Maybe Aerial Re-charging via other drones?<p>[EDIT] Or there are the Facebook planes: 
<a href="http:&#x2F;&#x2F;www.theverge.com&#x2F;2015&#x2F;7&#x2F;30&#x2F;9074925&#x2F;facebook-aquila-solar-internet-plane" rel="nofollow">http:&#x2F;&#x2F;www.theverge.com&#x2F;2015&#x2F;7&#x2F;30&#x2F;9074925&#x2F;facebook-aquila-so...</a>