Fuel Displacement & CO2 Benefits of Vehicle Electrification · 2015-01-20 · to be a Constraint to...

Fuel Displacement & CO2 Benefits of Vehicle Electrification

Al WeverstadExecutive Director Public Policy

General Motors Corporation

Electrification enables …

Important Questions

• What are the CO2 effects of electrically powered transportation?

• How do PHEV compare with E-REVs for Petroleum displaced and for CO2 generated?

• How does fleet petroleum consumption and CO2 generation vary with battery pack size?

• How useful are multiple charges per day?

• How useful is higher power charging?

Vehicle Types By Attribute

Vehicle

Type

Electric

Power

Onboard

Electric

Storage

Grid

Recharge

Electric

Driving

Capability

Preferential

Electric

Driving

Range

Limit

Mild HEV low low no no no Gasoline

Full HEV med low no

very

limited no Gasoline

PHEV med med yes Urban Only no

Gasoline +

Battery

E-REV high high yes Full yes

Gasoline +

Battery

BEV high highest yes yes yes Battery

Vehicle Type Characterized by Energy Use

0 25 50 75 100Driving Distance, km

Cu

mu

lati

ve

Ele

ctri

c En

erg

yC

um

ula

tive

G

aso

line

Ene

rgy

ConventionalFull HybridPHEV 4kWhrPHEV 8kWhrE-REV 4 kWhrE-REV 8kWhrBEV 12kWhr

Studies of US Vehicle Use

• Two Major Populations Studied:– Southern California Association of Governments

Regional Travel Survey, 2003• Speed vs. time of day, every second, aggregated days,

621 drivers

• Basis of single charge per day study 2007

– National Household Travel Survey, 2001 • Vehicle location vs. arrival times, several weeks,

separated days, >50,000 vehicles, >200,000 travel days

• Basis of multiple charge per day studies

Analysis Study Vehicles Normalized

• Based upon a 2009 Malibu, Full Hybrid, PHEV and E-REV was constructed. All achieve approximately 36 mpg charge sustaining FE on US Schedules

Conventional

or HEVPHEV E-REV

Charge Sustaining

Fuel Economy

36 [mpg]

6.53 [l/100 km]

Charge Decreasing

Electrical Energy

Consumption

[kw-hr/mile]

n/a0.350 [kw-hr/mi]

0.2175 [kw-hr/km]

Charge Decreasing

Energy Splitn/a 0.7 1.0

ZEV Power and Speed

Distance (miles)

0

0.1

0.2

0.3

0.4

0.5

0.6N

et

Ene

rgy

pe

r M

ile (

kW-h

r/m

ile)

0 50 100 150 250 300200

3%

21%

97%

Urban

Highway

US06

Mid-Sized Vehicle Simulated with SCAG Regional Transportation Survey Data

Examining the “Average Driver”

Distance (miles)

0

0.1

0.2

0.3

0.4

0.5

0.6N

et

Ene

rgy

pe

r M

ile (

kW-h

r/m

ile)

0 50 100 150 250 300200

Urban

US06

Mid-Sized Vehicle Simulated with SCAG Regional Transportation Survey Data

“Driver #231”27.4 Miles

308Whr/Mi

Driver #231’s Driving Day

SCAG Regional Transportation Survey Data

6:00am 7:00 8:00 9:00 10:00 11:00 noon 1:00pm 2:00 3:00 4:00 5:00

80

10

20

30

40

50

60

70

90

100

0

Time of Day

Spee

d –

Mile

s Pe

r h

ou

r

Morning Commute Afternoon Commute

6:30 am 6:40 6:50 7:000

10

20

30

40

50

60

70

80

90

100

6:30 am 6:40 6:50 7:000

10

20

30

40

50

60

70

80

90

100

Driver #231’s Morning Commute


Engine off – ZEV miles

Urban Capable PHEV6 engine starts18% energy from engine

Engine onSpeed exceeds urban schedule

E-REV0 engine starts0 % energy from engine

Engine onPower exceeds urban schedule

Engine OnBattery Energy Depleted

Engine on and off, – Hybrid Miles

3:50 4:00 4:100

10

20

30

40

50

60

70

80

90

100

3:50 4:00 4:100

10

20

30

40

50

60

70

80

90

100

Driver #231’s Afternoon Commute


1 initial engine start100% energy from engine

1 engine start5% energy from engine

Engine on and offBattery Energy Depleted

Urban Capable PHEV

E-REV

Engine on and offBattery Energy Depleted

Engine off – ZEV milesEngine on and off, – Hybrid Miles

Differences in PHEV and E-REV Energy Usage

• SCAG survey reveals that 30% of all aggregate driving energy is used at power levels and speed levels beyond the “Urban” power and speed levels (greater than 56 mph or greater than 53 kW)

• PHEV uses a 70% EV energy fraction and a 30% gasoline fraction in Charge Depleting (CD) Mode (energy remaining in the battery)

• E-REV uses a 100% energy fraction in CD Mode

Fuel & Battery Use vs Distance Driven

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.00 5.00 10.00 15.00 20.00 25.00 30.00 35.00

Fue

l Use

[ga

l]

Distance Driven [mi]

Fuel Use vs Distance

PHEV fuel use

EREV fuel use

• EREV and PHEV use same fuel for all travel beyond charge-

depleting operation.

