Scottish Natural Heritage: Two New Reports on Marine Renewables

Scottish Natural Heritage (SNH) have recently completed two reports relating to marine renewable energy developments and their potential impact on the environment.  These reports offer a risk assessment of the interaction between marine renewable devices and the diving birds and megafauna in the area.

The first report, Commissioned Report No. 773. A Diving Bird Collision Risk Assessment Framework For Tidal Turbines, was funded by Marine Scotland and is available through Marine Scotland and SNH.

The second report, Commissioned Report No. 791. Understanding the potential for marine megafauna entanglement risk from marine renewable energy developments, is available through SNH.

Summaries and links to both reports can be found below.

Commissioned Report No. 773. A Diving Bird Collision Risk Assessment Framework For Tidal Turbines

Marine tidal energy schemes are likely to make a substantial contribution to the mix of future energy sources within Scotland and the UK, but their environmental impacts are poorly understood. For diving seabirds, collisions with tidal turbines represent a potential way in which tidal energy developments may cause population-level impacts

This report describes an approach for assessing the collision risk of diving birds with tidal turbines, known as the exposure time population model (ETPM). The approach explores the collision rate required to achieve a critical level of additional mortality by estimating (i) thresholds of additional mortality for the population at risk of collision (via population modelling) and (ii) the potential time that each individual within the population is at risk of collision (via exposure time modelling).

Apart from the ETPM, there are a number of other models used to assess collision risk of marine wildlife. We currently do not favour any one model when undertaking a collision risk assessment.  All of the available models are likely to have imperfections, and the accuracy of the model predictions is dependent on the quality of the input data. Nonetheless, given the limited knowledge base and poor understanding of the underwater movements of diving birds and their behavioural responses to underwater devices, this approach is considered an appropriate and useful method for assessing collision risk of diving birds.

Commissioned Report No. 791. Understanding the potential for marine megafauna entanglement risk from marine renewable energy developments

Offshore wind is the largest sector representing a large proportion of the current and foreseeable installed generation capacity with over 5GW in the planning process, mostly off the East coast. Floating wind projects are currently also in the planning process but have yet to be consented and installed.

This report considers the potential entanglement risk to marine megafauna from moored marine renewable energy developments (MRE).  Existing information relating to entanglement is reviewed, and a qualitative risk assessment was developed to assess relative risk to marine megafauna on the basis of biological (body size, manoeuvrability etc.) and physical (mooring characteristics) risk factors.  Results suggest that MRE device moorings are unlikely to pose a major threat, but that some mooring designs pose a greater relative risk than others.  Recommendations are made to assist developers include relevant information in their development applications.