Climate change is a subject that is causing much concern worldwide; the changing of our environment will be detrimental to both humans and wildlife alike. Changes in energy such as wind power, solar energy or hydro power, as well as eating less or no meat may be the only ways we can save our planet.
Wind turbines are a source of renewable energy and one that many countries already utilise; the clean energy that they produce and their easy construction makes wind energy a prime candidate for saving the planet. However, their impact on wildlife is a subject that many scientists have been researching for years.
Wind turbine effects on wildlife
Onshore land use – Wind turbines situated on level land use more space than those located on hilly areas, but it is not the main structure of the turbine that uses all this space, it is the blades. Each turbine must be spaced approximately 5 to 10 rotor diameters apart.
In the US, studies found that they use between 30 – 141 acres (depending on the terrain) per megawatt of power. The land left between the wind turbines can still be utilised for livestock grazing, farming, roads or walking trails. Wind turbines can also be constructed on abandoned or unused industrial land, which reduces the use of good habitat or farmland. Despite this, many impacts of wind turbines on wildlife don’t just include direct mortality but also cause habitat fragmentation and destruction, noise pollution, predator attraction, and micro-climate change.
Albert Manville, an ecologist from the US, claims that as many as 440,000 birds are killed in the USA every year due to wind turbines. This is due to the birds migrating using the same strong wind currents that are highly beneficial for producing wind energy.
It is not just birds that are affected. California ground squirrels emit loud vocalizations to alert other members of their group if there is a predator nearby, and they may be forced to call even louder to compensate due to the turbine noise. A study of ground squirrels’ behaviour by using the playback of alarm calls was implemented. The study recorded their responses in two places, one close to the turbine and one further away. The individuals closer to the turbines had higher levels of awareness of their surroundings and returned to their burrows immediately after alarm calling, compared with those individuals further away from the site, indicating that the squirrels’ vigilance increased due to a decrease in hearing ability.
Despite this, another study conducted in Europe found that wintering farmland bird (corvids, gamebirds and Eurasian skylarks) distribution was not affected by the wind turbines. None were observed to avoid areas close to the turbines; however, pheasants were killed as they are the largest and least manoeuvrable of the bird species present. This study was highly important as it was the first to suggest the present and future construction of wind turbines would have little negative effect on farmland birds. Despite this information in other countries such as Spain, has discovered that up to 6 – 18 million wild birds and bats are killed by wind farms, a shocking statistic.
Offshore use – Wind turbines situated within the ocean are becoming more common in many countries, however the turbines are far larger to cope with both the weather and the strength of the sea. There are worries that the size of these offshore turbines could affect ocean activities such as fishing. Marine birds, fish and other marine wildlife can be impacted by these turbines, although most studies say this is minimal. Other studies suggest that they may even increase fish populations by acting as artificial reefs, in the same way as sunken ships do.
A study observing common eiders found that there were few fatalities due to turbines. The movement and noise of the blades rotating meant that the common eider avoided coming close to the turbines when flying into shallow waters, and numbers of the bird population remained the same.
The noise pollution from operating wind turbines is unlikely to induce hearing impairment of marine mammals. More studies need to be conducted as the low-frequency hearing abilities of different species of marine mammals varies, but it has been found that the noise impact on marine mammals is more severe when constructing the wind farms rather than when they are in full use.
The construction of the wind turbines themselves can actually cause huge environmental costs as well as affecting wildlife. The factors that are causing huge environmental impacts are the following:
- Sourcing of components/minerals (e.g. mining of minerals);
- Pollution from specialist factories which build the various components to make a wind turbine;
- Huge transport requirements between multiple specialist factories, and to the installation site;
- Preparation of the installation site (e.g. clearance of land, drainage of bogs);
- The production of concrete pillar bases; and
- The complex installation procedures for offshore turbines.
Some scientists believe that it is unlikely that some turbines would repay the carbon footprint by producing clean energy in their lifetime during their lifetime caused by creating them and installing them. Read more about the negative impact of wind turbines here.
