Scientists studying Scotland's Seagreen Offshore Wind Farm have identified how turbine foundations can influence ocean mixing and temperatures, with implications for environmental monitoring
New research has revealed how offshore wind farms can influence ocean temperatures and mixing, and why their effects depend on local conditions.
A team of scientists, led by National Oceanography Centre (NOC) senior research scientist Dr Michela De Dominicis, has found that while offshore wind turbine structures can alter ocean mixing and temperature, their effects depend strongly on the surrounding conditions.
Using a combination of advanced computer modelling and real-world observations collected at Seagreen Offshore Wind Farm, Scotland's largest offshore wind farm, researchers investigated how turbine foundations influence the movement of water in the ocean.
The modelling results, published in the journal Scientific Reports, suggest that the underwater structures can enhance the natural mixing of seawater, bringing cooler water towards the surface and warmer water towards the seabed.
In the model simulations, turbine-related mixing was associated with reductions in summer sea surface temperatures of around 0.1°C to 0.3°C within and around the wind farm. During the modelled 2023 marine heatwave conditions, cooling exceeded 0.5°C in some locations.
Effects Depend on Local Conditions
But the study shows there is not just one type of offshore wind farm effect. Instead, the type and level of impact depend on factors such as the season, tidal conditions and how layered the water column is.
Some areas are much more sensitive to additional mixing than others, particularly transitional zones between mixed and stratified waters.
Dr De Dominicis said that “offshore wind farm structures can increase mixing in the ocean, but this does not always lead to changes that we can easily detect”.
“Environmental conditions determine when and where these effects are strongest,” she said.
“By combining computer models with field measurements, we can identify when and where these changes are most likely to be detectable, and which areas are most sensitive to change. This could contribute evidence to future offshore wind site planning, as well as help to inform the design and environmental monitoring.”
Combining Models and Field Measurements
The research may help to explain why previous studies have sometimes struggled to identify clear changes caused by offshore wind farms. In many cases, the effects can be similar in size to natural variations in the ocean, making them difficult to detect.
Earlier EcoWind research projects in British waters have also examined how offshore wind development may alter water flows, seabed conditions and marine ecosystems, including in the eastern Irish Sea.
To overcome this challenge, the team – including researchers from NOC, the University of Aberdeen and the Scottish Government Marine Directorate – combined field measurements with numerical models.
The models helped identify when and where offshore wind farm impacts were most likely to occur, while observations collected by oceanographic instruments and autonomous gliders were used to assess and support the modelled findings.
Implications for Future Offshore Wind Monitoring
The scientists say the work offers valuable new insights for both scientists and decision-makers, providing a clearer framework for understanding when offshore wind farm impacts are most detectable and how future monitoring programmes can be designed more effectively.
The findings are relevant to environmental assessment as Ireland develops its national maritime area plan for offshore renewable energy.
The results suggest that carefully targeted observations, particularly during strongly stratified periods, are more likely to capture changes caused by turbine structures.
The full paper, Environmental controls on the detectability of hydrodynamic changes induced by offshore wind farm structures, is available in Scientific Reports.
More coverage: Power From the Sea – Offshore Renewable Energy.
