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The Evolution of Plug-in Electric Vehicle-Grid Interactions


              The Evolution of Plug-in Electric Vehicle-Grid Interactions
                                               David P. Tuttle and Ross Baldick
                                               The University of Texas at Austin
                                       Department of Electrical and Computer Engineering

Abstract -- Over the past decade key technologies have                 supply base, all the essential technologies are presently
progressed so that mass-market viable PEVs (Plug-In Electric           available to facilitate mass-market viable PEVs.
Vehicles) are now set to reach the U.S. market by 2010-2011.           The several types of PEVs can be categorized as follows:
  PEV-grid interactions comprise a mix of industries that have         - BEVs (Battery Electric Vehicles): a vehicle with a large
not interacted closely in the past. A number of these
                                                                       onboard battery that is charged via a power cord to the grid.
commercial participants have utilized the same basic business
model for nearly a century. The various participants include           This battery then provides the energy for the electric traction
vehicle manufacturers, utilities, and supplier firms who have          motor to propel the vehicle.
radically different business models, regulatory and legal              - eREVs (Extended Range Electric Vehicle): are BEV-derived
environments, geographical scope, and technical capabilities.          vehicles with the addition of an on-board gas engine-
  This paper will provide a survey of PEV technology trends, oil       generator which provides electrical energy to the motor once
price impacts, consumer behavior and preferences, policy               the initial battery charge is exhausted. This configuration
options, grid capabilities, standards, and business models.            solves the classic “range anxiety” problem of a BEV by
From an analysis of these factors this paper synthesizes and           providing an overall range equivalent to a traditional gas or
provides a likely scenario for PEV-Grid interaction over the
                                                                       diesel vehicle. Once its initial charge from the grid is
next decade.
                                                                       depleted or if the vehicle is never plugged into the grid, the
                                                                       eREV should appear operationally similar to a conventional
Keywords – Plug-in electric vehicles, battery electric vehicles,
plug-in hybrid vehicle, extended range electric vehicles, PEV,
                                                                       Hybrid Electric Vehicle (HEV).
BEV, PHEV, eREV, vehicle to grid.                                      - PHEVs (Plug-In Hybrid Electric Vehicles): are Hybrid
                                                                       Electric Vehicle (HEV) derived vehicles with larger batteries
                        I. INTRODUCTION                                and a charging cord to the grid added, which typically operate
                                                                       in a “blended” mode using both the gas engine and electric
F   or a century the promise of the electric automobile has
    been just that, a promise. Electric vehicles had initial
success in the early 1900’s and were developed and advocated
                                                                       motor together to radically reduce gas consumption. PHEVs
                                                                       also solve the traditional BEV range anxiety problem and
                                                                       should operate similarly to a traditional HEV if never plugged
by some of the best minds of the era, such as Thomas Edison.           into the grid.
However, once the internal combustion engine (ICE)                        There are meaningful differences in the underlying eREV
powertrain had progressed in range and convenience and an              and PHEV powertrain technologies. However, where useful
increasing number of gas stations were built, electric                 this paper will combine these two types of PEVs into a
powertrains were relegated to a small market niche of                  generic range-extended PHEV category to differentiate them
vehicular applications. Sales of mainstream electric vehicles          from non-range extended BEVs.
were inconsequential by the 1920’s. As technology                        While selling in low volumes due to its price, Tesla’s
progressed over the 20th century, updated electric prototypes          $109,000 Roadster performance BEV demonstrated the recent
were constructed but never achieved mass-market viability.             promise of the critical technologies. The Roadster raised
   The computer industry drove the development of                      awareness regarding the technology readiness. This
semiconductors, microprocessors, and related design tools,             awareness, in turn, reportedly helped to stimulate investment
processes, and fabrication and software which eventually               by established global vehicle manufacturers, which eventually
enabled critical PEV semiconductors, power electronics, and            led to committed efforts to produce mass-market viable
controls. Later, the consumer electronics industry drove the           vehicles such as the Chevrolet Volt, Nissan Leaf, Ford Focus,
volumes and costs of Lithium batteries, which now have                 and other vehicles under development. Once the first few key
sufficient energy density for automotive applications. While           global vehicle manufacturers announced plans for PEVs,
not yet at scale and mature volumes for a global automotive            other manufacturers apparently started to invest as a
                                                                       competitive response.
   This work was supported by Power Systems Engineering                    Fueling infrastructure has traditionally been a critical
Research Center (PSerc) under the project T-40 titled “Investigating
                                                                       impediment to the adoption of any alternative fuel based
of PHEV large scale penetration scenarios and aggregation options”,
and in part by the University of Texas at Austin.
                                                                       vehicle. For PEVs, home charging is a convenient and
   D. Tuttle and R. Baldick are with the Department of Electrical      reasonably priced alternative to publicly accessible charging
and Computer Engineering, The University of Texas at Austin, 1         infrastructure or even traditional gas stations. Driver
University Station C0803, Austin, TX 78712 (emails:                    residences are expected to be the dominant PEV charging,                  location for all types of PEVs (BEVs, eREVs, PHEVs). Some
                                                                       vehicle manufacturers are expecting that range-extended
                                                                       PEVs will enjoy much greater adoption rates than BEVs

