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TRB 11--4094
Promoting the Market for Plug-in Hybrid and Battery Electric Vehicles: The
Role of Recharge Availability
Feb 15, 2011
Word Count: 5862+6*250 = 7362 (including 6 figures)
Zhenhong Lin
Oak Ridge National Laboratory
National Transportation Research Center
2360 Cherahala Boulevard
Knoxville, Tennessee 37932
Phone: 865-946-1308
Fax: 865-946-1314
Email: linz@ornl.gov
David L. Greene
Oak Ridge National Laboratory
National Transportation Research Center
2360 Cherahala Boulevard
Knoxville, Tennessee 37932
Phone: 865-946-1310
Fax: 865-946-1314
Email: dlgreene@ornl.gov
Notice: This manuscript has been authored by UT-Battelle, LLC, under Contract No. DE-AC05-
00OR22725 with the U.S. Department of Energy. The United States Government retains and the
publisher, by accepting the article for publication, acknowledges that the United States
Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or
reproduce the published form of this manuscript, or allow others to do so, for United States
Government purposes.
Lin and Greene 1
ABSTRACT
Much recent attention is drawn to the provision of adequate recharge availability as one
means to promote the battery electric vehicle (BEV) and plug-in hybrid electric vehicle (PHEV)
market. What requires better understanding is the possible role of improved recharge availability
in the development of the BEV/PHEV market and the priorities the different charging options
should receive from the government. This study reviews the charging issue and conceptualizes it
into three interactions between the charge network and the travel network. Based on travel data
of 3755 drivers from the National Household Travel Survey (NHTS), we estimate the
distribution among the U.S. consumers of 1) PHEV fuel-saving benefits by different recharge
availability improvements; 2) range anxiety by different BEV ranges; and 3) willingness-to-pay
for workplace and public charging as added to home recharging. Using the ORNL MA3T model,
the impact of three recharge improvements is quantified by the resulting increase in the
BEV/PHEV sales. Overall, compared to workplace or public recharging improvement, home
recharging improvement appears to have a greater impact on the BEV/PHEV sales. The impact
of recharge availability improvement is shown to be amplified by faster reduction in battery cost.
Lin and Greene 2
INTRODUCTION
Battery electric vehicles (BEV) and plug-in hybrid vehicles (PHEV) receive tremendous
attention in recent policy discussions that aim at reducing petroleum use and greenhouse gas
emissions in the transportation sector (1,2). Public enthusiasm appears to be growing, as evident
by media coverage of the Nissan Leaf BEV and Chevrolet Volt PHEV. BEV offers the promise
of ultimate electrification of the personal travel but its massive commercialization still requires
further battery cost reduction and availability of adequate charging (3,4). PHEV integrate the
energy efficiency of hybrid powertrain with the ability to partially substitute electricity for
petroleum. PHEV is less expensive and less dependent on charging availability, and therefore
viewed as a bridging technology to BEV (1).
Although most experts agree that battery cost and performance are still the largest barrier
toward massive commercialization of BEV/PHEV (5-8), much attention is being paid to recharge
availability improvement. The growth of a BEV/PHEV market will likely be affected by how
fast and how well a charging infrastructure is deployed, but to what extent? How much of the
limited social resources should be devoted to improving the charging infrastructure? What
charging technologies at what locations should receive a higher priority of public funding
support? In responding to these policy questions, it is necessary to assess the role of recharge
availability in the transition of a BEV/PHEV market.
This study assesses the potential impact of improved recharge availability on both the
individual BEV/PHEV consumer and the BEV/PHEV market development. It should be noted
that this study focuses on the benefit side of recharge availability improvement and ignores the
cost side. In the following sections, the complicated recharge availability problem is
conceptualized into three network interactions. We then estimate the distribution among the U.S.
consumers of 1) PHEV fuel-saving benefits by different recharge availability improvements; 2)
range anxiety by different BEV ranges; and 3) willingness-to-pay for workplace and public
charging as added to home recharging. Finally, The ORNL MA3T model is used to analyze the
potential impact of recharge availability on the BEV/PHEV market.
INTERACTIONS BETWEEN CHARGER AND TRAVEL NETWORKS
While the charger network is viewed as a set of spatially distributed chargers, the travel
network consists of spatially and temporally distributed drivers, driving routes and parking
locations. This study proposes to conceptualize the occurrence of charging as the result of
interactions between the charger network and the travel network.
The Charger Network
The charger network can be described by availability, location type (home, workplace,
etc) and charging speed (Level 1, 2, 3) of each charger. More chargers enable more potential
BEV/PHEV buyers, but the role of an additional charger depends on its location due to the
associated parking time, parking frequency and technology constraints. Home recharging is
presumably more important because homes are where vehicles park the longest and most often.
