Everyone with an environmental conscience knows that we need more of our power to come from clean, renewable energy sources. Wind power is one of the oldest and best established green energy sources, and scientists predict that the U.S. could easily meet up to 20% of our energy needs using wind power alone. This is great news for the planet as a whole, since it means less carbon dioxide and other pollutants being spewed into our atmosphere. However, unless we take steps to protect them, it's bad news for bats.
Recently, the London Times reported on the results of a six-week study that monitored wildlife deaths at two wind farms in the Eastern U.S. The death toll was particularly severe for bats, with 1,764 deaths at one wind farm and 2,900 at the other. The Times also cites the results of another study in Montana that showed bats keeling over next to wind turbines at twice the rate of birds. According to the U.S. Geological Survey, migratory bats that roost in trees, such as the hoary bat, are the most common victims at wind farms, although all species of bats have been found.
What's causing the slaughter? Bird deaths at turbines are usually caused by trauma, when birds collide with the turbine blades. Bats, on the other hand, are able to use sonar to avoid the blades most of the time. However, the air pressure around a wind turbine is significantly lower than that of the surrounding air. This sudden drop in pressure causes severe internal injuries to bats if they fly too close. As the BBC describes it:
"A bat flying into the low-pressure zone finds its lungs suddenly expanding, bursting capillaries in the surrounding tissue which then becomes flooded with blood."- BBC
Poor bats! The impact of wind turbines on the bat population is a particular concern here in the U.S. Even before the country finally decided to start focusing on the development of clean energy sources such as wind, our bat population was already vulnerable. Bat populations in general have suffered from deforestation and the closing of caves and mines, which gives them fewer places to roost. Then, in the Northeast this year, an even more serious threat to bats emerged, with thousands of bats dying from a mysterious illness called "white nose syndrome".
The New York Times reported on white nose syndrome back in March. Nobody is quite sure what causes this illness, but it appears to spread rapidly among hibernating bats and has an almost complete mortality rate. The noses of affected bats turn white, and they waste away and die during winter hibernation. Many bats are afflicted by a fungus and/or pneumonia, but the researchers quoted in the article believe these may be secondary symptoms. Some scientists believe that a bacteria or virus might be the cause; others are investigating whether new pesticides could be causing or contributing to the problem. The suddenness, mysteriousness and deadliness of white nose syndrome bring to mind the colony collapse disorder affecting U.S. honeybee populations.
Whatever it is that's causing the illness, the consequences so far have been severe, with a death toll estimated at 11,000 bats or higher. A U.S. Fish and Wildlife biologist, Susi von Oettingen, was quoted in the New York Times saying "If we can't contain it, we're going to see extinctions of listed species, and some of species that are not even listed."
With bats already undergoing heavy mortality in the Northeastern U.S. from this illness and suffering elsewhere in the country from loss of habitat, it's easy to see how an increase in wind power could negatively impact populations. Even worse, bats are not fast breeders. Each female gives birth to one pup a year, so it takes a long time for bat populations to recover from a decline. Of course, every energy source has its advantages and its trade-offs. As the "comments" section of the London Times article demonstrates, it's easy to argue that bat mortality is a small price to pay to get electricity without greenhouse gases.
However, we also have a responsibility to protect the other creatures that share this planet. Aside from this moral responsibility, we should be concerned about bats because they are useful to humans. We often overlook bats because we rarely see them. Some consider them vermin, like flying mice. Other people are even afraid of them. In fact, bats are gentle, non-aggressive and an important part of the ecosystem.
What do bats do for us? Take a look at the following facts:
- Most bats are insectivores. They consume several times their body weight per day in insects. The insects they feast on are most often the ones we don't like: crop pests and/or mosquitoes. The New York Times notes that a study of freetail bats in Texas found that their presence saved cotton farmers 1/6 to 1/8 of the cash value of their crop, all without the use of toxic pesticides.
- Other bats eat flower pollen and nectar. In the process, they pollinate plants just as bees and butterflies do. In fact, at least 400 species of economically important plants rely on bats for pollination and to spread seeds.
- Even the dreaded vampire bat has helped scientists create an anticoagulant medication to treat heart disease.
America's newfound interest in renewable energy is long overdue. Climate change is a real problem and we need to address it. We have to reduce the amount of carbon dioxide and other green house gasess that we put in the atmosphere. Doing so effectively is impossible without wind power. So, what can we do to develop the potential of wind energy without devastating bat populations?
According to the BBC article, radar may provide a way to scare bats away from the turbines. Turbines could also be turned off at peak migrating times, a process known as feathering. However, this would interfere with power generation. Bat- and bird-killing turbine blades are essential to wind energy as we know it today.
What if we just got rid of the blades altogether? Some companies are developing systems to capture wind energy using kites instead of turbines. For example, a company called Kite Gen has developed a prototype for a kite-powered power generator. Kite energy is still in its early stages, but the idea is promising. Kites can reach higher, windier levels of the atmosphere than turbines can, so they could capture more power. They also create less of a visual disruption. Of course, the impact on wildlife has not been studied yet. The environmental concern statement on Kite Gen's website states:
"Specific and detailed analysis will have to be conducted for the Kite Gen power plants, but the higher operative height of the power kites appears to be a positive factor, considering also that the speed of the lines' movement decreases as they get closer to the steering units at ground level."- Kite Gen environmental concern statement
Kites fly at higher altitudes than turbine blades, so they should be less likely to interfere with birds and bats. Maybe taking turbine blades out of the picture completely can help us obtain the clean energy we need with less cost to wildlife. If nothing else, we need to do more research and development on ways to capture wind energy with minimal impact to our fellow creatures.