Tuesday, May 31, 2011
Avian Mortality by Wind Turbines
In this post we are going to explore this concept of death of birds due to wind turbines.
When a wind farm is installed in the path or a migratory route for birds, during the migrations the birds will come in contact with the large spinning blades and the result? Bird Mortality.
But on the other hand it us very uncommon for a wind farm to be cited in a migratory path since studies would have already revealed this in the early stages of planning.
"To help our understanding of turbine hazards to birds we'd like to make an analogy, to your bicycle. Turn your bike upside down or put it in a work rack, set it to the highest gear...the one you use to go fast on a level slope.... and now move the wheel slowly with your hand. The chain moves rapidly with only a few degrees of wheel rotation. This symbolizes today's cutting edge 1.5 mW turbines, which have a very large surface area of blade exposed to the wind and a gearbox that turns the dynamo quickly while the blades move slowly. Birds dodge these slow moving blades relatively easily.Now put the bike in the lowest gear...the one you use to climb hills...and move the wheel with your hand fast enough to turn the chain as fast as before. That symbolizes the 20-year-old "bird-o-matic" wind turbine design. Small blades with small surface areas have to turn rapidly to overcome the magnetic force of the dynamos, which generate electricity.Recapping: small blades, low surface area, lots of dead birds possible; very big blades, with large surface area exposed to wind, very few dead birds." From treehugger.com
The Altamont Pass Energy Farm - California
The Altamont Pass is the first modern wind farm in the US comprising of up to 4000 wind turbines of an older concept than what is being used today. This wind farm has one problem and will always be quoted by all who support the idea that Wind Turbines are the major contributors to avian mortality. The Altamont Pass is built on the path of migratory birds and is responsible for 4,700 bird deaths each year and is the highest in the U.S. This simple means that every turbine will at least kill a bird in each year. The 20 year old turbines are very attractive to birds because they can perch but usually death to the bird occurs.The Altamont Pass wind farm kills far more birds than any other farm in the United States. The total at that single wind farm with 4,000 turbines is 4,700 fatalities; the total for all wind farms in the United States, with more than 25,000 turbines in operation at any given time, is 10,000 to 40,000 per year.
With response to the Altamont problem, most new designs have more surface area exposed to the wind and therefor need to spin slower meaning less collision with birds. Also the citing of wind farms next to migratory paths has been reveiwed and restricted. The bird conservanists are more and more allowing wind farms to be installed with their own endorsement.
Offshore wind farms is the new thing and this would mean less collision with the birds.