given the combination of eREV/PHEV range extension with
the simplicity of infrastructure provided by home charging,
particularly AC Level-1 (120 Volt) charging.                                    II. PLUG-IN VEHICLE TECHNOLOGIES
   On the other hand, battery electric vehicles have a much
simpler all electric powertrain and the potential for lower        A. First Generation
production costs (as battery prices decline further) and lower
maintenance costs but have a greater need for public charging          The first-generation PEVs will establish “green”
infrastructure than range-extended PEVs given they have no         technology leadership and build brand equity for their
gasoline backup for longer distance travel. Actions which          manufacturers, help the vehicle OEM (Original Equipment
address and eventually leverage the “network effect” of PEV        Manufacturer, i.e. vehicle manufacturer) meet more strict
public charging stations would be beneficial to support non-       Federal government CAFE (Corporate Average Fuel
range extended BEVs or PEV owners without a garage and             Economy) fleet fuel economy standards, drive
further encourage PEV adoption. The classic example of the         R&D/manufacturing/supplier base learning, and provide test
network effect occurred in telephony where the greater the         beds to better understand the durability of batteries and other
number of telephones, the higher the value of each telephone       key components. Volumes are expected to be modest, but
given the user can progressively talk to more people since         meaningful. These PEVs will likely sell at low or negative
there are more telephones. In a somewhat similar fashion for       profit levels depending upon sales volumes, financial
public PEV charging stations, the greater the number of            accounting for the basic technology R&D amortization, sales
charging stations, the greater the adoption of PEVs, which         price, and battery warranty costs. The first generation will
then increases the profit potential or value for each charging     mainly be focused on bringing to market leadership PEVs
station, which then encourages an even greater number of           while maintaining the extremely high levels of reliability,
public charging stations to be installed. The challenge is         safety, and convenience that conventional vehicles provide
making the non-residential PEV charging infrastructure             today. Meeting these expectations could be a challenge given
ecosystem economics attractive so that the classic and critical    PEV technology is new and unproven in large scale customer
“chicken and egg” problem is transformed into a virtuous           deployments, which tend to surface problems not easily found
cycle of increasing numbers with a positive network effect.        despite manufacturers’ rigorous validation tests.
   On the other hand, urban public charging stations used             The global vehicle manufacturers perceive enough safety
during the day without intelligent charging communication          and durability risks with these first generation vehicles that
and control may be problematic by encouraging on-peak              they will avoid including two-way powerflow capability for
charging. Thus the combination of range-extended PEV               the near term. The vast majority of vehicles will likely
powertrains and home charging may be beneficial in a               include only Grid-to-Vehicle (G2V) power flow and the
number of ways: a lessened demand on public charging               driver will have on-board vehicle programmability to
infrastructure, less risk of peak electricity demand               manually set the charge window. Modest integrated
aggravation, lower overall costs of home charging                  communication capabilities will be included, which will
infrastructure given overnight charging with an AC Level 1         enable diagnostics and status from the vehicle, limited charge
(120 Volt) charger may be sufficient for eREVs/PHEVs (but          control to set “grid-friendly” charging windows, and control
not BEVs), and a smaller battery size required onboard the         of passenger cabin pre-heating or pre-cooling.
PEV itself.                                                           Unlike the inconvenience and costs associated with the two
   There is motivation to push for an alternative to reduce the    incompatible inductive and conductive California Air
United States’ dependence on oil (particularly foreign oil):       Resources Board Zero Emissions Vehicle (CARB ZEV) era
Energy security, environmental concerns such as oil spills or      chargers, the vehicle manufactures appear to have agreed
CO2 emissions, imported-oil based trade deficit, reduction in      upon the “SAE Surface Vehicle Recommended Practice
funds flowing to terrorist organizations from petrodollars, and    J1772, SAE Electric Vehicle Conductive Charge Coupler” as
reduced geopolitical entanglements. However, the incumbent         the standard for upcoming U.S. market vehicles. Supporters
advantage of petroleum fueled vehicles is considerable.            of this SAE-J1772-2009 standard include GM, Chrysler,
   The following section on Plug-In vehicle technologies will      Ford, Toyota, Honda, Nissan and Tesla [1]. SAE J1772
describe the key attributes which are likely to define the major   presently has two basic charging voltages: single phase AC
generations of PEVs. Subsequent sections will provide a            Level 1 (120 Volt) and AC Level 2 (240 Volt) up to a peak
survey of oil price impacts, consumer behavior and                 power transfer of 19.2kW. This common standard fosters
preferences, policy options, grid capabilities, standards, and     lower charging infrastructure costs and improved availability
business models. From an analysis of these factors this paper      and convenience of public and home charging stations.
will synthesize a likely (or at least plausible) scenario for         The combined electric and gasoline range of PHEV and
PEV-Grid interaction over the next decade given technology         eREVs will be comparable to conventional automobiles.
readiness, incentives or impediments to adoption, and key          Given range anxiety, advances in Lithium batteries, and other
enabling actions.                                                  consumer considerations the mass-market BEVs appear to
                                                                   have 100 mile range targets. As with conventional vehicle
                                                                   mileage estimates, “your actual (electric vehicle) mileage will
                                                                   vary” (typically, but not always in a negative fashion). Real

world electric range will likely vary significantly with driving   Chevrolet Volt eREV: 16kWh battery [4][5], estimated 65%
habits, terrain, and weather conditions given heavy electrical     SOC window, with a range of conversion efficiency estimates
loads such as passenger cabin heating and air conditioning         that vary between 2.5 to 5.7 miles/kWh based upon
systems.                                                           temperature, HVAC load, terrain, and driving techniques.
   The advertised electric range for PEVs will be based upon
a particular objective test cycle, such as the EPA LA4/UDDS        Upper bound optimal AER (Note: AER does not include the
drive cycle [2] for conventional vehicles. While these test        300 miles of gasoline extended range):
cycles are useful for purchase comparisons, the effective           R = 16 · 0.65 · 5.7 = 59.3 miles                     (4)
range a driver will experience will differ and importantly can
be expected to increase over time as technology progresses.        Lower bound harsh weather AER:
Similar to conventional vehicles, potential buyers should be        R = 16 · 0.65 · 2.5 = 26 miles                           (5)
aware that “their mileage will vary” with temperature,
terrain, and driver temperament. Once PEVs are introduced
into the market the true ranges will become apparent under         The range estimates for the Volt vary from a range of 25 to
varied conditions. The actual performance will then may            59 miles in sample Volt tests and 35 miles in the final test
affect market perceptions and further adoption. An                 results used by the EPA for the window sticker.
estimation of the PEV all electric range is described by the
relationship:                                                      These AER values are on par with both manufacturers’
                                                                   claimed nominal AER (of 100 for the Nissan Leaf and 40 mi
                 R = C • W        •η         (1)                   for the Chevrolet Volt, respectively), the harsh-weather range
                                                                   (of 62 mi and 25 mi, respectively) and the best-case ranges
With:                                                              (of 138 and 58 mi, respectively) indicated by formally
  R = all-electric range (AER)                                     released data and informal comments by spokespeople from
  C = Gross battery capacity (the battery size installed in the    GM and Nissan.
      PEV in kWh)
  W = State of Charge (SOC) window (i.e., the difference               Note that the range of conversion efficiency parameters
      between the highest SOC and lowest SOC that the              assume a 3500 lb to 3700lb vehicle with good aerodynamics
      vehicle’s control algorithm will allow) and                  (e.g. less than 0.29 Cd-Drag Coefficient). The Leaf’s
  η = conversion efficiency parameter (i.e., distance traveled     conversion efficiencies are assumed to be slightly higher
      per unit of energy consumed, in miles per kWh).              given its lower weight.
                                                                       Also, a range-extended PHEV in blended mode operation
                                                                   using a combination of the electric motor and gas engine for
  Each vehicle type or manufacturer will likely have a unique      propulsion will have a more complex estimate for electric
SOC window given different Lithium battery chemistries,            range beyond the scope of this paper. For example, Toyota
battery thermal management strategy, control algorithms,           has claimed a 13 mile AER for its upcoming 2012 Prius
market requirements for all electric range, and cost/durability    PHEV but at a maximum speed of 62mph. Speeds over 62
objectives. The results of applying this relationship to the two   mph require the gasoline engine to operate.
PEVs with the most information available and that are soon
to be introduced are as follows:
                                                                   B. Second Generation
Nissan Leaf BEV: 24kWh battery [3], estimated 90% SOC
window, with a range of conversion efficiency estimates that         Second generation PEVs will be developed with far greater
vary between 2.8 to 6 miles/kWh based upon temperature,            amounts of field and lab experience enabling improvements
HVAC load, terrain, and driving techniques.                        particularly in cost. Enhancements in battery control and
                                                                   efficiency will improve range or maintain range at decreased
Upper bound optimal AER: (Note: All Electric Range is the          costs. An example could be the first generation Chevrolet
total range of the battery electric vehicle)                       Volt 16kWh battery reduced to perhaps 10 or 12kWh while
   R = 24 · 0.90 · 6 = 129.6 miles                      (2)        maintaining a 40 mile All Electric Range (AER). Hence,
                                                                   second generation PEVs are likely to have more attractive
Lower bound harsh weather AER:                                     financial payback analyses. As PEV powertrain components
  R = 24 · 0.90 · 2.8 = 60.5 miles                         (3)     gain scale production economies and become less expensive
                                                                   (or if oil supplies are disrupted or prices increase
The range estimates for the Leaf vary from a range of 62 to        substantially) relative total cost of ownership improvements
138 miles in sample Nissan tests, approximately 100 miles          will drive further waves of adoption.
with the EPA LA4 cycle, and 73 miles in the final test results        Grid to Vehicle (G2V) SAE J1772 AC Level-1 (120 Volt)
used by the EPA for the window sticker.                            and AC Level-2 (240 Volt) charging capability will remain
                                                                   but likely improved with more substantial communication
                                                                   capability such as power line communications (PLC) between

