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Transportation Statistics Analysis for Electric Transportation

Plug-in Electric Vehicles (PEVs) are still in the initial stages of deployment in the American vehicle market. Much of the currently available data on PEVs is from special applications and early adopters. EPRI has analyzed existing transportation data on conventional vehicles from the National Household Travel Survey (NHTS) to study the potential long-term patterns of PEV use. This study used the NHTS data to investigate several aspects of potential PEV usage patterns and their effects on U.S. electric load. The researchers first analyzed how far vehicles are driven and where they spent time when parked. Results showed only a small variation in aggregate driving patterns across such factors as seasonal differences, rural and urban driving, income categories, or locations. Also, the primary charging location for most vehicles will be the home, with the workplace an important secondary location. They also calculated a "utility factor" for Plug-in Hybrid Electric Vehicles (PHEVs), which is the fraction of average driving performed on electricity, for ranges of 0–200 miles and charge powers of 1.44, 3.3, 6.6, and 19.2 kW. Findings were that PHEVs can achieve substantial degrees of electrification and that increased charge power has a relatively low benefit, especially above 3.3 kW. However, it is likely that higher-range vehicles will benefit from higher-power home charging and that charge power may impact the utility factor for all-locations charging. The primary impact of PEVs on utilities will constitute the charging load imposed by vehicles. Simulations using the NHTS data allowed the researchers to estimate the likely aggregate load shapes for PEVs under a variety of scenarios. The project team analyzed three charging powers—1.44, 3.3, and 6.6 kW—for a PHEV40 vehicle. They investigated the differences between weekday and weekend use and charging locations that included home only, home and workplace, and home, workplace, and commercial (all-locations) access. For home-charging only, they found that the peak of the average vehicle charging load will be less than 1 kW, even without controls, and that the magnitude of the charging peak has a low sensitivity to variations in vehicle consumption because of factors like weather. The primary impact of adding increased charging availability (workplace and commercial) will be the movement of the home-charging load to earlier in the day. Additionally, coincident load reduction will likely be less than what could be achieved through load control. In general, an increase in charging availability locations will lower the maximum average power and increase the displacement of gasoline by electricity.

Document Type:
Technical paper