Seals see no ‘barrier’ in SeaGen tidal turbine

A new study has found that the presence of SeaGen tidal turbine in Northern Ireland did not prevent harbor seals from passing through the channel, detecting only small effects in their movement associated with the device.

The study, conducted by SMRU Consulting with the Sea Mammal Research Unit, explored how the presence of a tidal turbine might affect the movement of harbor seals by analyzing tracking data from resident seals, before, during and after the installation of SeaGen in the Strangford Lough.

Data obtained from 32 electronic tags showed the SeaGen turbine did not prevent transit of the animals through the channel and therefore did not result in a ‘barrier’ effect, according to the study.

However, the animals’ behavior did change when the turbine was operating as the seals would swim past the turbine slightly less often, demonstrating the importance of allowing for behavioral responses when estimating collision risks associated with tidal turbines.

The study found that seals appeared to give the turbine a wide berth, typically passing either side of it by a few hundred meters, showing some degree of local avoidance compared with the pre-installation results.

“This study only looked at the effects of a single turbine rather than an array, and mitigation limited the ability to determine close range interactions. However, the study indicates that the effect of the turbine on Strangford Lough harbor seals was minor and that collision risk was reduced by the behavior of the seals,” the study states.

The research was commissioned due to concerns about the risk to seals posed by operating tidal turbines.

Having provided extensive engineering and environmental learning for the tidal energy industry, the SeaGen tidal turbine has reached the end of its operational life and will be removed from the Strangford Narrows over the winter of 2017/18.

Atlantis Resources became the owner of SeaGen in 2015 by having acquired Marine Current Turbines (MCT) from Siemens.

The 1.2 MW SeaGen tidal device was installed in 2008, and has since generated 10GWh of electricity from tides. The system consists of twin turbines, 600kW in capacity each, mounted on a crossbeam. The rotor diameter of each turbine is 16 meters.