On the inefficiency of vehicle-to-grid (V2G) power flow: Potential barriers and possible research directions

Transition to electric vehicles (EVs) is already under way. EVs are equipped with a drive train that is completely electric powered, with a fairly large on-board battery pack. More recently, EVs have been looked at as distributed sources of energy, whereby they could back up the power grid during critical high demand periods. With the help of an on-board battery pack, EVs can act as distributed generators and feedback energy to the AC grid. However, efficiency of energy conversion could become an issue in this power flow. Hence, vehicle-to-grid (V2G) power flow requires a detailed stage-by-stage efficiency analysis, to evaluate practical feasibility. This paper aims at introducing some of the issues in connecting battery-powered EVs to the electricity grid. The paper highlights few of the inefficiencies of V2G connection, especially from the point of view of power electronics converter energy conversion stages, and suggests some research directions for the near future, in order to possibly make V2G a practical reality.