Adopters of converted PHEVs appear used to plugging in when arriving home (9-10). While a
home charger may enable a new BEV/PHEV buyer, adding a workplace charger may make the
purchase more likely. For enthusiastic consumers without home charging, workplace charging
may be seen as an acceptable alternative, as workplace parking is usually long and routine for
most workers. Public chargers can equivalently extend the electric range. Public recharging may
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be important in alleviating the range anxiety of prospective BEV owners, and such benefits
should not be underestimated by the relative small portion of energy contributed by public
chargers. For example, BEV owners in Japan rarely use public chargers, but stated that they
would not have bought a BEV if those public chargers were not in place (11).
A charger’s range extension ability depends on the charging time and the charging speed.
Faster charging may be necessary in public places, where parking time is usually short. But for
consumers with home recharging and typical driving patterns, topping off partially depleted
battery may be more often demanded than full recharging. This could reduce the need for high
charging speed. For home or workplace recharging, the usual long parking time makes expensive
upgrade to faster charging less necessary, especially for PHEVs with a small battery.
Three levels of charging speeds are currently under consideration (12). Level 1 charging,
using a standard 110 volt, 15-20 usable ampere circuit, and is sufficient to fully charge a small
PHEV20 (PHEV with 20-mile CD range) sport-utility vehicle (SUV) during 7-9 hours of home
nighttime. Depending on residential areas, 50% -70% of households have access to Level 1
recharging (5,10). With Level 2 charging on a 220 volt, 40 ampere circuit, a full recharge
requires less than 4 hours for a PHEV40 SUV and about half hour for a PHEV10 small car.
Level 2 charging can be added to garages or parking lots at probably moderate costs, but
currently it is not commonly offered (1). Level 3 charging uses a 440 volt, three-phase circuit,
typically providing 60-150 kW of off-board charging power. Level 3 charging for PHEVs is
probably not necessary at home or even workplace where vehicle parking duration is normally
long. Safety concern and high cost also make Level 3 implementation for PHEV charging in
these places dubious, at least for the near term. However, Level 3 charging may be more
necessary for BEVs. A full recharge of a 150-mile BEV midsize car will likely require more than
10 hours with a Level 2 charger, but only 2-3 hours with a Level 3 charger. In commercial places
where drivers park and conduct personal or business activities, 1-2 hours of Level 3 charging is
sufficient to provide a full recharge for most PHEVs and can significantly extend the BEV
driving range.
Three Charger-Travel Interactions
Conceptually, three steps of interactions between the charger network and the travel
network mostly determine how, when and where the recharges take place and therefore the value
of the charger network to the BEV/PHEV owners.
The first interaction, named Attract & Change, regards how the change of one network
attracts that of the other. This includes the emergence, growth and upgrade of the charger
network in response to the increase of BEV/PHEV traffic and drivers in the travel network, and
the emergence, adaptation and growth of BEV/PHEV traffic and drivers in response to the
charger network. For example, a workplace is equipped with some chargers in its parking lot in
response to the observation that some employees drive BEVs to workplace and express need for
recharging. The built charger network may also impact the travel network. For example, people
may drive less after switching to a BEV. Do BEV owners buy a BEV because they drive less
than others or do they drive less because of owning the BEV? Will the provision of fast public
chargers encourage BEV owners to driver more? These questions are among many that concern
the correlation and causality between the charger network and the travel network.
The second interaction, named Opportunity Matching, regards the temporal and spatial
match between the two networks that determines the probability of a charger being available
where and when a recharge is possibly needed. This affects the potential for a BEV/PHEV
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consumer to increase the share of driving on electricity. As consumer surveys show, A PHEV
consumer, who have both home and workplace recharging, has a short commute distance and
rarely conducts non-commute travel, will have the opportunity to drive on electricity most of the
time (10).
However, even presented with the recharge opportunity, a BEV/PHEV consumer may or
may not let the recharge happen. Therefore, the third interaction, named Recharge Execution,
concerns the act of recharge when the opportunity to recharge is presented. If the Opportunity
Matching interaction concerns the probability that a recharge opportunity is presented, the
Recharge Execution interaction concerns the conditional probability of a recharge being
conducted. With the battery depleted, the BEV would require a recharge for continued vehicle
operation while the PHEV would not. When a recharge opportunity is presented, a BEV/PHEV
driver would consider the recharge urgency, recharge cost and hassle based on remaining battery
capacity, knowledge about the given charger, and knowledge about the next recharge
opportunity. The UC Davis survey reveals that the early PHEV consumers are generally
enthusiastic about any available opportunity to plug in their vehicle, but also found a few
consumers refuse to recharge because the available time for recharge is too short and probably
perceived as not worth the hassle (9, 10). Overall, it can be stated that the conditional probability
of recharge is greater with more perceived benefit or less perceived cost and these perceived
costs or benefits depends on the condition of the battery, the perceived recharge hassle, the travel
plan and the perception of the next recharge opportunity.
