Road Transport Emission Factors and Fleet Data Information from the National Atmospheric Emissions Inventory

Transcription

1 Road Transport Emission Factors and Fleet Data Information from the National Atmospheric Emissions Inventory Tim Murrells DMUG Meeting London 5 th December 2012

2 Introduction NO x emission factors Reasons for change What are the changes? Fleet composition Evidence What are the changes? PM, HC emission factors Factors for alternative vehicle technologies

3 Recent Trends in Roadside NO x Concentrations David Carslaw et al, 2011 Concentrations have been flat or weakly downward over the past 6-8 years

4 NO x ktonnes/yr) Recent Trends in Roadside NO x Concentrations Trend in conc.: -0.5% to -2%/year Mcycle Bus Artic HGV Rigid HGV Diesel LGV Petrol LGV Diesel car Petrol car Trends implied by UK inventory up to 2009 were not consistent with observations Trend in emissions: -6%/year

5 NO x Trends at Roadside Sites in European Cities

6 Approach in NAEI version of NAEI published in early 2011 NAEI used average DfT/TRL (2009) speed-related emission factors for different vehicle types, fuels and Euro standards with DfT traffic flow data and national fleet composition data Why cannot emission inventories explain trends in roadside NO x concentrations? Have Euro standards delivered expected improvements? Are real-world emission factors dependent on technologies?

7 Alternative Sources of Emission Factors for Road Transport in Europe New factors published in 2010/2011 COPERT 4 Supported by European Environment Agency for national inventory reporting under CLRTAP EMEP/CORINAIR Emissions Inventory Guidebook Average speed-related emission factors similar in style to UKEF COPERT 4 v8.1/v9 (November 2011) HBEFA v3.1 Swiss/German Handbook of Emission Factors (January 2010) Factors for many different traffic situations

8 NO x Emission Factors: Diesel Cars UKEF refer to previous factors used in NAEI up to 2009 version developed in 2010/11

9 Remote Sensing of Vehicle Emissions Carslaw et al, King s College 2011

10 NOx 31 kph Urban NO x Emission Factor: Diesel Cars UKEF COPERT RSD Euro 1 Euro 2 Euro 3 Euro 4 UKEF refer to previous factors used in NAEI up to 2009 version developed in 2010/11

11 NOx emission factor (g/km) NO x Emission Factors: Diesel Cars COPERT 4 factors Euro standard Euro 1 Euro 2 Euro 3 Euro 4 Euro 5

12 NO x Emissions for Euro V Heavy Duty Vehicles with SCR vs EGR NOx (g/km) 20,0 15,0 10,0 5,0 SCR EGR Emission Standard 0, Speed (km/h) Source: COPERT 4 manual (European Environment Agency, 2011)

13 UK Fleet Composition - ANPR Data Automatic Number Plate Recognition data from DfT for 256 sites in UK grouped into different road types for each year from Road Type England Scotland Wales Northern Ireland Total urban rural motorway Total Tells us: the age/euro mix of the fleet as seen on the road The petrol/diesel car mix on different types of roads

14 Diesel Car Mix on UK Roads in 2009: Previous NAEI Assumptions vs ANPR Evidence % diesel cars on road 60% 50% 50% 40% 41% 33% 35% 43% 30% 28% 20% 10% 0% NAEI urban rural m-way ANPR Previous NAEI fleet based on vehicle licensing data, travel surveys and assumptions about annual mileage - used to split km travelled by cars

15 % Euro standards on urban roads Euro Standard Mix for Cars on UK Urban Roads in 2009: Previous NAEI Assumptions vs ANPR data 100% 90% 80% 70% 57.6% 57.8% 52.5% 56.4% 60% 50% 40% 30% 20% 10% 0% 18.9% 19.2% 37.8% 34.5% 18.2% 17.8% 4.6% 4.2% 7.1% 6.9% 2.5% 2.0% NAEI ANPR NAEI ANPR Petrol car Diesel car Euro 1 Euro 2 Euro 3 Euro 4 ANPR data indicate fleets for LGVs and HGVs are newer than previously assumed in NAEI fleet. ANPR-based fleet data incorporated into latest NAEI

