HALIFAX — Two blades on a turbine placed in the Bay of Fundy to test the potential of tidal power have broken off as the massive forces of the bay’s currents flowed through the 400-tonne unit.
Nova Scotia Power and its partner OpenHydro, an Irish tidal power company, will now pull up the device to examine what went wrong in the first of three test projects. The firms said Friday that video images show two of the blades, made from composites of plastics and glass, have broken off the turbine, which is 16 metres in diameter.
The blades resemble the rotors on an aircraft turbine and are about three metres long. They have taken the brunt of onrushing currents in the bay since last November’s installation.
The system is located below the surface in the Minas Passage, about 10 kilometres west of Parrsboro, N.S.
Peter Corcoran, the chief financial officer of OpenHydro, said he wasn’t disappointed by the turn of events.
“The Bay of Fundy is one of the world’s best tidal sites and I guess the world’s best tidal sites don’t come easy,” he said.
Corcoran said OpenHydro will pay for retrieval, repairs and restoration of the site, and Nova Scotia Power’s ratepayers won’t bear any of the cost.
The estimated cost of the test project is $8.3 million. It has received $4 million in assistance from the federal government’s Sustainable Development Technology Fund.
“Any lessons we learn along this journey will only make ... the turbines stronger,” said Corcoran.
Some research indicates that the energy flowing through the bay has the potential to produce about 300 megawatts of electricity, enough power for more than 100,000 homes.
The Nova Scotia Power turbine is one of three projects designed to test the feasibility of tidal power in the bay. The project was also set up to examine the environmental impact on marine life, including fish and whales.
The companies say the unit will be pulled out of the water by late summer or early fall and engineers will examine instruments attached to the turbine that may explain why it happened.
Engineers will use data from instruments that record what was going through the turbines, the speed of the water and the forces exerted on the structure since last November.
Mark Savory, vice president of technical services at Nova Scotia Power, said it’s too early to speculate on the cause when he was asked if sea ice might have played a role in snapping off the blades.
Corcoran said the tests in the Bay of Fundy are more challenging than those being conducted by OpenHydro off the Orkney island of Eday, Scotland. The Bay of Fundy environment is turbulent and very dark, unlike the clear waters off Scotland. As a result, video images are fuzzy and brief.
The fleeting images that were captured were enough to tell the engineers the turbine had to be raised.
“We have managed to secure probably less than two seconds of the interior (of the turbines) ... the images indicate we’ve lost two blades,” said Corcoran.
It’s not the first challenge faced by the test project.
After the turbine was lowered to the Bay of Fundy floor, the companies lost contact with the wireless sensors attached to it. Engineers tried unsuccessfully to trigger the undersea acoustic modems, which upload information being collected by the sensors on the turbine.