RECHARGE AVAILABILITY AND PHEV FUEL-SAVING BENEFIT
For a PHEV user, the maximum possible fuel-saving benefit from improved recharge
availability occurs if and only if the PHEV switches from a lifetime constant charging-sustaining
(CS) operation before the improvement to a lifetime constant charge-depleting (CD) operation
after, and the user bothers to make such an “ideal” switch. Such a worst-to-best switch is only
theoretically possible and not necessary desirable, but the resulting fuel-saving benefit provides
the upper bound of consumer benefits from improved recharging availability and therefore worth
examining. As shown on Figure 1, this theoretical maximum fuel-saving benefit can be as much
as $7000 for the most frequent drivers and is in the range of $1000-$4000 for most drivers. This
curve is estimated based on the travel demand of a sample of 3755 drivers, who are full time
workers, mainly drive to workplace, and drive a relatively new car, from the 2001 National
Household Travel Survey (NHTS) data (13). The details of the sample have been covered by a
separate paper (5). Daily VMT variations over time and among drivers are represented in
calculating fuel cost and electricity cost, assuming $3/gge for gasoline and $0.1/kWh for
electricity.
The same driver sample is used to calculate the fuel-saving benefits of home recharging
to PHEV consumers assumed with no other recharging options. As shown on Figure 1, the
provision of home recharge only will result in a narrow range of $400-$500 of lifetime fuel-
saving benefit for the majority of PHEV10 owners, as shown in Figure 1. Whether or not this
range represents the allowed extra price for PHEV10 to compete with HEV depends on
consideration of other values of PHEV, such as the fewer trips to gas stations and the hedonic
value of being able to plug in and helping the country’s oil independency.
In comparison of the charging options, some frequent drivers may value home charging
less than the combined value of the other two options, because longer commute distance and
higher daily VMT may increase utilization of charging time at work and public places. For
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frequent drivers of PHEV10, the incremental fuel-saving benefits from workplace and public
recharging added to home recharging can reach up to nearly $1000 (Figure 1), based on the
assumption that the PHEV10 is charged at all three locations during work days and two locations
during non-work days. On the other hand, about 72% of consumers appear to value home
charging more.
Thus, the relative importance of recharge locations depends on driving intensity and
patterns. What appears to be clear is that the maximum fuel-saving benefit from better recharge
availability for PHEV is still much less than the extra premium for PHEV purchase in the near
term for the majority of consumers. This may suggest the limitation of improved recharge
availability in the event of no significant battery cost reduction. This argument can only be
strengthened by the consideration of the probably even lower actual fuel-saving benefit of PHEV,
because in reality PHEV consumers will not be given a recharge opportunity every time she
needs one (with respect to the Opportunity Matching interaction) and she will not always bother
to conduct the recharge even if she is given the opportunity (with respect to the Recharge
Execution interaction).
RECHARGE AVAILABILITY AND BEV RANGE ANXIETY
BEV consumers are expected to have at least one regular charging option, most likely
home recharging. For them, the value of additional recharge availability is to extend driving
range and alleviate range anxiety, which comes from the fear that an alternative transportation
means will need to be sought in days of expected long trips and even worse hassle will occur in
days of unexpected travel. A consumer is assumed to have a perceived uncertain daily driving
distance, described by the random variable x in miles per day following the probability density
function p(x) and up to M mile per day. Assume the regular charger enables a certain driving
range Rcd in miles, which is the lesser of the BEV range and the effective range that is
determined by the charging time and speed of the regular charger. The consumer is also assumed
to perceive some degree of availability of other recharging opportunities. Assume the consumer
perceive the probability (Q) of these opportunities being present when she need one, the charging
speed (E, in mile per hour charged), and the available charging time (T, in hour). The alternative
charging opportunities will result in a perceived effective range (R, as in Equation 1). The
probability (Pa) that the daily driving distance exceeding the effective range (Equation 2) or the
annual days (Na) of insufficient BEV range (Equation 3) can be used to measure the range
anxiety of the prospective consumer.
