Real world NOx and CO2 emissions from modern petrol and diesel passenger cars

Rosalind O’Driscoll APRIL meeting Tuesday 7th March @RS_ODriscoll

Outline

•  Methodology

•  Results

•  Discussion

•  Questions

Methodology

Portable

Emissions

Measurement

System

Methodology

•  150 vehicles in the study •  36 Diesel Euro 5 (D5) •  39 Diesel Euro 6 (D6) •  39 Petrol Euro 5 (P5) •  36 Petrol Euro 6 (P6)

•  Tested by Emissions Analytics in the Greater London Area

•  Test route approximately 100km long made up of urban and motorway driving

•  Motorway and urban sections of similar lengths, average speed, time idle etc. selected and used for comparison

Methodology: Test characteristics

Duration [s]

Distance [km]

A v e r a g e speed [km h-1]

% idle* Av e r a g e VSP [kW t-1]

R a n g e VSP [kW t-1]

Urban section 1800

12.4

(sd. 0.4)

24.7

(sd. 0.7)

18.1

(sd. 2.7)

1.38

(sd.0.1)

-5.2 to

8.4

Motorway section 900

24.4

(sd. 1.1)

97.7

(sd. 4.5)

0.1

(sd. 0.2)

10.7

(sd. 0.9)

-5.7 to

27.0

•  The urban section of the route is made up of A, B and C roads (UK) with speed limit of 50 km h-1

•  The motorway section of the route is made up of M roads (UK) with a speed limit of 110 km h-1

Methodolgy: Vehicles engine size

≤1.55ℓ >1.5ℓ to ≤ 2ℓ >2ℓ

Diesel 12.1% 65.1% 22.8%

Petrol 54.9% 37.6% 7.4%

Cars licensed by engine displacement in Great Britain in 2015 (DfT)

Results

Results: NOx emissions

Mean NOx [g km-1]

D5 D6 P5 P6

Motorway 0.66 0.32 0.031 0.03

Urban 0.71 0.44 0.093 0.041

D5 limit D6 limit P limit

Results: NOx emissions diesel vs. petrol

Motorway Urban Euro 5 x 21.3 x 7.6 Euro 6 x 10.7 x 10.7

Increase from petrol to diesel

Results: NOx improvements from Euro 5 to 6

Urban Motorway Diesel 38% 52% Petrol 56% 3%

Reduction in average NOx from Euro 5 to Euro 6

Results: NOx conformity factors

D5 limit D6 limit P limit

x 3.7 x 4.0

x 4.0

x 5.25

x 1.55

x 0.5 x 0.7

x 0.5

•  Average diesel conformity factor increased from D5 to D6

•  For petrol on P5 urban average exceeded type approval limit

•  4 D6 met the type approval limit on the urban section (~10%) •  5 D6 met the type approval limit on the motorway section

Results: NOx emissions urban vs. motorway

D5   D6   P5   P6  

8%   40%   190%   37%  

% increase in mean urban emissions compared with mean motorway

Results: NOx by engine displacement

Results: NO2 emissions

Urban Motorway Euro 5 x 13.2 x 21.5 Euro 6 x 32.7 x 40.1

Increase in average NO2 emissions from petrol to diesel

Results: NOx as NO and NO2

Results: CO2 emissions

Results: CO2 emissions petrol vs. diesel

14% 20%

31% 36%

39% 52%

%= increase from diesel to petrol

Weighted average

Urban 22% Motorway 8%

22%

0%

Results: CO2 urban vs. motorway

≤1.55ℓ >1.5ℓ to ≤ 2ℓ >2ℓ Weighted average

Petrol 29%   31%   44%   31%  Diesel 6%   14%   25%   16%  

% increase in mean urban emissions compared with mean motorway

Results: CO2 comparison to type approval limit

MOTORWAY •  Diesel: 59% meet 2015 limit

•  Petrol: 22% meet 2015 limit

URBAN •  Diesel: 23% meet 2015 limit

•  Petrol: 4% meet 2015 limit

MOTORWAY BELOW 130 g km-1 •  Diesel:14

•  Petrol:13

URBAN BELOW 130 g km-1 •  Diesel:2

•  Petrol:3

Results: CO2 PEMS comparison to official estimates

MOTORWAY •  Diesel: PEMS 22% higher

•  Petrol: PEMS 28% higher

URBAN •  Diesel: PEMS 40% higher •  Petrol: PEMS 65% higher

Results: CO2 Gasoline Direct Injection (GDI)

8%

11%

%= decrease from petrol to petrol GDI

!!particulates!!