0.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

8.00

9.00

10.00

0.00 5.00 10.00 15.00 20.00 25.00 30.00 35.00

Bat

tery

Use

[kw

-hr]

Distance Driven [mi]

Battery Use vs Distance

PHEV battery use

EREV battery use

Where are the Cars?

0.00%

10.00%

20.00%

30.00%

40.00%

50.00%

60.00%

70.00%

80.00%

90.00%

100.00%

Sun

day

04

:00

Sun

day

08

:00

Sun

day

12

:00

Sun

day

16

:00

Sun

day

20

:00

Mo

nd

ay 0

0:0

0

Mo

nd

ay 0

4:0

0

Mo

nd

ay 0

8:0

0

Mo

nd

ay 1

2:0

0

Mo

nd

ay 1

6:0

0

Mo

nd

ay 2

0:0

0

Tue

sday

00

:00

Tue

sday

04

:00

Tue

sday

08

:00

Tue

sday

12

:00

Tue

sday

16

:00

Tue

sday

20

:00

We

dn

esd

ay 0

0:0

0

We

dn

esd

ay 0

4:0

0

We

dn

esd

ay 0

8:0

0

We

dn

esd

ay 1

2:0

0

We

dn

esd

ay 1

6:0

0

We

dn

esd

ay 2

0:0

0

Thu

rsd

ay 0

0:0

0

Thu

rsd

ay 0

4:0

0

Thu

rsd

ay 0

8:0

0

Thu

rsd

ay 1

2:0

0

Thu

rsd

ay 1

6:0

0

Thu

rsd

ay 2

0:0

0

Frid

ay 0

0:0

0

Frid

ay 0

4:0

0

Frid

ay 0

8:0

0

Frid

ay 1

2:0

0

Frid

ay 1

6:0

0

Frid

ay 2

0:0

0

Satu

rday

00

:00

Satu

rday

04

:00

Satu

rday

08

:00

Satu

rday

12

:00

Satu

rday

16

:00

Satu

rday

20

:00

Sun

day

00

:00

Fleet Distribution during week

Home Residence Work School & Church Commercial Other Driving

How far do people drive?

Mid-Sized Vehicle Simulated on 2001 NHTS Data Set

Petroleum Displacement and CO2 Reduction- 3.3 kw Charging at Work & Home

•For the same size battery pack•The EREV displaces 60% of fuel versus 55% for the PHEV.•The EREV displaces 36% of CO2 versus 33% for the PHEV.

0

1

2

3

4

5

6

7

8

9

Conventional Vehicle PHEV EREV

kg C

O2

/day

8kWhr Pack, Work & Home ChargingVehicle Average CO2 per day

Ca. Grid CO2

Fuel CO2

Three Charging Scenarios Examined

• 1.1 kW charging: 15 Amp, 110 volt outlet – Restricted to at home only– 9 pm to 9 am; randomized start; charge until full – effectively one charge per day

• 3.3 kW charging: 15 amp, 220 volt outlet– Restricted to home and work– Charge at any time; charge until full – effectively two charges per day

• 6.6 kW charging: 30 amp, 220 volt outlet– Unrestricted location; wherever you park– Charge at anytime; charge until full – effectively unlimited charges per day

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

0 2000 4000 6000 8000 10000 12000 14000 16000

Gal

lon

s/D

ay

Battery Size [W-hr]

Fuel Use/Day vs Battery Size

EREV, Restricted Home Charging, 1.1kW

EREV, Charge at Home & Work, 3.3kw

EREV, Unrestricted Charging Everywhere, 6.6kW

0.7 PHEV, Restricted Home Charging, 1.1kW

0.7 PHEV, Charge at Work & Home, 3.3kw

0.7 PHEV, Unrestricted Charging Everywhere, 6.6kW

E-REV Fuel Displacement Advantage Grows with Increasing Battery Size, More Charging

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

0 2000 4000 6000 8000 10000 12000 14000 16000

Gal

lon

s/D

ay

Battery Size [W-hr]








Powertrain and Infrastructure can replace batteriesan example

Adding batteries reduces fuel use

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

0 2000 4000 6000 8000 10000 12000 14000 16000

Gal

lon

s/D

ay

Battery Size [W-hr]









The same fuel savings is achieved with 15% less

battery by using an EREV powertrain.

