Imagine that every skyscraper had on top of the buillding a large water reservoir. Say take around 5 floors near to the top and turn them in to a water tank. 

A pump on the floor level can send water up to be stored. Water can also be sent down, but it it passes through a turbine to generate electricity.

This is the Potential Building: an idea to store electrical energy from the grid when this energy is cheap, such as during dawn, and to release it during the peak hours.

Now it would mean a lot to the power grid if we had such large scale storage system, cities and cities with potential buildings.

It is a real tricky to make this economical, however.