September 21, 2008
Turbines aim to use tidal power
September 21, 2008
How it works
The idea is simple: As water flows, it spins the rotors and produces electricity. The turbines run according to the tide charts, which are as predictable as phases of the moon.
NEW YORK – On a recent morning, a crane sank a 16-foot rotor into the waters of the East River and divers swam deep to bolt it to the bottom. By early evening, as the northerly current sped up, the rotor began to spin, a big thunk sounded in the control room, a green light went on, and electricity began to power a nearby supermarket.
The scene represents an experiment in tidal power, using turbines that look like underwater windmills, and it is the first of its kind nationwide and one of only a few such pilot projects in the world.
"This is just the beginning of a project, but the project itself is emblematic of a whole new industry," said Trey Taylor, the president of Verdant Power, a small company that created the experiment and hopes to expand it to commercial use with 300 turbines in the East River that could power up to 10,000 homes in the city.
Engineers, policymakers and energy experts say projects like the East River tidal turbines are already placing this city at the urban vanguard of energy production. They say New York City is uniquely positioned to advance sustainable energy projects because of the city's enormous need for power, its high electricity costs, and the pressure for new sources created by its unusual rule that 80 percent of energy must be generated within the city.
The idea was rejected for state funding in 2000, only to be accepted a few years later.
The strength of the flows of the East River – which is technically not a river, but a tidal strait whose current switches direction throughout the day – makes it an ideal spot for generating power. The strength of the current also makes it hard on equipment. Swift-moving waters chewed up two previous types of turbines, which Verdant, a small, private company, installed in late 2006 and early 2007.
The first blades were fiberglass with a steel skeleton. Later, another set of rotors was made from aluminum and magnesium.
"The water was very powerful, so it broke the rotors," Taylor said.
The newest blades are made from an aluminum alloy, attached to rotors whose strength has been extensively tested. If all holds together, Taylor expects to apply for permission to expand and launch a commercial operation.
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