Can We Have Wind Power and Birds, Too?
By Hugh Powell
August 14, 2008
The answer emerging from recent research seems to be a hearty ‘yes,’ qualified by a ‘but let’s not rush into things.’ This was the sentiment offered by Ken Otter, of the University of Northern British Columbia, as he described a two-year study of bird migrations at a proposed $500 milion, 170 megawatt wind-power plant.
Wind power has emerged as a front runner in the world’s sudden longing for renewable energy sources. It’s clean, abundant, fairly straightforward to produce, and even pretty quiet compared with an oil derrick or coal plant. There’s just the small problem that the monstrous structures – the one at left is taller than a football field stood on end – present a sometimes-deadly obstacle to passing birds and bats.
Still, to the pragmatic, having wind power boils down to accepting a certain amount of dead birds. And you can put a number on the amount: At last week’s AOU meeting, I learned that existing wind-power plants typically kill about 1 to 12 birds per megawatt generated per year. (A megawatt can meet the electricity needs of roughly 1,000 Americans.)
Ken Otter’s task was to advise the Canadian power company about ways to get that number as low as possible. So he hauled out a mobile radar system to track birds as they flew over the steep-sided mountain ridges where the turbines would be built. Radars can’t identify bird species, so Otter also posted graduate students with binoculars to document what was flying over.
The challenge for wind farms is that migrating birds don’t fly randomly across the landscape – they follow the wind, too, and many fly at night, making it hard to see the rotating blades.
Raptors are especially vulnerable: they soar low along ridgelines, where they catch updrafts from wind deflected up the mountainsides – exactly what the wind turbines are there to do. And even though raptors migrate during daylight hours, Otter said, they don’t always do a great job of looking in front of them. The solution just isn’t as simple as putting wind turbines in places birds don’t travel, it seems.
But after two years of study, Otter found bird movements tended to be fairly predictable. Songbirds tended to fly safely above the height the turbine blades will be when they’re built later this year. Raptors tended to cross the ridge in a predictable zone, and they tended to come through in tight groups over just a few hours or days. By monitoring weather conditions, he said, he can warn the power company that raptors are probably on their way, allowing operators to shut down turbines long enough for the birds to pass by, without making the outage too costly.
This is why preparatory studies are valuable. Even though wind power is a green energy source that we’re right to feel enthusiastic about, it does have a cost that can be minimized. Different settings – shapes of ridgelines, prevailing wind patterns, migratory routes – mean that each new wind farm will present different hazards to birds. But with a little forethought and brain power, we can reduce the costs birds pay to satisfy our own energy demands.
Wind power will never be harmless to birds. After all, radio towers kill birds, and they’re just a latticework of metal bars that’s completely motionless. But climate change and pollution kill birds, too; it’s just harder to measure (or fix). As Otter said at the end of his talk, “I’d like to see these turbines go in, because the alternative is they’re going to build coal plants.”