Equation 1
Equation 2
Equation 3
These three equations help link the factors that affect BEV range anxiety. Alleviation of
range anxiety means reducing the probability of daily VMT exceeding the effective range R. To
accomplish that, the BEV consumer can choose to adjust her travel behavior by reducing days of
long distance travel, i.e. adjusting her density function p(x). Without travel behavior change, the
consumer needs to increase the effective range R by: 1) having adequate charging time or speed
with the regular charger to ensure a full utilization of the battery; 2) having more non-regular
chargers to increase the possibility of available charging when needed; 3) having faster charging
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speeds with these non-regular chargers; 4) making more time available for charge waiting; and 5)
getting a longer-range BEV. While the first three measures are related to provision of charging
infrastructure, the viability of the fourth measure depends on the consumer’s own situation, e.g.
value of time.
To quantify range anxiety, the distribution of Na among the U.S. new car drivers is
calculated. The same 3755 new car drivers from the NHTS 2001 data are used to represent the
possible BEV buyers in the U.S. Based on the 3755 distinct gamma functions that represent the
drivers’ daily VMT distributions, the days of insufficient range are calculated based on Equation
3 for each driver. These drivers are sorted based on Na associated with 100-mile BEVs and thus a
BEV range “cost curve” can be graphed to show the increasing difficulty to alleviate the range
anxiety of more potential BEV buyers (Figure 2). What appears interesting is the diminishing
value of a larger BEV range. Take the driver who drives 20209 miles annually, typically drives
34 miles daily (thus for the gamma distribution, mode=34, mean=55), and ranks about 70% in
the 100-mile range cost curve. The number of insufficient BEV range days is 55 days with a 100-
mile BEV and drops to 20 days with a 150-mile BEV and 7 days with a 200-mile BEV.
Not surprisingly, consumers of larger BEV will have less range anxiety. More
interestingly, between drivers, a driver who has greater range anxiety when compared based on
shorter range BEVs does not have greater range anxiety when compared based on longer range
BEVs. This reflects the importance of considering daily VMT variations over time and among
drivers.
For interpretation convenience, the monetary value of Na is also provided on the
secondary vertical axis by assuming an arbitrary $15 penalty per day of insufficient range. A
possible upper bound of this daily penalty is the daily rate of a delivered rental car based on the
assumption that a BEV consumer will feel no range anxiety if such a rental car is provided for
free in days of insufficient range. However, a BEV consumer with easy access to another car in
the household may perceive little range anxiety. Without enough information to segment
consumers by household vehicle ownership and accurately estimate the daily value of range
anxiety, we assume the $15 to approximate the average, which may involve great uncertainty and
needs to be further investigated. What the resulting monetary values in Figure 2 imply is that it is
difficult for a 200-mile BEV to satisfy the majority of drivers, not to mention a 100-mile BEV,
unless driving behavior changes significantly after the BEV purchase.
For BEV owners with home recharging only, the provision of workplace and public
charging can increase R, reduce Na and therefore alleviate range anxiety. Such change of Na
measures the incremental value of the workplace and public charging to BEV consumers and
represents their willingness-to-pay. The resulting Na reductions of the 3755 drivers are sorted
based on the 100-mile BEV results (Figure 3). Not surprisingly, consumers of larger BEV will
value the additional charging less. More interestingly, between drivers, a driver who values the
additional charging availability more when compared based on shorter range BEVs does not
necessarily value it more when compared based on longer range BEVs.
RECHARGE AVAILABILITY AND BEV/PHEV SALES
The ORNL MA3T Model
To assess the role of charging improvements in the BEV/PHEV market, we conduct an
integrated analysis based on the Market Acceptance of Advanced Automotive Technologies
(MA3T) model developed by Oak Ridge National Laboratory (ORNL). We briefly describe the
MA3T model as below and refer the readers to our separate paper (5) for the model details.
Lin and Greene 7
The MA3T model at its core employs the discrete choice theory to simulate the
competition of BEV and PHEV against conventional internal-combustion-engine (ICE) vehicles
(gasoline and diesel), hybrid vehicles (gasoline and diesel), hydrogen-ICE vehicles, fuel cell
hybrid vehicles (FCV), and fuel cell PHEV (FCPHEV). PHEVs with different levels of CD
range are considered. The MA3T considers the U.S. light-duty personal vehicle market for the
time horizon of 2005-2050. Key aspects of consumer value reflected in the market projection are
vehicle price, fuel economy, energy price, distribution of daily driving distance, government
PHEV incentives, recharging availability, learning-by-doing, technology novelty, and make &
model diversity (Figure 4). The MA3T model represents a total of 1458 market segments,
covering 9 regions, 3 residential areas, 3 driver types, 3 technology adopters, 3 home recharging
situations (Level 1, Level 2, and neither), and 2 workplace recharging situations (with or without
workplace recharging).
