In a comment on this post, Svend Rumbold points out that the data about bird and bat mortality is probably based on impacts with conventional horizontal axis turbines and not the vertical axis models. Digging a little deeper into the sources for the Climatewire story, I find these things:
- Bird and bat mortalities from wind turbines are becoming more significant problems globally because of the phenomenal increase in the wind energy industry – now growing more in developing countries than in industrialized ones. (See the Renewables 2011 Global Status Report, by REN21.)
- Curiously, the 116-page REN21 report mentions vertical axis turbines only once, and it was in relation to ocean technology – suggesting to me that almost all of the growth in wind farms involves horizontal axis turbines.
- The American Bird Conservancy is actively promoting bird- and bat-friendly wind projects, and the organization endorses a set of recommendations that was developed in 2007 by the U.S. Fish and Wildlife Service Wind Turbine Guidelines Advisory Committee.
- The 2007 advisory guidelines are all about landscape planning and say virtually nothing about technology choice. The emphasis is on landscape-level analysis and site selection, detailed site studies, site construction best management practices, post-construction mortality studies, and other monitoring. It seems that there is some degree of confidence that better site selection can lead to fewer mortalities.
- U.S. politics enters the equation: U.S. Fish and Wildlife Service issued new draft guidelines in July – guidelines that the wind industry applauds and the American Bird Conservancy opposes because most of the wildlife protection language has been removed.
- The bat research cited in Climatewire is this: Baerwald, E.F., G.H. D’Amours, B.J. Klug, et al. 2008. Barotrauma is a significant cause of bat fatalities at wind turbines. Current Biology 18 (16): R695-R696. The same authors published a study in July of this year where they document their bat migration research based on bat mortality on wind farms in Alberta, Canada.