I have a strange fixation with deserts. It has to do with the fact that of all places on Earth, they are among the few ones that remain "unclaimed".

The idea would be to produce a solar fuel on deserts. Various chemical reactions fueled by concentrated sunlight are possible. This fuel would then be transported to the cities. 

A variant of this idea is the following: I always image it as a black object, for example round. You would leave those objects in the desert sun all day, and they would charge. It could take a long time until they are fully charged. It would store an enormous amount of energy.

Then you would collect them and take to the cities. I've tried to imagine this energy absorbing material, but couldn't come up with anything concrete. It is just what it is, an inspiration of sorts.

Note: It could also be a powder that you spread to the ground.