Biosis Collision Risk Model

Wind energy is a vital part of the transition to clean, renewable energy. Wind farms now operate in each in every Australian State and further wind energy projects continue to be planned for both the onshore and offshore environments. Unfortunately, both here and internationally some species of birds and bats have been found to collide with turbines at commercial-scale wind farms.

A growing body of evidence from operating wind farms demonstrates that, while a few species are prone to collision, many others do not collide with turbines or do so extremely rarely. Nonetheless, collisions represent an impact on affected species and significant efforts are being made to reduce their occurrence. A variety of sophisticated technologies are becoming available for this purpose and a number of these show real promise for substantially resolving this issue. In the meantime, consideration of collisions with turbines is an important part of pre-approval assessment of the impacts of new wind farms on birds and bats.

More than twenty years ago, in partnership with Symbolix Pty Ltd, Biosis developed a mathematical model designed to provide quantified estimates of collision risk for birds. The Biosis Collision Risk Model has continued to be refined and remains the only model developed for this purpose in the southern hemisphere. It has been applied widely in environmental assessments across the Australian wind energy sector. For a proposed wind farm the model takes account of the particular geometry, specifications and layout of turbines along with large sets of data for bird flight activity obtained from the site. It isn’t feasible to readily measure the frequency of the flights of most bats, so the model cannot be applied to bats.

Using relevant input parameters, the model provides estimates of the annual number of potential collisions for each species of bird. It has recently been possible to evaluate the performance of the model by comparing its estimates with the accumulated experience for collisions by eagle species at operating wind farms. The model’s estimates closely match actual collisions. So, the model offers wind energy companies and regulatory authorities a sound basis for this aspect of environmental impact assessment for proposed wind farms.

Further reading on the Biosis Collision Risk Model