the Electric Vehicle Supply Equipment (EVSE) and PEV,
ZigBeeTM wireless communications between the smartmeter
and EVSE/PEV, vehicle integrated wireless capability
typically over digital cell phone networks, or 802.11 WiFi TM
wireless communications between the PEV and a home area
network (HAN). These enhanced communications will
enable more sophisticated Grid-PEV interactions and more
intelligent charging with CO2/energy-price signaling or
perhaps limited regulation-up/regulation-down grid ancillary
services, which may generate revenue for the PEV owner.
Additional standards efforts (such as SAE International             Figure 1: Existing SAE J1772 AC Level-1/AC Level-2
J2847) are underway to enable more sophisticated                    Coupler also under consideration by SAE International and
communications between the PEV, the home area network,              IEC as the DC Level-1 Coupler, (Source: Gery Kissel,
and the meters/utility. Also, AC Level-2 charging speed may         7/28/2010)
be improved further by increasing the current capability to the
maximum 80A limit (instead of 240 Volt/30A or 40A) where
supported by the premise electrical infrastructure.                   IEC 62196 supports single phase and a three-phase AC
   By the second generation timeframe, the advantages of the        rapid charge power feed, which is available at some European
various PEV architectures will become clear to customers, the       premises. The SAE J1772 and IEC committees are jointly
technology will have advanced further, and costs/performance        pursuing a strategy of driving a single global specification for
will likely have been improved. Vehicle manufacturers may           the ultra-fast high-capacity “hybrid” connector and interface
have enough knowledge about technologies and PEV                    which is a superset of the round J1772 connector or IEC
consumer behaviors and preferences to offer an increased            62196 connector. This hybrid connector has 2 additional DC
diversity of vehicle platforms using the same basic electric        power pins mounted below its round section, which is used
powertrain components or derivatives. For example, given            for the backward compatible J1772 or IEC 62196 connector
the strong torque capabilities of electric motors, differentiated   (Figure 2)
performance PEVs will likely be announced that have far                 It is unclear whether regional requirements or preferences
more moderate prices (compared with the $109,000 Tesla              will eventually preclude a single global standard. Note that
Roadster). Performance cars traditionally have a higher sales       high-capacity DC charging ports have been previously
price and provide larger profit margins for vehicle                 defined. The Nissan Leaf can include a Japan Automobile
manufacturers. These greater margins can more profitably            Research Institute/Tokyo Electric Power Company
recover the additional costs of the electric powertrain and         (JARI/TEPCO) DC charging port. However, this
batteries by providing the customer with “guilt-free                JARI/TEPCO interface is not accepted as an industry
performance”. Increased number of PEV types and                     standard for the U.S. or Europe at this time and may, or may
performance, lower costs, more familiarity with PEVs may            not, be adopted by SAE International or IEC committees
then increase PEV adoption rates.                                   given its lack of backward compatibility to the J1772 and IEC
                                                                    62196 connectors. While a single standard is certainly
                                                                    desirable, inter-continent differences may in the end have
C. Third Generation                                                 inconsequential impacts on PEV adoption and economics.
                                                                    Each continent presents sufficient volumes to enable scale
  Third generation PEVs may be substantially defined as             economies and negligible numbers of PEVs will travel
vehicles with an industry standard ultra-fast high-capacity         between continents.
interface to the vehicle (beyond AC Level 2) deploying an off-
vehicle charger or with two-way powerflow capabilities. The
next generation higher capacity charging infrastructure
architecture is likely to be DC Level 2 charging supporting a
maximum powerflow of approximately 100kW. Note that
the existing AC Level-1 (120 Volt) and AC Level-2 (240
Volt) standards use an AC power flow between the EVSE and
an on-board PEV vehicle charger. While the manufacturers
of PEVs destined for the U.S. market have apparently
standardized on the SAE J1772 AC Level-1 (120 Volt) and
AC Level-2 (240 Volt) interface (Figure 1), for other markets        Figure 2: Proposed DC Level-2 Charge Coupler under
(such as Europe) the International Electrotechnical                 consideration by SAE International and IEC (Source: Gery
Commission IEC 62196 standard may be adopted as the PEV             Kissel, 7/28/2010)
charging interface.

    Over the first decade progressively more sophisticated        PEVs may act as a distributed storage node with their large
communications, control, and power flow capabilities will be      battery storing less-expensive off-peak energy from the grid
incorporated as vehicle manufacturers gain field experience       or locally generated renewable energy from rooftop solar
with batteries, electronics, PEV driving habits, and as clearer   panels, providing power for the premise, or releasing excess
business models emerge that allow manufacturers to be             energy back to the grid during higher priced peak demand.
profitably compensated for the costs and risks of more            Estimates for the revenue potential for the PEV owner from
sophisticated Grid-PEV interactions.                              ancillary services vary. A large portion of the variation in
    The first reverse powerflow configuration may be Vehicle      estimates appears to be from varied market price assumptions
to Load (V2L) [6]. V2L capability will enable the PEV to act      for ancillary services in the different regions, and differences
as a construction-site generator to an isolated load. An          in assumptions on the costs of aggregation and vehicle
example of this configuration would be a PEV pickup-truck         availability to the aggregators. V2G capability and
which would include an on-board charger, converter, and bed       aggregators would be required to support ancillary services
mounted power outlets.                                            such as regulation up, regulation down, and spinning reserves
   The PEV could act as a home backup generator in a              for the grid independent system operator [9][10]. The
vehicle-to-home (V2H) configuration. Multiple PEVs                limitations to using the PEV for advanced V2G will likely be
acting in concert with a local aggregator/coordinator could       related to the challenge of implementing assured and secure
support a larger isolated building/mobile command                 communications particularly between the aggregator and the
center/Military mobile hospital in a Vehicle-to-Premise (V2P)     large number of PEVs, the amount of the potential income,
configuration.                                                    the additional wear on the PEV battery, and the degree of
  Basic Vehicle-to-Grid (V2G-net-metered or V2G-NM)               inconvenience to the driver.
interactions could leverage the PEV as a distributed storage         The use of PEV range extending engines to generate
node to capture locally generated energy from photovoltaic        energy (and create compensating revenues for the PEV
panels or store low-cost off-peak energy for later release back   owner) which is then fed back to the grid to reduce grid peak
to the grid at higher peak rates through “net-metering”. Net-     demand has questionable likelihood of achieving mass
metering capability enables a home’s electric meter to            adoption given the complexities of control, unattractive
effectively run backward to credit the customer’s account         economics and emissions compared to traditional very large
when their local generation (such as rooftop solar panels)        scale grid generation.
produce more energy than their home demands. The excess              Another concept is to use coordinated PEVs as a grid
energy is fed back into the grid. Unlike residential              feeder backup. The need for assured communication and the
photovoltaic panels which may provide excess power back to        complexity of coordination make the use of PEVs for feeder
the grid simply based upon total sunlight available and the       backup extremely challenging. Orchestration of this concept
local load, the increased communication and control of PEV        would require coordinated isolation of the feeder through grid
can provide greater coordination and optimization of reverse      protection and isolation devices such as relays, breakers, and
power flow to the grid.                                           fuses. It would also require real time estimation of cold start
   Additional configurations of two-way power flow to the         load conditions and cold start coordination across multiple
grid with both G2V combined with Vehicle-to-Home/Vehicle-         vehicles (given it is likely that that multiple coordinated
to-Premise/Vehicle-to-Grid capability will likely require an      vehicles will be needed to serve an entire feeder) and
off-vehicle EVSE /power outlet/transfer switch designed to        estimation of the load on the feeder and generation capability
meet the required premise building electricity codes (such as     of the combined set of vehicles. Algorithms to address issues
“islanding” when the grid power is off) and perhaps an            from different feeder configurations (single-phase or multiple
industry standard high-capacity interface if large amounts of     phase feeders, for example) would also need to be created.
energy flow are required.                                         Coordination of frequency, voltage, and reactive power
   To recover their incremental R&D, manufacturing, and           support across multiple vehicles would be required. Graceful
warranty costs the vehicle manufacturers will likely charge an    coordination of shutdown of PEV generation and resumption
additional premium for a two-way powerflow capable                of grid supplied power would also be required.
interface and an off-board charger/power outlet/transfer
switch box.
                                                                                         III. OIL PRICES

