Study Finds Reduction in Turbine Bat Kills - Green Inc. Blog - NYTimes.com:
". Twenty-one dead bats were found when turbines were fully operational, while 11 were found when turbines were turned off during low-wind phases....
The bat-saving measure came with a cost. Given the wind farm’s generating capacity, that one percent could theoretically translate to as much as 1,000 megawatt hours per year.
Using the going rate of $70.00 to $90.00 per megawatt hour of wind energy, that’s a potential $70,000 to $90,000 annual hit to the bottom line."
BTW this is also an example of how framing (context) matters. For instance. What if the following were the headline? "Would you pay $9,000 to save a single bat?"