Offshore wind farms in Australia: How do we assess their impacts?

What are the challenges of assessing the cumulative impact of offshore wind projects?

Our coastlines are home to a diverse range of local marine animal and plant life. They support active fishing industries and leisure activities. They also have a strong and unique cultural significance to Australians.

The only way developers can progress multiple offshore wind farm projects is through ‘declared areas.’ These are the zones the government identify as suitable for offshore wind development. They may be thousands of square kilometres in size and spread across multiple states. Measuring and assessing potential impacts at this region-wide scale, along with other pressures on our coasts and oceans, will be challenging. Climate-related effects make this task even more tricky.

Assessing the cumulative part of an EIA is often an afterthought once completing the other main studies. And it usually has the smallest budget allocated to it. From previous experience, this has often meant searching for other approved projects in a similar area that may occur at the same time and simply listing them. But we would not usually measure those values or include them in a risk assessment.

We cannot ignore the issue of collective effects when dealing with multiple projects within one declared area. Developers will need to know exactly how their project might add to the broader environmental impacts in the area where they are working (and possibly beyond). They’ll also need to know how to measure these effects. They’ll have to think about what types of responsibilities or offsets they might need to apply during operation of their offshore wind farm. And they must count the costs for monitoring and lowering the increasing effects. This could lead to partnerships between all interested parties to explore combined project impacts.

What’s a suitable scale to assess cumulative impact?

Working out appropriate spatial and temporal scales is vital to assess the cumulative impact of offshore wind. For example, it should be broad enough to take account of the distribution and life cycles of the species affected. For migratory species, this area could be vast.

To illustrate this, let’s put ourselves back in the feathers of our migratory seabird. Shearwaters (or mutton birds) are common in Australia and are just one example of birds that tackle long annual migrations. A one-way trip to Alaska can be up to 16,000 kilometres, and weaker individuals often don’t survive the long journeys. So, let’s say our feathered friend is already exhausted from the flight home, back to southern Australia, and had to use extra energy to contend with severe weather issues, find a new habitat, and free itself from some plastic waste. It must then navigate through not one but multiple sets of wind turbines to complete the journey. The extra energy used could be too much for some birds who would otherwise survive.

It would be impossible to consider all cumulative effects on this seabird population over its long journey, but where do we draw the line? And how many other offshore wind farm projects can we expect a developer to have to consider in their EIA’s? 

Offshore wind legislation: Where are we at in Australia versus globally?

The key piece of legislation guiding the development of offshore wind in this region is the Offshore Electricity Infrastructure Act 2021 and related laws. These laws are like those for land-based development. However, what we’re seeing is an increasing demand for ‘marine land’ (the entire marine environment). This is a complex area to review, so it’s important to work out the cumulative impact that different industries have on its many features.

In Australian law, the area, size, and position of the declared areas are important when looking at the degree of possible development. We need more clarity on how the cumulative impact of offshore wind in this region can balance between what’s happening across the world. The developer must think about this global factor, such as the migration patterns of wildlife. However, it is vital to understand the extent to which developers are responsible for controlling the impact on a particular species.

Australian legislation could draw on law used in other countries, such as the US government’s National Environmental Policy Act 1969. They outline current best practices for their region. We might look at the UK impact assessment model. The model requires developers to think about collective impacts at different regional scales and particular times during the project. We haven’t faced a strong need to assess the cumulative impact in this region. We’ve not had to assess our projects alongside neighbouring project developers. From our experience, using the principles and methods used in other countries may reduce uncertainty for developers in this region. It would also improve the safeguards needed to reduce the possible cumulative impact.

There’s an opportunity for new laws that focus on the marine environment in our region. This could mean working these new rules into existing law. Combining existing and new rules would make industry and activity-specific law more consistent. 

How could you assess cumulative impact?

Using our migratory seabird, let’s look at a potential process to illustrate a possible cumulative impact scenario.

Step 1: Identify sensitive environmental species. For example, our shearwater.

Step 2: Gather information. Because there’s tracking data available for shearwaters, we can make informed decisions about where they fly, and the likelihood, timing, and frequency of them coming across turbines. We can also use knowledge about their physical traits to help understand their risk of crashing into the structures.

Step 3: Identify the factors that produce an impact for a single project. For example, physical structures, light, noise, and seabed disturbance could all affect our seabird.

Step 4: Identify other projects and activities in the region that could have collective impacts on the same factors that produce an impact. By systematically mapping out these factors we can show where multiple impacts affect our shearwater.

Step 5: Analyse the results to identify and calculate the major collective risks. For example, the collision risk for a single project may have a minor effect on the shearwaters as a population. But when scaled-up to three or four projects in one area, the impact could be vast. You can calculate the risk level on a particular species for one offshore wind project and scale it up to include multiple projects and activities. Is it still okay in terms of population-level effects?

Step 6: Develop appropriate guidance and critical thresholds. Once we have these, we can assess the cumulative impact. Honestly, this is more easily said than done. Ideally it has regulatory guidance.

Step 7: Avoid, reduce, or offset. Think about the design, where to put, or how the windfarm operates in the development area—not just the single project. That way you can lessen the potential cumulative impact. Working with and coordinating with neighbouring developments and industries is key. It will provide better outcomes.

Step 8: Set appropriate performance measures, monitor outcomes, and work out actions if you haven’t been able to achieve the right results.

What tools might assist us in assessing the cumulative impact of offshore wind projects in Australia?

The steps suggested above are idealistic. It could be costly to developers, especially if they need to collect source data over large geographic ranges. It could also add to the overall project timing and delivery. One way to help make the process easier is to develop and apply new tools to efficiently collect, analyse and monitor data.

For our shearwaters, a simple satellite tag or lightweight geo-logger can track the birds’ long journey. It can provide helpful information about behaviour when facing offshore wind turbines. Consultants can combine risk studies with GIS to identify locations or times where risk thresholds are high. 

If we can manage data sharing better, it would help everyone to understand local and global best practice and create knowledge banks of information. One of the benefits of data sharing could include control studies to improve detailed design and construction methods and operations. Not only that it can also include other users of the Declared Area and surrounding areas. This would help to avoid impacts by creating knowledge tools and data sources to inform developers when they’re reaching thresholds. These knowledge tools will benefit our shearwater population by giving us a complete and accessible database of their movements and showing where they are at any given time.

Knowing the who, where and when of migration can help guide decisions about where to build wind turbines to avoid bird mortality. For example, BirdCast™ is a radar-based tool created by a group of US government, university, and private organisations. It predicts and monitors bird migration in real-time, including during the night. This device could help protect our shearwater friend by warning windfarm managers when to restrict operations. It can also minimise any disruption to the windfarm. Stantec has also developed products to streamline the collection of regional bird data with digital tools such as Onlooker and BirdIT.

Our UK team recently used our digital consenting risk model on a project to create an environmental risk impact profile for an offshore wind farm area and cable access. The model clearly showed areas of environmental risk. Knowing about these risks early in the development process creates an effective way to identify alternative options. This process saved time and reduced costs during the project viability stage.

Where to from here?

Our shearwater has shown us how offshore wind project developers need to think about the collective impacts of their proposed wind farms. How? By thinking about the whole environment rather than focussing on single projects. The developers can use clever tools to help collect data to understand the current state of the environment. In Australia, we could use the usual variety of environmental risk assessment methods. However, we need clear guidance from the government about how to assess combined effects. To do this, global and local factors need to be considered as a specific ‘ecosystem.’