Nova Scotia Turns the Tide With Bay of Fundy Turbine

Prototype unit, housed in steel casing 16 meters in diameter, weighs 300 metric tons.

*PHOTO COURTESY OF CAPE SHARP TIDAL*

Dedicated Cape Sharp Tidal barge towed turbine to the Minas Passage installation site.

*PHOTO COURTESY OF CAPE SHARP TIDAL*

After successfully retrieving a novel tidal turbine system deployed in the Bay of Fundy last November, a Nova Scotia research team is upgrading its second turbine and monitoring equipment for another deployment in 2018.

Inspection at Port Saint John has found that the overall exterior of the recovered Cape Sharp Tidal turbine is in good condition, according to an Emera spokeswoman. “The focus right now [for the 4-MW Cape Sharp Tidal project] is on improving efficiency and reliability,” says Kevin Harnett, systems engineering manager at OpenHydro, an in-stream tidal turbine technology developer and manufacturer based in Ireland.

Cape Sharp Tidal, a joint venture between Emera and OpenHydro, was the first of five in-stream tidal energy projects to deploy at the Fundy Ocean Research Center for Energy (FORCE) berth site and the first to grid-connect its in-stream tidal turbine in Nova Scotia.

These tidal technology developments are benefitting from provincial government support for tidal energy, including recent amendments to Nova Scotia’s Marine Renewable Energy Act of 2015, which seeks to open up the Bay of Fundy for additional demo projects. Situated between New Brunswick and Nova Scotia, the Bay of Fundy has 2,500 megawatts of extractable tidal potential, according to the Nova Scotia Dept. of Energy.

Christian Richard, the senior Emera representative responsible for Cape Sharp Tidal, notes that, while “in-stream tidal technology is in its infancy, there is a great deal of potential.”

Resembling a Ferris wheel, the turbine, which is mostly steel and 16 meters in diameter, weighs 300 metric tons and has 10 glass-reinforced plastic fins on its rotor, Harnett says. The base weighs about 700 metric tons; together, the base and turbine stand about 21 m high. “This is the strongest and heaviest turbine designed to withstand the powerful Bay of Fundy tides,” Harnett says.

An eighth-generation OpenHydro, Open-Center design, it comprises four key components: a horizontal axis rotor, a direct-drive permanent magnet generator, a hydrodynamic duct and a subsea gravity-base foundation. As tides ebb and flow, powerful ocean currents rotate the blades at 6 to 8 rpm, creating clean energy.

“Simplicity is a key advantage of the design, with no lubricants, seals or gearbox,” Harnett says. “The turbine base sits directly on the seabed floor, remaining stationary under its own weight.”

“The Cape Sharp Tidal turbines are engineered specifically for the FORCE site, [which has] some of the strongest tides in the world,” Harnett says.

In October, Nova Scotia amended its Marine Renewable Energy Act to permit demonstration projects up to 5 MW, according to an energy department spokeswoman. Companies also will be able to sell the generated electricity at a lower price than existing renewable-energy feed-in tariffs. No more than 10 MW of total power will be authorized under the amendment, and operators still are required to have all applicable permits and environmental approvals.

“This will make it easier for developers to assess innovative, lower-cost tidal energy technologies and bring them to market faster,” the spokeswoman says.

Feed-in tariffs in Nova Scotia are currently 53.5¢ per kilowatt-hour, which are paid to the power producer, says a Fundy research center spokesman. “Designed as an incentive, the tariffs provide some certainty.”

Nova Scotia Energy Minister Geoff MacLellan says, “Technology in this industry is evolving rapidly, and if we don’t adapt, we risk being left behind. By taking this next step, Nova Scotia remains a world leader in developing clean, renewable tidal energy.”

Johanna Knapschaefer, ENR’s New England Special Correspondent, has been writing about trends in design and construction of buildings, bridges, tunnels and other infrastructure for more than a decade. She also profiles award-winning industry leaders and delves into broader construction issues such as workforce training, worker safety and health, climate change remediation and emerging offshore wind and tidal energy developments. Over the past two decades, her articles have appeared in Architectural Record, BusinessWeek, the Boston Globe, American Banker, Modern Metals, BusinessNH Magazine, Pittsburgh Magazine and many other publications. Johanna is fluent in Japanese, and taught English and academic writing in the Science and Engineering Department of Ritsumeikan University, Kyoto, while living in Japan for eight years.

When not writing, Johanna enjoys mountain climbing, singing and playing her Spanish guitar.

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