16 NAEI Road Transport Emission Factors and Fleet Data Speed-emission factor equations for all vehicle classes Guidance on emission degradation calculation

17 NAEI Road Transport Fleet Data Basic fleet mix: from DfT 2011 traffic (vkm) projections England (exc London) London Scotland Wales N Ireland England Urban Petrol car 56.1% 55.2% 53.6% 50.1% 47.7% 45.4% 43.3% 41.3% (outside London) Diesel car 26.0% 26.7% 28.1% 31.3% 33.4% 35.4% 37.3% 39.0% Petrol LGV 0.8% 0.7% 0.5% 0.5% 0.4% 0.4% 0.4% 0.4% Diesel LGV 11.5% 11.8% 12.2% 12.5% 12.8% 13.1% 13.4% 13.6% Rigid 1.7% 1.7% 1.6% 1.7% 1.8% 1.9% 2.0% 2.0% Artic 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% Bus and coach 1.6% 1.6% 1.6% 1.5% 1.5% 1.4% 1.4% 1.3% Motorcycle 1.9% 1.9% 2.0% 1.9% 1.9% 1.9% 1.9% 1.9% Rural Petrol car 51.9% 51.3% 50.0% 46.3% 43.8% 41.4% 39.2% 37.1% Diesel car 27.1% 27.5% 28.7% 31.9% 33.9% 35.9% 37.7% 39.4% Petrol LGV 0.9% 0.8% 0.6% 0.5% 0.5% 0.5% 0.4% 0.4% Diesel LGV 13.0% 13.3% 13.8% 14.1% 14.5% 14.8% 15.1% 15.5% Rigid 3.0% 3.0% 2.9% 3.1% 3.2% 3.4% 3.6% 3.7% Artic 2.4% 2.4% 2.4% 2.3% 2.3% 2.2% 2.2% 2.2% Bus and coach 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% 0.7% Motorcycle 1.1% 1.1% 1.1% 1.1% 1.1% 1.1% 1.1% 1.1% Motorway Petrol car 42.7% 42.9% 42.0% 37.8% 35.0% 32.3% 29.8% 27.5% Diesel car 32.4% 32.1% 33.0% 36.7% 39.0% 41.2% 43.3% 45.2% Petrol LGV 0.8% 0.7% 0.5% 0.5% 0.4% 0.4% 0.4% 0.4% Diesel LGV 11.2% 11.4% 11.7% 12.1% 12.5% 12.8% 13.2% 13.5% Rigid 4.2% 4.1% 4.1% 4.4% 4.7% 5.0% 5.3% 5.6% Artic 7.9% 7.8% 7.8% 7.6% 7.4% 7.3% 7.1% 7.0% Bus and coach 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% 0.4% Motorcycle 0.5% 0.5% 0.5% 0.5% 0.5% 0.6% 0.6% 0.6%

18 NAEI Road Transport Fleet Data Fleet mix by Euro class: Petrol cars, diesel cars, petrol LGVs, diesel LGVs, rigid HGVs, artic HGVs, buses and coaches, mopeds and motorcycles Inside, outside London Fleet mix by engine size (cars and motorcycles) vehicle weight (HGVs and buses) catalyst status (OK or failed) Euro V HDVs: SCR or EGR Detailed fleet data for London from TfL LGVs HGVs Buses (by technology) Taxis

19 Example: Fleet Projections for Cars 1. UK Car Fleet Composition Projections - Proportion of VKM by Euro Standard and Catalyst Status 1a) UK - Petrol Cars Fleet Composition - All Pollutants Note: When the catalyst of a petrol car is failed, emission factors for Pre-Euro 1 are assumed. Petrol cars Euro Standard Catalyst Status Pre-Euro 1 NA Euro 1 OK FAIL Euro 2 OK FAIL Euro 3 OK FAIL Euro 4 OK FAIL Euro 5 OK FAIL Euro 6 OK FAIL ALL b) UK - Diesel Cars Fleet Composition - NOx Calculations Note: Failure rates of SCR system apply only to Euro 6 diesel cars and LGVs; when the SCR system is failed, NOx emission factors for Euro 5 are assumed. Diesel cars Euro Standard Catalyst Status Pre-Euro 1 NA Euro 1 NA Euro 2 NA Euro 3 NA Euro 4 NA Euro 5 NA Euro 6 OK FAIL ALL This information is embedded in Emission Factor Toolkit

