The European Marine Energy Centre (EMEC) has completed a series of drifting acoustic surveys around Orbital Marine Power’s O2 tidal turbine at the Fall of Warness site in Orkney. The surveys, carried out in July and August 2025, form part of the EU-funded FORWARD2030 project under the Horizon 2020 programme.
The objective was to quantify and characterise underwater noise generated by the O2 turbine, which has been operating at the site since 2021. Understanding the acoustic footprint of tidal devices is a key requirement for assessing potential impacts on marine ecosystems and for supporting evidence-based permitting of new projects.
The monitoring campaign deployed SoundTrap hydrophones encased in drogues, suspended 5m below the surface. Each system was tethered to a buoy with an additional float carrying a flag, light, and GPS tracker to ensure positional accuracy and safe retrieval.
To minimise vessel interference, EMEC’s team switched off engines and sonar during deployment, allowing the hydrophones to drift passively with the tide. This method aligns with international standards (IEC TS 62600-40:2019) and is considered more effective at high-flow tidal sites than fixed seabed installations, which can introduce hydrodynamic noise.
The monitoring approach was developed with input from acoustic specialists at the University of Washington, whose DAISY design informed EMEC’s drift-based solution.
The campaign began with control surveys at Westray South, a comparable tidal site without turbines. Baseline noise data were recorded as hydrophones drifted up to 1000 metres during flood tides.
Subsequent surveys were conducted around the O2 turbine in collaboration with Orbital Marine Power. Across two operational survey days, EMEC completed 45 drifts, capturing data along the turbine’s port side and downstream wake. Most drifts lasted approximately three minutes, with some extended for additional coverage. A subset of drifts deployed dual hydrophones simultaneously to enhance localisation of sound sources.
The collected acoustic data is now being processed. Field notes are being digitised and recordings segmented using GPS tracks. The results will inform a detailed acoustic profile of the O2, providing insights for both regulators and developers.
According to EMEC, the surveys reinforce the importance of robust environmental monitoring in the ocean energy sector. By supplying high-quality, standardised acoustic data, EMEC aims to strengthen regulatory confidence and streamline permitting, contributing to the sustainable scale-up of tidal power technologies.
