Corey Cavalier, PE, CFM

Most people think of dams when they think of hydropower.  Traditionally, the dams have been used in part to build up potential energy by piling up water upstream and convert it to greater kinetic energy by running the water through batteries of turbines.  These structures have fallen out of favor as concern has grown as to their impact on wildlife, most especially as to salmon migration.  As a result, there are many mitigation measures such as fish ladders and some dams have been eliminated altogether.

However, there is another alternative in the use of turbines for hydropower: placement directly into natural currents and tides.  At this time, there are several initiatives to implement this design.  One company, Hydro Green Energy out of Houston, is installing these turbines in the Mississippi River at Hastings, Minnesota and in the East River at New York City. Another company, Free Flow Power Corp out of Massachusetts, is planning to install turbines in the Mississippi River in Louisiana.

This new use of technology does bring its own concerns, especially with river transport.  With dams, it is obvious where the hazard is and a set of locks may be provided in order to travel beyond the man-made obstruction.  These turbines are underwater, however, and the water level changes over time.  As a result, those operating river barges on the Mississippi are concerned that they may at some time run into the structures, thus both causing damage to each and disrupting a main artery of freight traffic.  It is therefore uncertain as to whether or not the Louisiana project will be allowed to proceed.

Tags: civil engineering, hydropower, water