Why birds should avoid solar furnaces

The world’s largest solar furnace, in Odeillo in the French Pyrenees, was built in 1968. The furnace could, when newly constructed, concentrate solar power by a factor of 16,000, but this has decreased to a multiplier of around 9,500 as temperature variation has moved the mirrors out of alignment. It can reach temperatures of 3,500°C and is used for testing materials, including heat shields for spacecraft.

Concerns have been raised about a solar thermal power plant in the Mohave Desert because the plant had been igniting birds that flew over the facility. Federal biologists estimated that as many as 6,000 birds may have been incinerated by the Ivanpah Solar Plant every year. The plant consists of a 14 km² array of mirrors which follow the Sun, focussing light onto three 40-storey tall towers. Located on a migratory route, the Pacific Flyway, birds approach the towers to eat insects attracted by the focused beams of light. In response to concerns about the bird deaths, a number of operational adjustments were suggested including clearing land and covering ponds around the plant to make it a less attractive roosting site. Since changes were introduced, the avian mortality rate at the facility has been significantly reduced.