1. EXECUTIVE SUMMARY

Plug-in hybrid electric vehicles (PHEVs) are under evaluation by various stakeholders to better
understand their capability and potential benefits. The cost associated with providing charging
infrastructure for PHEVs, along with additional costs for onboard power electronics and added battery
capacities associated with PHEV technology, will be key factors in the success of PHEVs.

PHEV charging parameters, including charge power, charge energy, and charge times, can be
established by evaluating typical daily vehicle trips and daily vehicle miles traveled. Actual PHEV driver
behavior and an evaluation of charge power requirements (based on experience with charge
characteristics of various battery chemistries) bring additional light to charging infrastructure
requirements for PHEVs. Upon conducting these evaluations, it was concluded that 40 miles of charge
depleting range is necessary for an average PHEV if no infrastructure is available outside of the owner's
primary residence. If public charging infrastructure is available, allowing PHEV charging outside of the
owner's primary residence, the charge depleting range can be lowered to 13 miles. It is, therefore,
considered important to evaluate charging infrastructure in both residential and commercial settings
because the availability of a rich charging infrastructure can reduce the onboard energy storage
requirement (i.e., battery size) for PHEVs.

Typical charging infrastructure scenarios evaluated include (1) overnight charging at a home garage,
(2) overnight charging at an apartment complex, and (3) opportunity charging at a commercial facility.
Each scenario was described, the infrastructure and onboard power electronics requirements determined,
and the typical cost for the infrastructure and onboard power electronics developed.

Using charge times and estimated costs for onboard power electronics to support various charge
levels and charge depleting vehicle ranges, it is shown that Level 2 charge times are significantly shorter
than Level 1 and increase as battery size increases. It is further shown that battery size and therefore,
charge times can be reduced by providing a rich charging infrastructure that allows charging away from
the residence or apartment where the vehicle is housed overnight. When comparing the cost of onboard
electronics and a battery to support a larger (PHEV-40) battery versus a smaller (PHEV-10) battery for a
mid-size vehicle (using the most favorable battery cost of $300/kWh), it can be seen that the additional
range comes at a cost of $8,268 (Page 32). This compares to a cost of $1,852 (Table 6-5) to provide
additional Level 2 commercial facility charging infrastructure, allowing the reduced range PHEV-10 to be
used as effectively as the longer range PHEV-40. Therefore it can be concluded that overall transportation
system cost can be reduced by providing rich charging infrastructure rather than compensating for lean
infrastructure with additional battery size and range.

2. INTRODUCTION

Hybrid electric vehicles (HEVs) have achieved familiarity and acceptance by private consumers and
fleets in the United States. HEV sales in the United States have grown from 9,367 in 2000 to 324,318
through 2007d . HEV popularity in government fleets has been driven by mandates to reduce fuel
consumption. The public sector’s reasons are somewhat more varied, ranging from environmental
concerns, to image, to fuel savingse.

The methodology used to establish PHEV charging parameters, including charge power, charge
energy, and charge times, began with an evaluation of typical daily vehicle trips and daily vehicle miles
traveled based on data from the 2001 National Household Survey. Additionally, an evaluation of actual
PHEV driver behavior and an evaluation of charge power requirements (based on experience with charge
characteristics of various battery chemistries) were conducted.

Based on the results of these evaluations, typical charge infrastructure scenarios were developed,
including (1) overnight charging at a home garage, (2) overnight charging at an apartment complex, and
(3) opportunity charging at a commercial facility. Each scenario was described, the infrastructure and
onboard power electronics requirements determined, and the typical cost for the infrastructure and
onboard power electronics developed.

Using this information, costs were developed for (1) PHEV charging infrastructure, (2) electrical
energy for charging, (3) onboard power electronics required for battery charging, (4) probable vehicle
changes to accommodate various charging options, and (5) additional battery capacity to support a
charge-depleting operation.

3. PLUG-IN HYBRID ELECTRIC VEHICLE TRIP ANALYSIS

To establish PHEV charge parameters, a general understanding of the typical daily trips and total
daily vehicle miles traveled must be obtained.

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