Plug-in HEVs: A Near-Term O

Reduce Petroleum Consu

from FY05 Milestone Rep

Tony Markel, Michael O’Keefe, Andrew 

Jeff Gonder, Aaron Brooker

National Renewable Energy Laborat

Golden, Colorado

January 19, 2006

NREL/PR-540-39415Presented to DOE management staff on September 14, 2005 at the DOE headquarters in WContent updated January 19, 2006 for final publication. 
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Project Objective

• Assess the opportunity for a future r

program that will address plug-in hyvehicle (PHEV) market & technolog

• Approach

– Collect and assemble information and 

enhance our understanding of the ben

of plug-in hybrid technology
Messages

• Plug-in HEVs have the best near-te

reduce petroleum consumption by sdemand to a variety of domestic sourenewables

• Systems integration/optimization are 

provide commercially viable options

– Battery technology development critica

pathway depends on application, vehicand utility integration approach
The Perfect Storm

• Petroleum consumption has steadily 

increased while domestic production has continued to decline

• World oil production will likely peak within 

the next 5-15 years

• Recent increase in gasoline price is 

indicator of growing tension between supply and demand

What

’s o

s o

0 0.51

1.5

2

2.5

Aug 11,

1987

May 07,

1990

Jan 31,

1993

Oct 28,

1995

Jul 24,

1998

Apr 19,

2001

Jan 14,

2004

Oct 10,

2006

Weekly National Average Gasoline 

Retail Price ($/gal)

Source: U.S. Department of Energy, Energy Information Administration

05

10152025

1940 1950 

Petroleum (mmb/day)

Gasoline price - 75% rise in 5 years!

S
Vehicle Technology Options 

Petroleum Consumpti

• Hybrid electric vehicles (charge-sustaining

– Combines petroleum engine with a small ener

used over narrow window of operation

• Plug-in HEVs (charge-depleting)

– Use larger energy storage device with the abil

both on-board and off-board sources with a peproviding continuous fast refuel operation

• Fuel cell hybrid vehicles 

– Replaces the petroleum engine with highly effi

consuming hydrogen from non-petroleum sour

charge-sustaining or charge-depleting

• Electric vehicles

– Large energy storage is the only source of pro
0

50

100150200250300350400

2005 2010 2015 2020 2025 2030 2035 2040

Year

Per Vehicle Cumulative Fuel Savings 

(barrels of oil)

FCHEV (100%)PHEV (65%)HEV (30%)

• • 

 PHEVs provide the best combination of rate and tim

significant fuel consumption reduction benefits while cell technology is being developed

Cumulative Petroleum Saving

of Technology Option

High Impact Path High Impact Path
1

10

100

1,000

10,000

10,000 100,000 1,000,000 10,00

Number of PHEVs

Annual Barrels of Oil Saved 

(millions)

1,000,000 PHEVs Could Save 

Barrels of Oil Annual

It has taken 5 years to hybrid vehicles in the 

Annual US Consumption

Daily US Consumption

(5
Messages

• Plug-in HEVs have the best near-te

reduce petroleum consumption by sdemand to a variety of domestic sourenewables

• Systems integration/optimization are 

provide commercially viable options

– Battery technology development critica

pathway depends on application, vehicand utility integration approach
Plug-In HEV Design Opt

• Typical Plug-in HEV characterized by All 

Electric Range (AER)

– AER - miles driven after a full recharge until the 

gasoline engine first starts to assist

• Alternatively, Plug-in HEV design may focus 

on maximizing the electric-only miles dispersed throughout a driving pattern

– maximizes the effective and efficient use of 

grid-electricity

• Combination of these two scenarios likely to 

provide optimal reduction in petroleum consumption

– Use grid-electricity to off-set use of gasoline 

improve cycle average efficiency of the engine

So
Component Sizing and Control O

Battery power sufficient to provide EV-only operation

60 

PHEV10 Mid-Size Sedan (fixed battery energy)
Component Sizing and Control O

Only a few EV miles but many more blended miles

PHEV10 Mid-Size Sedan (fixed battery energy)
Component Sizing and Control O

Battery is < half the original power and 30% cheaper, but fuel economy drop is < 10%

PHEV10 Mid-Size Sedan (fixed battery energy)
Component Sizing and Control O

Below 20kW battery, lost regen impacts consumption

PHEV10 Mid-Size Sedan (fixed battery energy)
Component Sizing and Control O

Cylinder deactivation in large engine could be used to regain efficiency

PHEV10 Mid-Size Sedan (fixed battery energy)
Performance Variability Ch

• Larger engine provides better 

continuous performance

– Charge-sustaining fuel economy 

improvement potential directly related to engine downsizing

– Peak power capability is a function 

of battery/motor power

• Battery power capability varies with 

state of charge

– In charge-sustaining mode, 

battery/motor must be sized to maintain performance

• If vehicle performs best when fully 

charged, it is an incentive for the consumer to recharge often

Plug

-in HEV10 battery even at low SOC lev

in HEV10 battery even at low SOC lev

power and twice the available energy of t

power and twice the available energy of t

battery battery

05

1015202530

0 10 20 30 40 

State o

Discharge Power - 10s (kW)

