In this 2006 photo, a Verdant Power turbine is lowered into the river off Roosevelt Island. This one failed. (Associated Press)
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 pour into 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.
Mayor Michael R. Bloomberg has sought to make New York the cleanest and greenest major city in the country. He has faced setbacks -- for example, when his congestion pricing plan to reduce the number of cars in Manhattan was killed by the state legislature. He was mocked when he spoke of placing windmills on bridges and skyscrapers, and a few New York tabloids ran illustrations of wind turbines on the Brooklyn Bridge and the Empire State Building.
Still, he has asked private companies to submit ideas to develop wind, solar and water energy projects. And for the past year, his administration has supported the water turbines, a project many years in the making.
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.
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 the first two 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.
But the capacity of the turbines is not the only stumbling block. There were years of environmental testing on the site, including an investment of more than $2 million to monitor the impact on fish and migratory birds. Both have avoided the big, clunky turbines thus far, Taylor said, but regulations require ongoing inspections.
The city needs new ways to generate energy because existing transmission lines from upstate are inadequate and the city's needs are growing, said James Gallagher, energy expert at the city's Economic Development Corp.
"We need generation within the city, and anything we can add in terms of clean, efficient, new generation, has a value to it," he said.
He and other analysts say tidal power is a small piece of the city's energy equation. In fact, New York is learning the rules of the game for its own brand of urban sustainable energy production: The winds and waters of this port city can be harnessed, but only in certain places. Tidal power is reliable, but small-scale. Wind power is cheap but rare. Solar power is unreliable, inconstant and expensive but easy to install.
Experts warn that before these alternatives are widely adopted, New York will have to upgrade its antiquated grid system, which is currently incapable of incorporating a great deal of power from multiple small sources.
The city's peak energy consumption is 12,000 megawatts at any given moment, said Stephen Hammer, the director of the Urban Energy Program at Columbia University. "The question is, 'What's our goal? How much of that 12,000 megawatts total do we want to try to achieve? What kind of cost burden do we want to bear to achieve it?' "
So far, support has been relatively strong on Roosevelt Island, the quiet community between Manhattan and Queens that is the project's base. Developers began building that support in 2001, long before any installation, beginning with neighborhood meetings.
"I think it's a great thing," said Pia Doane, 63, speaking as she shopped for fruit at the Gristede's supermarket the project powers. She said she'd rather live in view of a turbine than a smokestack, such as those at the massive power plant just across the water, which she calls Asthma Alley. "This current has a big force," she said. "We should use it."