Globally, the transportation sector remains significantly dependent on fossil fuels, with an array of sobering, negative environmental and social impacts. To decarbonize this sector, the International Energy Agency suggests that plug-in electric vehicles must make up at least 40% of new vehicle sales globally by 2040 to be on track to stabilize greenhouse gas concentrations at 450 ppm . Others similarly argue that diffusion of plug-in electric vehicles (PEVs), including plug-in hybrid vehicles (PHEVs) and battery electric vehicles (BEVs), at a similar or even more ambitious scale or scope is necessary to achieve deep greenhouse gas (GHG) reduction targets.
Nonetheless, the acceptance and adoption of PEVs will invariably impact electricity grids due to increased electricity demand and the temporal shifting of demand peaks—offering both benefits and risks to electricity systems. Over the past two decades, researchers have explored various notions of intelligently integrating grid operations with PEVs, including terms such as vehicle-to-grid [5, 6] (V2G), grid-integrated vehicles  (GIV), and vehicle-grid-integration (VGI) . These connected concepts describe efforts to link transportation and electricity systems in ways that may provide synergetic benefits to both. VGI has more recently developed as a sort of umbrella term to encompass unidirectional integration efforts, such as ‘smart’ or ‘controlled’ charging (now sometimes called V1G), as well as bidirectional integration, namely V2G. However, in this paper we utilize V2G because it reflects the most commonly applied term in the literature. Technically, a V2G configuration means that personal automobiles have the opportunity to become not only vehicles, but mobile, self-contained resources that can manage power flow and displace the need for electric utility infrastructure (see figure 1). They operate as vehicles when drivers need them but switch to become power sources or opportunities for energy storage during peak hours, recharging at off-peak hours such as later at night . However, the literature often confuses V2G with other types of vehicle-grid-integration.