Better Integrated Response for Diminishing Strikes in Offshore Wind Flight Environments (BirdSafe)

WHY

Offshore wind farms can pose a risk to migrating birds, which may collide with the spinning turbine blades and die as a result. Bird migration is a common natural event, with billions of birds from many species travelling between their breeding and wintering areas each year. This is especially common in northern regions.

Different species migrate at different times. Long-distance migrants, which breed in northern areas and winter in (sub)tropical regions, can start migrating as early as June. Short-distance migrants leave later, with some spending the winter in the United Kingdom. These birds cross the North Sea twice yearly, mainly in autumn from late September to November.

Like thrushes and starlings, most songbirds migrate at night to avoid predators. Because of this, the most significant risk of collisions with offshore wind turbines occurs during the nighttime migration of songbirds. Some of these species are particularly vulnerable to wind turbine collisions.

So far, there’s little data on how many wind turbine related bird casualties there are and how (song)birds behave inside offshore wind farms. Instead, predictions rely primarily on computer models. As a result, we do not know how much current and future wind farms affect migrating songbirds.

To better understand the real impact, we need more data on how songbirds move toward and through wind farms. Measures like the “Start/Stop” procedure for wind farms are used to reduce bird casualties. This involves turning off turbines or slowing them down (curtailment) when many birds are expected to fly through. To do this effectively but also to ensure stable wind power supply, accurate bird migration forecasts are needed at least 48 hours in advance.

Even though the current Start/Stop system uses the best available knowledge, we do not know how well it actually works or how to improve it. Meanwhile, shutting down turbines during bird migration will have more impact in the coming years as the number of wind farms and our dependency on their energy supply will increase. Ineffective curtailment also lead to extra CO2 emissions from backup power plants that must fill the gap.

WHAT

This BirdSafe project aims to balance bird safety, energy security and operational costs better. This will be done by measuring how birds move around and through wind farms and individual turbines and how often they collide with turbines. Based on this data, we will improve and innovate models to predict bird collisions. The project focuses mainly on songbirds during autumn migration, as more birds fly at turbine height during this season than in spring. The collected data will be shared with project partners and made public after the project has ended.

To address the challenges, we need to:

• Collect high-quality data on bird migration;
• Understand bird behaviour and build reliable models;
• Develop practical recommendations with key stakeholders.

Collecting data We will install over 80 night cameras distributed over several wind turbines, and we place bird radars in at the Hollandse Kust Zuid (HKZ) wind farm. To expand the database further, the Gemini wind farm will share its radar data. We will use the radar systems to track bird movements around and through the wind farm. The cameras will monitor bird activity near individual turbines. The images will be processed to map flight paths and bird densities through the wind farm.

Analysing data and modelling behaviour With the collected data, we will develop a model to estimate the collision risks of migrating songbirds and a bird flow model to determine bird behaviour through a wind farm. In doing so, we most likely identify turbines with higher bird densities and collision risks based on various parameters, such as the wind farm's layout and the turbines' operational status. Radar experts help interpret the collected data, including bird numbers and flight heights. Ecologists provide insight into bird behaviour and help build accurate models based on the findings.

Developing recommendations Based on the data and models, we will make recommendations for curtailment of offshore wind turbines. In cooperation with the Start/Stop project team, we will propose improvements for the operation of wind farms, considering ecological, security of energy supply and financial considerations. The recommendations will be discussed with all relevant stakeholders, including NGOs, government agencies, TenneT and wind farm owners.

EXPECTED RESULTS

The results of the project are:

• A hardware design and a method to effectively measure bird migration in and around a wind farm and the realisation of an extensive – publicly accessible - data base with radar and camera measurements of bird movements and bird collisions.
• Insights of bird flows and flight behaviour during peak migration events.
• Improved empirical bird collision and bird flow models.
• Alternative strategies for managing wind farm activities during migratory bird movements. Including consideration of potential advantages and disadvantages of the different options, from an ecological, security of supply and financial perspective.
• Outreach programme to relevant stakeholders in the Netherlands and neighbouring countries and the public.