.S. Department of Energy to make progress toward the nation’s goals of a carbon-free electricity sector by 2035 and a net zero emissions economy by 2050.”
The benefits of hydropower include reliability, flexibility, 24/7 operating capacity that is not dependent on sun or wind and, critically, storage. Pumped-storage projects generate 93 percent of all utility-scale storage by flowing water from a high reservoir to a low reservoir during peak demand times. At low demand times, the water is pumped back up for reuse.
However, hydroelectric dams need a consistent supply of water which is often captured by flooding a large amount of land for a reservoir. Given the social costs of habitat alteration, altered flow regimes, and Indigenous rights to fish and water, the Department of Energy seeks to study alternative hydropower deployments and ensure that all stakeholder concerns are addressed through the newly funded program. The DOE projects that the study will help improve outcomes for hydropower technologies and environmental mitigation efforts. The stakeholders include the DOE, industry, Tribes, and disadvantaged communities in remote areas where hydropower and river restoration projects are often sited.
The power of multiple stakeholders working together can be found in tiny Dillingham, Alaska. The Nushagak Electric and Telephone Cooperative (NETC) is developing a low impact hydroelectric project. Located on a remote arm of Bristol Bay, the Nushagak River has the world’s largest run of sockeye salmon. Fishing is critical to this community’s survival, which is only reachable by boat or plane.
NETC is working with the DOE to harness the power of a natural twenty-eight foot drop in elevation that occurs through a series of falls located in a strategic oxbow of the river. Studies show that diverting part of the flow will generate sufficient power for Dillingham and five nearby communities without building a dam or artificial upstream lake. A secondary benefit of electrifying this community will be the installation of fiber-optic cable for high-speed internet on the new power poles from the hydroelectric station. Permitting and construction of this project are expected to take eight to10 years, with enduring benefits for all stakeholders.
Conduit hydropower, which uses water from irrigation canals and water supply pipelines to drive electricity generating turbines, is another alternative. According to a new study by the Oak Ridge National Laboratory (ORNL), conduit hydropower has the potential to power more than one million homes by adding 1.41 gigawatts of electricity to the U.S. power grid.
“You can think of conduit hydropower as low hanging fruit, and what has been started is a mere drop in the bucket,” says Shih-Chieh Kao, water power program manager at ORNL. “For all its benefits, the biggest barrier is a general lack of awareness of conduit hydropower’s potential.”
Yet another source of hydropower comes from capturing the power of tidal water movement. In South Korea, the Sihwa tidal power plant generates one-way power twice a day at high tide. Using 10 water turbine generators and a system of sluice gates to capture the tide flowing into a reservoir, the plant, currently the world’s largest, produces 552.7 gigawatts of electricity annually. According to the International Hydropower Association, this is enough to support the household needs of 500,000 people. The United States is looking into similar marine technology.
“Innovation in the marine energy side is significant in many different ways,” Moreno states. “What excites me about working in marine energy is that it’s potentially a source of large scale renewable energy generation for coastal communities, whether big cities or remote communities, that don’t have any other source of power generation.”
The 2021 Bipartisan Infrastructure bill is helping upgrade existing hydroelectric resources. Projects include adding pumped storage capacity and retrofitting nonpowered dams for hydro generation. A 2016 DOE study indicated that the United States could expand from then-current capacity of 101 gigawatts to nearly 150 gigawatts by 2050 without adding new dams.
Rye Development has 22 run-of-the-river projects in its portfolio that use natural flow to spin turbines and generate power. “We see an opportunity for hydropower that really is going to have a limited impact on the environment,” says Paul Jacob, Rye’s chief executive. “That for us dictates where we go; we start out looking for dams that are there for an essential purpose. By and large, those are navigation dams or dams that are on flood control properties, and most of those projects are maintained and owned by the Army Corps of Engineers.”
In Pittsburgh, for example, a newly powered dam will soon be providing 25 percent of the electricity required by the University of Pittsburgh. Other projects are underway in Kentucky and Louisiana. “This is a resource where infrastructure is already built, the dams are still being maintained, and they are not going away,” Jacob says. “So why not capture that energy and use it?”
In answer to those original questions, “Hydropower has served as a reliable source of renewable energy in the United States for nearly 150 years, and it will continue to be a source of both clean energy and power system flexibility critical to achieving the nation’s climate goals,” says Moreno. “Through this project, we can uplift the efforts of diverse hydropower stakeholders who are focused on achieving these goals while respecting rivers’ environmental and cultural importance.”
Headline photo: A rendering of the Allegheny Lock and Dam #2 project to electrify a dam near Highland Park Bridge in Pittsburgh. Photo illustration by Rye Development.