dKC Copyright MOBILE SOURCES 101 Presented by: Rob Klausmeier de la Torre Klausmeier Consulting, Inc Harold Garabedian Vermont Agency of Natural Resources

dKC Copyright Estimation of In-Use Emissions What will be covered: EPA’s MOBILE model –What are emission factor models –Description of MOBILE6 –How does MOBILE6 differ from MOBILE5

dKC Copyright Background Attainment demonstrations must be made using estimates of emissions from vehicles in actual use. Vehicles in actual use often do not receive proper maintenance, and in some cases, their emission control systems are deliberately tampered with. As a result, the average emission rate for vehicles in actual use often exceeds the appropriate emission standard.

dKC Copyright EPA’s MOBILE Model States must use EPA’s MOBILE model to estimate emission factors. The current model is MOBILE6. MOBILE6 estimates emission rates for each pollutant in terms of grams per mile, i.e. grams emitted per vehicle mile traveled (VMT). Emission factors are calculated for different vehicle types; then they are multiplied by appropriate weighting factors to develop a composite emission factor for each VMT in an area. Total emissions are calculated by multiplying emission factors by total VMT.

dKC Copyright 2001 Introduction5 What is MOBILE6? Computer model written in FORTRAN which is based on US EPA’s MOBILE5a model Calculates emission factors (g/mi) for a “Fleet Average Vehicle” Used for gasoline and diesel, on-road vehicles Calculates EF for: –light duty gasoline vehicles –light duty gasoline trucks (3 categories) –heavy duty gasoline vehicles (8 categories) –light duty diesel vehicles –light duty diesel trucks (2 categories) –heavy duty diesel vehicles (8 categories) –motorcycles –gasoline buses –diesel buses (transit/urban and school) Exhaust and Evaporative Hydrocarbon Emissions (HC) Exhaust Carbon Monoxide (CO) Exhaust Nitrogen Oxides (NOx) Future Enhancements likely to include: –PM –Toxics –Greenhouse gases Developed by US EPA, Office of Mobile Sources, Ann Arbor Michigan

dKC Copyright 2001 Introduction6 What Can the Model Do? Analytical Tool that can be applied for Air Quality Planning Can be used to estimate emission impacts from: –Future Vehicle Fleets –Diesel/Alternate Fuel Use –Vehicle Speeds –Roadway types –Ambient Temperature –Fuel RVP/Oxygen content/Sulfur content/RFG –Air Conditioning –Cold Starts –Inspection/Maintenance Programs –On-Board Diagnostics –Vehicle Tampering –New Vehicle Standards –Other Strategies Evaporative Controls Refueling Controls

dKC Copyright REFER TO BARRETT CAC MOBILE6 PRESENTATION

dKC Copyright Emission Factor Assumptions The emission factors in the MOBILE model are based upon assumptions about how different factors affect vehicle emissions. Emission factors take into consideration the following: A. Vehicle emission control technology (i.e., the emission standards that the vehicles were designed to comply with);

dKC Copyright Emission Factor Assumptions Cont. B. Deterioration of emission control performance. How vehicle emissions increase as a vehicle accumulates miles. The Basic Emission Rate (BER) = zero mile level + (Deterioration Factor) x accumulated mileage. The BER is a function of the following: - Assumed owner maintenance and tampering habits - Vehicle age assumptions - Mileage accumulation assumptions - Emission Control Technology

dKC Copyright Emission Factor Assumptions Cont. C. Vehicle types: - Gasoline powered cars vs. light trucks - Diesel powered heavy-duty vehicles

dKC Copyright Emission Factor Assumptions Cont. D. Vehicle use assumptions: - Ave speed - % cold start, % hot start, % hot transient

dKC Copyright Emission Factor Assumptions Cont. E. Ambient parameters: - Temperature - Cloud cover (new MOBILE6 input) - Altitude (high or low)

dKC Copyright Emission Factor Assumptions Cont. F. Fuel parameters: - Reformulated gasoline (RFG) - % sulfur - % oxygenates

dKC Copyright Emission Factor Assumptions Cont. G. I/M Program parameters - Vehicle coverage: type and model year - Emission Test Type OBDII Tailpipe test: IM240, ASM, idle, etc. - Evap test type: gas cap pressure test, tank pressure test, purge (not done but modeled) - Anti-tampering program, e.g. cat inspection - Start date - I/M credits are calculated assuming that the program identifies certain percentages of high emitting vehicles and brings the emission levels for these vehicles to assumed values based upon the emission test standards (cutpoints).

dKC Copyright Emission Factor Assumptions Cont. User can vary inputs for items C to G. User cannot vary BERs and responses to user inputs.

dKC Copyright Changes for MOBILE6 Emissions, fleet and activity data Structural changes Input and output formats Documentation

dKC Copyright Basic Exhaust Emissions Update in-use deterioration estimates for light duty cars and trucks. New emission standards (LD and HD)

dKC Copyright 2001 Fuel18 Effects of Fuel Composition Updated effects of oxygenated fuels on CO emissions Explicit effects of sulfur on exhaust emissions –including long-term and irreversibility effects. Explicit modeling of natural gas vehicles

dKC Copyright 2001 Fuel19 Overview Most modern gasoline-fueled vehicles use catalysts to reduce HC, CO, and NO x emissions Sulfur is a catalyst poison. Increased sulfur levels in fuels thereby increase emissions through catalyst deactivation

dKC Copyright 2001 Fuel20 LEV Normal Emitter Composite Emission Effects Based on Regression Coefficients NOx CO HC NMHC

dKC Copyright “Gross Liquid Leakers” Many vehicles may have leaks of liquid gasoline, but NOT all are “Gross Liquid Leakers” Only the highest emitting of the leakers are “Gross Liquid Leakers” Some vehicles may be “Gross Liquid Leakers” on only some of the tests

dKC Copyright 2001 I/M22 OBD Assumptions Equal Treatment for all three pollutants MIL-on Rate: –Ability of the OBD system to work properly. –Assumed to be 85 percent - (Based on 2x stds Highs) –No Deterioration with Mileage or Time Motorist Response Rate to OBD Outside of I/M –Under 36,000 miles:90 percent –Between 36,000 and 80,000 miles:10 percent –Over 80,000 miles: 0 percent

dKC Copyright 2001 I/M23 OBD Assumptions (Con’t) I/M Identification Rate –Ability of the OBD system to find high emitters in an I/M program. –Assumed to be 90 percent. After I/M Repair Emission Level of OBD Failures –Assumed to be 1.5 times FTP standard. No change over time or mileage.

