Assessing the potential impact of workplace charging for a group of commuters

A PHEV demonstration project gave 80 consumers within the Northern California counties of Sacramento, Yolo and San Joaquin the opportunity to drive a PHEV-conversion for at least one month each in lieu of one of their existing vehicles. Households decided for themselves when, where, and how much to charge the PHEV, if at all. Out of the 80 households, 25 were characterized as plausible future PHEV owners who also commuted to a workplace. Each of the PHEV-conversions was equipped with loggers which recorded all travel and charging data. To estimate the potential implications of added workplace charging infrastructure across a group of commuting households, each household’s vehicle usage is simulated with six hypothetical PHEVs, the design characteristics of which are outlined in Table 2 of this paper. Combining each household’s usage data with the hypothetical designs allows their PHEV-conversion experience to be generalized beyond the specific PHEV-conversion to plausible future PHEV designs. Since most households did not have access to charging infrastructure at work, charging events are simulated for each household every time they arrive at their workplace. Comparison between the recorded behavior and the simulated workplace charging case allows for an exploration of the potential impacts of workplace charging on the individual and fleet utility factor, workplace charging infrastructure requirements, and grid load. Workplace charging increases the total fleet average utility factor, however, the benefit varies considerably by household and vehicle charge depleting range. Based on simulation results, up to 75% of commuters would be able to use 1.44 kW charging without experiencing a decrease in electric miles driven, and workplace charging creates a new peak vehicle charging load on the grid in the morning, in the range of 0.8 to 1.4 kW per PHEV.