As more and more people will live in big cities, by placing Power Plants on the rooftops you don't have to fly it in from the other side of the world, you are able to grow it on the location itself.
Semakin banyak orang tinggal di kota besar, dengan menaruh Power Plants di atap, Anda tidak perlu menerbangkannya dari sisi dunia lain, Anda bisa menumbuhkannya di situ.