D. Fourth Generation                                                    The influence of oil prices on PEV adoption rates would
                                                                  at first appear straightforward. The higher the retail price of
  With assured two-way communication and control,                 gas and diesel fuel, the more compelling the economics of
additional software, and grid aggregators fourth generation       alternatives such as PEVs. However, some studies have
PEVs may be enabled to generate revenue for the owner             concluded that the long term effect of U.S. retail fuel prices
through the use of their onboard battery and gasoline             on vehicle purchasing decisions is modest and slow [11]
generator.                                                        when fuel prices are typically a minor portion of a family
   PEVs of the future can be used as a source for grid            budget. Consumer behavior that affects demand is shaped by
ancillary services or peak power sales back to the grid [7][8].   the availability of gasoline, the rate of change of price, and

then the absolute price [12]. While the future rate of price           IV. CONSUMER BEHAVIOR AND PREFERENCES
change and absolute price are difficult to predict, the low
relative retail price of U.S. gasoline mutes reactions to price.        Market adoption dynamics can usefully be described in five
Also, the incumbent advantage that the hydrocarbon re-              stages which characterize the buyers: innovators, early
fueling infrastructure has from a network effect is                 adopters, early majority, late majority, and laggards [13].
considerable.                                                       The value proposition and perceived risks of PEVs will likely
    Credible sources have for years debated global producer         change over time. The compelling value proposition to
capacity to continuously increase supply (“Peak Oil”). Over         innovators and early adopters is being the first to purchase
many decades, the global oil industry has continuously              PEVs given their perceived environmental benefits, image,
improved exploration, production (E&P), and recovery                and exclusivity despite higher total cost of ownership (TCO)
methods, which has extended the supply of available oil at          than conventional vehicles. Innovators and early adopters
reasonable prices. Cambridge Energy Research Associates             are willing to pay a price premium for a more
(CERA) estimates that the world has consumed                        environmentally sensitive or alternative fuel vehicle despite
approximately 1 trillion barrels of oil cumulatively and that       potentially very long payback periods determined by a pure
approximately 2 trillion more barrels will likely be available      TCO financial analysis. The next wave of early majority
for future use but at higher prices. As conventional sources of     purchasers will enjoy nearly the same perceived benefits at a
oil diminish, higher prices will drive new sources (e.g.            cost progressively nearing traditional vehicles as successive
Canadian Tar Sands or biofuels) maintaining supplies while          generations of PEVs ramp up volumes and costs are reduced.
simultaneously driving efficiency improvements that typically       Late majority purchasers will view PEVs as a means of
decrease or moderate the growth of aggregate demand over            providing more economical or sustainable transportation. It
time.                                                               is unlikely that PEV adoption will be so great over the next
   Nevertheless, the world’s conventional oil supplies are          decade that laggards (the last group) will purchase them.
exhaustible and will eventually diminish at some time in the             There are numerous risks perceived by customers:
future. It is simply a matter of when and at what price points      technology related, supplier related, and range/use related
new multi-year cycles of exploration and production                 risks. The technology risks clearly are from the batteries,
innovation, efficiency/conservation enhancements, and               control and power electronics, and software. Given there is
alternatives are launched and then come online with some            little field experience with PEVs, it is reasonable to expect
number of years delay. One of the few projections with              some number of teething problems. However, vehicle
certainty is the likely volatility of prices over the long term.    manufacturers’ steady focus on quality, apparent success with
For a U.S. focused analysis, given political realities it is fair   HEV durability, and the ability to easily upgrade the software
to assume that neither a meaningful gas price floor nor             sets expectations that the problems will be minor or quickly
significant carbon or road tax will be implemented in the near      addressable. Vehicle manufacturers with global resources,
future that would substantially raise retail fuel prices and        large strong dealer networks that assure service or parts
hence purposely encourage alternatives. Absent                      availability over the long term, and credibility to back their
internalization of carbon and energy security costs, U.S. gas       warranties given the long life and costs of vehicles will tend
prices are inexpensive to the extent that any alternatives will     to substantially reduce perceived purchase risk to potential
likely be more expensive either in initial purchase price or        PEV buyers.
overall total cost of ownership in the short term for early              It is important to note that usage and range risk are
generation PEVs. PEV adoption rates will likely be more             clearly different for the various types of PEVs. For example,
driven by the success of compelling vehicle designs and             BEVs will likely have a higher perceived usage risk to
image, improved costs over time, and other differentiating          customers given their more limited range and greater
characteristics than purely a financial advantage. Hence,           dependency on public charging infrastructure while possibly
U.S. retail fuel prices will likely have minimal impact on          having a lower perceived technology reliability risk due to
adoption rates alternatives over the next decade unless some        their relatively simple all-electric powertrain.
“tail” event occurs such as a large supply disruption or                A method of reducing the perceived risks of purchasing a
substantial decline in the value of the dollar that causes a long   PEV is to design the product to be more compatible with
term oil price increase that would clearly boost adoption rates.    existing paradigm/models/behaviors and also by dividing the
   While PEVs are likely to be introduced first in the U.S.         steps of adoption into smaller increments. The first step
market, it is conceivable that these vehicles may enjoy faster      could be eREVs/PHEVs which can effectively operate as a
adoption rates in regions such as Europe and Japan that             hybrid after depleting their grid charge (or if they are never
maintain meaningfully higher fuel prices through specific           charged by the grid) and have no range anxiety. Over time,
fuel tax policies meant to encourage efficiency and alternative     as drivers realize that the majority of their actual commuting
fuel vehicles.                                                      needs are met by a 40 mile range, public charging
                                                                    infrastructure becomes sufficiently convenient, or as drivers
                                                                    also retain ownership of a conventional vehicle they may then
                                                                    become comfortable with 100 mile range BEVs.

