  The sharing economy has disrupted housing and transportation sectors.
Homeowners can rent out their property when they are away on vacation, car
owners can offer ride sharing services. These sharing economy business models
are based on monetizing under-utilized infrastructure. They are enabled by
peer-to-peer platforms that match eager sellers with willing buyers.
  Are there compelling sharing economy opportunities in the electricity sector?
What products or services can be shared in tomorrow's Smart Grid? We begin by
exploring sharing economy opportunities in the electricity sector, and discuss
regulatory and technical obstacles to these opportunities. We then study the
specific problem of a collection of firms sharing their electricity storage. We
characterize equilibrium prices for shared storage in a spot market. We
formulate storage investment decisions of the firms as a non-convex
non-cooperative game. We show that under a mild alignment condition, a Nash
equilibrium exists, it is unique, and it supports the social welfare. We
discuss technology platforms necessary for the physical exchange of power, and
market platforms necessary to trade electricity storage. We close with
synthetic examples to illustrate our ideas.
