power has become an important competitor in the race for clean
energy, but like many newer developments, it needs some work. One
issue associated with wind power is bat and bird-related fatalities
due to the spinning blades of the turbines. However, researchers may
have solved this problem with a slight
change in speed.
Arnett project leader from the Bat
Conservation International in Austin, Texas, along with John
Hayes, co-author of the study from the University
of Florida, have studied bat fatalities
associated with wind turbines and concluded that altering
the speed slightly would reduce a large percentage of these deaths.
turbines within the United States are programmed to start producing
power when wind speed reaches 8 or 9 mph. The speed at which wind
turbines begin producing power is the cut-in speed, and those with a
low cut-in speed tend to run more often than those with a high cut-in
speed because they begin running at lower speeds in the first place.
Hayes and their research team recorded bat fatalities while observing
12 out of 23 turbines at the Casselman
Wind Project in Somerset County, Pennsylvania. They stayed
for 25 summer and fall nights in 2008 and 2009 (because wind speeds
are low this time of the year), and found that the less time a wind
turbine is running, the better because bats cannot
be harmed by blades that aren't in motion. Following this logic,
Arnett suggests raising the cut-in speed of wind turbines to 11 mph,
which would result in a reduction of bat fatalities by approximately
44 to 93 percent and an annual power loss of less than one percent.
is the only proven mitigation option to reduce bat kills at this
time," said Arnett. "If we want to pursue the benefits
associated with wind energy, we need to consider the local ecological
impacts that the turbines could cause. We have already seen a rise in
bat mortality associated with wind energy development, but our study
shows that, by marginally limiting the turbines during the summer and
fall months, we can save bats as well as promote advances
in alternative energy."
notes that reducing bat fatalities is essential because bats help
with pollination and pest management, making them an important part
of ecosystem health nationwide.
do you see such a win-win result in a study," said Arnett.
"There is a simple, relatively cost-effective solution here that
could save thousands of bats. This is good news for conservation and
for wind energy development."
study was published in Frontiers
in Ecology and the Environment on
quote: The same people that do these studies also state that turbines kill birds
quote: For bats, vision is important for foraging and homing, and for predator avoidance. Mesopic vision (at light levels that stimulate both the rods and the cones) is particularly relevant at dusk and dawn and on brightly moonlit nights. For flower-visiting and nectar-feeding bats like those studied here, UV vision should increase foraging success, as many flowers visited by bats show UV reflection.
quote: While the total number of birds killed in the US each year fluctuates, Michael Fry of the American Bird Conservancy estimates that US wind turbines kill between 75,000 and 275,000 birds per year.
quote: Blade rotational speed was a significant negative predictor of collisions with turbine blades, suggesting that bats may be at higher risk of fatality on nights with low wind speeds
quote: This followed previous research that showed that bats can have their lungs ruptured from the sudden low pressure of passing turbine blades: the bats are actually drowning in mid-air. It is not necessary for the bats to collide with the turbines, bats don't even need to come in physical contact with the turbine blades. A blade passing close by is enough to be fatal—an unexpected hazard that was previously unsuspected.
quote: Yet a July 2008 study of the wind farm at Altamont Pass, California, estimated that an average of 80 golden eagles were killed there by wind turbines each year.