                         V. POLICY                                    - Actions which accelerate common standards for ultra-fast
                                                                        high-capacity charging
   There are a wide variety of local, state, and federal entities     - Policy that support roaming charging at attractive prices
and actions that can encourage PEV adoption. These actions              at a wide variety of convenient locations.
can generally be categorized as being grid or grid-vehicle            - Actions that encourage smart home technology
related, or being related to the vehicle itself.                        deployment, particularly ones synergistic with PEVs.
The objectives of these actions would ideally be:                     - Policy that enables income producing PEV related
- Reduce the perceived and real risks and costs with                    services in the future such as grid ancillary services.
    purchasing a PEV                                                  - Actions which enable the future collection of road taxes
- Increase the dissemination of accurate performance data to            (similar to gasoline taxes) or the allocation of carbon
    ensure PEVs meet purchasers expectations,                           credits
- Decrease the costs, complexity, or inconvenience of
    buying and using a PEV and create a compelling                      Utilities appear to be very excited about the potential large
    advantage for PEVs over traditional vehicles.                   scale of additional controllable load (and revenue) created by
- Enable and encourage intelligent charging which avoids            PEVs. Existing grid load is traditionally characterized as
    aggravating critical-peak demand and encourages                 price inelastic [14] and expecting reliable, relatively
    charging with low CO2 sourced electricity                       inexpensive energy at any time in any desired amount. The
- Ensuring electricity continues to maintain an attractive          ability for a customer to use whatever amount of energy
    cost advantage as an alternative transportation fuel            whenever desired has been part of the fundamental value
- Encourage investments in charging and communication               proposition of grid energy long embedded in consumers’
    infrastructure essential to enable advanced PEV-Grid            minds. Many ideas have surfaced from grid participants
    interactions.                                                   related to new ways to leverage and control PEVs. Some of
- Encourage investments and market mechanisms which                 these ideas may face consumer resistance given they may
    increase the synergistic interactions possible between          attempt to counter to long lived and deeply-embedded
    PEVs and the grid that further enable the increased use of      consumer behaviors and expectations that change the
    zero emissions generation by fostering strong coincidence       fundamental value of electricity to customers.
    of PEV charging with renewable generation.
                                                                      Vehicle related actions could include:
   There are numerous methods for legislative and regulatory          - Actions that reduce the real or perceived durability risk
bodies to encourage PEV adoption, encourage key technology              to PEV purchasers or resale values (e.g. Federal mandate
development, improve pricing and emissions signaling                    for a 10 year/100,000 mile battery warranty with clear
mechanisms and communications investments, stimulate                    performance criteria)
complimentary investments in renewable generation,                    - Providing realistic PEV electric range information under
transmission, and distribution, better utilize grid assets, and         varied conditions to potential PEV purchasers (similar to
accelerate the economic development of smartgrid technology             mandated EPA fuel efficiency estimates on the window
which can foster strong coincidence of PEV charging with                stickers of conventional vehicles).
renewable generation.                                                 - The rapid promotion of industry common standards for
                                                                        PEV battery tests and performance to encourage
Grid or Grid-Vehicle related actions could include:                     competition and price reductions.
  - Freedom to create vehicle-specific tariff structures with         - Promotion of methods to provide a common interface to
    attractive and flexible TOU off-peak, seasonal, or real             foster second-use of PEV batteries to increase the
    time pricing programs.                                              residual value of batteries no longer suitable for vehicular
  - Actions that enable real time broadcast of price, CO2, or           use. By increasing the residual value of these original
    renewable generation capacity information to vehicles               batteries, the overall battery costs are lowered.
    through such mediums as local FM radio RDS (Radio                 - Education programs for the public to advocate and
    Data System) sub-bands or HD/Digital radio stations to              explain the different types of PEVs to facilitate more
    enable on-board PEV computers to optimize their                     informed consumer choice, increased purchase
    charging behaviors.                                                 satisfaction, and hence increased adoption.
  - Actions which reduce the costs and inconvenience of               - Increased CAFE credits for vehicle manufactures to
    installation of residential, workplace, and public                  encourage a greater diversity of PEV models and lower
    charging stations through common national codes.                    prices to increase adoption.
  - Actions that make public charging stations profitable             - Increased or extended funding for pre-competitive
    (unlike the CARB ZEV experience) e.g. subsidies while               research in automotive batteries either through individual
    the number of PEVs being publicly charged is low,                   grants or consortia to advance durability, lower costs,
    parking space allocations, advantaged permitting for co-            increase power/energy density, and increase competition.
    location with complementary businesses which are
    outside the traditional gasoline refueling station                Policy which affects the vehicle directly, such as specified
    paradigm.                                                       battery warranty lengths are challenging to implement in an

optimal fashion. A balance must be achieved. For example,          generation PEVs will likely be inconsequential to the grid.
mandating a long battery warranty period may reduce                Simple driver entry of a cooperative charge window will
perceived risk by the consumer which then may increase             likely be sufficient to avoid significantly exacerbating peak
adoption. However, if the costs of this warranty are too great,    loads and will be acceptable to early adopters. As increasing
the manufacturer may need to increase the vehicle price to the     numbers of PEVs are sold, local grid to vehicle
point that this higher price then discourages adoption.            communications broadcasting will be useful for emissions and
                                                                   price signaling. Later, two-way communications that
                                                                   transmit the present and desired state-of-charge (SOC),
  VI. GRID CAPABILITIES, INFRASTRUCTURE, AND                       powerflow, and other parameters will be useful in enabling
                  CONCERNS                                         Demand Side Management (DSM), Opportunistic charging,
                                                                   Load Acting As Resource (LaaR), and various forms of
    According to a recent study, with only modestly well-          ancillary services.
behaved charging, the existing U.S. energy grid can support            With the diversity of utilities, of utility deployed
84% of the light duty vehicles in U.S [15]. The only real          technologies, and of utility technical capabilities it is likely
constraint the existing grid has in supporting this massive        that PEV-OEM-Utility communication will likely be the first
number of PEVs in the U.S. is the avoidance of charging            mechanism implemented through vehicle-integrated wireless
during the most extreme periods of peak demand on the grid         pathways such as GM’s On-Star before PEV-ZigBee/PLC-
[16][17]. An example is late in the afternoon on a very hot        Smartmeter-UtilityBackhaul communications pathways are
summer day with extreme air-conditioning loads. The                broadly implemented [18]. These vehicle manufacturer
critical charge avoidance periods will vary by region,             controlled or enabled solutions will likely provide a secure
weather, and year but likely constitutes less than a few           portal for utilities to indirectly connect to a particular vehicle
hundred hours of an 8760 hour year for generation,                 but with unknown incremental costs and communication
transmission, and distribution. The key to avoiding these          assuredness. Technologically sophisticated PEV
periods is the implementation of modest coordination of            manufacturers can certainly implement indirect PEV-Grid
charging windows, staggered charge starting, and avoiding          communications, but the latency, liability, security,
critical peak demand aggravation.                                  ownership, and costs may not be acceptable to utilities or
   To first implement rudimentarily intelligent PEV charging       PEV drivers.
G2V power flow will likely be controlled by the driver                The control strategy for grid independent system operators
manually setting the charge window in the PEV’s on-board           (ISOs) will have to adapt to mass numbers of controllable
computer. “Grid advised”, automated, or real time charge           PEVs. ISOs presently centrally control a relatively small
window control could be sent from the system operator,             numbers of large devices (such as large scale generators).
aggregator, or retailer to the PEV by a variety of                 But with large numbers of relatively small distributed devices,
communication pathways discussed in this paper. Vehicle to         such as PEVs, the control strategy may be more optimal using
Load (V2L) construction site generator configurations are          decentralized control through price or emissions signaling
“off-grid” hence have no communications or coordination            particularly if the vehicle can receive local real time price,
requirement with the grid.                                         CO2, and generation information over a variety of methods
   V2H or V2P where the reverse power flow is only to an           such as FM radio RDS sub-bands or HD/Digital radio
isolated premise requires only communication between the           airwaves.
off-vehicle EVSE/outlet/transfer switch device(s) and the             Given the thousands of utilities each with the freedom to
vehicle(s) and no external communication functions beyond          choose their own technologies and multiple technical
the premise. V2G-net-metering should also have low                 solutions possible, it is likely that vehicle manufacturers,
external communications demand given its focus is using net-       owners, and utilities will all benefit from PEVs providing a
metering to lower a cumulative electric energy bill. V2G-net-      commonly used configurable communications socket or a
metering would be technically enabled but only financially         common PEV-EVSE communications interface where the
attractive if there were sufficient price differences at various   EVSE is then used as a bridge to the required residence
times of the day or the premise has, for example, local solar      HAN/SmartMeter-AMI interface. With a standardized
generation and the added PEV battery wear is assured to be         interface, individual communication interface modules can be
minimal.                                                           installed that support the many potential standards such as
    Advanced V2G to create income from grid ancillary              ZigBeeTM, 802.11 WiFITM, WiMaxTM, cell phone, or PLC
services is a sophisticated concept that would require assured     which could be selected based on regional needs, terrain, cost,
communications and coordination, aggregating entities to           or utility preferences.
control large numbers of V2G participating PEVs, and                   Public and workplace charging infrastructure will evolve
sufficient economic incentives to provide ancillary services.      over time but with the most used charging location likely to
    The continuous improvements in PEV-Grid                        remain the residential garage. PEV buyer clustering is likely,
communications capabilities are essential to enable advanced       which will require distribution analysis and occasional
interactions but may also be important for mitigating the          upgrades. Commercial fleets with home-base charging will
impacts of very large numbers of PEVs charging from the            develop as PEV costs improve over time and become
grid. The volumes and energy consumption of the first              economically attractive. Given longer refueling/recharging

