Air Pollution from vehicles

• Pollution is an unhelpful word

• Idling…?

• London Ultra Low Emission Zone

• Bus emissions

• Oxford Emissions Maps

• Recent developments in vehicles

Contents

• An ideal combustion engine vehicle emits the following:

Pollution is an unhelpful word

• An ideal combustion engine vehicle emits the following:

• CO2

• H2O

Pollution is an unhelpful word

• A typical combustion engine vehicle emits the following:

• CO2

• H2O

• Particulates

• NO + NO2

• Unburned HydroCarbons

• CO

• and other “unregulated” emissions

Pollution is an unhelpful word

• A typical combustion engine vehicle emits the following:

• CO2

• H2O

• Particulates

• NO + NO2

• Unburned HydroCarbons

• CO

• and other “unregulated” emissions

• What can we do about this?

Pollution is an unhelpful word

• This is all “pollution” (depending on who asks)

• Strategies for reducing these are widely different

• Policies need to be carefully designed to consider all of these “pollutants”

• A wide range of technologies are employed to control these “pollutants”

• Passive vs active

• Temperature matters

• Ecatalysts?

• Hybrids?

• All add cost and efficiency penalties

Diesel Pollutant

Vehicle calibration All Active

DOC HC, CO, NO Passive

DPF PM Passive

EGR NOx Active

LNT NOx Passive

SCR NOx Active

Gasoline Pollutant

Vehicle calibration All Active

TWC HC, CO, NOx Passive

GPF PM Passive

Vehicle emissions control

CO2

• A wide range of technologies are employed to control these “pollutants”

• Passive vs active

• Temperature matters

• Ecatalysts?

• Hybrids?

• All add cost and efficiency penalties

Diesel Pollutant

Vehicle calibration All Active

DOC HC, CO, NO Passive

DPF PM Passive

EGR NOx Active

LNT NOx Passive

SCR NOx Active

Gasoline Pollutant

Vehicle calibration All Active

TWC HC, CO, NOx Passive

GPF PM Passive

Vehicle emissions control

CO2 Require temperature to be effective

• Under all circumstances stopping a vehicle idling will reduce:

• CO2✔

• H2O✔

• Particulates

• NO + NO2

• Unburned HydroCarbons

• CO

• and other “unregulated” emissions2011 Ford Fusion petrol

Idling – all bad?

• For other pollutants:• Particulates• NO + NO2• Unburned HydroCarbons• CO• and other “unregulated” emissions

• This will vary hugely depending on:• Vehicle• Vehicle (age)

• Generally not applicable to Euro 6 +• Vehicle journey history

• Vehicles fitted with stop/start take this into account

0

200

400

600

800

1000

1200

1400

NOx HC CO

Emis

sio

n (

mg)

30s Idle

Restart

1900% 450%

39000%

HC NOx CO

‘Hot’ restart

2.75 mins 10 mins 3.3 hrs

Cold restart

11.9 mins 6.3 hrs 7.7 hrs

Idling – all bad?

0

5

10

15

20

25

30

35

40

45

50

NOx HC CO

Emis

sio

n (

mg)

30s Idle

Restart

1900%

450%

• For other pollutants:• Particulates• NO + NO2• Unburned HydroCarbons• CO• and other “unregulated” emissions

• This will vary hugely depending on:• Vehicle• Vehicle (age)

• Generally not applicable to Euro 6 +• Vehicle journey history

• Vehicles fitted with stop/start take this into account

0

200

400

600

800

1000

1200

1400

NOx HC CO

Emis

sio

n (

mg)

30s Idle

Restart

1900% 450%

39000%

HC NOx CO

‘Hot’ restart

2.75 mins 10 mins 3.3 hrs

Cold restart

11.9 mins 6.3 hrs 7.7 hrs

Idling – all bad?

• From 8 Apr 2019

• Euro 3 for motorcycles

• Euro 4 for petrol

• Euro 6 for diesel

• Euro VI for lorries & buses

London ULEZ

• From 25 Oct 2021

• Euro 3 for motorcycles

• Euro 4 for petrol

• Euro 6 for diesel

• Euro VI for lorries & buses

London ULEZ

• From 25 Oct 2021

• Euro 3 for motorcycles

• Euro 4 for petrol

• Euro 6 for diesel

• Euro VI for lorries & buses

London ULEZAre these the appropriate

technology levels?

• Euro 3 for motorcycles

• Euro 4 for petrol

• Euro 6 for diesel

• Euro VI for lorries & buses

* - different measurement method, assumes Euro VI double decker bus

0E+00

1E+12

2E+12

3E+12

4E+12

5E+12

6E+12

7E+12

8E+12

9E+12

1E+13

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

Petrol Diesel Motorbike Buses & Lorries*

PM

(#/

km)

CO

an

d N

Ox

(g/k

m)

NOx

CO

PM

London ULEZ

• Euro 3 for motorcycles

• Euro 4 for petrol

• Euro 6 for diesel

• Euro VI for lorries & buses

* - different measurement method, assumes Euro VI double decker bus

0E+00

1E+12

2E+12

3E+12

4E+12

5E+12

6E+12

7E+12

8E+12

9E+12

1E+13

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

Petrol Diesel Motorbike Buses & Lorries*

PM

(#/

km)

CO

an

d N

Ox

(g/k

m)

NOx

CO

PM

London ULEZCan this really happen?

