Modelling Motor Vehicle EmissionsModelling Motor Vehicle Emissions

The ApplicationsThe Applications

of of

EMFAC in Hong KongEMFAC in Hong Kong

Mobile Source Emission GroupMobile Source Emission Group

Environmental Protection DepartmentEnvironmental Protection Department

Run-down of the Workshop

9:00 – 9:30 Registration

9:30 – 10:00 Guideline on Modelling Vehicle Emissions, and EMFAC-HK

10:00 – 10:15 Tea Break

10:15 – 1:00 DemonstrationQuestions and Answers

Purpose of the Workshop

- To explain the background of developing the Guideline on Modelling Vehicle Emissions;

- To demonstrate the applications of the Guideline in local EIAs.

BackgroundBackground

The existing practice: The existing practice:

- Making reference to the vehicle tailpipe - Making reference to the vehicle tailpipe emission database in MOBILE; andemission database in MOBILE; and

- Having regard to the local motor vehicle Having regard to the local motor vehicle emission control measures;emission control measures;

- Working out a common set of fleet averaged Working out a common set of fleet averaged vehicle emission factors for the whole Hong vehicle emission factors for the whole Hong Kong.Kong.

BackgroundBackground

- Vehicle tailpipe emissions are sensitive to driving Vehicle tailpipe emissions are sensitive to driving patterns (In EMFAC, they are characterized by patterns (In EMFAC, they are characterized by average vehicle speeds), ambient conditions, etc.average vehicle speeds), ambient conditions, etc.

- A common set of fleet averaged vehicle emission A common set of fleet averaged vehicle emission factors irrespective of driving patterns - no longer factors irrespective of driving patterns - no longer accepted by advanced countries like the EU and accepted by advanced countries like the EU and the USA.the USA.

Guideline on Modelling Vehicle EmissionsGuideline on Modelling Vehicle Emissions

- To help EIA consultants to come up with a suitabl- To help EIA consultants to come up with a suitable set of project specific fleet averaged vehicle eme set of project specific fleet averaged vehicle emission factors;ission factors;

- Not binding on EIA consultants;- Not binding on EIA consultants;

- EIA consultants free to adopt it or otherwise;- EIA consultants free to adopt it or otherwise;

- Deviations from the Guideline acceptable if there - Deviations from the Guideline acceptable if there are good justifications.are good justifications.

Guideline on Modelling Vehicle EmissionsGuideline on Modelling Vehicle Emissions

For RSP, NOx, CO and VOCs:For RSP, NOx, CO and VOCs:

- EMFAC-HK- EMFAC-HK

For SOx and lead.:For SOx and lead.:

- Mass-balance equation (Ref.: USEPA’s PART 5 - Mass-balance equation (Ref.: USEPA’s PART 5 Model).Model).

EMFAC-HKEMFAC-HK

- Adopted from California Air Resources Adopted from California Air Resources Board’s EMFAC2002 with modifications to Board’s EMFAC2002 with modifications to cater for local factors such as local vehicle cater for local factors such as local vehicle fleet characteristics.fleet characteristics.

- Alternatives are USEPA’s MOBILE6, Alternatives are USEPA’s MOBILE6, MOVES, EU’s COPERT and German Swiss MOVES, EU’s COPERT and German Swiss HandbookHandbook

EMFAC-HKEMFAC-HK

Key features of modelling methodology:

- based on driving patterns characterized by average vehicle speeds;

- taking into account vehicle emission design technologies and vehicle emission deterioration rate;

- other local factors.

EMFAC-HKEMFAC-HK

The model is a tool for estimating project specific fleet averaged vehicle emission factors and vehicle emission inventories for the following primary pollutants:

• hydrocarbons (TOG, THC, VOC/ROG, CH4)•　 carbon monoxide (CO)•　 nitrogen oxides (NOx)

•　 particulate matters (PM10 & PM2.5)　

EMFAC-HKEMFAC-HK

Modelling the following tailpipe emissions:

•　 Running exhausts;

•　 Starting exhausts (for petrol vehicles only).

EMFAC-HKEMFAC-HKSupporting Data for ModellingSupporting Data for Modelling

Supporting Data for Modelling:

• Engine-specific;

• Local fleet composition and characteristics;

• Project specific (traffic pattern, ambient conditions).

EMFAC-HKEMFAC-HKSupporting Data - Engine Specific Supporting Data - Engine Specific

• Zero mile emission factors (ZMEF) – hard-coded in the model and provided in the graphic user interface (GUI) in the form of different technology group indexes for selection (Appendix III of the Guideline);

• Engine emission deterioration rates (DRs) – hard-coded in the model.