times required for PEVs over conventional vehicles, public        standards may improve public, commercial, or fleet charging
charging infrastructure may be better suited for locations not    capabilities with charge times closer to traditional gas
traditionally used for conventional vehicle refueling. Instead    powered vehicles or to provide increased flexibility of
of conventional gas stations where drivers tend to want to        charging duration and rate to enable improved coincidence
spend the least amount of time possible, the PEV public           with renewable generation sources. PEV-Grid
charging location paradigm will likely be locations that          communications standards are not required for basic G2V
drivers desire to spend considerable time such as shopping        charging but are necessary to implement advanced PEV-Grid
malls, restaurants, movie theatres or where the vehicles are      interactions. Advanced PEV-Grid interactions include grid-
regularly parked for long periods such as employer, mass-         advised charging, opportunistic load deployment, cashless
transit, or airport parking lots. As employers provide daytime    roaming charging with fair/attractive pricing and
charging stations in their parking lots, intelligent charging     convenience,
capabilities will be needed to avoid aggravating high-peak        demand-side management (DSM), load acting as resource
charge periods over the course of the year.                       (LaaR), two-way power flow, and ancillary services. These
    Shopping center public charging stations with free AC         advanced interactions have considerable opportunity to
Level-1 (120 Volt) or AC Level-2 (240 Volt) charging may          improve costs, lower emissions, and improve convenience for
become a tool for retailers to attract PEV drivers to their       the driver.
stores, shop longer, and purchase more goods. The energy          The standards organizations include (but are not limited to):
cost is likely minimal for AC Level-1 or AC Level-2                - SAE International (Formerly, Society of Automotive Engineers)
charging. By making the charging free, these particular            - The Institute of Electrical and Electronics Engineers (IEEE)
EVSEs could be lower in cost since they do not require             - The International Electrotechnical Commission (IEC)
authentication and secure transaction processing capability.       - The National Institutes of Standards and Technology (NIST)
                                                                   - The North American Energy Standards Board (NAESB)
These EVSEs would likely not be ultra-fast high-capacity for
                                                                   - openHAN (
a number of years given increased energy costs, unsettled          - HomePlug and SmartEnergy profile
standards, and increased EVSE costs and safety concerns.              (
   Multifamily residences and street based parking present an      - ZigbeeTM (
infrastructure investment challenge which likely will not be       - National Electric Code (NEC)
addressed at a large scale until PEVs achieve substantial          - Underwriters Labs (UL)
market adoption. PEV drivers who live in multifamily               - EPA Federal Test Procedures (FTP) to create objective fuel
dwellings or park on the street may strongly prefer range-           economy/energy efficiency comparisons for city and highway
extended PEVs (over BEVs) combined with access to                    AER, miles/kWh or blended mode gasoline/electric efficiency
charging at their workplace or where they shop. If these
drivers do not have an opportunity to charge, then the            Given the complex mix of participants, backgrounds, business
extended-range PEV can still simply and beneficially operate      models, regulatory environments, financial incentives and
similar to a conventional HEV.                                    objectives it is likely to take considerable time to converge on
   Some of the greatest challenges to building a public           standards that enable the most sophisticated PEV-Grid
charging infrastructure will be the initial costs, siting for     interactions.
convenience, reserving parking spaces, long charge times,
and the potential for low or negative returns on investment
for owners of public charging stations. For the first decade      VIII. BUSINESS MODELS OF CRITICAL PARTICIPANTS
AC Level-1 (120 Volt) and AC Level-2 (240 Volt) public                TO IDENTIFY INCENTIVES AND MOTIVATIONS
charging stations will likely dominate. Later, ultra-fast high-
capacity public charging stations may become more pervasive       A. Vehicle Manufacturers
as large numbers of PEVs are on the road. These ultra-fast
high-capacity charging stations will create heavy, sporadic         Vehicle manufacturers (commonly called original
loads on the distribution network which may have a                equipment manufacturers or OEMs) business models are
meaningful effect on feeders and may require local storage to     simple: profitable sales of vehicles with green/energy
condition the distribution feeder to maintain power quality       secure/alternative fuel image attributes have proven to be
[19]. Most public stations will likely need to include            advantageous in building brand image and goodwill but have
authentication and secure transaction capabilities for            had difficulty in achieving profitability in the U.S. market
commerce.                                                         given relatively low gas prices. Product safety, liability,
                                                                  warranty cost, customer satisfaction, and recall costs are also
                                                                  critically important to OEMs. Profits can typically be
                     VII. STANDARDS                               achieved through higher vehicle sales of a popular vehicle
                                                                  that help recover considerable fixed development and tooling
  The most critical standards development efforts underway        costs and lower component costs as volumes increase. The
are related to the charging infrastructure, particularly ultra-   profit per vehicle tends to also increase with the number of
fast high-capacity charging beyond the J1772 AC Level-2 and       options installed. Beyond the incremental revenue from a
PEV-Grid communications. High-capacity charging                   “V2L/V2H/V2P option” at the time of vehicle purchase, it is

