Cape Sharp Tidal turbine coming out for equipment upgrades

The group behind a demonstration tidal turbine in the Bay of Fundy says the device is working as expected, but it will be removed later this month for modifications to control centre components, and for repairs and adjustments to some of its monitoring equipment.

The Cape Sharp Tidal Venture turbine, a joint project between Emera Inc. and OpenHydro, started producing electricity for the Nova Scotia grid on Nov. 8. On Wednesday, in announcing plans to remove the turbine later this month, the group also released an interim report detailing data collected until January from monitoring devices.

The hardware adjustments and upgrades to some of the turbine control centre (TCC) components are related to the device's ability to transform power from the generator into power compatible with the grid.

"Taking steps to ensure the TCC continues to perform its critical function is key to how we'll measure success of this demonstration phase, and advance our understanding about the viability of tidal energy as a source of clean, renewable power," spokeswoman Sarah Dawson said in an email.

Useful data despite challenges

The time out of the water will also allow for repairs and adjustments to some of the monitoring equipment.

Of the four hydrophones attached to the turbine, two functioned well and consistently, while one delivered data intermittently and another, located on the top of the turbine, was not responding.

"This will be investigated during the retrieval activities," said the report.

OpenHydro will remove the turbine later this month and transport it to Saint John before redeploying it at the Fundy Ocean Research Center for Energy just outside Parrsboro, N.S., whenever the work is complete

A spokesperson for the Environment Department said it was the company's decision to remove the turbine and everything about its operation to this point continues to meet the terms of the environmental approval.

The report said more than enough data was collected from the two fully functioning hydrophones to meet monitoring requirements, which focused on harbour porpoises, the mostly commonly occurring marine mammal in the area. The report said no other marine mammals were detected by the hydrophones.

Video camera not working

The imaging sonar attached to the turbine is working, monitoring an area approximately 60 metres by 104 metres, but it will be repositioned when the equipment is removed to help reduce false positives for species detection and "provide a broader view plane of the water column."

A video camera attached at the base of the turbine will also be examined.

It has logged no data since the turbine was deployed and the removal will provide a chance to see if there is a way to make it work. The interim report tempers expectations, however, saying the camera "was a supplemental component of the monitoring program and, given the harsh environmental conditions, it may not be suitable to continue its use."

Sounds 'indistinguishable' from water flow

The report also said preliminary data collected from one of two acoustic recorders on the ocean floor suggest the sound of the turbine operating is "indistinguishable from water flow noise in the Minas Passage below 60 Hz [hertz]."

A second recorder, positioned farther away from the turbine, will be retrieved when conditions are less harsh.