• Very low levels of NOx across the vehicles

• BUT

• Unregulated particulates from Petrol and motorbikes at Euro 3/4

• Ultra Low NOx Zone?

* - different measurement method, assumes Euro VI double decker bus

YES! – over 1000x more PN from Euro 4 petrol

Data from: Braisher 2010-01-0786, TFL In-service emissions performance of Euro 6/VI vehicles, https://doi.org/10.1016/j.scitotenv.2017.11.271, 2009-01-1841, equaindex.com, Particle Emissions of Powered Two Wheelers AECC, 2017-01-0985

1E+0

1E+1

1E+2

1E+3

1E+4

1E+5

1E+6

1E+7

1E+8

1E+9

1E+10

1E+11

1E+12

1E+13

1E+14

1E+15

0

1

2

3

4

5

6

7

Petrol (GDI) Petrol (PFI) Diesel Motorbike Buses &Lorries*

PM

(#/

km)

CO

an

d N

Ox

(g/k

m)

NOx

CO

PM

NB

log scale1,000x

10,000x100,000x

London ULNZ

EEA Report No 21/2016

Euro 6 PM limit

Non-exhaust emissions

• Non-exhaust emissions are already higher than engine-out

• EVs emit PM too

0

10

20

30

40

50

60

Small Car Medium Car Large Car

PM

(m

g/km

)

Road wear PM2.5

Road wear PM>2.5-PM10

Road wear PM10

Brake wear PM2.5

Brake wear PM>2.5-PM10

Brake wear PM10

Tyre wear PM2.5

Tyre wear PM>2.5-PM10

Tyre wear PM10

• Euro V hybrid with SCR (251,000 miles)

• Euro VI with SCR (119,000 miles)

• Euro 5 passenger car 7-seater diesel no SCR (80,000 miles)

Bus emissions

Bus stop manoeuvre

Uphill climb: exhaust is hot=low NOx

Parked cars and other obstructions

Speed bumps for school

Downhill, low load so little NOx produced (but SCR cooling)

Bus manoeuvre around school

Comparison of 3 x Eu VI Blackbird Leys

Bus stop location correlates with emissions: Wikimedia maps

Map data © OpenStreetMap contributors

Comparison of 3 x Eu VI Blackbird Leys Engine off stop

Catalyst cools Associated “spike” in NOx

Bus stop location correlates with emissions: Wikimedia maps

Map data © OpenStreetMap contributors

Effects of 4-min engine switch-off Eu VI

24

NOx

Ex temp

Wikimedia mapsMap data © OpenStreetMap contributors

Speed bump (PHEV)

Plugin hybrid emits ~1km worth of NOx per speed bump

Speed bump (PHEV)

Oxford Emissions Maps

https://oem.eng.ox.ac.uk

• This is a “solvable” problem with today’s technology

• Petrols AND DIESELS near zero local pollutants

• EQUA index

• Nearly 90% of 2019 MY vehicles tested exceed Euro 6 gasoline RDE NOx

• www.equaindex.com

• ADAC RDE tests (Germany)

• Vehicles emitting zero NOx

• Euro 6d temp

• Euro 7

Recent developments in vehicles

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

2016 2017 2018 2019 2020

Model year

Equa index A+

Car

RDE NOx

(mg/km) Car

RDE NOx

(mg/km)

Audi A8 50 TDI 15 Mercedes A 180 d 40

BMW 520d Steptronic 5 Mercedes C 220 d 0

BMW 520d Touring 1 Opel Astra 1.6 D 1

BMW X2 xDrive 20d 23 Peugeot 308 SW BlueHDi 180 30

Citroen Berlingo BlueHDI 130 7 Volvo XC60 D5 AWD 56

Honda Civic 1.6 i-DTEC 101 VW Golf 1.6 TDI SCR 14

Kia Ceed 1.6 CRDi 22

• TEVVA / UPS plug-in hybrid

• 400 km range

• 100 km electric-only

• Geo-fenced

• Integration with CAZs / urban areas

• Same carrying capacity

• Current trial in Birmingham and Southampton

Recent developments in vehicles

• Pollution control from vehicles is top priority

• Many current efforts focus on NOx

• Non-exhaust emissions are a majority today

• Road layouts have substantial impact on emissions• Oxford Emissions Maps help understand this

• Incentivise switches to modern vehicles

Conclusions

Oxford Air Quality Meeting

• felix.leach@eng.ox.ac.uk

• www.eng.ox.ac.uk/tpsrg

• https://oem.eng.ox.ac.uk

Thank you