Streams

Tidal Power: Can the East River Generate Electricity?

Thursday, April 05, 2007

Approximately 14 percent of all electrical power in New York State comes from hydropower. Many environmentalists believe that figure should be higher. They see hydropower as a way of reducing our reliance on the fossil fuels that contribute to global warming. In our ongoing series on how the New York region is preparing for climate change, WNYC’s Beth Fertig looks at one small company that’s now experimenting with a new form of hydro-electric power right in the East River.

Part of Feeling The Heat, a climate change series

REPORTER: It doesn’t look like much from here on Roosevelt Island. But this narrow slice of the East River directly opposite Queens could be a powerful form of energy.

CORREN: You have first of all a big fast river, you have to have fast currents, that’s what it’s all about, it’s embedded in civilization not middle of arctic or something.

REPORTER: Dean Corren is Director of Technology Development for Verdant Power.

MAN: Hey, you guys want to put some ropes on the next one?

REPORTER: He and his engineers are getting ready to harness the strength of this tidal estuary with the help of turbines.

CORREN: All of us, our team together, has built six turbines to go underwater here that capture the kinetic energy of the flowing water without any dams. They’re sort of like underwater windmills. And as the tide goes in and the tide goes out, the flood and the ebb, they capture some of the energy and convert it directly to electricity

REPORTER: Electricity that can be used to power homes and businesses. On a bright sunny morning, recently, Corren’s team stood on the shoreline while a barge delivered equipment that could only be installed during a slack tide.

CORREN: When the tide stops we gotta go. We can only do this stuff when water’s not running.

REPORTER: As he descended a ladder to the water’s edge, a huge crane was taking four white rectangular frames off the barge and gently laying them in the water.

Each frame is about 20 feet long and contains three ultrasonic devices. They were especially designed for observing fish. Verdant can’t get a permit until it proves to state and federal agencies that the turbines won’t hurt migrating wildlife. But Corren predicts that shouldn’t be a problem.

A barge drops off sonar devices, mounted on a large frame, for monitoring how turbines affect East River fish

CORREN: The turbines actually turn very slowly. They’re five meters in diameter - that’s 16.4 feet - and they turn at about 34 RPM. Quite stately is my term for it. Also leading edges are very rounded and blunt. Also the inner part turns very slowly. So there’s only a very small area that could actually hurt fish if they were to hit it.

REPORTER: And those tests are just beginning. In a former shipping container that’s been turned into a control room, Verdant has spent several months already studying the habits of East River wildlife. Analyst Hannah Abend uses her computer to look at underwater images captured by a different sonar device last year.

ABEND: So I’m going to show you example of what a school of fish looked like before the turbine was actually in the water.

REPORTER: Verdant conducted a test run with a single turbine back in December. Abend says she saw a few herrings, a striped bass and a cormorant. But they stayed away from the turbine – which was located about a quarter of the way out in the river.

ABEND: One of the interesting things I’ve discovered from analyzing all of this data is that generally the fish hang around the rocks, they hang around during slack tide when the turbine isn’t moving at all because water really quiet. They don’t like fast currents. They also don’t hang out that fa,r they like the safety of the rocks. And so this bodes very well for having turbines in river environments like this.

REPORTER: The test turbine operated for more than a month, until engineers discovered a problem with its blade. In that month Verdant says it generated about 8000 kilowatt hours during active tide cycles – enough to power a couple of homes for a year. The electricity was used by the Gristedes supermarket on Roosevelt Island – proving the East River could generate power. Verdant’s founders compare that to the flight of the Kitty Hawk because tidal power is still in its infancy.

Alternative forms of hydropower were first explored in the 1970s. But they were abandoned when the energy crisis ended. Now that global warming has triggered a new interest in renewable, clean sources of energy, researchers in Europe and the United States are once again experimenting with tidal power. But there’s a big obstacle.

THRESHER: It’s a lot easier to do things on land than it is in the water.

REPORTER: The turbines may LOOK like windmills. But they’re actually much more complicated, according to Robert Thresher, director of the National Wind and Technology Center in Denver, Colorado.

THRESHER: You have to get out there, you have to have boats, you have to have crews, if you’re going to put a foundation in, you can’t just dig a hole with a back hoe and pour in foundation. It’s more complicated than that. So just working in the water is more complicated even in rivers or tidal streams. And then if you’re in estuary you have salt water, which is a corrosion issue that you just don’t have with wind turbines.

REPORTER: That’s not to say it isn’t possible. Thresher is a big proponent of alternative sources of energy, and he says tidal power is definitely viable. Unlike wind, tides are predictable because they come in cycles. It’s just going to take more research… and more money.

Verdant says it’s spending more than 6 million dollars on the East River project. A third of that money alone is going toward the fish monitoring, and other regulatory and permitting issues. Hannah Abend and her coworkers envision a day when a couple of hundred turbines off the coast of Roosevelt Island could generate enough power for up to five thousand homes. And since they only depend on the moon and the tides, she says these turbines could be part of a whole mix of power plants that use nature to reduce our reliance on fossil fuels.

ABEND: I would love to see this type of power plant in place where you can have distributed energy, a solar field, a wind field, an underwater tidal field to power up local communities, to power up - if you’re in rural area and you have water supplies this is a way to get power as well. It really opens up the possibilities for different sources of power and greener sources of power.

REPORTER: Verdant power is scheduled to deploy a total of six turbines later this month for testing – just as bass migration begins. The company is also applying for permits to test in Long Island sound. If the company can prove it can successfully generate power without hurting wildlife, New York may find a whole new use for its waterways. For WNYC I’m Beth Fertig.

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