CURWOOD: So, how about some good news about the challenge of climate change. Well there’s now an experiment in New York City to make electric power from a way you might not expect. It seems to be clean, and certainly has no climate changing gases, no ugly towers, or waste products. From the East River of New York City, Beth Fertig of member station WNYC has our report.

FERTIG: The East River is actually a tidal strait that flows along the East Coast of Manhattan, connecting Long Island Sound to New York Harbor. For some engineers, it’s not just a body of water but a powerful, potential source 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 it’s not in the middle of arctic or something.

FERTIG: Dean Corren is Director of Technology Development for Verdant Power. We’re standing on the shore of Roosevelt Island, a residential community which sits in the river between Manhattan and Queens.

FERTIG: It’s off the coast of this skinny island that Corren and his engineers are preparing to operate a group of tidal 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.

FERTIG: Electricity that can be used to power homes and businesses. On a bright sunny morning, Corren’s team stands on the shoreline while a barge delivers equipment that can 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.

FERTIG: As Corren climbs down a ladder to the water’s edge, a huge crane takes four white rectangular frames off the barge and gently lays them in the water.

FERTIG: 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 to operate until it proves to state and federal agencies that its turbines won’t hurt migrating wildlife. But Corren predicts that shouldn’t be a problem.

FERTIG: And those tests are just beginning.

FERTIG: In a former shipping container that’s been turned into a control room, Verdant has spent several months 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 an example of what a school of fish looked like before the turbine was actually in the water.

FERTIG: Verdant conducted a test run with a single turbine at the beginning of this year. 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 the water is really quiet. They don’t like fast currents. They also don’t hang out that far they like the safety of the rocks. And so this bodes very well for having turbines in river environments like this.

FERTIG: The test turbine operated for more than a month, until engineers discovered a problem with its blade. In that time, 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.

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

The turbines may look like windmills. But they’re actually much more complicated, says Robert Thresher, who has studied tidal power as 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 a foundation. 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.

FERTIG: That’s not to say it isn’t possible. Thresher is a big proponent of alternative sources of energy, and he says tidal power has great potential. Unlike wind, tides are predictable because they come in cycles. It’s just going to take more research… and more money to resolve questions of environmental impact and commercial viability.

THRESHER: Cause people haven’t done it before, the permitting’s not worked out. When people are permitting they don’t know what to worry about so they worry about everything.

FERTIG: The Federal Energy Regulatory Commission says about there are about fifty applications for permits by companies experimenting with tidal power, from Washington State to Florida and Maine.

FERTIG: Verdant says it’s spending more than six 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. If they can pass the initial hurdles, 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 5000 homes. And because they’re underwater, she says there’s little fear of neighborhood opposition.

ABEND: A neat way to look at it would be this is like the quietest electric plant ever or power plant ever because you’ll never see them and if everything is working well, you’ll just get power from the current.

FERTIG: Verdant’s new turbines are being tested just in time for bass migration. The company is also applying for permits to test in Long Island Sound. For Living on Earth I’m Beth Fertig in New York.