Plug-in Hybrid Electric Vehicle Energy Storage System Design

Advanced Automotive Battery Conference by

Tony Markel and Andrew SimpsonNational Renewable Energy Laboratory

May 19th, 2006

With support from theU.S. Department of Energy

Office of Energy Efficiency and Renewable Energy FreedomCAR and Vehicle Technologies Program

Presented at the Advanced Automotive Battery Conference held May 17-19, 2006 in Baltimore, MarylandNREL/PR-540-40237

2

The Perfect Storm

• Petroleum consumption has steadily increased while domestic production has continued to decline

• World oil production predicted to peakwithin the next 5-15 years

• Recent increase in gasoline price is indicator of growing tension between supply and demand

WHATWHAT’’S OUR PLAN?S OUR PLAN?

0

5

10

15

20

25

1940 1950 1960 1970 1980 1990 2000 2010

Petr

oleu

m (m

mb/

day)

Domestic ProductionDomestic Consumption

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

Source: Hubbert Center Newsletter #99/1 R. Udall and S. Andrews

Gasoline price - 85% rise in 5 years!

0

0.5

1

1.5

2

2.5

3

3.5

Aug 11,1987

May 07,1990

Jan 31,1993

Oct 28,1995

Jul 24,1998

Apr 19,2001

Jan 14,2004

Oct 10,2006

Jul 06,2009

Wee

kly

Nat

iona

l Ave

rage

Gas

olin

e R

etai

l Pric

e ($

/gal

)

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

3

Light Duty Fleet Oil Use - Impact of HEVs on Consumption

0

2

4

6

8

10

12

14

16

2000 2005 2010 2015 2020 2025 2030

Year

Oil

Con

sum

ptio

n (M

PBD

)

2005 AEO Base CaseHEV Scenario

Oil Use Reduction with HEVs

3 MBPDOil use same as today!

This highly aggressive scenario assumes 100% HEV sales from 2010 onwards…

Produced using VISION model, MBPD = million barrels per day

HEVs unable to reduce consumption below today’s consumption level

4

Light Duty Fleet Oil Use - Impact of PHEVs on Consumption

0

2

4

6

8

10

12

14

16

2000 2005 2010 2015 2020 2025 2030

Year

Oil

Con

sum

ptio

n (M

PBD

)

2005 AEO Base CasePHEV Scenario

Oil Use Reduction with PHEVs

4 MBPD

This highly aggressive scenario assumes 100% HEV sales from 2010 and 50% PHEV40 sales from 2020 onwards…

Oil use reduction!

Produced using VISION model, MBPD = million barrels per day

PHEVs reduce oil consumption with a transition to electricity

PHEVs on E85 ??

5

Recent PHEV Prototypes

EnergyCS Plug-In Prius HyMotion Escape PHEV

AC Propulsion Jetta PHEV

AFS Trinity Extreme Hybrid™

Esoro AG H301

DaimlerChrysler Sprinter PHEV

Renault KangooElect’road

6

PHEV Batteries

Johnson Controls / SAFT Cobasys

HymotionValence Technologies

7

Battery Characteristics

0

200

400

600

800

1000

1200

1400

1600

1800

2000

0 5 10 15 20Power to Total Energy Ratio (kW/kWh)

Pow

er D

ensi

ty (W

/L)

NiMHLi-ion

0

200

400

600

800

1000

1200

1400

1600

1800

2000

0 5 10 15 20Power to Total Energy Ratio (kW/kWh)

Spec

ific

Cos

t ($/

kWh)

ProjectedCurrent Status

0

200

400

600

800

1000

1200

1400

0 5 10 15 20Power to Total Energy Ratio (kW/kWh)

Spec

ific

Pow

er (W

/kg)

NiMHLi-ion

Lower power to energy ratioleads to lighter, smaller, and

less expensive energy storage system

8

All-Electric vs Blended Strategy

• Engine turns on when power exceeds battery power capability

• Engine only provides load that exceeds battery power capability

• Engine turns on when battery reaches low state of charge

• Requires high power battery and motor

-30

-20

-10

0

10

20

30

40

50

60

70

0 5 10 15 20 25 30 35 40Distance (mi)

Pow

er (k

W)

