CONFLICTING INTERESTS IN DEFINING AN 'OPTIMAL' BATTERY SIZE WHEN INTRODUCING PHEVS Frances Sprei Physical Resource Theory Department of Energy & Environment Chalmers University of Technology

Sten Karlsson, Lars-Henrik Kullingsjö

Transportation Seminar, Stanford 2013-11-15

Research question How will the choice of objective function influence the

optimal battery size? • Total Cost of Ownership savings of the car fleet • Electric drive fraction of the car fleet • Number of PHEVs in the car fleet

How are the results affected by: • Costs of converting HEV to PHEV • Subsidies • Charging possibilities?

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PHYSICAL RESOURCE THEORY, DEPT. OF ENERGY & ENVIRONMENT | FRANCES SPREI

The database 445 privately driven Swedish cars Car model 2002 and younger GPS installed for 1-2 months June 2010-Sept 2012

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PHYSICAL RESOURCE THEORY, DEPT. OF ENERGY & ENVIRONMENT | FRANCES SPREI

0

5

10

15

20

25

30

35

40

<30y 31-45 46-60 >60

Shar

e (%

)

Age (yrs)

Age distribution of main driver

region

main driver

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PHYSICAL RESOURCE THEORY, DEPT. OF ENERGY & ENVIRONMENT | FRANCES SPREI

Parameter Average for cars with data (Set

data)

Averagea from vehicle register

Model year 2006.37 2006.12

Maximum engine power (kW)

98.2 99.5

Cylinder volume (cm3)

1819 1812

Curb weight (kg) 1456 1457

Fuel use (liter/100km)

7.22 7.26

CO2 emission (g CO2/km)

176 177

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PHYSICAL RESOURCE THEORY, DEPT. OF ENERGY & ENVIRONMENT | FRANCES SPREI

0%

5%

10%

15%

20%

25%

30%

35%

Shar

e

Trip distance

Trip distance distribution

Share of trips

Share ofdistance

Methodology Shift to PHEV when TCO is lower than corresponding HEV Costs included: • Annuity of investment costs • Yearly fuel and electricity costs

𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚 𝑠𝑚𝑠𝑚𝑚𝑚𝑠 = 𝑑𝑒, 𝑚

(𝐴𝐴𝐴) ∗ (𝑝𝑓𝑒𝑓 − 𝑝𝑒𝑒𝑒)

𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚 𝑐𝑐𝑠𝑐 = 𝛼𝛽−1𝑐𝑒𝑒

There is also an annualized investment cost besides battery 𝐶𝑓𝑓𝑓

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PHYSICAL RESOURCE THEORY, DEPT. OF ENERGY & ENVIRONMENT | FRANCES SPREI

Marginal annual distance driven on electricity

Fuel and electricity prices

Specific energy use

Methodology Shift to PHEV when TCO is lower than corresponding HEV Costs included: • Annuity of investment costs • Yearly fuel and electricity costs

𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚 𝑠𝑚𝑠𝑚𝑚𝑚𝑠 = 𝑑𝑒, 𝑚

(𝐴𝐴𝐴) ∗ (𝑝𝑓𝑒𝑓 − 𝑝𝑒𝑒𝑒)

𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚 𝑐𝑐𝑠𝑐 = 𝛼𝛽−1𝑐𝑒𝑒

There is also an annualized investment cost besides battery 𝐶𝑓𝑓𝑓

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PHYSICAL RESOURCE THEORY, DEPT. OF ENERGY & ENVIRONMENT | FRANCES SPREI

Annuity

Utilized share of battery

Marginal battery cost

Fixed parameters

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PHYSICAL RESOURCE THEORY, DEPT. OF ENERGY & ENVIRONMENT | FRANCES SPREI

Parameter Value

Specific fuel use, ef 0.45 kWh/km

Specific electricity use, ee 0.15 kWh/km

Fuel price, pf 0.2 $/kWh

Electricity price, pe 0.2 $/kWh

Annuity, a 0.15 yr-1

Utilization share, b 0.7

RESULTS

Cfix low (200$) and night time charging only

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PHYSICAL RESOURCE THEORY, DEPT. OF ENERGY & ENVIRONMENT | FRANCES SPREI

Marginal battery cost ($/kWh)

Opt

imal

bat

tery

siz

e (k

m)

PH

EV

sha

re o

f veh

icle

fle

et

Aver

age

cost

sav

ing

per P

HE

V ($

)

Pot

entia

l ele

ctric

driv

e fra

ctio

n

Individually TCO Fleet TCO EDF Nbr of PHEV

Cfix high ($3500) and night time charging only

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PHYSICAL RESOURCE THEORY, DEPT. OF ENERGY & ENVIRONMENT | FRANCES SPREI

Individually TCO Fleet TCO EDF Nbr of PHEV

Marginal battery cost ($/kWh)

Opt

imal

bat

tery

siz

e (k

m)

PH

EV

sha

re o

f veh

icle

fle

et

Aver

age

cost

sav

ing

per P

HE

V ($

)

Pot

entia

l ele

ctric

driv

e fra

ctio

n

Cfix low, night time charging, subsidy $5000

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PHYSICAL RESOURCE THEORY, DEPT. OF ENERGY & ENVIRONMENT | FRANCES SPREI

Fleet TCO EDF Nbr of PHEV Dotted with subsidy

Opt

imal

bat

tery

siz

e (k

m)

PH

EV

sha

re o

f veh

icle

fle

et

Aver

age

cost

sav

ing

per P

HE

V ($

)

Pot

entia

l ele

ctric

driv

e fra

ctio

n

With workplace charging as well

Marginal battery cost ($/kWh)

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PHYSICAL RESOURCE THEORY, DEPT. OF ENERGY & ENVIRONMENT | FRANCES SPREI

Opt

imal

bat

tery

siz

e (k

m)

Low Cfix High Cfix

Conclusions and discussion • Optimizing on electric drive fraction results in larger

battery sizes • Optimizing for nr of PHEV’s may reduce electric drive

fraction compared to other options • The extra costs of converting HEV to PHEV may delay

introduction of viable PHEV (to around 400$/kWh) • If these extra costs are low a subsidy may create a sub-

optimal low battery size • Work place charging increase both share of PHEVs and

electric drive fraction • Short-term goals vs long-term goals

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PHYSICAL RESOURCE THEORY, DEPT. OF ENERGY & ENVIRONMENT | FRANCES SPREI

Future work • Looking at the effect of super credits in the EU for

vehicles with CO2 emissions under 50g/km • Logging 100, 2 car households (tot 200 vehicles) for

BEVs

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PHYSICAL RESOURCE THEORY, DEPT. OF ENERGY & ENVIRONMENT | FRANCES SPREI

Thank you for listening! For more info: S Karlsson, 2013, The Swedish car movement data

project - Final report, PRT report 2013:1 Kullingsjö, LH, Karlsson, S, 2012, The Swedish car

movement data project, EEVC, Brussels 2012 Kullingsjö, LH, Karlsson, S, Sprei, F, 2013, Conflicting

interests in defining an ‘optimal’ battery size when introducing the PHEV?, EVS27, Barcelona, 2013

2014-02-17

PHYSICAL RESOURCE THEORY, DEPT. OF ENERGY & ENVIRONMENT | FRANCES SPREI