There are several updates of the model since our last publication (5). First, the battery
replacement cost to the consumer is removed from the model. Such a modification is based on
the announced battery warranties of Leaf and Volt. Second, in representing the expiration of the
federal purchase incentives for PHEV/BEV, each PHEV or BEV technology has its independent
cumulative production for expiration and has 3 manufacturers. These two updates are expected to
result in a more optimistic projection of the PHEV/BEV market. Third, the model now allow the
users to configure the percentages of consumers with access to home and workplace recharging
and also allow specification of public recharging availability measured by the probability of a
recharging opportunity present at public places when visited.
Scenario Definition
To run MA3T, the current and future levels of recharge availability and technology cost
need to be specified. Based on various sources (5, 9, 10), it is assumed that currently 52% of
consumers have Level 1 home recharging and the rest do not have home recharging, 5% of
consumers have Level 1 workplace recharging, the rest do not have workplace recharging, and
the probability that an recharging opportunity is available at a visited public place is zero.
The deployments of chargers for homes, workplaces and public places will likely affect
each other, but are assumed to be independent in this study for the purpose of isolating the
impact of each. The recharge infrastructure deployment is assumed to be exogenous and not
affected by the BEV/PHEV sales. Such an interaction is likely, but beyond the study scope.
Also because of the study purpose on impact comparison, deployment progress is
assumed to be as fast as possible, instead of reflecting ongoing or proposed activities. Therefore,
when home recharge improvement is assumed, it means that the percentage of consumers with
Level 2 home recharge grows linearly from 0% in 2010 to 100% in 2025 and the percentage of
consumers with Level 1 home recharge keeps constant at 52% until 2018 and decrease after that
to 0% in 2025. When workplace recharge improvement is assumed, it is assumed the percentage
of consumers with workplace recharge grows from 5% in 2010 to 100% in 2025. When public
recharge improvement is assumed, it is assumed the probability of available Level 3 recharge
opportunity at the visited public place grows from 0% in 2010 to 100% in 2025. These simplified
deployment scenarios are not meant to predict the future reality, but for the purpose of analyzing
the possible impact of each recharge option by 2025.
Based on literature information (1, 12), we assume charging rates of 1.1 kW, 6kW, and
90kW for Level 1, 2 and 3 charging, respectively. For either home or workplace recharging,
consumers are assumed to perceive no waiting burden. Public charging is assumed to occur as a
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secondary purpose at the destination, e.g. charging at a restaurant. Therefore, no value of
charging time is considered in the paper.
The electricity charged is affected by charging time, charging speed and the battery state-
of-charge (SOC). Because of such complexity, it becomes necessary to assume some typical
daily routes for simplification. We assume a workday driving route is in the sequence of home,
workplace, a public place and home, and a non-workday route (weekends, holidays or vacations)
is in the sequence of home, a public place and home. The available charging time per day is
assumed to be 8 hours for home, 7 hours for workplace, and 2 hours for a public place.
The Reference battery cost projection reflects the technical potential according to expert
estimates (5, 14, 15). The Reference battery costs seem to be much higher than what people are
guessing about the Leaf battery. The Nissan Leaf is equipped with a 24 kWh battery and priced
at $32,780, which implies less than $400/kWh in battery cost. We have insufficient information
to verify the battery cost of Leaf, but we use the Battery20 case to reflect an optimistic battery
cost projection where the battery cost reduction is 20 years earlier than in the Reference case.
Therefore, there are 10 scenarios being simulated:
1) Reference: Experts projected battery cost; current recharge infrastructure unchanged till
2025.