difficult to see how OEMs will be enthusiastic about their        clustering concern may be since each utility has its own
PEVs participating in advanced two way power flow                 transformer loading design guidelines and financial
interactions that increase risks of component failures,           considerations. It should be noted that PEV clustering effects
warranty costs, and safety/liability exposures without            on the distribution system with AC Level-1 (120 Volt) or AC
competitive, regulatory, or grass-roots pressure.                 Level-2 (240 Volt) charging should be primarily a financial
    U.S. vehicle purchasers express the desire for exceptional    concern of typically regulated transmission & distribution
fuel economy but are resistant to pay any additional price to     service providers (TDSPs) or integrated municipal or coops
allow the OEM to recover the incremental costs associated         who are concerned with cost recovery for the potential
with the required technologies. Between Federal government        upgrades. Transformer loading is not a technical problem in
mandates for higher fleet average fuel efficiency and             search of a breakthrough. If the transformer or lines are
customer reluctance to pay a premium for substantial fuel         overloaded, they can be replaced with larger capacity ones
efficiency improvements given low gas prices, the number of       preemptively or after a failure. It should also be noted that
highly efficient hybrid vehicle sales such as the Prius are       charging systems beyond the already capable AC-Level-2
modest even today at approximately 2% to 3% of total vehicle      (240 Volt) systems may create further stresses on distribution
sales. Over time, through a combination of declining PEV          system infrastructure. However, it is unclear that ultra-fast
technology costs, increased gas prices, and income from grid      charging with a very high capacity interface such as DC-
ancillary services paid to the owner the authors expect PEVs      Level-2 (500 Volt) will become viable for home charging
to gain meaningful market adoption and profitability for          given the extremely high cost of the charge station and the
OEMs.                                                             questionable need for less-than-30 minute residential
                                                                  charging. Over the past century, distribution systems had to
B. Grid participants                                              be upgraded from waves of adoption of home appliances, air
                                                                  conditioning, and then electronics. PEVs (as well as large
   Grid participants include generators, transmission and         Plasma/LED HDTVs and other modern loads) can be
distribution firms, energy retailers/municipals/coops,            considered the next wave and a new revenue source for grid
independent system operators, and grid aggregators. Grid          participants in the same tradition.
participants would benefit most significantly from increased          Aggregators can function at the premise or ISO level.
energy sales to PEVs. The incentives and impacts to               Premise aggregator functions can enable multiple PEVs using
participants will likely be regional and dependent upon the       V2P to support a specific isolated building through reverse
regulatory landscape and associated market design.                power flow. Aggregators are useful to enable ancillary
   The incentives and implications for electric generators will   services [22], advanced intelligent charging, DSM, and
be mainly dependent upon the market design and regulatory         opportunistic loads by intermediating between ISOs and
environment that the generator operates under. Unregulated        thousands of PEVs in a particular region. For example, in
generators will benefit from increased PEV loads throughout       the ERCOT context, qualified scheduling entities (QSEs)
the day, and may actually derive increased profits if PEV         could act as aggregators and, for example, offer ancillary
charging aggravates peak charging which may increase peak         services into the market, with a minimum of 1MW in the
marginal energy prices and market clearing prices.                ERCOT zonal market or 100kW in other markets or the
Regulated generators may have incentives, regulatory              upcoming ERCOT nodal market [23].
directives, and guaranteed returns which lead them to be             The strength of the financial incentives to invest in
more concerned with influencing PEV charging in ways              advanced V2G-enabled ancillary services fosters considerable
which avoid aggravating peak electric demand.                     debate presently. Some analyses indicate that PEV ancillary
If non-intrusive mechanisms are deployed to avoid charging        services could generate an attractive income to help offset the
that aggravates critical peak demand, then the incremental        higher initial PEV purchase price [24]. Other studies
energy sales should be particularly profitable given they         indicate that the financial payback may be more modest [10].
would require minimal, if any, additional capital equipment       Regional market differences may explain a meaningful
investments. This benefit may be particularly advantageous if     portion of such differences.
vehicle specific energy sales help to compensate for reduced        An ISO’s key objectives are the maintenance of grid
revenue from greater building efficiency improvements or          stability and reliability while enabling the delivery of lowest
demand side management (DSM) programs or if PEVs enable           cost electricity in their respective region and the reduction of
greater economic incorporation of renewable energy.               emissions from generation. As non-profit entities, ISOs are
   Distribution system owners may experience the most             driven by regulatory requirements, operating standards,
meaningful impacts if local distribution transformers are         guidance from their respective regulators such as public
stressed from PEV clustering [20][21]. The predominant            utility commissions (PUCs), NERC, EPA, and others, and
concern is whether the additional load from multiple PEVs         feedback from their respective grid participants. The degree
charging through a single distribution transformer may            to which the various ISOs aggressively pursue and invest in
increase either increase the peak load or temperature, or         capabilities to enable sophisticated PEV-Grid interactions
reduce the night-time cooling, all of which may reduce the        will likely be unique for each ISO and strongly determined by
service life of the transformer. Only experience will confirm     PUC, Federal, state, and local mandates for emissions
how minor or significant the PEV distribution transformer         reductions and renewable portfolio standards. There is no

pure profit incentive for the ISO to drive sophisticated PEV-                            IX. CONCLUSIONS
Grid interactions.
   Residences are expected to be the dominate charging                  PEV-grid capabilities will be defined not only by the rate
location. Workplace charging of fleets, rentals, and employee       of technology development but will likely also be guided,
vehicles is expected to be the next most pervasive, but still far   accelerated, or limited by the regionally unique financial
less popular than residential charging. For a number of             incentives, regulatory structure and requirements, and values
years, public charging is expected to be the least pervasively      of each participant.
deployed location (Figure 3).                                         Vehicle OEMs are fundamentally driven to create PEVs
                                                                    with compelling design, image, and features that will create
                                                                    profitable vehicle sales. Safety and durability are, of course,
                                                                    also critical and fundamental objectives. The additional
                                                                    software cost to enable “grid friendly” charge window
                                                                    programming is negligible and hence expected to be
                                                                    incorporated in all PEVs. More advanced grid-advised or
                                                                    renewable generation coincident charging can be enabled by
                                                                    relatively simple broadcast of emission or price related
                                                                    information to PEVs. Algorithms programmed into the PEV
                                                                    on-board computer can then deduce the optimal charging
                                                                    profile. With more advanced communications and grid
                                                                    aggregators, the sale of limited regulation up/regulation down
                                                                    ancillary services could produce revenue for the PEV owner
                                                                    by regulating G2V charging of the vehicle.
                                                                         Enabling basic two-way power flow for V2L, V2H, or
                                                                    V2P adds extra hardware costs, adds risk of stress and failure
   Figure 3: Hierarchy of likely charging locations                 to PEV components and battery, and increases product
                                                                    liability exposure. An extra cost V2L contractor site
   For a number of years, every PEV will likely charge from         generator or V2H/V2P backup generator option that avoids
home (or home base) at night. Public charging stations              the need for sophisticated external communication and
reduce range anxiety for BEV owners, provide a location             coordination could be profitable for vehicle manufacturers.
where PEV owners can further reduce their petroleum                 PEVs enabling V2L, V2H, V2P or basic V2G-Net-Metering
consumption by daytime charging, or provide a charging              capability can likely be profitably offered as an extra cost
location for drivers who otherwise would not purchase a PEV         option once sufficient field experience has been gained to
given they street park or do not have their own residential         understand and address key technology failure mechanisms.
charging location. From the CARB ZEV experience, public             Given there are few dependencies upon advanced external
charging station owners will likely have difficulty in              communications and control or industry standards
achieving profitability without subsidies. Public charging          development, this option holds promise of commercialization
stations would likely need to deploy a gas-station like model       as soon as vehicle manufactures can profitably engineer a
to be profitable, These pubic charging stations may require         sufficiently robust hardware and software solution.
ultra-fast high-capacity charging stations and large numbers           V2G with limited communication could be useful and
of PEVs on the road in order to create sufficient energy sales      financially attractive in regions with substantial time-of-use
volumes and asset utilization for the charging station. Lower       price differentials or premise solar or wind generation which
cost public charging stations may be able to achieve                is net-metered back to the grid. Over the next five to ten
profitability even with modest AC Level 2 energy flow if the        years, introduction of the most advanced V2G capability
equipment and facilities costs are minimized, but charge            which supports the sale of a rich set of ancillary services is
times would be much longer than the traditional 10 to 15            expected to be limited by the availability of assured PEV-Grid
minute required at a conventional gas station hence the             communications and two-way power flow capability and
charger may need to be at a non-traditional location where          control on the PEV. The varied communication and control
the driver has other activities to occupy their time (e.g.          pathways, reliability requirements, other performance
shopping, movies, restaurant). Profitability may also be            parameters, and financial payback are complex and all areas
achieved by higher pricing of the public charging service than      of further research. Vehicle manufacturers may also be
typical retail residential energy prices. Key challenges for        hesitant to offer this capability for a number of years until the
public charging stations are standards to enable charge times       wear mechanisms and risks are well known and they
that are comparable to traditional gas stations, achieving          understand how to profitably offer this feature.
sufficient energy sales volumes to enable profitability, and           Grid participants are typically motivated by increased
success at installation of public charging stations where           vehicle-specific energy sales while also avoiding the
drivers typically spend considerable time.                          aggravation of critical peak demand. To encourage PEV
                                                                    adoption to create this demand, grid participants will be
                                                                    focused on safe, convenient, and cost effective access to

