airship
The possibilities of who is behind these French drones are almost endless: Al-Qaeda or some other terrorist organisation; hackers trying to discover and eavesdrop on wireless networks operating at the power stations; Google map street view etc.
Given the going's on with the Siven's barrage at the moment it came as no surprise that French lunchtime TV yesterday had the likes of Greenpeace and/or one of the more militant environmental groups in it's list of usual suspects..as you say the list of possibilities is endless..
Barrage de Sivens - LaDépêche.fr