Discover Copper Online

Winter 2004

Currents Create Current

A new way of generating power based on water flow avoids building dams, which require years of costly construction and often harm aquatic life. Verdant Power, Arlington, Virginia, is developing copper-wound underwater turbines that can generate power from strong river or tidal currents.

An underwater turbine from Verdant Power. They spin too slowly (30 rpm) to harm any passing fish.

A"farm" of up to 300 of the turbines will be installed soon in New York's East River between the borough of Queens and Roosevelt Island. The 15-foot-diameter turbine props will be located about eight feet below the surface and are mounted on pylons anchored to the bottom of the 30- to 40-foot-deep channel. Depending on the direction of the tide flow, the units swivel 180° on the pylons. This site was chosen for its fast 6-mph flow and because it is not a ship channel. Nor would the turbines harm fish - an initial test of a small turbine showed that it rotated at 30 revolutions per minute, too slow to harm aquatic life. The project is currently in its second phase, with six turbines now operating in the river.

Rendering of 15-foot-tall water turbines in New York's East River.

There are other appeals of the turbines over the old way of utilizing water flow. Nearly all sites suitable for hydroelectric damming have been long taken, and there are so many rivers and tidal flats to exploit. And, while the turbines can be installed close to where the power is needed, hydroelectric power generated by dams is usually far from where it's needed, requiring building of many tall towers to support miles-long power cables.

If all 300 turbines are installed, they will generate 10 megawatts to be sold to the local power utility, according to Verdant's president, Trey Taylor. The turbines can be swung upright, which facilitates maintenance. Because of slack tide, when ocean tides cause the water to change direction, the turbines don't generate power for six hours a day.

New York State's need for power is growing so fast that the state government is encouraging the installation of the turbines. It has subsidized the project with a grant of $1.5 million towards its total cost of $20 million. Residents of Roosevelt Island back the project enthusiastically because it doesn't generate any air pollution, a nuisance for the islanders because of nearby power plants.

Besides New York, there's great interest in Verdant's turbines in the U.K. During a recent visit there, Taylor was seeking a partner to manufacture the turbines locally and install them in the many sites in the U.K. blessed with strong currents.


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