charging stations. In order to avoid aggravating peak             progression of PEV-grid interactions is synthesized and
demand grid participants will likely encourage grid friendly      summarized in Table 1.
charge windows through simple peak/off-peak pricing
programs combined with manual driver inputs to the PEV on-
board computer, the offer of subsidized home EVSE
installation in return for demand response control, or
rudimentary signaling of CO2 and prices to the PEV over
various communication pathways.
  Significant investment and interest in advanced V2G PEV-
Grid interactions will likely require policy action or regional
specific circumstances which create sufficient financial
  Using PEVs as synergistic grid storage will be more
compelling to utilities when new sources of fast ramp/zero-
CO2 generation, spinning reserves or regulation ancillary
services are needed to enable greater deployment of
intermittent renewable generation. This increased thrust for
greater renewable generation and hence sophisticated PEV
storage control may be most strongly accelerated by
increasing renewable portfolio credits, renewable fuel credits,
production tax credits, carbon taxes or other policy actions.
   PEV purchasers will evolve over time from innovators, to
early adopters, early majority purchasers, late majority
purchasers, and laggards. Innovators and early adopters will
be willing to pay a premium for green or alternative fuel
vehicles and are typically tolerant of early innovation
problems. Early majority purchasers will appreciate the
green or alternative fuel vehicle technologies but will be
sensitive to substantial costs or inconveniences above
conventional vehicles. Late majority purchasers will likely be
much less emotionally attached to green or alternative fuel
vehicles and demand a better overall cost or some other clear
form of differentiated value from a PEV over traditional
vehicles. Laggards will select PEVs only when it they
become a substantial portion of the market and have
absolutely clear advantages, or when they have no alternative.
    This paper includes a comprehensive attempt to articulate
the most important factors which affect PEV adoption,
characteristics, capabilities, and interactions with the grid
over the next decade. A likely, or at least possible,

                                              Table I
                               Progression of PEV-Grid Interactions

                                                       Communications              PEV-Grid Interaction
PEV Generation              Power Flow                  Characteristics                 Characteristics
First Generation    Grid-to-Vehicle (G2V)         Over cell phone network (if   G2V with manual driver
                                                  any)                          programmed “grid friendly”
                                                                                charge window
Second Generation   Grid-to-Vehicle (G2V)         Real-time broadcast of CO2    G2V with advanced
                                                  and price information to      intelligent charging aligned
                                                  PEVs                          with renewable generation

                                                  Grid-to-PEV                   G2V with limited regulation
                                                  communications via            up and regulation down
                                                  aggregator                    ancillary services
Third Generation    Grid-to-Vehicle (G2V) plus    EVSE-PEV communication        V2L for construction site
                    Vehicle-to-Load (V2L)         only (no external             generator

                    Grid-to-Vehicle (G2V) plus    EVSE-PEV communication        V2H for home backup
                    Vehicle-to-Home (V2H)         only (no external             generator (isolated through
                                                  communications)               premise transfer switch)

                    Grid-to-Vehicle (G2V) plus    EVSE(s)-PEV(s)                V2P as building backup
                    Vehicle-to-Premise (V2P)      communication only (no        generator (isolated through
                                                  external communications)      transfer switch and
                                                                                coordinated by a local

                    Grid-to-Vehicle (G2V) plus    EVSE-PEV communication        V2G-Net-Metered: Local
                    Vehicle-to-Grid-Net Metered   only (no external             generation (such as rooftop
                    (V2G-NM)                      communications)               photovoltaics) with reverse
                                                                                power flow of excess energy
                                                                                and net-metering.

Fourth Generation   Grid-to-Vehicle (G2V) plus    Assured secure two-way        V2G-Advanced: Grid
                    Advanced Vehicle-to-Grid      Grid-PEV communication        Ancillary Services provided
                    (V2G-Advanced)                                              by two-way power flow of
                                                                                PEV battery energy and/or
                                                                                local generation (such as
                                                                                rooftop photovoltaics)

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    revenue,” Journal of Power Sources, 2005, pp. 1-12.        the electricity grid, Electric Power Research
[8] A. N. Brooks, “Vehicle-to-Grid Demonstration               Institute, Electric Transportation, PHEV-2009
    Project: Grid Regulation Ancillary Service with a      [22] C. Guille and G. Gross, “A conceptual framework
    Battery Electric Vehicle” Contract number 01-313           for the vehicle-to-grid (V2G) implementation,”
    Prepared for the California Air Resources Board,           Energy Policy, vol. 37, no.11, pp.4379-4390, 2009.
    2002, pp. 1-3.                                         [23] ISO/RTO Council, 2010 North American Demand
[9] ISO/RTO Council and KEMA Inc, Assessment of                Response Characteristics,
    Plug-in Electric Vehicle Integration with ISO/RTO
    Systems, December 2009                                     c=jhKQIZPBImE&b=2613997&ct=8400541&notoc
[10] Casey Quinn, Zimmerle, Daniel, and Bradley,               =1
    Thomas., The effect of communication architecture      [24] W. Kempton and J. Tomic, “Vehicle-to-grid power
    on the availability, reliability, and economics of         fundamentals: Calculating capacity and net
    plug-in hybrid electric vehicle-to-grid ancillary          revenue,” Journal of Power Sources, 2005, pp. 1-12.
    services, Journal of Power Sources, 195 (2010) 1500-
    1509, V2G Ancillary Service Architecture Modeling
    and Analyses, PHEV-2009 conference presentation,                             XI.   BIOGRAPHIES
    August 2009.
[11] Musti, S. Kortum, K, Kockelman, K. “Household         Dave Tuttle received his B.S. and Master of Engineering
    Energy Use and Travel: Opportunities for Behavioral    in Electrical Engineering with Highest Honors from the
    Change“,89th Annual Meeting of the Transportation      University of Louisville, Speed Scientific School in 1981
    Research Board and forthcoming in Transportation       and 1982 and an MBA with the Dean’s Award from the
    Research Record Part D                                 University of Texas at Austin in 1991. He was
[12] R. Tillerson, CNBC, 2008, interview with              responsible for designing microprocessors and leading
    ExxonMobil CEO Rex Tillerson                           microprocessor and systems development teams at IBM
[13] E. Rogers, Diffusion of innovations (4th ed.). New    (1982-2000). He later formed a design team for Sun
    York: Free Press.1995                                  Microsystems in Austin, Texas focused on
[14] S. Stoft, Power Systems Economics: Designing          multicore/multithread microprocessor development. He
    Markets for Electricity, 2002                          is a Research Fellow and PhD student in the Department
[15] Kintner-Meyer, M. Schneider, K., Pratt, R,            of Electrical and Computer Engineering at the University
    IMPACTS ASSESSMENT OF PLUG-IN HYBRID                   of Texas at Austin. His current research interests are
    VEHICLES ON ELECTRIC UTILITIES AND                     PEVs, PEV interactions and synergies with the electric
    REGIONAL U.S. POWER GRIDS, Pacific                     grid, and renewable energy.
    Northwest National Laboratory, November 2007,

Ross Baldick (F’07) received his B.Sc. in Mathematics
and Physics and B.E. in Electrical Engineering from the
University of Sydney, Australia and his M.S. and Ph.D.
in Electrical Engineering and Computer Sciences in 1988
and 1990, respectively, from the University of California,
Berkeley. From 1991-1992 he was a post-doctoral fellow
at the Lawrence Berkeley Laboratory. In 1992 and 1993
he was an Assistant Professor at Worcester Polytechnic
Institute. He is currently a Professor in the Department
of Electrical and Computer Engineering at The
University of Texas at Austin.

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