Pilot projects ready for take-off

Described as a significant historical event, in January 2012 the US’ Federal Energy Regulatory Commission (FERC) issued its first pilot project licence for a tidal energy project. Located in New York City’s East river, the project is owned by Verdant Power and known as the Roosevelt Island Tidal Energy (RITE) scheme.

“Issuing a pilot licence for an innovative technology is a major step in the effort to help our country meet our renewable energy goals,” FERC Chairman Jon Wellinghoff said. “FERC’s pilot process is doing what it should: allow for exploration of new renewable technologies while protecting the environment.”

FERC developed the pilot licence process in 2008 to allow developers to test new hydrokinetic technologies, to determine appropriate sites and to confirm the technologies’ environmental effects without compromising FERC’s oversight.

Projects eligible for a pilot licence must be:

• Small.

• Short term.

• Located in an environmentally non-sensitive area.

• Removable and able to be shut down on short notice.

• Removed, with the site restored, before the end of the licence term unless the licensee obtains a new licence.

• Initiated by a draft application with appropriate environmental analysis.

“The licensing process itself is pretty short, about one year,” Verdant Power’s president Trey Taylor explains. “And FERC has been wonderful in its support in the sense that it has streamlined the process.”

Although FERC’s actions have helped companies like Verdant Power to develop hydrokinetic technologies, it still took the company ten years to get to this licensing threshold for the RITE scheme. Preceding this point had been six years of permitting and environmental studies.

“There’s an onerous regulatory process in the US,” Taylor comments on the obstacles that new hydrokinetic technologies have to overcome. “It’s not easy to develop as you not only have to have the money but need to do the right kind of testing. We began testing technology approved by the Department of Energy in 1995. We did three-phase testing in New York starting in 2001 when we had our first single unit in the water. Then in 2006 we put in the world’s first array of six tidal turbines which were grid connected.”

Tidal influence

The East river is a 27km long tidal strait connecting the waters of the Long Island Sound with those of the Atlantic Ocean in New York Harbour. It is not a freshwater river but a saltwater conveyance passage for tidal flow and is predominantly controlled by tidal influence.

The 1050kW scheme will generate electricity from turbine generator units mounted on the riverbed, capturing energy from the tidal flow. Verdant Power’s kinetic hydropower system turbines will capture energy from the flow in both ebb and flood directions by yawing with the changing tide, using a passive system with a downstream rotor.

“We have a three-blade downstream axial flow rotor and use the nose cone to orientate the turbine to the water current,” Taylor explains. “So in the case of the tides in the East river the turbine can turn around to get the ebb and flood tides.”

The turbines in East river are also positioned in an offset arrangement. “We inadvertently came to that conclusion as were looking at existing wind turbine modelling and how to space turbines,” Taylor says, going on to talk about kinetic energy in water currents. “If you take a percentage of that energy out you need to allow enough distance for the water current to restore itself before you take another percentage of energy out, otherwise it will take the path of least resistance and the water current will start to move around the turbines.”

The first six-turbine array in the water was a set of three rows of two units. The blade design was good, according to Taylor, but the material was not strong enough and the blades broke. A slow cascade effect illustrated the effect of one turbine on another.

“So we came to a better arrangement and new design of deployment,” Verdant Power’s president says. “We put the turbines in a tri-frame to allow water current to flow and regain speed before energy is taken out. Each tri-frame is offset at the proper distance.”

RITE Project phases

Verdant will conduct a three-phased development approach for the RITE project and will consist of:

• Phase 1 - 3x35kW, 5m diameter axial flow turbines mounted on a single tri-frame, installed in year 1.

• Phase 2 - Nine additional 35kW, 5m diameter axial flow turbines mounted on three tri-frame mounts, with a total installed capacity of 420kW installed in year 3.

• Phase 3 - Eighteen additional 35kW, 5m diameter turbines mounted on six tri-frame mounts installed in year 5 with a total installed capacity of 1050kW.

In addition, the work will encompass installation of 480V underwater cables from each turbine to five shoreline switchgear vaults that will interconnect to a control room and interconnection points. There will also be appurtenant facilities for navigation safety and operation.

After the completion of phase 3 the pilot project is estimated to have an annual generation of 2.4GWh. The pilot licence issued to Verdant Power is for 10 years.

Funding for the project has been supported by the New York State Energy Research and Development Authority (NYSERDA). In May 2010 it announced the award of US$11.3M to help develop and commercialise 25 innovative renewable energy projects. The RITE project was one of several demonstration schemes awarded a share of US$4.7M of funds

“Having received global attention, this project stands as one of the most advanced hydrokinetic projects ever devised,” NYSERDA said. “It is sited in the heart of a metropolitan market and subject to continuous extraordinary flow conditions.”

Verdant Power is also working on another hydrokinetic project on the St Lawrence river with support from the Canadian government. The Cornwall Ontario River Energy (CORE) project has the potential to deliver 15MW of installed capacity using a continuous river flow setting. Major funding for this scheme is being provided by the Ontario Ministry of Research and Innovation. The non profit organisation Sustainable Development Technology Canada has provided funding for phase 1, with additional project funding being provided by the Ontario Power Authority Technology Development Fund.

FERC says that it has witnessed rising interest in the development of hydrokinetic projects, having issued 100 preliminary permits to study the feasibility of developing a specific project. Another nine entities are in the pre-filing stages of developing licence applications, with three licence applications already having been filed.

For more details on Verdant Power’s projects, please visit verdantpower.com