In this early November photo, the 1000 tonne turbine can be seen in the deployment barge Scotia Tide, just before being lowered to the seafloor. credit:
“This is a proud and historic moment,” said the province’s energy minister, Michel Samson, as he flicked the switch to begin channelling two million watts of tidal electricity into the Nova Scotia grid.
Dubbed the Open-Centre Turbine, the 1000-tonne, 10-blade device was lowered to the ocean floor earlier this month before being plugged into the Nova Scotia power grid via underwater cable.
Capable of generating two megawatts, the experimental device generates as much electricity a standard-sized wind turbine. Or, as an official statement put it, the device is generating enough energy for “500 Nova Scotia homes.”
The turbine is the creation of Cape Sharp Tidal, a joint partnership of the Nova Scotia utility Emera and the Irish turbine company OpenHydro. Along with the planned installation of a second turbine, the total project is estimated to cost at least $30 million, of which $6.3 million was provided by federal grant.
Much like Niagara Falls — which Nicola Tesla selected as the site to the world’s first hydroelectric power plant in 1895— the Bay of Fundy has long fascinated engineers for its energy potential.
The U.S. Federal Power Commission, for one, was sketching out plans as early as 1924. “The power the tides could furnish … is limited only by the vastness of the seven seas and by the eternal journey of the moon around the earth!” declared the always optimistic Popular Science at the time.
Every day, the Atlantic Ocean pushes 160 billion tonnes of water into the bay. According to the region’s favourite factoid, this is more water moved than all the world’s freshwater rivers combined.
There is already a land-based tidal power plant in Nova Scotia, however. The Annapolis Royal Generating Station, opened in 1984, operates similar to a conventional hydroelectric plant; tide water is captured in a storage pond and then fed out through turbines.
But the Open-Centre Turbine is North America’s first “in-stream” tidal power plant. Rather than relying on a massive system of dams, ponds and earthworks, this power plant is simply placed on the bottom of the ocean to silently soak up the energy of incoming tides.
However, the Bay of Fundy has not been kind to previous attempts to turn it into an electrical workhorse.
The Annapolis Royal Generating Station, for one, didn’t quite turn out to be the energy juggernaut planners had assumed.
In 2009, a prior attempt at an in-stream turbine in the Bay of Fundy ended in utter failure. Engineers dramatically underestimated the bay’s tidal power. Within days of an Irish-made 400-tonne turbine being lowered to the seafloor, all of its blades had been twisted and seized.
Even the Open-Centre Turbine was subject to months of installation delays due to weather.
This time around, engineers are more worried about marine life. Wind turbines, famously, have a penchant to kill vast quantities bats and birds midair. And even the storage pond for the Annapolis station has trapped a couple whales.
It’s why researchers will be keeping an eye on what they call “ocean life interactions with the device.” Essentially, they’ll be checking to see if the turbine is chopping up lobsters or bothering passing whales with noise.
Ultimately, engineers figure that a network of turbines could generate 7,000 MW of electricity from the Bay of Fundy tides — slightly more than Ontario’s Bruce Nuclear Generating Station, which ranks among the world’s top 20 power plants.
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