New research into the impact of tidal power turbines on marine wildlife carried out at the site of a pioneering project in Northern Ireland has concluded previous estimates may have “significantly” overestimated the threat.

The study, which looked at the ‘hit-rate’ for silver eels in Strangford Loch where the 1.2MW SeaGen prototype turned between 2008 and 2019 when it was decommissioned, suggest only 0.3% of the snake-like fish – rather than the previously estimated 1% – would have been killed during operation.

Using a high-precision model developed by HR Wallingford that factored the “real swimming behaviours” of a range of species that live in the Loch – one of the highest ranking locations for marine biodiversity in Europe with over 2,000 species recorded and a migration route for over 15,000 silver eels – researchers found the likely impact was “significantly lower than predictions using older methods”.

“Our study looked at the collision rates for silver eels swimming through Strangford Loch as they migrate from the river to the sea,” said Tom Benson, project manager at HR Wallingford, which published its findings in the journal Renewable Energy.

“There is plenty of evidence to show that eels swim near the surface at night and deeper in the daytime. Using this information, we were able to demonstrate that just 1.1% of silver eels would have collided with the SeaGen turbines, significantly lower than predictions using older methods. In the future, we also hope to include the effect of fish actively avoiding turbine blades.”

Rémi Gruet, CEO of industry body Ocean Energy Europe, said: “This study offers yet more evidence that ocean energy can develop in harmony with marine wildlife. It reinforces existing research showing that tidal turbines do not represent a threat to fish or mammal populations.

“The ocean energy sector will continue its rigorous environmental monitoring programmes to ensure it keeps little to no impact on marine flora and fauna, even as more devices are put in the water.”

The SeaGen unit was the world’s first industrial-scale tidal power turbine, a ‘surface piercing’ design that featured twin 16-metre-diameter rotors that could be raised and lowered into the water on a central foundation column, was installed installed in 2008 by then-owner Marine Current Turbines and later acquired by Siemens and sold on to Simec Atlantis Energy. The turbine produced 11.6GWh of power over its operating life.

Despite a global potential estimated as large as 300TW, tidal power remains an industry in its infancy, with Simec Atlantis Energy one of the few developers championing the sector, through project such as its 6MW MeyGen project off Scotland – about to graduate to its next, 80MW phase, as a hub for energising the world’s first ocean-powered data centre , a multi-hundred-megawatt array off France, and a single-turbine demonstrator off Japan.

Simec Atlantis Energy CEO Tim Cornelius told Recharge: “MeyGen continue to work with Scottish government, regulators and universities to utilise the latest developments in marine science to predict with increasing accuracy the behaviour of marine life around operational tidal turbines, and in doing so increase the evidence base to support the build out of tidal arrays across the UK.”

In Canada, UK outfit Sustainable Marine Energy and local player Minas Tidal have agreed to co-develop their test berths at the Fundy Ocean Research Centre for Energy in the Bay of Fundy off Nova Scotia, as a 9MW project, creating the largest in-stream tidal array in North America so far.