Bat fatalities at wind farms; Curtailment a more common practice

The recent discovery of a dead endangered bat at a Pennsylvania wind site led to the immediate shutdown of night-time operations of a wind facility. The practice has become more widespread I recent years.

Unlike a few years ago, the wind industry has been armed with studies and procedures that lead to immediate actions to prevent further fatalities, which have been deployed in sensitive areas populate by migrating birds and bats.

On September 27, Duke Energy Corporation notified the U.S. Fish and Wildlife Service that a dead Indiana bat, a state and federally protected species, had been found at its 35-turbine, North Allegheny Wind facility.

The facility, located in Cambria and Blair Counties in Pennsylvania, has been in operation since September 2009, and the bat carcass was located during voluntary post-construction mortality monitoring, FWS said.

Duke Energy stopped operating the wind farm at night "to prevent additional mortalities of Indiana bats," spokesman Greg Efthimiou said.

Efthimiou said the company will continue to switch off the farm a half hour before sunset and a half hour after sunrise until mid-November, when the migration season of the endangered Indiana bat generally ends.

The ridge is in the section of the Appalachian Mountains that extends into West Virginia, where the issue of bat mortality first gained prominence a few years ago.

The bat carcass was discovered by a contracted technician and brought to the office at the end of the day per Duke standard procedures.

Duke immediately curtailed night-time operations of the turbines at the North Allegheny facility, and reported the incident to the Pennsylvania Game Commission and the Service. The FWS said it is currently reviewing the incident.

A project in West Virginia was itself endangered when the Beech Ridge project avoided denial of its permit when wind developer Invenergy and the Animal Welfare Institute reached a proposed settlement in federal court. The developers sought an "incidental take permit" from the U.S. Fish and Wildlife Service, recognition that some fatalities will occur from an otherwise lawful activity.

The actual settlement that was agreed upon allows the turbines to be in 24 hour operation between mid-November and April 1 when the bats are hibernating. For the remaining months the turbines may only operate in the daylight hours.

In other locations, bat and bird monitoring has led to wind curtailment. Not the most lucrative solution, as curtailment cuts into wind plant revenue, but it helps avoid a PR disaster-in-the making.