2013 study out of Pacific Northwest National Laboratories analyzes the economic value that an intelligent vehicle charging infrastructure (IVCI) can deliver.
Vehicle-to-grid (V2G) services require a bi-directional interface between the electric vehicle supply equipment (EVSE) and the power grid, and take advantage of the fact that vehicles are idle approximately 90 percent of the time. A significant literature has developed over the past decade on the value that plug-in-vehicles (PEVs) can provide serving as distributed energy storage devices. While the penetration of PEVs is still low relative to conventional vehicles, experience on PEV usage and charging behaviors is being gained from the several thousand PEVs that have already been sold.
The EV Project is an initiative funded by the U.S. Department of Energy with several private sector partners that involves studying 6,000 PEVs in several regions across the country with qualifying and associated EVSE infrastructure. The project collected data on vehicle charging and infrastructure use to investigate the current and future grid impacts and lost economic benefits associated with not having in place an IVCI. This analysis serves to highlight the importance of moving more quickly to develop interoperability standards between EV, EVSE, and the emerging smart grid infrastructure.
An IVCI can be deployed to manage the timing of PEV charging, which provides economic value to ratepayers by minimizing infrastructure investments and to PEV owners through lowcost charging strategies. Shifting charging to off-peak periods either indirectly through time-of-use (TOU) rates or directly through utility control can defer investments in generation, transmission and distribution infrastructure. Furthermore, this allows greater utilization of the existing grid infrastructure (e.g., amortizing existing investments over a larger number of MWh delivered).
Based on EV Project data, the median delivered energy on a typical weekday in all regions and all charging locations is equal to 50.7 MWh. The scenario described above would shift 23.0 MWh of charging load, which occurs between 5:00 pm and 12:00 am, to the off-peak period between 12:00 am and 7:00 am.
The table below presents the total annual PEV charging cost savings based on shifting an average of 23 MWh of load to off-peak daily (assuming 3,000 of the 6,000 EV project vehicle owners would benefit from moving to a TOU rate).
Annual PEV Charging Savings for PV Project Vehicles Moving to TOU Rates
As depicted in the above table, over a ten year period, the total potential savings from shifting charging of all EV Project vehicles (6,000 PEVs) to offpeak periods is well over one million dollars and perhaps as high as $10 million (assuming rate differential between peak and off-peak periods of $0.02/kWh and $0.15/kWh respectively).*
*The low range is based on the EV Project PEV fleet providing spinning reserves based on the lowest annual average prices from various wholesale power markets in 2011 of $3.37 MWh for 2,190 hours a year with a 5 kW power vehicle-to-grid (V2G) grid connection. In contrast, the high end of the range is based on the highest 2011 market prices for providing regulation services of $16.42/MW-h for 5,081 hours a year with a 15kW V2G grid connection.