PHEV10 (power)
Cost and Life Challen

• Deep cycling of batteries tends to s

number of cycles before end of life

– Characterization of real-world cycling i

• Cost of advanced batteries high und

volume production situation

– Selection of battery characteristics and 

management provides solutions

Existing data sets provide limited view of fu

Existing data sets provide limited view of fu

Need more data to support conclu

Need more data to support conclu
Battery Cycle Life Da

• Existin• Need t

high ain PHE

Source: Presented by Christian Rosenkranz (JCI) at EVS 20
Battery Cost Model: Specific Cost vs

Taylor D. & Browning L. (2003) “Simplified Life Cycle Cost Analysis of Plug-in HEHEVs & Conventional Vehicles in 2012”, EVS20 Plug-In HEV Workshop, Long Be

• Slope and 

magnitude of relationship are long-term and debatable

Projections
Optimal Depth of Discharge (DOD) is D

Battery Life and Cost, Vehicle Life, Du

Requires systems approac

HEV20, 40 mile trip - Annual Cost Breakdown

$-

$200.00$400.00$600.00$800.00

$1,000.00$1,200.00$1,400.00$1,600.00$1,800.00$2,000.00

HEV0 100% 80% 73.3% 60% 40% 2

DOD window

Annual cost 

Battery cost Optimum DOD = 73%

decreases as 

life increases

Battery life exceeds 

vehicle life

Energy costs increase as battery weight increases

Battery cost and life 

assumptions highly 

influential
Designing for Requirements Pro

Effective PHEV Solutio

Plug-In HEV Annual Cost savings relative to HEV0 vs. Trip distance (

as a percentage of HEV0 Annual Costs

-160%-140%-120%-100%

-80%-60%-40%-20%

0%

20%40%

0 10 20 30 40 50 60 70 

Trip distance (miles)

Cost Saving (%) 

• Maxim• Only i

and m

Large relative cost penalty when trip length << AER - battery is under-utilized

Peak cost saving reduces for larger AER

Daily Distance Distribution Cost effective solutions capture larpercentage of trips
Development of Vehicle Requ

Based on Real-World Drivi

• Optimal design for greatest cost/ben

dependent on duty cycle 

• National personal transportation sur

a potential data source

• St. Louis data used as 

an example data set

• Similar data sets for Similar data sets for 

other areas required to other areas required to fully characterize fully characterize national behavior national behavior

22
St. Louis Travel Data Ana

Daily Driving Distance Slightly Shorter than 1

02468

1012

0

0-5

5-10

10-15

15-20

20-25

25-30

30-35

35-40

40-45

45-50

5

Daily Dis

Frequency (%)

1995 NP

<25 mi

<33 m

St. Louis is a fair
0 5 10 15 20 25 30

0

50

100150200250300350

Cumulative gallons of fuel consumed for 227 vehicles modeled

Local Time (hr)

Gas Equivalent Consumption (gal)

Conventional vehicleMidsize PHEV

Preliminary PHEV In-Use Fuel Co

• 8647 total miles driven• 100% replacement of 

sample fleet

• 1452 kWh for recharge

Each vehicle in St. Louis data set was modeled both as a co

Each vehicle in St. Louis data set was modeled both as a co

Morning 

commute 

electrified!

26.6 mpg

106 mpg

& 

168 Wh/mi

Assumes $2.50/gal and 6¢/kWh
Optimal Configuration & Associate

Based on Realistic Market Pen

• Technical Target Tool (T3) competes PHE

conventional, and FCHEVs

• Sales predictions based on vehicle attribu

•Ou

– – 

INPUTS

OUTPUTS OUTPUTS
Automotive

Perspective

Opportunity for Collabor

• Multidisciplinary challenges can be 

with collaborative effort

ba

v

Communities

in-use experience

Systems Analysis Systems Analysis

design for application

Energy Ana

Energy Ana

utility forecas

Energy Storage Energy Storage

thermal, life, 

cost, performance

Distributed Energy Distributed Energy

grid integration
• Additional Needs

– Collaborative multidisciplinary modeling effo

integration and implementation opportunities 

HOMER®,...)

– Support the development of parametric ba

models through data collection

– Estimate market penetration potential and 

Plug-in HEVs using analysis tools

• Planned FY06 Activities

– Explore design options to address 

challenges and define requirements

– Develop realistic 24hr PHEV drive cycle 

including charging for life cycle testing

– Demonstrate technology viability and 

functionality

Future Work

F• • • 
Messages (Just a Remin

• Plug-in HEVs have the best near-te

reduce petroleum consumption by sdemand to a variety of domestic sourenewables

• Systems integration/optimization are 

provide commercially viable options

– Battery technology development critica

pathway depends on application, vehicand utility integration approach