Mitigating Underwater Noise Impacts on Marine Mammals

Australia is in the early stages of developing its offshore wind farm capabilities. This is part of its promise to use more renewable energy and cut greenhouse gas emissions.

Australia aims to reach net-zero emissions by 2050. By 2030, renewable energy should make up 82% of electricity. Offshore wind is now a key part of Australia’s energy plan¹.

The construction of wind farms can create underwater noise. This noise can injure or disturb marine mammals like humpback whales and fur seals. These marine animals rely on sound for communication, navigation, and foraging, making them particularly vulnerable to noise pollution.

As Australia’s offshore wind projects grow, developers must find ways to reduce impacts. This is important to get approval for their projects. Noise mitigation is crucial because regulatory bodies require comprehensive Environmental Impact Assessments (EIAs) that demonstrate how developers will minimise harm to marine ecosystems.

By addressing these concerns, developers can get the permits they need to move forward with their projects. This helps balance ecological responsibility with the growth of clean energy².

A humpback whale fluke rises above the water

The Data Challenge in Environmental Impact Assessment

One challenge for offshore wind developers is understanding what data is required to inform a robust EIA. This can delay projects from moving to the next stage for approval.

This challenge is especially true for underwater noise impacts, particularly during the construction phase, which can be the most harmful to marine mammals. Consideration of noise mitigation strategies by developers is essential to address the concerns of noise pollution.

Solutions to Minimise Risk and Maximise Advantage

Advanced Data Visualisation Tools

Advanced data visualisation tools can be used to present complex environmental data in an easily understandable format. This approach enhances data accessibility and transparency, allowing stakeholders to visualise survey data interactively and download detailed reports. By making data more accessible, these tools enable the development of robust mitigation strategies and facilitate the process of securing regulatory approvals. This method has proven effective in numerous projects, demonstrating its value in advancing offshore wind development while ensuring environmental protection.

Bubble Curtains

Bubble curtains are a widely used noise mitigation technique in parts of Europe, such as Germany. These curtains form a bubble barrier around the construction site. They absorb and deflect sound waves, which considerably lowers noise levels. This method works well to protect marine mammals from underwater noise during pile driving.

Developers can use bubble curtains around the world, for example, they are being used in new offshore wind sites, like the US East Coast and parts of Asia³⁴. By using this method, infrastructure owners can greatly lower the noise from their construction work which helps to protect marine life.

Low Energy Hammers

Low energy hammers are another solution that minimises underwater noise during construction. These hammers reduce the energy used in pile driving, thereby decreasing the noise generated. In some cases, operators can drive larger hammers at low energy levels, which helps to further reduce noise impacts.

The soft start technique can also be used. This means slowly increasing the hammer’s energy. It helps reduce the loud noise at the start of pile driving. This slow rise in noise allows marine mammals to hear it and swim away from the construction site. This helps lower the chance of injury from noise pollution.

Acoustic Deterrent Devices (ADDs)

ADDs emit sounds that deter marine mammals from entering construction areas. By creating an acoustic barrier, these devices encourage marine mammals to move away from potentially harmful noise levels. Many offshore wind projects have successfully used ADDs. They keep marine life safe by preventing injury from construction activities.

Population Consequences of Disturbance (PCoD) Modelling

PCoD modelling is essential for quantifying the impact of offshore wind farms on marine mammal populations. This modelling approach helps in creating a robust EIA by addressing critical knowledge gaps.

By providing thorough assessments of potential impacts, population modelling helps the development of effective mitigation strategies and ensures compliance with environmental protection regulations. Consequently, PCoD modelling has helped support informed decision-making on projects around the world.

A close-up of a fur seal having laid left side in a pool of water, with partially dry and partially wet fur

Conclusion

As Australia works towards getting approval for its first offshore wind farm, leading the way for further future consents, APEM Group can share lessons from Europe, having supported over 60 offshore wind farms. Through experience and horizon scanning, we help clients avoid challenges before they become major problems. Using advanced technology and developing new methods, we gather, analyse and interpret the data, which helps developers get the exact information they need to make decisions and support a robust EIA.

APEM Group’s expertise in navigating complex regulatory environments ensures that our clients’ projects meet all necessary compliance standards. Taking into consideration the above solutions to minimise risk and maximise advantage, our comprehensive approach includes:

• Review of relevant legislation, guidelines, and planning conditions: Ensuring that all regulatory requirements are met from the outset.
• Technical advice on noise impact requirements: We provide advice on what to do before and after getting approval.
• Data acquisition, collation and review: Collecting and analysing data within and adjacent to the wind farm site to understand the marine wildlife population and environmental context.
• Cumulative impact assessment: Assessing the combined effects of multiple impacts and developing effective mitigation and compensation strategies, where required.
• Reports to strengthen and support research conclusions: Delivering comprehensive documentation and proposed mitigation measures for EIAs and regulatory submissions.
• Environmental monitoring services: Continuously monitoring environmental conditions to ensure ongoing compliance and protection of marine ecosystems.
• Stakeholder engagement strategies: Engaging with relevant government authorities and other stakeholders to facilitate project approvals and address concerns.