20 Urban Road Transport NO X Emissions Relative to 2002 Change relative to 2002 emissions Trend to NAEI09 Updated NOX EFs Final NAEI10 Trend to 2008: Use of new emission factors and fleet data still does not close the gap between trends in emissions and roadside concentrations

21 Emissions trend relative to 2003 Trend in NO x emissions on roads nearest each AURN monitoring site in London Croydon - Purley Way Enfield - Derby Road Greenwich - Blackheath Greenwich - Trafalgar Road Greenwich and Bexley - Falconwood Haringey - Haringey Town Hall Hounslow - Chiswick High Road Kensington and Chelsea - Cromwell Road Kensington and Chelsea - Kings Road Kensington and Chelsea - Knightsbridge Lewisham - New Cross Richmond Upon Thames - Castlenau Tower Hamlets - Mile End Road Watford (Roadside) Westminster - Marylebone Road 2010 NAEI - Urban RT emissions

22 PM 10 (g/km) at 31kph PM 10 (g/km) at 31 kph Exhaust Emission Factors for PM: NAEI vs COPERT Diesel cars NAEI COPERT COPERT factors for PM lead to similar trends in road transport emissions compared with current DfT/TRL factors used in NAEI and EFT Pre Euro 1 Euro 2 Euro 3 Euro 4 Euro 5 Euro 6 Euro 1 Diesel LGVs NAEI COPERT Many more contributions to roadside PM makes it more difficult to use roadside measurements to verify exhaust emission inventory trends 0 Pre Euro 1 Euro 2 Euro 3 Euro 4 Euro 5 Euro 6 Euro 1 Increasing importance of non-exhaust PM

23 Exhaust Emission Factors for NMVOCs: NAEI vs COPERT Petrol cars NAEI COPERT COPERT factors for HCs are generally lower for most vehicle classes (but not every) compared with current DfT/TRL factors used in NAEI and EFT and lead to lower overall road transport emissions Euro 1 Euro 2 Euro 3 Euro 4 Euro 5 Euro 6 Verification work by Dick Derwent - trends in HC measurements at Marylebone Road tend to support the road transport inventory

24 Trends in Hydrocarbon Concentrations at Marylebone Road Dick Derwent published in RoTAP report (2012)

25 Vehicle Technologies We are entering an era where knowledge of emission standard is not enough information to model traffic emission Even for conventional petrol and diesel vehicles, a wider range of technologies are used to meet standards, improve fuel efficiencies E.g. SCR vs EGR Low carbon technologies Different types same CO 2 performance, different air pollutant emissions, different cycle dependence Alternative fuels National uptake rates who knows?

26 Emission Factors for Alternative Vehicle Technologies and Fuels Literature review Information from TfL EMEP Emissions Inventory Guidebook (where possible) Scaling factors (or g/km emission factors) developed for different technologies relative to conventional petrol or diesel equivalent NO x, PM, CO 2

27 Emission Factors for Alternative Vehicle Technologies and Fuels Passenger cars Full hybrid electric (Toyota Prius) Plug-in hybrid electric E85 bioethanol LPG HGVs Buses Retrofit DPF B100 biodiesel Retrofit DPF Retrofit SCR Retrofit SCR TfL performance standards B100 biodiesel CNG/biogas Hybrid electric

28 Emission Factors for Alternative Vehicle Technologies and Fuels In some cases, very difficult to pin down a factor with any certainty Few measurements high uncertainty Variation in engineering design for notionally the same technology brings high variability in emission performance, even directional change. Dependent on drive cycle Hybridisation Not always certain what vehicles and cycles the emissions information reported in the literature can be compared against Retrofit technology - performance specification? TfL and London buses

