c. Plug-in Electric Vehicles
Kempton (2010) discusses the potential for plug-in EVs using ‘Vehicle-to-Grid’ (V2G) controls to alleviate the need for other forms of technology to maintain ancillary grid services (particularly spinning reserve and frequency regulation). Most cars in the USA are only used for 1 hour per day and have oversized batteries for the occasional long trip. V2G controls allow for a two-way flow of power, which utilizes the spare capacity of the vehicle’s battery to respond to demand for regulation services (Kempton 2010). Kempton et al (2008) show that this technology can successfully be employed to simultaneously meet the needs of the average driver as well as the needs of the grid throughout the course of a day. This has much to do with the nature of frequency regulation, which typically requires both regulation-up and -down several times throughout the course of an hour. Therefore, the vehicle’s battery need not be completely drained or filled to provide regulation services (Kempton et al 2008).
Furthermore, the incorporation of V2G means that vehicle owners will be compensated by utility companies for their services (Kempton et al 2008), which may provide additional incentives for car owners interested in switching from combustion-engine vehicles to EVs. In other words, the use of V2G may facilitate the reduction of GHG emissions more than simple ES or non-V2G EVs by reducing the number of traditional cars and by allowing for the benefits illustrated elsewhere in this study. This solution may be particularly appealing in the USA where the transportation system is dominated by the use of personal cars. In fact, Kempton (2010) optimistically estimates that within the next ten years (i.e. during the first half of the time period this study is considering) half of the fleet in the PJM territory could be plug-in EVs, which could provide 15 GW (30 GWh) of ES (or approximately 1 MW of ancillary ES for every 100 plug-in EVs). Finally, an additional benefit of using V2G rather than other alternative forms of ancillary ES is that utilities can avoid the bulk of additional costs because they only need to pay for the smart-grid controls while the owners of the vehicles pay for the battery systems.
Whether utility companies elect to rely upon plug-in EVs, the ancillary ES technologies highlighted in section II.2.c., or some combination of the two, it is clear that within the next two decades ancillary grid needs could be met without relying solely upon traditional fossil-fuel generator capacity. Thus, this study shall consider the need for a minimum amount of such capacity to no longer be the strict limiting factor suggested by previous studies (e.g. Østergaard 2006 & 2008).
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