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NOx EMISSIONS OF DIESEL CARS

In the lab and on the road Richard Smokers, Rob Cuelenaere & Norbert Ligterink

Presentation at hearing by the European Parliament’s EMIS committee

Brussels

May 24, 2016

Introduction

TNO = Netherlands Organisation for

Applied Scientific Research

2 | NOx emissions of diesel vehicles in the lab and on the road 24 May 2016

INDUSTRY HEALTHY LIVING URBANISATION

ENERGY DEFENSE, SAFETY &

SECURITY

Automotive

Sustainable

Transport &

Logistics

relevant

departments

www.tno.nl

SUMMARY

Real-world emissions of diesel vehicles

TNO measurements show significantly higher NOx emissions of diesel

passengers cars and vans on the road than on type approval test

Euro 5 (2009) passenger cars: factor 3 to 4

Euro 6 (2014) passenger cars: factor 2 to 6

Euro 5 (2010/11) LCVs: factor 3.5 (Class I & II) to 6 (Class III).

This picture is consistent over a wide range of tested makes / models

Dutch emission factors, used for assessing air quality (policies), are based on

test results that are representative for real-world use

The recently accepted RDE (Real Driving Emissions) test is an important

improvement but attention to details of implementation is paramount


HOW / WHAT DO WE MEASURE?

Test programmes TNO

Test programmes

LD: 2-wheelers, passenger cars and vans

HD: trucks and buses

measurement of pollutant emissions and CO2

Since 1986 in a sequence of projects for the Dutch Ministry of Infrastructure and

the Environment

Goals

Insight in real-world emissions for Dutch air quality policy

Representative emission factors important for Dutch implementation of

European Air Quality Directive

Insight in performance of new technologies and effectiveness of stimulation

Input for (Dutch contribution to) regulatory process in Brussels

Tests are not intended for enforcement or identifying fraud



State-of-the-art test methods


1970: roller bench TNO Automotive, Delft 2011: state-of-the-art lab at Horiba in Oberursel (D)

2011: PEMS-measurements on the road 2014: TNO-development of SEMS


Co-evolution of vehicle technology and

measurement methods


graph for the

case of

passenger cars


Average PM emissions of diesel passenger cars

limit real-world

Introduction of DPF (since 2007) leads to very low real-world PM exhaust

emissions from diesels (significantly below the 4.5 mg/km Euro 5b/6 limit)

From Euro 5 onwards comparable to PM emissions of petrol vehicles

REAL-WORLD EMISSIONS

DPF effective in reducing PM of diesels

EURO 5 DIESELS

NOx very sensitive to deviations from TA

test conditions

22 of the 23 tested car and van models show significantly elevated NOx

emissions under real-world test conditions compared to type approval test

Emissions on RW test cycles (lab) and on the road (PEMS) all

factor 3 - 4 (cars) or 3 - 6 (vans) higher than on type approval test

Difference cannot be explained by difference in driving dynamics

NOx emissions sensitive to deviations from TA test conditions, e.g.:

Use of other test cycles on roller bench

Test with warm start instead of cold start

Comparable results in Europe since 2011:

TNO observations confirmed by EMPA (Switzerland) and JRC

TNO concludes: Laboratory tests according to type approval procedure no

longer representative for real-world emissions


EURO 6 DIESELS

Mixed picture in lab, factor 2 to 6 above

TA limit on the road

Pre-series Euro 6 vehicles, tested in 2010, showed promising RW NOx results

on CADC test cycle

Vehicles tested in 2012 – 2015 show

mixed behaviour on different tests in the lab

some are very sensitive to different tests / test conditions

some have low emissions on all lab tests

consistently high NOx when tested on the road with PEMS or SEMS

one exception with low NOx emissions on the road


Average NOx emissions of petrol and diesel passenger cars

limit diesel

limit petrol

RW diesel

RW petrol

NOx limit for diesel higher than for petrol



NOx of petrol and diesel vehicles


limit diesel

limit petrol

RW diesel

RW petrol

For petrol strong reduction of RW NOx emissions



Developments for petrol vehicles


limit diesel

limit petrol

RW diesel

RW petrol

Between Euro 1 and 5 the RW NOx emissions of diesel passenger cars have

remained largely constant

Improvements for Euro 6 but final picture not yet clear



Developments for diesel vehicles

INTERPRETATION

Optimisation towards test procedure?

