Kinetic Hydropower

Do we know what is swimming under the surface of the East River? Could there be a bottom-dwelling relic of the Crustacean era? Or perhaps a modern three-bladed turbine lurking on the East side of Roosevelt Island? While the former may exist, the latter is definitely extant, with thirty more on the way within the next three years.

These turbines, as seen in Figure 1, generate electricity through a process called kinetic hydropower. The current of the East River, which always flows at roughly greater than five miles per hour, spins the blades of the turbine. The fifteen-foot diameter blades rotate at a “nearly constant, slow rate [of around] 40 revolutions per minute.” This is more than a hundred times slower than the propellers of outboard motors. The spinning rotors power an inductor, which generates an electric current.

The thirty turbines, installed as ten triframe units, would produce 1MW (mega watt) of power. See Figure 2 for a diagram of the triframe concept, and Figure 3 for the proposed site of installation along the eastern side of Roosevelt Island.

Kinetic hydropower’s efficacy has already been proven. From 2006 to 2008, “Verdant Power operated six full-scale turbines successfully demonstrating the Free Flow System as an efficient source of renewable energy.” The turbines worked flawlessly, delivering “70 megawatt hours of energy/dots during 9,000 turbine-hours of operation.” Only five of the turbines generated electricity — a total of 175kW (kilo watt). The sixth contained a device for measuring torque (called a dynamometer). The power was then delivered to a Gristedes supermarket and a Roosevelt Island Operating Corporation (RIOC) Motorgate parking garage on Roosevelt Island. When the test was first opened in late 2006, Verdant Power’s turbines became the first of their kind to deliver energy to an end-use customer.

Kinetic hydropower is cheaper than solar power when compared by cost of installation. Solar power in New York County has an installation cost of slightly less than $12 per watt to install, whereas the Verdant turbines cost around $5 per watt. The price for installing the prototype turbines was expensive, and the installation costs are expected to decrease to around $2.40 per watt.
Verdant Power is in the process of filing a license with the Federal Energy Regulatory Commission for permission to install around thirty more turbines, bringing the capacity up to 1MW — enough to power 800 New York homes. In the more distant future, Verdant Power hopes to install a total of 300 turbines, with a capacity of up to 10MW.

As for the fish, they will be just fine.

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