Results: Summary

•  Euro 6 Diesel NOx

emissions were 11 times higher than petrol

•  For engines of the

same size petrol CO2 emissions were between 14- 52% higher than diesel

•  Average petrol urban

CO2 emissions were 22% higher than diesel

Discussion

Discussion: UK Jan 2017 car registrations

UK January 2017 new car registrations compared to

2016 •  Diesel down 4% to 45% •  Petrol up 9% to 51% •  AFV up 20% to 4% •  Total sales up 3%

Total Petrol Diesel AFV JAN2017 174564 88507 78778 7279

Source: SMMT

Discussion: Different kind of Low Emission Zone?

•  Discriminate by actual real driving emissions instead of Euro Standards -Is there an alternative? Is there any way of discriminating between the low NOx diesels that meet the standard (~10%) and those that don’t? (EQUA index)

•  Discriminate on the basis of CO2 as well as NOx

•  If we ban diesels will people transfer to petrol of the same size? If yes then there is a big CO2 penalty. Even if they downsize there is a CO2 penalty, especially for urban driving

•  Switch within the diesel fleet to the clean ones this would help the NOx/

NO2 without a CO2 penalty. The difficulty is lack of enforcement.

Alternative Fuel Vehicles

•  Market share of AFV reached 4% for the first time in January 2017

•  Mostly (~80%) petrol electric hybrid like the Toyota Prius

•  Average trip length in the UK in 2014 was 11.3km

•  Nissan leaf range ~ 150 km

•  Prius plug in hybrid has an electric range of 16km, Chevrolet Volt plug in hybrid has an electric range of 80 km

Summary

•  Diesel is not the solution to the petrol problem

•  Petrol is not the solution to the diesel problem

Questions?

Thank you for listening.

Image Sources

http://emissionsanalytics.com/ http://www.autocarpro.in/news-national/2025-diesel-car-share-fall-nearly-major-auto-markets-9653 http://www.theicct.org/sites/default/files/publications/ICCT_Pocketbook_2016.pdf http://rebloggy.com/post/drawing-art-hipster-vintage-indie-nature-lungs/108200730596 https://www.smmt.co.uk/2017/02/uk-new-car-market-kick-starts-2017-with-milestone-for-alternatively-fuelled-vehicles/ https://www.carbonbrief.org/ccc-cut-uk-emissions-61-by-2030-for-fifth-carbon-budget http://www.eeb.org/index.cfm/library/clearing-the-air-a-critical-guide-to-the-new-nec-directive/ https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/579200/

Emissions_airpollutants_statisticalrelease_2016_final.pdf https://www.gov.uk/government/statistical-data-sets/env02-greenhouse-gas-emissions https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/

496942/2014_Final_Emissions_Statistics_Release.pdf https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/514912/road-use-statistics.pdf

MOTORWAY 21%

RURAL 43%

URBAN 37%

Distribution of KM driven throughout the road network Source: DfT

UK Transport Statistics

2014 motor vehicle traffic kilometres driven by vehicle type in Great Britain

Source: DfT

2014 total = 501.5 billion km

CO2: Reduction commitments

Source: CCC

Methodology: Speed and acceleration of sections

Vehicle Specific Power of sections

CO2 [g km-1] Weighted average   ≤1.55ℓ >1.5ℓ to

≤ 2ℓ >2ℓ

URBAN Petrol 180.6 225.6 308.6 207.1 Diesel 142.3 162.4 203.6 169.3

% increase 27% 39% 52% 22% MOTORWAY

Petrol 140.2 171.7 213.7 157.5 Diesel 133.8 142.9 163.2 146.4

% increase 5% 20% 31% 8%

NOx [g km-1]

D5 D6 P5 P6

Motorway 0.66 0.32 0.031 0.03

Urban 0.71 0.44 0.093 0.041

NO2 [g km-1] D5 D6 P5 P6

Motorway

0.2823 0.1445 0.0131 0.0036

Urban 0.3159 0.219 0.0239 0.0067