(PHEV-> EREV)

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

0 2000 4000 6000 8000 10000 12000 14000 16000

Gal

lon

s/D

ay

Battery Size [W-hr]









The same fuel savings is achieved with 50% less battery by a combination of an EREV

powertrain and charging at work.


0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

0 2000 4000 6000 8000 10000 12000 14000 16000

Gal

lon

s/D

ay

Battery Size [W-hr]








EREV,Unrestricted 20kW Charging

EREV, Unrestricted 250kW Charging

The same fuel savings can be achieved with 75% less pack if level 2

charging is available everywhere.

However, adding Level 3 charging offers only an

additional 5% reduction in pack size …

Powertrain and Infrastructure increase fuel savingsan example

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

0 2000 4000 6000 8000 10000 12000 14000 16000

Gal

lon

s/D

ay

Battery Size [W-hr]








EREV,Unrestricted 20kW Charging

EREV, Unrestricted 250kW Charging

PHEV->EREV

Charging at work

Level 2 Charging everywhere

Level 3 Charging everywhere

Infrastructure Capacity Does not Appear to be a Constraint to Vehicle Electrification

0.00

100.00

200.00

300.00

400.00

500.00

600.00

700.00

800.00

900.00

Sun

day

04

:00

Sun

day

08

:00

Sun

day

12

:00

Sun

day

16

:00

Sun

day

20

:00

Mo

nd

ay 0

0:0

0

Mo

nd

ay 0

4:0

0

Mo

nd

ay 0

8:0

0

Mo

nd

ay 1

2:0

0

Mo

nd

ay 1

6:0

0

Mo

nd

ay 2

0:0

0

Tue

sday

00

:00

Tue

sday

04

:00

Tue

sday

08

:00

Tue

sday

12

:00

Tue

sday

16

:00

Tue

sday

20

:00

We

dn

esd

ay 0

0:0

0

We

dn

esd

ay 0

4:0

0

We

dn

esd

ay 0

8:0

0

We

dn

esd

ay 1

2:0

0

We

dn

esd

ay 1

6:0

0

We

dn

esd

ay 2

0:0

0

Thu

rsd

ay 0

0:0

0

Thu

rsd

ay 0

4:0

0

Thu

rsd

ay 0

8:0

0

Thu

rsd

ay 1

2:0

0

Thu

rsd

ay 1

6:0

0

Thu

rsd

ay 2

0:0

0

Frid

ay 0

0:0

0

Frid

ay 0

4:0

0

Frid

ay 0

8:0

0

Frid

ay 1

2:0

0

Frid

ay 1

6:0

0

Frid

ay 2

0:0

0

Satu

rday

00

:00

Satu

rday

04

:00

Satu

rday

08

:00

Satu

rday

12

:00

Satu

rday

16

:00

Satu

rday

20

:00

Sun

day

00

:00

Wat

ts

Axis Title

Expected Charger Wall Power8kW-hr EREV, 3.3kW Charger, Charge at Work & Home

Even at higher Peak Charge rates, Grid Capacity Does not Appear to be a Large Issue

0

200

400

600

800

1000

1200

1400

0 2000 4000 6000 8000 10000 12000 14000 16000

Wat

ts

Battery Size [W-hr]

Expected Peak Electrical Power

EREV, Restricted Home Charging, 1.1 kW

EREV, Charge at Home & Work, 3.3kW



0.7 PHEV, Charge at Work & Home, 3.3kW


1. E-REVs offer an advantage over PHEVs for fuel displaced and CO2 reduced. This advantage is more pronounced with larger batteries. E.g, an 8 kWhr E-REV will give an 11% reduction in fuel consumed relative to an 8kWhr PHEV. (3.3 kW charging at home and work)

2. Since E-REVs are more likely to be produced with larger batteries than PHEVs, an 8kWhr E-REV shows an 23% reduction in fuel consumed and CO2 generated compared to a 2kWhr PHEV. (3.3 kW charging at home and at work

3. If renewable electricity is used CO2 reduction is equal to fuel displacement.4. The grid capacity impact of introducing PHEVs and E-REVs is not, in general,

great. Considering an 8kWhr E-REV using a 3.3kW charge has an expected peak grid load roughly of roughly 800 Watts. This is equivalent to two plasma TVs.

5. Making charging available at work significantly improves the ability of an E-REV or PHEV to displace fuel. For instance, a 8 kWHr E-REV charged at 3.3 kW at home and at work will lower fuel consumption by 24% when compared to 1.1kW charging restricted to use only at home.

6. An infrastructure improvement allowing multiple charges per day is one factor that could allow a reduction in E-REV or PHEV battery size while maintaining similar levels of petroleum displacement and CO2 reduction.

Conclusions

Thank You!

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Fuel Displacement & CO2 Benefits of Vehicle Electrification · 2015-01-20 · to be a Constraint to...

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