Turbines transect flight paths, threaten species

By Natalie Helms

TILIRAN, Costa Rica ­– Trees bent backwards on the Costa Rican mountainside as the powerful trade winds whipped across the green landscape.

The howling wind fought and pushed back against the group of students struggling to move forward to the edge of a cliff for a view of Lake Arenal in the distance. Massive wind turbines were scattered on the mountain’s crest to the left and right. The white giants towering overhead took advantage of earth’s natural force as the blades spun at an impressive speed.

Wind power is one of the largest renewable energy sources in Costa Rica behind hydropower; about 95 percent of the country’s total energy is renewable.

Long known for its ecotourism and environmental consciousness, Costa Rica’s wind energy efforts reinforce this notion. But opponents say the turbines contribute to the death of the nation’s birds and bats. The turbines in a wind farm are systematically placed in areas exposed to high winds. Arranged like this, it’s more likely they will disrupt bird migration patterns.

More birds than bats die per year in collisions with wind turbines worldwide, according to Monteverde Institute Executive Director Debra Hamilton.

Although bats successfully use echolocation to find objects with reverberated sound, a rapid change in air pressure close to the turbines inflicts too much stress on the bat’s lungs and causes death.

Bat expert Kelly LaVal explained that bats use a method equivalent to GPS that allows them to fly the same route back and forth to their destinations. A turbine in the way of that path could result in a blade striking a bat. A solution would be to simply move the turbines, but energy companies are often uncooperative, LaVal said.

Hamilton and world-renowned bat biologist Richard LaVal say more studies on the effects of wind farms have been conducted in the United States and Canada than in Costa Rica, opening the door for primary research in tropical countries.

Increasing popularity of the renewable energy source has sparked media coverage and public attention in the United States and Canada. The death and disruption of bird and bat species inhabiting Costa Rica’s North American neighbors is proven by several studies conducted there.

Despite the lack of information, Richard LaVal proposes a low cost solution: slow the turn speed of turbine blades. An experiment published in the Journal of Wildlife Management showed that bat deaths were reduced by more than 50 percent when the speed was lowered.

New horizontally spinning blades and spiral shaped designs are also being explored. These would reduce the threat to bats as well as birds, Richard LaVal said. The technology is in the early stages of development so it has not yet been tested in the field.

Until a compromise is reached or more research is completed, the giant turbines will continue to reign over the Costa Rican slopes.

3 thoughts on “Turbines transect flight paths, threaten species

  1. Chris Helms says:

    Nicely written Natalie! Great information about a big problem.

  2. Peggy Riordan says:

    I had not thought about how the turbines would effect migration patterns before. Great info and glad I learned something new for the day!

  3. Debbie Allen says:

    Good reporting on a timely topic.

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