America’s Hydropower Opportunity
As the nation continues to seek methods of energy production that reduce environmental impacts, hydropower is a viable and valuable option, especially given the number of non-powered existing dams.
By Col. Miro Kurka, P.E., PMP, M.SAME, USA (Ret.), and Sondra Retzlaff, M.SAME
Built in 1941, Mahoning Creek Dam outside Pittsburgh began producing hydropower in 2013. PHOTO BY FRANK RANSLEY, MEAD & HUNT
The United States has a rich history of building infrastructure to grow the nation, the economy and the national defense. This infrastructure includes more than 83,000 dams that provide a variety of benefits including flood risk reduction, water supply, navigation, recreation and hydroelectric power. Yet despite the high number of dams across the country, only about 2,500 generate hydroelectricity—a mere 3 percent of the total. Most of these projects are more than 40 years old.
Over the past 10 years, Mead & Hunt has had experience with new hydro development at existing dams, feasibility studies, and hydro maintenance and rehabilitation projects that improve power production. The lesson learned is clear: By developing hydropower at existing non-powered dams, dam owners and operators can minimize costs while increasing the development of clean, renewable energy resources.
LEVERAGING EXISTING ASSETS
In April 2012, Oak Ridge National Laboratory published An Assessment of Energy Potential at Non-powered Dams in the United States. The report indicated untapped potential for clean, renewable energy if hydropower were added at non-powered dams and improved at existing facilities. Currently, 78-GW of conventional and 22-GW of pumped-storage hydropower are produced by powered dams in the United States. The potential power generation at non-powered dams could be as much as 12-GW (enough to power 4.8 million homes). This represents a possible 15 percent increase in hydropower.
The push for green, clean, renewable energy that reduces carbon emissions is ongoing worldwide. Using existing dams for hydropower is one of many ways to advance our national renewable energy goals. While there are many other available means to produce clean renewable energy, including solar, wind, biomass, biofuels and nuclear power generation, there are limitations to all of these power sources, including weather variability and waste disposal. Hydropower is proven and reliable. Because it can quickly go from zero power to maximum output, it provides essential back-up, especially for variable wind and solar generation as well as peaking power for high-load periods.
Unfortunately, very large upfront capital costs and environmental concerns make new dams very difficult to permit, finance and build. Because existing dams have already overcome these impediments, they are a viable option for new hydropower. Adding hydro to an existing dam is much more acceptable to the environmental community and regulators and more practicable for financers and developers.
REVITALIZING OLD DAMS
Recently, new hydro was added to existing infrastructure at Mahoning Creek Dam in Pennsylvania and the Black River Falls Dam in Wisconsin. These projects showcase successful hydropower development at federal and non-federal dams.
The Black River Falls Dam was originally constructed more than 110 years ago to power sawmills. Over time, it became a source of electricity for the community. When the time came to reconstruct the spillway, the owner decided to add a low-flow hydropower unit to meet federal minimum flow requirements and gain an additional source for inexpensive, clean, renewable energy. The new low-flow turbine is a double-regulated, vertical Kaplan unit that can operate over a range of 50- to 320-ft³/sec and can provide up to 410-kW of additional power generation. It increases installed hydroelectric generation capacity and helps to fill generation gaps between the operating points of the two existing units, enabling power generation over a broader range of river flows.
Since the dam manages water flow from a nearly 1,600-mi² watershed, and the dam is central to the community, the project required close coordination with the Wisconsin Department of Natural Resources. Funding was a significant challenge with the community’s small population of 3,600. With the assistance of a low-interest loan from the federal rural development program, the community was able finance the project without adversely affecting the municipal utility’s ratepayers.
Meanwhile, Mahoning Creek Dam, owned and operated by the Pittsburgh District of the U.S. Army Corps of Engineers (USACE), was built in 1941 to provide flood control in the Allegheny River basin. High energy prices over the past decade and a renewable energy grant made it an attractive hydro opportunity. Using a collaborative project delivery model, the owner/developer and the designer worked with the contractor to permit, design, build and commission a new hydropower facility that can produce up to 6-MW of electric power.
The new facility uses durable, low-maintenance systems that made construction cost-effective and has lowered operational costs. The hydroelectric project includes inlet and outlet works, a 1,200-ft long penstock, and a powerhouse with two generators powered by Francis turbines. While as a USACE project, it faced additional approvals including an Independent External Peer Review and a Semi-Quantitative Risk Assessment, close collaboration with USACE and the Federal Energy Regulatory Commission (FERC) allowed the project to meet federal requirements and overcome regulatory challenges.
At both Mahoning Creek and Black River Falls, federal loan assistance and grant funding helped mitigate the initial capital costs.
With so many potential hydroelectric projects, it is difficult to know where to begin. A feasibility study, such as Hydropower Resource Assessment at Non-Powered USACE Sites, prepared by the USACE Hydroelectric Design Center in July 2013, is a great starting point. Though this study is at the “30,000-ft level” it still provides a good basis for the potential developer. It can be refined with a detailed study of the particular site that addresses the potential of the new project or upgrade, including available physical energy, technology, project cost, environmental impacts and regulatory requirements.
In Mead & Hunt’s experience, $60,000 to $150,000 invested in a thorough feasibility study will save many more times the amount spent when developing a new hydroelectric project.
The push for green, clean, renewable energy that reduces carbon emissions is ongoing worldwide. Using existing dams for hydropower is one of many ways to advance our national renewable energy goals.
MAINTAINING AND UPGRADING
In addition to adding new hydropower to existing dams, our national hydroelectric infrastructure needs to be maintained and upgraded. Non-federal hydropower facilities must meet FERC regulations that protect life, property and economic interests. This can be challenging in the face of reduced budgets and increasingly rigorous agency requirements.
Large investor-owned utilities, such as Pacific Gas and Electric, employ teams of consultants and contractors to perform civil, structural, electrical and mechanical engineering tasks to meet FERC requirements and to improve the reliability, efficiency and generating capacity of their projects. They value their projects and look to maximize return-on-investment.
Many smaller hydropower producers, including rural electrical cooperatives, paper mills and independent power producers, lack the funding to upgrade and sometimes even to maintain their facilities—especially in an environment of low oil and natural gas prices. Without investment possibly provided by state and federal tax credits, many of these smaller producers may stop operations.
Federal hydroelectric projects also face challenges with maintaining, modernizing and upgrading aging facilities in a fiscally austere environment. Over the past decade, the generation trends as reflected by unit availability and forced outages have shown a significant decline. Potential solutions include public-private partnerships and direct customer funding. This is the model used in the Columbia River Basin in Oregon where the Bonneville Power Administration provides funding for non-routine maintenance and capital improvements through the sale of electricity.
Hydroelectric power is one of the oldest renewable energy sources, having provided clean, reliable, and inexpensive power since the late 1800s.
As the United States balances its energy production from fossil fuels to a larger reliance on non-carbon sources, hydroelectric generation is often overlooked. It is older and not nearly as popular as wind or solar.
Hydropower, however, has many advantages, including a surge capability and a relatively low lifecycle cost after the initial investment. By developing hydropower at existing non-powered dams, we can minimize the initial capital costs and increase the development of clean, renewable energy resources. New technology also can increase the capacity of existing hydroelectric facilities.
Better harnessing what we already have: That is true energy efficiency.