Possible origins for observed emission behaviour can be:

(increasing levels of) optimisation of hardware and control software to the

specific conditions prescribed by the Type Approval test procedure

Engine loads (NEDC + settings derived from coastdown test)

Engine temperature at start of test

Ambient temperature window (20 - 30°C) during test

Limited duration of test (1180 sec.)

OR

various kinds of “defeat devices”

Both lead to strong sensitivity of emission behaviour to small variations from the

TA test conditions


INTERPRETATION

Optimisation towards test procedure?


NOx emissions

TA limit

test conditions

qualitative

illustration

Robustness of emissions to variations in test conditions (within boundaries of

“normal” real-world driving) is neither tested nor required by current regulation

ROBUSTNESS

No effective In-Use Compliance

In practice responsibility of OEMs for emission performance is limited to cars as

they leave the factory, tested under very specific conditions

Type Approval

Conformity of Production (CoP)

Durability requirements only tested after controlled ageing

Follow-up of OBD-signals is responsibility of the vehicle owner

OEMs can discard results from on-road measurements as “not according to the

official EU test procedure”

Effectiveness of emission legislation for reducing real-world emissions requires

test of vehicles in-use (= outside the factory and outside the lab)


CONSEQUENCES

Cities failing to meet EU air quality

standard for NO2 in time

High NOx emissions of modern diesel cars and vans, combined with increased

share of diesels in passenger car fleet, lead to:

High NO2 concentrations in cities

AND

Reduced effectiveness for local policy measures to reduce NO2 such as:

Fleet renewal, e.g. by scrappage

schemes

Environmental zoning

Cities having to implement a large

number of additional (and often

costly) air quality measures


RESULTS 2010-2015

What has TNO done with the results?

Results w.r.t. high RW NOx emissions of diesels have been shared with:

Ministry of Infrastructure and the Environment, RDW, involved importers /

OEMs, municipalities and other stakeholders

Public reports and scientific papers

Used for annual updates of national emission factors

Results provided as input for legislative process in Brussels

Important input for start development of RDE (Real Driving Emissions) based

on PEMS in 2012

Results shared with JRC and ERMES colleagues

TNO reports sent to Dutch parliament by Ministry

Large public stakeholder meetings in Feb. 2014 and June 2015

Press releases at events and with publication of new reports


REGULATORY DEVELOPMENTS

Effects of WLTP and RDE

WLTP, new laboratory test (2017), has limited impact on RW NOx

Cycle more representative for real-world driving: but broader engine

optimisation appears possible

Still a lab test with very specific conditions

Based on experience, lab tests are considered unsuitable for assessing real

world pollutant emissions of modern cars

RDE, measuring emissions on the road with PEMS (introduction 2017-2021)

Good start for effective regulation

Separate evaluation of emissions in urban traffic is essential for air quality

Net stringency determined by balance between height of Conformity

Factor, width of test regime, and method for evaluation of test results

Attention to detail necessary in further specification and implementation of test

and evaluation procedure



CONTACT

WWW.TNO.NL

ABBREVIATIONS

CADC Common Artemis Driving Cycle

CO2 Carbon Dioxide

CoP Conformity of Production

DPF Diesel Particulate Filter

EGR Exhaust Gas Recirculation

EMPA Swiss Federal Laboratories for Materials

Science and Technology

ERMES European Research on Mobile

Emission Sources

FTP Federal Test Procedure (US test cycle)

HD Heavy Duty

JRC Joint Research Centre (of the European

Commission)

LD Light Duty

LNT Lean NOx Trap

NEDC New European Driving Cycle

NO2 Nitrogen Dioxide

NOx Nitrogen Oxides (NO + NO2)

OBD On-Board Diagnostics

24 May 2016 20 | NOx emissions of diesel vehicles in the lab and on the road

PEMS Portable Emissions Measurement System

PM Particulate Matter

RDE Real Driving Emissions

RDW Dutch road vehicle (and type approval)

authority

RW Real-World

SCR Selective Catalytic Reduction (using

AdBlue)

SEMS Smart Emissions Measurement System

(TNO development)

TA Type Approval

TNO Dutch Organisation for Applied Scientific

Research

WLTP Worldwide harmonized Light vehicles Test

Procedures

THANK YOU FOR YOUR ATTENTION

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