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

SOC

(%)

enginemotorSOC

All-Electric

-30

-20

-10

0

10

20

30

40

50

60

70

0 5 10 15 20 25 30 35 40Distance (mi)

Pow

er (k

W)

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

SOC

(%)

enginemotorSOC

Blended

9

0 10 20 30 40 50 600

0.1

0.2

0.3

0.4

Fuel

Con

sum

ptio

n

PHEV20 on LA92

0 10 20 30 40 50 600

20

40

60

80

100

Energy Storage System Rated Power (kW)

CD

Mod

e P

etro

leum

Cons

umpt

ion

Red

uctio

n (%

)

Electricity (kWh/mi)

Gasoline (L/mi)

Blended

All-E

lectric

Blended vs. AER Consumption Tradeoff

• Reducing ESS power should reduce cost, mass, volume

• 50% reduction in power still provides almost all of the fuel consumption benefit

* CD = Charge DepletingP

ower Battery Limit

Battery

Engine

10

PHEV Battery Sizing Alternatives

0

10

20

30

40

50

60

0 5 10 15 20 25 30Energy (kWh)

Pow

er (k

W)

PHEV20 - BlendedPHEV20 - AERPHEV40 - BlendedPHEV40 - AER

50% SOC Window70% SOC Window

AER

Blended

11

Battery Life

• PHEV battery likely to deep-cycle each day driven: 15 yrs equates to 4000-5000 deep cycles• Also need to consider combination of high and low frequency cycling

Data presented by Christian Rosenkranz (Johnson Controls) at EVS 20

4000

50%

70%

12

PHEV Battery Cost Requirements for 5 Year Payback

$-

$500

$1,000

$1,500

$2,000

$2,500

$3,000

0 5 10 15 20 25

Power-to-energy ratio (kW/kWh)

Batte

ry s

peci

fic c

ost (

$/kW

h to

tal)

NiMHLi-Ion

PHEV3.5

PHEV5

PHEV10

EXPANDED 70% SOC WINDOW FOR ALL PHEVS

Projected battery costs

Current battery costs?

HEV0

HEV0 PHEV3.5

$4.30 / gal.

$2.15 / gal.PHEV20

(19,000 mi/year, 52 mi/day avg.)Assumed electricity cost = 9c/kWh

PHEV40

$-

$500

$1,000

$1,500

$2,000

$2,500

$3,000

0 5 10 15 20 25

Power-to-energy ratio (kW/kWh)

Batte

ry s

peci

fic c

ost (

$/kW

h to

tal)

NiMHLi-Ion

PHEV3.5

PHEV5

PHEV10

EXPANDED 70% SOC WINDOW FOR ALL PHEVS

Projected battery costs

Current battery costs?

HEV0

HEV0 PHEV3.5

$4.30 / gal.

$2.15 / gal.PHEV20

(19,000 mi/year, 52 mi/day avg.)Assumed electricity cost = 9c/kWh

$-

$500

$1,000

$1,500

$2,000

$2,500

$3,000

0 5 10 15 20 25

Power-to-energy ratio (kW/kWh)

Batte

ry s

peci

fic c

ost (

$/kW

h to

tal)

NiMHLi-Ion

PHEV3.5

PHEV5

PHEV10

EXPANDED 70% SOC WINDOW FOR ALL PHEVS

Projected battery costs

Current battery costs?

HEV0

HEV0 PHEV3.5

$4.30 / gal.

$2.15 / gal.PHEV20

(19,000 mi/year, 52 mi/day avg.)Assumed electricity cost = 9c/kWh

PHEV40

$-

$500

$1,000

0 5

PHEV20

PHEV40

$-

$500

$1,000

0 5

PHEV20

$-

$500

$1,000

0 5

PHEV20

PHEV40

What’s value of other benefits• Less trips to gas station• Being “Green”• …

13

Conclusions

• Plug-in hybrid technology can reduce petroleum consumption beyond that of HEV technology

• The study highlighted some of the PHEV design options and associated tradeoffs

— Expansion of the energy storage system usable state of charge window while maintaining life will be critical for reducing system cost and volume

— A blended operating strategy as opposed to an all electric range focused strategy may provide some benefit in reducing cost and volume while maintaining consumption benefits

• The key remaining barriers to commercial PHEVs are battery life, packaging and cost