How sustainable are drones?

Drones delivering packets

Drones – or Unmanned Aerial Vehicles – offer a new way of seeing and interacting with the world we live in. Their increased numbers and presence, from people taking beach videos to states using them in war, often provoke strong opinions.

But what we’d like to know is, could this little machine revolutionise energy use amid our rapidly changing lifestyles, in an environmentally sustainable way?

How sustainable are drones?