2) ImproveHomeRechargeOnly: Fast deployment of home chargers, all homes with Level
2 charging by 2025
3) ImproveWorkRechargeOnly: Fast deployment of workplace chargers, all workplaces
with Level 3 charging by 2025
4) ImprovePublicRechargingOnly: Fast deployment of public chargers, 100% probability
by 2025 of available Level 3 charging opportunity at any visited public place
5) ImproveAllRechargeLocations: Combined ImproveHomeRechargeOnly,
ImproveWorkRechargeOnly, and ImprovePublicRechargingOnly
6) Battery20: No recharge improvement; battery cost advanced by 20 years
7) ImproveHomeRechargeOnly+ Battery20: combined ImproveHomeRechargeOnly with
Battery20
8) ImproveWorkRechargeOnly + Battery20: combined ImproveWorkRechargeOnly with
Battery20
9) ImprovePublicRechargingOnly + Battery20: combined
ImprovePublicRechargingOnly with Battery20
10) ImproveAllRechargeLocations + Battery20: combined ImproveAllRechargeLocations
with Battery20
Result and Discussion
Given the current policies, technology status, and charge availability, the model shows a
PHEV annual sales of nearly 2 million by 2025 (Figure 5), but projects little penetration by BEV
(Figure 6). The major barrier is the battery cost, as the cost of a near-term PHEV10 is expected
to be about $5,500 to $6,300 more than that of an equivalent non-hybrid gasoline midsize car (1),
not to mention the even higher cost of PHEV40 and BEV. It should be noted that we consider
150-mile BEVs, rather than 100-mile BEVs. Within the PHEV market, PHEV10 with its much
cheaper battery cost appears to be more cost effective for most consumers than PHEV 40, as the
fuel-saving benefit of larger battery will be restrained by limited charging availability. With
home charging only, BEVs for its limited range cannot satisfy the occasional, but probably
important, needs for long-distance travel, and therefore may be more appealing to multi-vehicle
Lin and Greene 9
households, where a conventional vehicle with no range concern is available during days of
long-distance travel.
Improved charging availability allows PHEV owners to reduce fuel cost and BEV
shoppers to perceive less range anxiety, and therefore can affect market acceptance of
BEV/PHEV (Figure 5 and Figure 6). For a particular PHEV owner, such a fuel-saving benefit
depends on the coordination among the location and charging speed of the chargers, the battery
capacity to store onboard energy, and the spatial and temporal driving patterns. Larger battery
capacity allows a long trip without operation on the CS mode. Faster charging speed along the
route enables the electric drive to continue without hours of stay at the station. With the current
recharge infrastructure, a PHEV will be operated on the CS model for much of the miles
travelled, especially for frequent drivers of small-battery PHEVs. Better charging availability
allows increase in the portion of travel distance on the CD mode and predicts more value for
prospective PHEV consumers.
However, without significant technology improvements or policy changes, increase in
charge availability alone is unlikely to result in a substantially higher BEV/PHEV penetration. In
other words, inadequate charging availability will not be the key barrier in holding back the near-
term penetration of BEV/PHEV. As discussed previously, even with a worst-to-best theoretical
switch, the fuel-saving benefit from PHEVs will be still below half of the extra price of buying a
first-generation PHEV. Because of the variation of travel route and distance and the constraint of
battery storage capacity, most of PHEV consumers will receive far less than the maximum fuel-
saving benefit even with widespread recharge infrastructure. Improved charging availability
alone does not significantly boost the BEV sales either, as the model predicts, because the BEV
battery cost still overwhelms the fuel-saving benefits and range anxiety reduction.
On the other hand, if substantial progress in reducing battery cost is concurrently
achieved, the impact of recharge infrastructure deployment on the market acceptance of
BEV/PHEV can be greater. As Figure 5 and Figure 6 show, the sales differences between
charging scenarios enlarge when battery cost decrease. If technology progress is made to reduce
battery cost or more incentives are provided for BEV/PHEV consumers, the fuel-saving benefit
perceived by PHEV buyers and the range anxiety reduction perceived by BEV buyers due to
better recharge availability will become more significant relative to the decreased price gap with
conventional vehicles. The model projects that the resulting PHEV sales from better recharge
availability in the near term can be much greater if progress in battery cost reduction is made 20
years earlier (Figure 6), and such an effect is more evident for BEVs.
Similarly, the impact of technology improvement can be strengthened by improved
recharge infrastructure deployment. The potential market base for the BEV/PHEV will be
expanded by equipping more homes with recharge capabilities and further excited by adding
chargers to workplaces and public places. A larger and higher-potential market base resulting
from better recharge availability will enable greater sales impact of cost reduction. As the model
projects, the 20-year technology advance boosts the BEV sales in 2025 by 10 thousands with
improved recharge availability, but by less than 1000 without it (Figure 6).
Among the three locations, improved home recharging is shown to have the most impact
on PHEV/BEV sales (Figure 5 and Figure 6), because home is usually where a vehicle parks the
most often and longest, resulting in more recharging energy and fuel-saving benefit. Some
experts stated that 97%-99% of charging energy will be delivered at home (16). Even with
available workplace or public charging, consumers will probably feel more convenient and less
stressful to charge at home. Surveys show that consumers state stronger preferences for home
Lin and Greene 10
recharging. Other surveys show that BEV users with home recharging rarely use public
recharging and some PHEV users refuse available recharging during weekdays because of the
hassle they perceived (9).
