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December 2012 Policy Study, Number 12-12


Water, Water Everywhere, but Not a Drop for Power


Potential New U.S. Hydroelectric Power Sources



The first requirement for hydropower production is a dam to control the water flow. There are over 80,000 dams already built and operating in the United States to control water flow. Currently, only 2,500 of them produce electricity. The energy potential of the water either sitting in reservoirs behind or released from these dams is simply wasted.


The U.S. Department of Energy recently released a new report on the electrical power that could be generated from non-powered dams (NPD) in the U.S.[24] According to this report, the potential is significant. “An Assessment of Energy Potential at Non-Powered Dams in the United States,” released in April 2012, reviews and analyzes the possibilities and suggests an expanded direction for economic development, private investment, and renewable energy efforts in Iowa, as well as the rest of the country.


Initially, DOE reviewed 54,391 NPDs for their energy potential. The carefully formulated, pro-forma estimate of total potential capacity from these NPDs is 12 gigawatts, with annual energy generation of 45 terawatt hours. This is about 15 percent of the current hydropower produced in the U.S.[25]


In the United States it takes about one megawatt of electricity to power 400 homes for a year. A gigawatt is equal to 1,000 megawatts. Therefore, a gigawatt would provide electricity for about 400,000 homes per year, and 12 gigawatts would power about 4.8 million homes.[26] Though these are rough estimates, and the Department of Energy is careful to say that actual production would be less – increases in hydropower production of electricity could be a significant new addition to the energy mix in the U.S.


Importantly, because the dams controlling the water are already in place – with the largest operated and maintained by the U.S. Army Corps of Engineers – much of the environmental impact and analysis, development cost, and time investment has already been incurred. Adding power generation capability to these dams can potentially be done with lower cost, less risk, and in a shorter timeframe than building many other power sources, if the regulatory process is not onerous. Unfortunately, this is a big “if.”


The list of 54,391 dams was further narrowed, through a fairly comprehensive process, to a review of the top 100 dam sites. Twelve of these top 100 sites are on rivers in Iowa, primarily the Mississippi.[27] As you come down from the Upper Mississippi, dams numbers 9 to 18 are all in the top 100 for potential electricity generation. The initial estimate is that hydroelectric power plants on the Mississippi dams have a potential capacity of 590 megawatts, or enough electricity for about 236,000 homes. The following table outlines the 12 dams, some of which are jointly controlled with Illinois.



Hydropower plants on the two dams on the Des Moines River – Red Rock and Saylorville – have a potential capacity of another 90 megawatts, which could produce enough energy to power 36,000 homes. This is about 40 percent of the homes in Des Moines.[28] Again, the Department of Energy is careful to say that many factors would impact the electrical power production capacity on the dam sites, but the potential is there. A hydroelectric license has been issued and development is progressing at the Red Rock location.


At other sites, such as Lock and Dam #19 on the Mississippi River at Keokuk, Iowa, the power plant was an integral part of the initial construction. The Keokuk dam is used to manage a river fall of 28 feet, the largest on the Mississippi, and is critical to the successful movement of water traffic. This power facility is a run-of-river design with low-head turbines, and has been used for 100 years. It is the only power generating dam on the Mississippi. When first built it was the “largest power house in the world” and was considered an engineering and technology marvel. Construction cost about $578 million in today’s dollars.[29]


Today, there are problems with sediment in-fill and aging of both the dam and the hydroelectric power facility.[30] Currently the turbines are being replaced, with new stainless steel blades. They have an expected useful life of another 100 years.


In addition to these major dams on the Mississippi and Des Moines Rivers, there are many dams used for flood control and recreation, such as those on the Iowa and Cedar Rivers, as well as even smaller, “low-head” dams which can still be used to generate electricity. Many of these dams were originally used for both flood control and electricity generation, but the power plants were closed in the 1970s as they aged and became inefficient.


In many ways, they are even more important than those major opportunities identified by the Department of Energy. The costs and regulatory barriers to development on the Mississippi River are significant because of the project size and complexity. The development cost and regulatory approval time to retrofit minor dams, often owned by city governments, with small or modular hydroelectric turbines, may make them better initial opportunities for both private developers and local governments.




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