Could East River Tides Help Power NYC?

by |January 14, 2011

Typically, discussions about hydropower center around hydroelectric dams and ocean wind turbines. That could change, however, if Verdant Power – an energy company based out of New York – succeeds in its latest venture.

Roosevelt Island, pictured above, is the site for the tidal power plant proposed by Verdant Power. This is also where the clean energy company set up its two-year test site. (Source: Wikimedia)

On Monday, Verdant announced that it had filed an application with the Federal Energy Regulatory Commission to construct what would be the first tidal power plant in the United States. The company is currently seeking approval to install around 30 tidal power turbines just off of Roosevelt Island in New York City’s East River.

While this would be the company’s pilot project, Verdant is a small company with big aspirations and hopes to scale the number of turbines in the East River up into the hundreds. According to Verdant’s chief executive, the application to the FERC is the product of almost a decade of work done by Verdant and its partners to make tidal power a viable addition to the nation’s clean energy portfolio.

Between 2006 and 2008, the company installed six turbines near Roosevelt Island, the proposed site for the new tidal power plant. The goal was to test the viability of clean energy generated by the swift tides of the river and to observe what consequences, if any, the turbines produced. At the strategically chosen location (the East River has particularly strong tides because it is technically a tidal straight and not a river), the turbines set records for hydrokinetic power generation.

Turbines being lowered into the East River test site set up by Verdant Power in 2006. (Source: Verdant Power)

The energy they created during the two-year test period was distributed to businesses on Roosevelt Island, including a Gristede’s supermarket. Verdant called their scheme the first system of grid-connected tidal turbines in the world. If the FERC approves their recent application, the turbines could supply additional businesses on Roosevelt Island and eventually up to 8,000 homes in nearby Queens and Manhattan.

Based on the performance of the test turbines, Verdant estimates that the proposed power plant would generate 1 megawatt of electricity, a fraction of the 50 to 500 megawatts of tidal power that the company estimates could be generated in New York state. They also point out there would be the potential to increase the size of the power plant in the future simply by installing more turbines in the area around Roosevelt Island.

A major concern raised by environmentalists in response to tidal power is the effect on aquatic flora and fauna. Verdant’s trial, however, proved that tidal turbines don’t injure fish; during the two-year period, analysts did not observe a single instance of a fish (and they observed an abundance of species) getting struck by a turbine blade.

Birds fly near a wind farm in upstate NY. Injuries to wildlife are a major concern for all alternative energy projects involve turbines; however, tidal turbines have proved to cause many fewer injuries to animals than do wind turbines like the ones pictured above. (Source: The Post-Standard, Syracuse.com)

This finding is startling when compared to the contentious claim that birds are injured by wind turbine blades. One reason the two similar technologies have different rates of wildlife casualties is that water is much denser than air, which means that tidal turbines move much more slowly than do wind turbines while generating the same amount of energy.

For those who insist that a tidal power plant in the East River (or anyplace else, for that matter) would be harmful for aquatic life, I’d point out that the tons of waste we dump into rivers and oceans every day are probably more so.

Although the turbines were a success on many fronts during the two-year trial, they didn’t function perfectly: on occasion, the strong currents broke the triple-bladed turbines. Since 2008, Verdant has been experimenting with stronger turbine construction materials capable of enduring intense tidal force. The turbines that the company will install if they receive federal approval will be made of carbon epoxy composite.

Underwater turbines like this one could be the next wave of alternative energy. (Source: Verdant Power)

So what, exactly, makes tidal energy such a great idea? Well for starters, it’s much more reliable than most other alternative energies: tides are easy to predict and will never cease (and if they do, we’ll have bigger problems to worry about than energy sourcing). In addition, this form of clean energy could be employed in coastal cities throughout the US and would help address what’s referred to as ‘transmission congestion’ (a term applied to towns or cities struggling to meet their residents’ energy demand) in many of them. The technology is even being employed in the Indian state of Gujarat, where construction will commence later this year on Asia’s first commercial-scale tidal power plant in the Gulf of Kutch.

In the big picture, if tidal power proves to be an efficient source of clean energy, chances are it could enable us to deal with a number of other environmental problems (both regional and global in scale) relating to energy and water pollution. At the very least, it might diminish the impetus to drill for oil in the ocean floor, a practice that might have a few ecological consequences associated with it.

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Lakis Polycarpou
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Great piece Katie. I certainly agree that tidal turbines are visually less offensive than wind turbines (especially in an urban area) and have the advantage of less intermittency. I do take issue with the whole wind-turbines killing birds argument though, which John Laumer takes on in Treehugger: http://www.treehugger.com/files/2006/04/common_misconce.php Not sure of his source, but he says that between 100 million and a billion birds die each year from colliding with windows — how many orders of magnitude is that above any possible wind-turbine death? In any case, you hint at the bigger insanity — how crazy is it when we… Read more »