29 Emission Factors for Alternative Vehicle Technologies and Fuels Example for passenger cars :NO x Vehicle Type Alternative fuel / technology Full hybrid electric vehicle (petrol HEV) Emission factors [g/km] Scaling factors Urban Rural Mway Urban Rural Mway Relative to Model Year Data source Euro 4 petrol Average scaling factors calculated from 2009 EEA Emission Inventory Guidebook (June 2010) emission factors for full hybrid car at typical average speeds Comment Based on measurements for a Toyota Prius. These are the only data available and it cannot necessarily be assumed that other models will achieve the same reduction in emissions Euro 5 petrol Assumes emission scaling same as for Euro 4 Passenger car/van Plug-in Hybrid Electric Vehicle (petrol-phev) Euro 5 petrol Based on study by Helms et al (2010) "Electric vehicle and plug-in hybrid energy efficiency and life cycle", lms%20et%20al.%20(2010)%20electric%20vehicl es%20(tap%20conference%20paper).pdf emissions No emission measurements available. Estimated from assumptions about the fraction of distance likely to be done under electric motor on each road type Battery Electric Vehicle (BEV) All Zero emissions. Refers to emissions at point of use, not full fuel-cycle emissions All Zero emissions. Refers to emissions at point of use, not full fuel-cycle emissions Fuel Cell Electric Vehicle (FCEV) E85 Bioethanol All Emissions from fossil fuel petrol AQEG (2011) report on biofuels Based on previous NAEI report reviewing impact of biofuels on AQ emissions The Guidebook provides speed-related emission functions and the following speeds (30, 60 and 70 mph) have been used to derive the emission factors for urban, rural and motorway as shown here.. Passenger car LPG EEA Emission Inventory Guidebook (June 2010) assume 25% reduction relative to Euro 4 assume 25% reduction relative to Euro 4 Emission factors are subject to change on review

30 Release Plan NAEI are finalising the factors Peer review by DfT Tables of factors with supporting text will be available on NAEI website Implementation in EFT Will need to be keep under constant review as further evidence emerges

31 Conclusions (1) New exhaust emission factors for NO x and fleet composition have been compiled and are available on NAEI website and included in EFT Recent Euro standards for light duty diesel vehicles not delivering the expected improvements for NO x under real-world conditions Use of new emission factors and fleet data closes the gap between trends in emissions and roadside concentrations of NO x, but there is still a gap Euro 5, 6? Primary NO 2 Importance of technology: SCR vs EGR

32 Conclusions (2) The EEA COPERT 4 source of emission factors of PM and VOCs have been adopted by the NAEI for national modelling of road transport emissions, but do not indicate such significant differences with previous UK factors Verification analysis on HCs do not indicate major discrepancies PM exhaust? Knowledge of Euro standards is no longer sufficient Increasing variety of vehicle technologies entering the fleet Increasingly important to understand technology mix, but getting this information is difficult Emission factors for many alternative technologies are very uncertain and variable Different levels of performance in retrofits, hybrids Procurement specification key to performance A set of emission factors for most main technologies will be made available and incorporated into EFT

33 Acknowledgements The NAEI work is supported by Defra, the Scottish Executive, Welsh Assembly and Department of the Environment in Northern Ireland: Sarah Honour, Emily Connolly (Defra-ALE) Ricardo-AEA colleagues who made a major contribution to this work are Yvonne Pang and Helen Venfield Much of the analysis on NO x trends was carried out by David Carslaw and colleagues at King s College. Grateful for figures and many useful discussions Grateful for advice and much useful information from Yvonne Brown (Bureau Veritas), Claire Cheriyan, Finn Coyle and colleagues at TfL who have been most helpful Analysis on hydrocarbon trends by Dick Derwent (rdscientific)

34 Tim Murrells Principal Consultant Ricardo-AEA The Gemini Building Fermi Avenue Harwell Didcot OX11 0QR Tel: +44 (0) E: W: Copyright Ricardo-AEA Ltd This presentation is submitted by Ricardo-AEA. It may not be used for any other purposes, reproduced in whole or in part, nor passed to any organisation or person without the specific permission in writing of the Commercial Manager, Ricardo-AEA Ltd.