The impact of the availability of one recharging option is conditional on the availability
of another recharging option. For example, available workplace recharging may be more
important to consumers without home recharging. It is unclear whether enabling workplace
recharging will generate more incremental BEV/PHEV sales from those with home recharging
than from those without. In normal cases, home recharging is considered necessary for owning a
BEV. For long distance travel, the BEV owner will likely have to use another vehicle, unless fast
public recharging is available along the trip. Therefore, fast public recharging can be an
important supplement to home recharging in promoting BEV sales, especially when BEV
becomes price competitive.
Although recharge infrastructure has often been thought as a facilitating factor for
BEV/PHEV penetration, there are likely synergies between charger deployment and a growing
BEV/PHEV fleet. With increasing popularity of BEV/PHEV, businesses will more likely
provide recharging to attract consumers; apartment complex and new homes may increasingly
use recharging capabilities as a selling point. At certain market stages, deployment of chargers
can be partially driven by sales of BEV/PHEV. As observed in our market simulation, the
growth of the PHEV market can motivate the deployment of public recharging stations, leading
to the emergence of the BEV market (5). The key question is what needs to be done to push the
market quickly into such a synergetic state.
SUMMARY
This study conceptualizes the BEV/PHEV recharge availability issue into three steps of
interactions between the charger network and the travel network. Based on varying daily VMTs,
the study then quantifies both the upper bound and the more realistic level of fuel-saving benefits
for PHEV owners from improved charge availability and quantify the BEV range anxiety of the
prospective U.S. new car owners. Using the ORNL MA3T model, the impact of improvement on
home, workplace and public recharging is quantified by the resulting increase in the BEV/PHEV
sales. Overall, home recharging is shown to have a greater impact on the BEV/PHEV sales. The
impact of recharge availability improvement is shown to be amplified by faster reduction in
battery cost. On the other hand, future technology progress will also have a larger impact if a
better recharge infrastructure is in place.
ACKNOWLEDGMENT
The authors gratefully acknowledge the support of the U.S. Department of Energy’s
Vehicle Technologies Program. The views expressed are the authors’ and not necessarily those
of the Department of Energy.
REFERENCES
1. National Research Council, 2009, Transitions to Alternative Transportation Technologies
—Plug-in Hybrid Electric Vehicles, The National Academies Press, Washington D.C.,
ISBN: 0-309-14851-0.
2. EPRI (Electric Power Research Institute)/NRDC (Natural Resources Defense Council).
2007. Environmental Assessment of Plug-in Hybrid Vehicles. EPRI Report# 1015325
Lin and Greene 11
3. Markel, T. and A. Simpson (2006). "Cost-Benefit Analysis of Plug-In Hybrid Electric
Vehicle Technology," Journal of World Electric Vehicle Association Vol.1, 2006
4. Kromer, M. A. and J. B. Heywood (2008). A Comparative Assessment of Electric
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0459, Int. Journal of Engines 1(1): 372-391, SAE World Congress, Tory, MI, April 14-17,
2008.
5. Lin, Zhenhong and David Greene (2010). The MA3T Model: Projecting PHEV Demands
with Detailed Market Segmentation. 2010 TRB Annual Meeting CD-Room.
6. Vyas, A. D., D. J. Santini, et al. (2009). “Plug-in Hybrid Electric Vehicles’ Potential for
Petroleum Use Reduction: Issues Involved in Developing Reliable Estimates,” TRB 88th
Annual Meeting Compendium of Papers DVD, Paper #09-3009.
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wheels Energy Use and Greenhouse Gas Emissions Analysis of Plug-in Hybrid Electric
Vehicles. Argonne National Laboratory report ANL/ESD/09-2.
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Learning from Consumers: Plug-In Hybrid Electric Vehicle (PHEV) Demonstration and
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09-21
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Vehicles: Anticipating Consumer Recharge Potential and Design Priorities,” TRB 88th
Annual Meeting Compendium of Papers DVD, Paper #09-1272.
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12. Kevin Morrow, Donald Karner, James Francfort. Plug-in Hybrid Electric Vehicle
Charging Infrastructure Review. Idaho National Laboratory report INL/EXT-08-15058.
November 2008.
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14. Plotkin, S., M. Singh, et al. (2009). Multi-Path Study: Vehicle Characterization and Key
Results of Scenario Analysis. Argonne National Laboratory report ANL/ESD/09-5.
15. Rousseau, A. (2009). Personal Communication on Vehicle Data from Powertrain System
Analysis Toolkit (PSAT) Z. Lin. Knoxville, TN.
