[Photo credit: Verdant Power]

It's been a long, hard, waterlogged slog, but New York City might finally be getting some energy from beneath the surface of the East River.  This past week Verdant Power installed--for the third time--a turbine on the river's bed, with hopes to capture the energy of tidal ebb and flow.  The first two attempts proved the concept well enough--fish steered clear of the metal blades, the biggest ecological concern going in--but the turbines blades were torn off by the currents, which were far stronger than anticipated.  When considering the end goal of producing electricity from these currents, this proved to be a failure of the most promising sort.

You see, the East River is more of a tidal channel than a typical river.  The strong tides funneled in from New York Harbor flow at a much faster rate than a typical river of this depth and volume, and the currents reverse twice a day.  That means, of course, that more energy can be captured by any submerged turbines, but they've got to be durable enough to handle theload.

The new turbine is made of state-of-the-art aluminum alloy, the first of its kind in the country, and the company's reps say it should hold up, having tested this version rigorously before installation.  (The first blades were made of fiberglass stretched over a steel frame and tore to pieces almost immediately; the second iteration were aluminum magnesium and lasted a couple of months before pulling off their hubs.)  If these new alloy blades prove tough enough, a total of 300 will be put online, pumping electricity (up to 10 Megawatts) around the clock to 10,000 households (and a supermarket and hospital, amongst other commercial buildings) through a transmission line to Roosevelt Island.

The anticipated supply load (10 MW) is The East River project is modest, but would prove a symbolic victory in Mayor Bloomberg's stated plans to produce much of New York City's electricity within the five boroughs (or not far offshore) from clean, carbon-free sources.  In a city that boasts over 500 miles of waterfront-and is virtually swarmed by tidal currents-Verdant's East River tidal experiment could provide a scalable model that taps into this power of the orbiting moon.  

Check out Verdant Power's video rendering of the underwater turbines in action:

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