  As the popularity of electric vehicles increases, the demand for more power
can increase more rapidly than our ability to install additional generating
capacity. In the long term we expect that the supply and demand will become
balanced. However, in the interim the rate at which electric vehicles can be
deployed will depend on our ability to charge these vehicles without
inconveniencing their owners. In this paper, we investigate using fairness
mechanisms to distribute power to electric vehicles on a smart grid. We assume
that during peak demand there is insufficient power to charge all the vehicles
simultaneously. In each five minute interval of time we select a subset of the
vehicles to charge, based upon information about the vehicles. We evaluate the
selection mechanisms using published data on the current demand for electric
power as a function of time of day, current driving habits for commuting, and
the current rates at which electric vehicles can be charged on home outlets. We
found that conventional selection strategies, such as first-come-first-served
or round robin, may delay a significant fraction of the vehicles by more than
two hours, even when the total available power over the course of a day is two
or three times the power required by the vehicles. However, a selection
mechanism that minimizes the maximum delay can reduce the delays to a few
minutes, even when the capacity available for charging electric vehicles
exceeds their requirements by as little as 5%.