16. Woodard, Tracy, representing Nissan Motor Co., Ltd. (2010). Department of Energy
Plug-In Vehicle and Infrastructure Workshop, Washington, DC. July 22, 2010.
DEFINITIONS/ABBREVIATIONS
BEV
battery electric vehicles; vehicles powered by a battery only
CD
charge depleting; one mode of PHEV powertrain operation
CS
charge-sustaining; one mode of PHEV powertrain operation
E
charging speed
FCPHEV
fuel cell PHEV
FCV
fuel cell hybrid vehicles
ICE
internal combustion engine
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M
maximum daily VMT, the upper bound of x
MA3T
the Market Acceptance of Advanced Automotive Technologies model
developed by ORNL
Na
annual days of insufficient BEV range
NHTS
National Household Travel Survey
ORNL
Oak Ridge National Laboratory
p(x)
probability density function of x
PHEV
plug-in hybrid electric vehicle
PHEV10/20/4
0
a PHEV with 10/20/40 miles of CD range, respectively
Q
probability of being able to access a charger when in need of one
R
perceived effective range of BEV
Rcd
the PHEV CD range or the BEV range in miles
SOC
battery state of charge
SUV
sport-utility vehicle
T
available charging time
VMT
vehicle miles travelled
x
random variable, representing daily VMT of a driver
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List of Figures
Figure 1 Fuel-saving Benefit of Recharge Availability for PHEV10
Figure 2 BEV Range Anxiety Supply Curve
Figure 3 Demand Curve for Range Anxiety Alleviation
Figure 4 Illustrative Diagram for the ORNL MA3T Model
Figure 5 Impact of Recharge Availability on PHEV Penetration, Conditional on Battery Cost
Figure 6 Impact of Recharge Availability on BEV Penetration, Conditional on Battery Cost
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Figure 1 Fuel-saving Benefit of Recharge Availability for PHEV10
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Figure 2 BEV Range Anxiety Supply Curve
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Figure 3 Demand Curve for Range Anxiety Alleviation
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NMNL
Module
LBD
V2G
Stock
Technology
Risk
Model
Availability
Range & Fuel Availability
Sales Policy
Maker
Vehicle Usage
and Scrappage
Fuel and
Electricity Use
Tailpipe and
Lifecycle GHG
input
output
feedback
input
output
feedback
ANL/PSAT
ORC Survey
Census2000
EIA/AEO2009
NHTS2001
UCD
PHEV Survey
ANL/Greet
Refuel&Recharg
Infrastructure
Purchase Discount, Tax
Credit, Free Parking,
Free HOV, etc
Figure 4 Illustrative Diagram for the ORNL MA3T Model
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0
1
2
3
4
5
6
7
8
2012
2014
2016
2018
2020
2022
2024
Reference
ImproveHomeRechargeOnly
ImproveWorkRechargeOnly
ImprovePublicRechargeOnly
ImproveAllRechargeLocations
Battery20
ImproveHomeRechargeOnly+Battery20
ImproveWorkRechargeOnly+Battery20
ImprovePublicRechargeOnly+Battery20
ImproveAllRechargeLocations+Battery20
Projected PHEV Sales in millions
by scenario of recharge deployment
Note: 1. Reference assumes existing policites, recharge availability and moderate technology progress. 2.
Battery20 stands for 20 years earlier reduction of battery cost. 3. Deployment of each recharge option is
assumed to be aggressive during 2017-2025. 4. Projections generated by ORNL MA3Tmodel. 5. the temporary
kinks are due to expiration of the ARRA PHEV subsidies.
Figure 5 Impact of Recharge Availability on PHEV Penetration, Conditional on Battery Cost
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0
2
4
6
8
10
12
2012
2014
2016
2018
2020
2022
2024
Reference
ImproveHomeRechargeOnly
ImproveWorkRechargeOnly
ImprovePublicRechargeOnly
ImproveAllRechargeLocations
Battery20
ImproveHomeRechargeOnly+Battery20
ImproveWorkRechargeOnly+Battery20
ImprovePublicRechargeOnly+Battery20
ImproveAllRechargeLocations+Battery20
Projected BEV Sales in thousands
by scenario of recharge deployment
Note: 1. Reference assumes existing policites, recharge availability and moderate technology progress. 2.
Battery20 stands for 20 years earlier reduction of battery cost. 3. Deployment of each recharge option is
assumed to be aggressive during 2017-2025. 4. Projections generated by ORNL MA3Tmodel. 5. the temporary
kinks are due to expiration of the ARRA PHEV subsidies.
Figure 6 Impact of Recharge Availability on BEV Penetration, Conditional on Battery Cost
