About wings: birds, bats and wind turbines

One of the nature protection issues that concerns the public during the development of wind power plant (WPP) projects is the protection of birds and bats; therefore, scientific survey of the intended operation areas is essential. Ornithologists and chiropterologists are currently conducting research and on-site surveys at the planned locations of Latvenergo AS wind farms. The results obtained there will be used in the subsequent stages of project development in order to find the optimal solutions for the coexistence of biodiversity and renewable energy generation.

One of the key factors to be taken into account in the development of WPP projects is the impact on biological diversity. The potential impact of WPPs on avifauna and bats is one of the typical impacts related to the construction and operation of wind farms. Accordingly, to respect the bird and bat habitats, Latvenergo AS has contracted certified ornithologists and chiropterologists in the very early stages of the project, who began their research this spring in several areas to survey, collect data and assess the actual situation. This will allow to identify any potential conflict situations and plan mitigation measures in time so that the number of collisions and deaths of birds and bats is kept to a minimum. Field research is taking place at 6 planned WPP locations and will continue throughout this year.

The challenge of coexistence of WPPs with the bird population is nothing new
The natural bird population in Latvia is diverse; therefore, balancing the interests of avifauna and wind power is a great challenge when planning wind farms. There are many birds in Latvia, and the most sensitive group of them – diurnal birds of prey, as well as specially protected birds – are uniformly distributed throughout the country. For example, no other European country has so many lesser spotted eagles as does Latvia. Their population of Latvia in 2018 was estimated at 4,334 pairs, making Latvia one of the core areas of the global population with approximately 20% of the global population [1].

When designing a wind farm, according to the law [2], the minimum permissible distance of wind power plants that is safe for the birds must be determined by a certified ornithologist as part of the EIA process.

In order to reduce the impact on wild birds during the planning, construction and operation stages, various new tools and methods are being tested in Europe and elsewhere in the world, which could supplement the safety equipment of WPP turbines, reducing collision risks. Several countries have developed collision risk models, which use practical survey data and monitoring data from operating WPPs to study the impact of the number and layout of turbines in planned WPP farms, as well as to select their final placement.

Norway, for example, is developing various innovative solutions, such as the use of ultraviolet radiation, radar and image processing systems, etc., which are being tested at the Smøla WPP park [3]. Some countries use various passive visual deterrents – painted towers and blades, various patterns. There are places in the EU, however, where they are not allowed. During short and predictable periods of time, for example during the migration season, the method of temporary WPP stoppage has experimentally proven its effectiveness in preventing bird collisions and causing minimal loss of energy generation. In some cases the DtBird®104 video detection system is used, which automatically identifies birds and can independently perform two types of action to reduce the risk of bird collisions: emit active warning sounds and/or to stop the turbine. Although the technologies mentioned here still need some improvements, when combined with other technology, they are designed and are being improved to reduce the impact of WPP on wild birds to a minimum, thus harmonising the generation of renewable electricity with the environment where it is taking place.

Another type of flying fauna to consider in the context of WPPs are bats. Studies [4] have shown that the greatest impact of WPPs on bats happens near forest edges, watercourses and water bodies where bats congregate, as well as during the autumn migration period starting from the end of July to the beginning of October (90% of cases). It is worth mentioning that, unlike birds whose deaths near wind turbines are mostly accidental, bats in most cases approach WPPs deliberately – both because these objects under certain conditions attract insects that bats feed on, and, in some cases, to use WPPs as roost sites (shelter), as well as using the rotor towers as navigation landmarks.

The European Guidelines on the Conservation of Populations of European Bats or EUROBATS [5], are used to assess the impact of WPPs on bats.

Since the latest studies suggest that wind turbines can attract bats even if the risk of collisions has been assessed as low, bat monitoring should be carried out for the first two years after the construction of the WPP and the option of restricting the WPP operation in case of bat deaths or increased risk of death should be considered. Chiropterologists (bat experts) recommend such measures in EIA statements for WPP farms in Latvia [6].

To reduce the risk of death of bats, it is recommended to equip the WPP with an automatic adjustable mode (bat mode) – to stop the operation of turbines during key periods of bat migration. The bat mode is currently the most widely used solution, but there are other efficient ways to reduce the potential impact of wind farms on bat populations. New solutions to deter bats are actively being sought, for example, placing ultrasonic generators on turbines that create a high-frequency sound that is unpleasant for bats but inaudible to humans to keep bats away from wind farms [7] and to ensure a lower future impact on the bat population already during the wind farm construction stage.

Another method is to repel insects, which would make the rotor less attractive to bats as a potential feeding site. Such studies have been carried out by US scientists and it has been found that ultrasonic devices are effective and reduce the potential impact on bat populations in the immediate vicinity of wind farms.

Appropriate location of WPPs and the associated infrastructure is the most logical mitigation measure to avoid negative impacts not only on birds and bats, but the wildlife in general.

Wind energy is considered one of the cleanest and safest forms of energy; however, it is impossible to fully avoid impact on avifauna and bats. Nevertheless, by doing adequate research, looking for the most successful solutions, including the layout of WPP and the most efficient technologies, it is possible to ensure that the impact caused by wind farms is minor and does not exceed reasonably permissible levels.

[1] BERGMANIS, U. 2019. Mazā ērgļa Clanga pomarina aizsardzības plāns Latvijā. Latvijas Dabas fonds, Rīga

[2] Regulations No. 240 of the Cabinet of Ministers of April 30, 2013. "General Regulations for the Planning, Use and Building of the Territory", Paragraph 163

[3] Innovative Mitigation Tools for Avian Conflicts with wind Turbines, https://www.nina.no/english/Research/Projects/INTACT

[4] [5] Rodrigues L., Bach L., Dubourg-Savage M.-J., Karapandža B., Kovač D., Kervyn T., Dekker J., Kepel A., Bach P., Collins J., Harbusch C., Park K., Micevski B., Minderman J. 2015. Guidelines for consideration of bats in wind farm projects — Revision 2014. EUROBATS, Publication Series No. 6 (English version). UNEP/EUROBATS Secretariat, Bonn, Germany, 133 pp, https://www.eurobats.org/sites/default/files/documents/publications/publication_series/pubseries_no6_english.pdf

[6] Opinions on the construction of wind power plants "Dobele" and "Pienava" in Dobele and Tukums municipalities contained in environmental impact assessment reports and on the environmental impact assessment report of the construction of the wind power plant park "Laflora" in Līvbērze parish of Jelgava municipality, Environment State Bureau.

[7] Sara P. Weaver, Cris D. Hein, Thomas R. Simpson, Jonah W. Evans, Ivan Castro-Arellano, Ultrasonic acoustic deterrents significantly reduce bat fatalities at wind turbines, Global Ecology and Conservation, Volume 24, 2020, e01099, ISSN 2351-9894, https://doi.org/10.1016/j.gecco.2020.e01099

Dainis Kanders, Environmental Risks and Development Project Manager of Latvenergo AS