Offshore wind turbine foundations may cool ocean surface by mixing seawater

New research from the PELAgIO ECOWind project highlights how offshore wind farms can influence ocean temperatures and mixing patterns, with their effects varying based on local conditions. Led by NOC's Michela De Dominicis, the team found that while wind turbine structures can alter seawater movement and temperature, these changes depend heavily on surrounding environmental factors.

Utilizing advanced computer modeling and data from Seagreen Offshore Wind Farm in Scotland, the researchers discovered that turbine foundations can enhance natural seawater mixing, bringing cooler water to the surface and warmer water to the seabed. This can lead to reductions in summer sea surface temperatures of 0.1°C to 0.3°C within and around the wind farm, with cooling exceeding 0.5°C under extreme marine heat wave conditions.

However, the impact of wind farms on ocean mixing is not uniform; it varies depending on factors such as season, tidal conditions, and water column stratification. Some areas may be more sensitive to additional mixing, particularly where the water column layers are transitional. De Dominicis emphasized that while offshore wind farms can increase ocean mixing, the effects are not always easily detectable, as environmental conditions play a crucial role.

By integrating computer models with real-world observations, the study identifies when and where these changes are most likely to be detected, aiding future site planning and environmental monitoring. The research aims to clarify why previous studies have had difficulty identifying clear effects, as the impacts can often be similar in size to natural ocean variations.

Collaborations between NOC, the University of Aberdeen, and the Scottish Government Marine Directorate helped validate the findings through a combination of field measurements and numerical modeling. Professor Beth Scott from the University of Aberdeen noted the importance of this work in providing accurate estimates of offshore wind farm impacts on the ocean environment, aiding in the design of more effective monitoring programs.