Vehicle-to-Grid Definition

V2G technology can be defined as a system in which there is capability of controllable, bi-directional electrical energy flow between a vehicle and the electrical grid. The electrical energy flows from the grid to the vehicle in order to charge the battery. It flows in the other direction when the grid requires the energy, for example, to provide peaking power or “spinning reserves.” It should be noted that this is the way V2G would work if a vehicle had such capability, but there are currently no original equipment manufacturer (OEM) vehicles available to the general public with V2G in the United States.Studies indicate that vehicles are not in use for active transportation up to 95% of the time (Letendre and Denholm 2006) and the underlying premise for V2G is that during these times, the battery can be utilized to service electricity markets without compromising its primary transportation function. Subsets of V2G technology include vehicle-to-home (V2H; when the electric vehicle is at a residence) or vehicleto-building (V2B; when the electric vehicle is at a commercial building). In these cases, the battery power is used to supplement the local building electrical load without transfer to the electrical grid. Note that this still effectively displaces building load from the grid, which effectually provides a load-shed function. Alternatively, if there is a power outage from the grid, this permits emergency backup power to continue building processes