Wind turbine effects on bats
Bats are often easily impacted by the human population due to the fact they are long-lived and have very low reproductive rates so their population growth is slow (you can read more about bats and their lifecycle here). Any drastic changes to their habitats or roosts can cause dramatic declines and threaten populations. Wind turbines have been recorded doing so.
Most bats should be able to avoid the blades by using echolocation. However, they may still harm bats due to the changes in pressure as the turbine blades rotate, which can cause haemorrhages. More information on this can be seen in the infogram oppostire.
Some wind farms are situated in areas where there are poor foraging opportunities for bats and where there are no migratory pathways, in order to reduce the number of bat fatalities. However, in other areas, bat fatalities are very high. In the US, this was higher in areas where there are prairie and agricultural lands with roosting sites, foraging opportunities and migratory routes. Of the 47 species of bats known to live in the USA and Canada, 21 of these have been reported to have died due to wind turbines.
In Germany, an estimated 10-12 bats are killed annually per wind turbine. Within the last ten years of the development of wind turbines in Germany, it is estimated that a shocking two million bats may have been killed in total.
In 2016, the University of Exeter conducted research on UK bats and turbines. After reviewing 29 wind farm sites that had known evidence of bat activity, they estimated that there are at least 64 fatalities per month overall across all sites in the study.
Effects on different bat species
The vast majority of bats killed worldwide are not just migratory species that fly at high altitudes. Species that tend to feed on the wing, are fast flying are just as vulnerable – gleaning insectivorous bats and frugivorous bats (fruit-eaters) are also killed by wind turbines, but at far lower levels.
In another study based in Germany, 72% bat fatalities were from the noctule bat, whereas only 28% were migratory species of bat. A high proportion of deaths were female from the migratory species of bats, but of the local species the main victims of turbines were juveniles. Migratory noctule species have a high vulnerability to being killed by wind turbines, again mainly females and juveniles.
The majority of the bats killed in southern Europe have been Pipistrellus species, Nyctalus species and Leisler’s bats. Rarer species such as the barbastelle, Myotis species and long-eared bat species have also been killed but in far fewer numbers.
Mitigating these effects
Although there has been a negative impact to wildlife, research into wildlife behaviour and advances in wind turbine technology have actually helped to reduce these mortalities. For example, scientists have discovered that bats are most active when wind speeds are lower. With this information wind turbine companies have concluded that turbines should be motionless during times of lower wind speeds, which in turn could benefit bats, and would not affect power production. In Germany they implemented the same method which documented that there were around 50% fewer bat fatalities due to having a lower wind speed. Better site selection for turbines can also benefit bats: by choosing areas unsuitable for bat habitation, bat mortalities can be lowered.
Researchers at Aberdeen University are currently making progress on projecting electromagnetic signals from radar as a method to try to deter bat species from coming into contact with turbine blades.
Bats rarely fly over the ocean, so offshore wind turbines are another solution to reducing bat fatalities. Their impact on marine wildlife is also far lower than land-based turbines. The Nysted offshore wind farm in Denmark was built in a duck flyway; however, duck deaths were recorded to be very low, less than 2 birds per year per tower built.
The Eurobats guidelines propose that wind turbines should not be situated closer than 200 metres to woodland, whereas Natural England suggest that the blade tips of the turbines should be at least 50 metres away from woodland or hedgerows.
A Spanish company called Vortex bladeless has designed a turbine without any blades. Instead it is designed to vibrate in the wind, harnessing that to make it into energy. According to the company these new turbines are 53% cheaper to make and 51% cheaper to operate than normal wind turbines as well as the fact that would have potentially less impact on the environment due to the lack of blades.
There is no denying that wind energy has an important part to play in trying to conserve our planet for future generations. However, more time needs to be devoted to studying the impacts that this renewable energy will have on our environment and our wildlife. By doing this, we can benefit both the future of humans and wildlife populations by making informed decisions, using both the advantages and disadvantages in order to develop turbines that are less environmentally damaging and safer for wildlife, as well as preventing climate change.
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Author: Ashley Dale