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)
• 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
• www.eng.ox.ac.uk/tpsrg
• https://oem.eng.ox.ac.uk
Thank you