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Jan 27, 2010 - Rising fuel costs for conventional power plants have made the construction of low-head hydroelectric projects at existing lock-and-dam facilities an economical option for power companies. Making these projects even more attractive: requirements by some states that a certain percentage (typically 15 percent) of power be from green sources; and the possibility that the federal government will pass a carbon tax, or cap-and-trade legislation.
The U.S. Army Corps of Engineers, the authority that owns and operates the locks and dams, requires impact studies for hydropower projects. Any powerhouse built at a lock-and-dam structure must not adversely affect the authorized purpose(s) of the Army Corps project by impeding navigability or creating sedimentation patterns that would require more frequent dredging. The Corps requires modeling to ensure that the design will not cause those negative impacts.
After work on several lock and dam models in recent years, Alden will develop both physical scale models and computer models in 2010 for proposed AES NA Hydro, LLC projects at two Ohio River lock-and-dam sites near Evansville, Indiana. PB Power, a Company of PB Americas, Inc., is acting as the architect-engineer for the projects. The physical models will be 1/120 scale covering three miles of river and will provide insight into how the installation of powerhouses will affect hydraulic conditions. The Army Corps will use a model towboat and barge flotilla to test navigation both before and after the powerhouse and tailrace portions of the models are installed.
To develop accurate river models, Alden field specialists toured the locks and dams on the river last year, observing the design in detail from a boat and measuring bathymetry and river velocities. Rather than outsourcing this task to another consulting firm, Alden used its own in-house field expertise. This makes the process more efficient by limiting the need for inter-company communication as the models are constructed and implemented.
The computer model will forecast the bathymetric impact—how the powerhouses affect sedimentation downstream from the lock-and-dam structures. The positioning and design of the powerhouses can be adjusted in both models to help find the optimum solution with minimum impacts. With a total of 21 locks and dams on the Ohio, and dozens more on the Mississippi River and other rivers, growth potential for this market is promising. Once the powerhouses are built, the cost of fuel—flowing river water—is free forever. Therefore, these projects reap benefits many decades after construction is completed.
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