Ten megawatts is just a fraction of the energy used around New York City every day. But it is enough to power anywhere from 5,000 to 10,000 New York City homes annually. A hydropower pilot project in the East River is working toward delivering 10 megawatts of “green” power to the city – without the environmental drawbacks of many other sources.

That’s the end goal of Verdant Power’s ongoing East River experiment, which yielded construction of the world’s first array of grid-connected hydrokinetic turbines. The RITE Project, short for Roosevelt Island Tidal Energy, deployed six three-blade units about two years ago that converted the kinetic energy from tidal and river currents into electricity. Now Verdant Power is seeking government approval to expand the installation to 30 turbines in the waterway’s East Channel, lying between Roosevelt Island and Queens.

More dramatic, Verdant’s draft license application filed this fall with the Federal Energy Resource Commission, the agency charged with hydropower oversight, proposes installing an additional 100 units in the West Channel’s UN security zone that is closed off to boat traffic. This latter installation will require a separate license. A full expansion of the project, which would entail installing nearly 300 turbines, has the potential to generate 10 megawatts of average annual power.

The company’s six-turbine prototype was created to gather data for its FERC license application. Although the turbines logged an unprecedented delivery of 80 megawatt hours of grid-connected electricity to a nearby Gristede’s supermarket and parking facility, the turbines also malfunctioned twice, leaving them defunct for most of the time they were in the water. In October, Verdant installed improved aluminum magnesium alloy rotors which have kept the turbines turning since then.

While the turbines were operational, Verdant used a combination of hydroacoustic transducers and state-of-art ultrasound imaging to monitor how fish were reacting to the functioning turbines. According to company president Trey Taylor: “For the most part there is no impact on fish.”

“What we witnessed was safe fish passage,” says Taylor. “We gathered a lot of data to be analyzed to validate or verify what we witnessed, which in essence was fish just swimming around the turbines.”
Environmental impact

Verdant’s environmental monitoring is a crucial aspect of this project. The East River is a tidal strait that connects Upper New York Bay with the Long Island Sound. The waterway harbors a broad diversity of fish species, including the endangered shortnose sturgeon. But behavior and migration patterns of the river’s marine life are varied and, to a large extent, unknown.

To date, Verdant claims to have spent more money on environmental testing than on the turbines themselves – but the company’s efforts have not eliminated concerns.

In December, FERC invited comments on Verdant’s draft application. Responding agencies include the state Department of Environmental Conservation (DEC), the U.S. Army Corps of Engineers, the U.S. Fish and Wildlife Service, and the United Marine Division Local 333, a longshoreman’s association. DEC raised the most detailed criticisms of the project, indicating dissatisfaction with Verdant’s environmental impact studies. One comment letter said that Verdant’s monitoring plan for the 30 turbine build-out is not well defined, existing data are inconclusive, and final data reports were not provided for review.

“This is a very unique project,” said DEC spokeswoman Lori Severino, “which leaves room for many uncertainties on how this will impact fish habitat.” Further study of the seasonal and daily variation in fish migration is needed, Severino said. Such variations can be effectively analyzed only through a prolonged and continuous study, which Verdant was not able to do because of the turbine failures. She added that although Verdant has often been receptive to the state’s data needs, “there have been struggles at points in communications.”

“Information from test field efforts should have been provided in the draft license application to provide verification … of the sampling methodologies used during the collection of baseline fisheries data,” she said.

Other agencies recommended adjustments to Verdant’s proposed monitoring plan. Because marine life may react to 30 turbines quite differently from the way they do to six, recommendations suggested that monitoring be more frequent in reporting, and broader in testing methods.

The public comment period for the draft application was closed last month, according to Celeste Miller, a spokesperson for FERC. There will be another opportunity for public comment, however, once the final application is filed.

The Bloomberg administration, for its part, has had little to say about the project. “The City supports the expansion of clean, renewable power constructed in an environmentally responsible way,” spokesman Jason Post wrote in a statement.

Cables and kinks

Taylor contends that although he can understand that DEC still has many questions, his company’s modular systems should not warrant the same kind of exhaustive environmental review that a conventional hydropower project would. Unlike a conventional hydropower project, which requires a 30-year license from FERC, Verdant’s turbines can be more easily removed if anything goes wrong. This modular quality, specific to hydrokinetic systems, has encouraged FERC to create a brand new pilot license, which is what Verdant will be applying for between March and April, according to their FERC filings. The company is asking for a 10-year license, although such pilot licenses are typically five years in duration.
Some observers raise other safety concerns, as well. Erik Baard, founder of the Long Island City Community Boathouse, stated that the cables of the six test turbines presently are too close to the surface, presenting hazards to boaters and kayakers.

“They have got to create a safer cable, rope and buoy system, because what they have now is not safe enough,” Baard said. “I also emphatically don’t want them narrowing or interfering with our navigation. The cables that go to the turbines can do that.” Neither Mr. Baard nor the Long Island City Boathouse filed comments with FERC, but he hopes that Verdant will redesign the 30 turbine array so that connecting cables have more slack, allowing them to drop deeper into the water. Taylor, however, said there will be adjustments to the cables, but no radical changes.

Separately, the United Marine Division Local 333 also commented on navigational safety, stating in a letter to FERC that more comment time was needed, and “a tug-and-barge industry meeting should be set up to allow for more discussion.” Pointing to the project’s greening goals, the letter expressed that “it would be a very painful irony to see a catastrophic oil spill was caused by a well-meaning but poorly executed alternative test project.”

If this project ends up getting it right, though, the ability to harness free-flowing tides and currents can contribute significantly to the world’s renewable energy needs. “This is emission-free electricity,” said Roger Bedard, an ocean energy specialist at the Electric Power Research Institute. “Given that it displaces either coal, oil or natural gas, then there will be less carbon greenhouse gases put into the atmosphere, and that is certainly a positive environmental benefit.”

If the final application is accepted, the company expects that installation of the 30 turbines will begin in mid-2010. Verdant is also planning tidal projects in Puget Sound in Washington state, and the St. Lawrence River, which divides New York state and Canada.

– Hashim Rahman