Wind Energy Planning

A radar beam can reduce bat activity near wind turbines by almost 40% a new study has revealed.

According to the University of Aberdeen, radar beams could be used as a precautionary measure to divert bats away from potential hazard zones. The turning blades of wind turbines could pose a risk to UK bats but researchers have discovered from practical trials that a stationary radar beam can reduce bat activity in wind farms.

Research author Paul Racey from the University of Aberdeen said that collision risk from wind turbines is a risk to bats in the US and mainland Europe – specifically to migrating bats. Little is known about the effect of more modern taller wind turbines on different bat species in the UK.

The bat diversion radar tests involved both a rotating and a stationary antenna that used two different radar signals with different pulse lengths. The results showed that a fixed antenna was most effective at keeping the bats away. Radar signals led to a drop in bat activity of nearly 40% in an area 30 metres from the device. Bats were apparently unharmed by the radar and returned once the radar was switched off.

The researchers said that with refinement and purpose-built radar transmitters, the effect could “be even greater…we want 80- 90% reduction in bat activity,” said Racey.

Scientists do not yet understand why bats avoid radar signals. Suggested explanations include radar energy heating up the bats’ wings or ears said Racey.

The Department for Environment, Food and Rural Affairs (Defra) in the UK – has in light of evidence from outside the UK now commissioned a three-year study to collect information on the effect wind farms are having on bats in the UK.

In March 2009 Defra commissioned the University of Bristol and the Bat Conservation Trust (BCT) to carry out a research project on bats and wind turbines: ‘Determining the impact of wind turbines on bat populations in Great Britain’. The initial phase was to establish what information and research is currently available on bats and wind turbines. Phase 2 of the project is planned to commence this month and will comprise a three-year project gathering data on bat activity and bat fatalities at wind farms in England, Scotland and Wales.

The Bat Conservation Trust’s Position Statement on wind farms says that they support the development of sustainable energy but believes that it is imperative that the possible harmful effects on bats and other wildlife are taken into account before deciding on the siting of wind turbines both large and small.

The BCT are concerned with the positioning of mid-sized wind turbines in hedgerows. BCT also opposes the move to make the installation of these small-scale household wind turbines permitted development (ie not requiring submission of a planning application).

BCT want to see monitoring undertaken at existing wind energy sites and monitoring of all new turbines, whether large or small. BCT hopes that future updates of the British Wind Energy Association’s guidance on wind farm development and nature conservation will reflect the need to consider bats in the planning of wind farms.