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Beginning in 2002 and through several rotor changes Verdant Power Turbines Verdant Power has now retrofitted two of its tidal turbines with 5th-Generation rotors and successfully re-installed the units in the East River. The two grid-connected 35kWe turbines are now delivering clean renewable energy from the tides of the
East River to a Gristedes supermarket and the RIOC Motorgate parking structure on Roosevelt Island in New York City. Verdant Power’s Kinetic Hydropower Systems use axial-flow turbines, resembling present-day wind turbines, installed underwater to convert the kinetic energy of tides and rivers into electricity without the use of dams.

The use of the ocean tides for energy is not new. In 620 AD in Northern Ireland at the Nendrum Monastery Mill a tidal mill was built. It used a millpond that was filled with seawater at high tide, which was released through a sluice and fed along a channel to the mill's horizontal wheel as the tide receded. England's Domesday survey book showed around 400 tidal mills in 1086. Nendrum Monastery Tidal Mill

The Company’s new state-of-the-art rotor assembly (blades and hub) was optimized for enhanced structural strength and was subjected to a comprehensive and rigorous testing regimen at the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL), the nation’s primary laboratory for renewable energy and energy efficiency research and development. The entire rotor assembly passed these tests successfully without incident.

“We are extremely pleased to have these next-generation, NREL-tested rotors on our turbines and operating in the East River,” stated Ron Smith, Verdant Power CEO. “As with all of our efforts at the RITE Project, this retrofit advances the technology for generating tidal power, bringing this much needed form of renewable energy one step closer to global implementation.”

This installation is part of Phase 2 of Verdant Power’s Roosevelt Island Tidal Energy (RITE) Project, which leads the world in the development of tidal turbine technology. Through RITE, Verdant Power installed what stands as the world’s first grid-connected array of tidal turbines. In 2007, the 4th-Generation rotors installed on these turbines experienced structural failures, though all other system components operated beyond expectations, with water-to-wire efficiencies of 30 - 40% and the delivery of over 45 MWh of energy, a world first and record.

The new rotors were retrofitted onto the turbines within a day’s time, employing local resources.

“This effort clearly shows an advantage of Verdant Power systems—their simplicity,” stated Smith. “Because of their simple and modular nature, we were able to remove a turbine during the slack tide one day, and have it ready for replacement the next morning. We were also able to hire local companies to support the work rather than seeking out rare, highly-specialized services.”

Since 2005, Verdant Power has been gathering operational and environmental data from the turbines at the RITE Project with plans to apply for a commercial license from the Federal Energy Regulatory Commission (FERC) in 2008. The RITE Project has received major funding from the New York State Energy Research and Development Authority (NYSERDA) and the New York City Economic Development Corporation.

Sources: Verdant press release, British Archaeology, Wikipedia, http://www.nendrum.utvinternet.com/tmill