EMFAC-HKEMFAC-HKSupporting Data - Local Fleet SpecificSupporting Data - Local Fleet Specific

• Vehicle age distribution for each vehicle class (the existing one posted on EPD’s website);

• Annual mileage distribution vs. vehicle age (a set of default distribution is provided in the model);

• Daily trips per vehicle (for petrol vehicles only; hard-coded in the model);

• Distribution of high emitters vs. vehicle age (hard-coded in the model)

EMFAC-HKEMFAC-HKSupporting Data – Project Specific (I)Supporting Data – Project Specific (I)

• Fleet composition in respect of emission control design standards and the retrofit of after-exhaust treatment devices for each model year (first registration year) – existing distribution posted on EPD’s website;

• Diurnal variation of vehicle kilometer travelled (VKT); and

• Diurnal variation of total daily trips (to be explained in the examples)

EMFAC-HKEMFAC-HKSupporting Data – Project Specific (II)Supporting Data – Project Specific (II)

• Distribution of VKT fractions for each average speed bin;

• Ambient temperature and relative humidity.

EMFAC-HKEMFAC-HKProject Specific Input DataProject Specific Input Data

Diurnal Variation of VKTDiurnal Variation of VKT

• Site-specific figures should be used whenever available.

• In the absence of site specific figures, they can be estimated based on the traffic data in the Annual Traffic Census (ATC) Report of the Transport Department for roads bearing similar road traffic pattern.

EMFAC-HKEMFAC-HKProject Specific Input DataProject Specific Input Data

VKT Distribution for Vehicle Speed BinsVKT Distribution for Vehicle Speed Bins

References:

• Speed vs. volume/capacity ratio (like those published in Comprehensive Transport Study, CTS-3, report) diurnal variation of traffic flow from ATC

• Posted speed limits on roads obtained from Highway Department

EMFAC-HKEMFAC-HKProject Specific Input DataProject Specific Input Data

VKT Distribution for Vehicle Speed BinsVKT Distribution for Vehicle Speed Bins

Mandatory requirements:

• Maximum speed for buses and goods vehicles > 5.5 tonne is 70 km/hr.

EMFAC-HKEMFAC-HKProject Specific Input DataProject Specific Input Data

VKT Distribution for Vehicle SpeedVKT Distribution for Vehicle Speed BinsBins

For peak hour

• Roads with similar traffic patterns; or

• Average vehicle speeds can be estimated from speed vs. volume/capacity ratio.

EMFAC-HKEMFAC-HKProject Specific Input DataProject Specific Input Data

VKT Distribution for Vehicle SpeedVKT Distribution for Vehicle Speed BinsBins

For non-peak hour,

• Can be estimated from roads with similar traffic patterns

• Average vehicle speeds can be estimated from speed vs. volume/capacity ratio, or

• Average vehicle speeds can be taken to be the same as the speed limits of the concerned roads (for speed limit > 50 km/hr)

Link Speed Flow CurvesLink Speed Flow Curves

0

1 0

2 0

3 0

4 0

5 0

6 0

7 0

0 X Y ZV o lu m e /c a p a c i t y r a t io

Sp

ee

d (

km

/hr)

V f

V 1

V u

V m

Link Speed FlowLink Speed Flow Curves (CTS-3)Curves (CTS-3)

Road Type Vf Vu V1 Vm X Y Z

Rural Road A 60 55 35 22 0.4 1.0 1.2

Rural Trunk Road 75 70 45 30 0.4 1.0 1.2

Urban Local Distributor 30 30 12 5 0.1 1.0 1.2

Urban District Distributor 40 40 22 11 0.1 1.0 1.2

Urban Primary Distributor 50 50 27 16 0.2 1.0 1.2

Urban Trunk Road 70 70 45 30 0.4 1.0 1.2

Expressway 90 85 65 40 0.4 1.0 1.2

EMFAC-HKEMFAC-HKProject Specific Input DataProject Specific Input Data

Ambient Temperature & Relative HumditiesAmbient Temperature & Relative Humdities

• At least one year of recent hourly ambient temperature and relative humidity data.

• Obtained from Hong Kong Observatory representative data - from a weather station either nearest or having similar characteristics as the study area;

• 90% valid data in the data set.

EMFAC-HKEMFAC-HKOthersOthers

• Delete the Inspection and Maintenance Option in the model.

• The Guideline may be reviewed from time to time. Reference should be made to the latest version.

Thank you!!Thank you!!