dKC Copyright 2001 I/M24 Phase-in IM240 vs. Phase-in ASM2525 for PFI HC Emissions

dKC Copyright 2001 I/M25 Phase-in IM240 vs. Phase-in ASM2525 for PFI NO x Emissions

dKC Copyright 2001 I/M26 FTP HC Emission Effect of OBD and OBD I/M on Tier1 Cars

dKC Copyright 2001 I/M27 FTP NOx Emission Effect of OBD and OBD I/M on Tier1 Cars

dKC Copyright Heavy Duty Emissions New emission standards New conversion factors Will be adjusted for HD NOx excess

dKC Copyright 2001 Heavy-Duty29 Excess NOx Emission Levels Due to the HD Defeat Device and Mitigation Strategies (Offsets) Draft MOBILE6

dKC Copyright Running MOBILE6 Prepare a M6 input file and save From Windows, double-click on the M6DRAFT.EXE application icon A DOS window will appear Enter the input file name at the prompt âNote: remember to include path if input file is in a different directory/folder than the RUN folder Hit return

dKC Copyright Example: Simplest Input File Header Run Scenario MOBILE6 INPUT FILE: RUN DATA MIN/MAX TEMP: FUEL RVP:7.0 SCENARIO REC: Scenario Title Text CALENDAR YEAR:2010 END OF RUN

dKC Copyright EXAMPLE MOBILE6 RUNS

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dKC Copyright COMPARISON OF HIGHWAY MOBILE SOURCE EMISSIONS INVENTORY FROM MOBILE1 THROUGH MOBILE6 Alison K. Pollack 1, Christian E. Lindhjem 1, Dave Brzezinski 2, Rosa Chi 1 1 ENVIRON International Corporation 101 Rowland Way, Suite 220, Novato, CA Office of Transportation and Air Quality, EPA Ann Arbor, MI 48105

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dKC Copyright TWO TYPES OF RUNS PERFORMED Runs with the 1990 Clean Air Act Amendments (CAAA) turned off. Basic emissions rates (g/mile) calculated by the models are shown for direct comparisons across models. Runs with all emissions regulations applicable at the time of release and those additions (shown in the table describing each model) of the models for a 'typical' high ozone southern metropolitan region. The results (in tons per day) show the changes in total on-road emission inventories with different versions of the model.

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dKC Copyright OTHER EMISSION FACTOR MODELS

dKC Copyright EPA Non-Road Emissions Model EPA has recently developed a model to estimate Non-road emissions. The model is similar in concept to MOBILE5 in that it projects emission factors for a wide variety of vehicle types under different operating conditions. This model is described in detail in supporting documentation provided by EPA.

dKC Copyright Other Models Used for Projecting Mobile Source Emissions In addition to MOBILE5/6 and EPA’s off-road model, other models are used to estimate mobile source emissions. EPA’s Complex Model for fuel evaluation; EPA’s mobile-toxics model (MOBTOX5b); and PART5 – EPA’s particulate emission factor model.

dKC Copyright Gasoline Fuel Properties – The Complex Model The Complex Model estimates the impact of changes in fuel properties on exhaust and evaporative emissions. It is a useful tool for evaluating the impact of reductions in fuel sulfur content on vehicle emissions. In addition, it provides a means of estimating the impact of fuel properties on toxic emissions as it outputs toxic emission factors for the key toxic compounds; benzene, 1,3butadyene, etc. The state of California has developed a similar model that estimates the impact of fuel properties on toxic and criteria pollutants.

dKC Copyright EPA’s MOBTOX5b Model MOBTOX5b has been developed to estimate toxic emission factors for in-use highway vehicles. MOBTOX5b applies exhaust and evaporative toxic adjustment factors for various vehicle classes and technologies to MOBILE5b TOG emission factors. It allows the user to model benzene, formaldehyde, acetaldehyde, 1,3-butadiene, and MTBE emissions. The model allows the user to specify a large number of alternative scenarios: –basic emission rates, and the vehicle mileage level at which rates of deterioration begin to increase. –differences in exhaust toxic fractions of TOG between normal and high emitting vehicles in calculating emission rates. –Impacts of aggressive driving and air conditioning usage on toxics. –impacts of fuel reformulation programs and changes in vehicle emission control technology can also be addressed with the model.

dKC Copyright PART 5 PART5 is EPA's model for estimating particulate matter (PM; from vehicle exhaust and from vehicle interaction with roads) and sulfur dioxide (SO 2 ) emission factors for gasoline and diesel on-road vehicles. As with MOBILE5a, the emission factors are expressed in grams of pollutant emission per mile traveled. You have been provided with the code and Users’ Guide for PART5

dKC Copyright Estimating Vehicles Miles Traveled (VMT) Vehicle miles traveled (VMT) is usually estimated based upon traffic demand models. Fuel consumption also is used to estimate VMT. For example, ConnDOT uses their PERFORM travel demand forecasting model to develop VMT estimates. This model estimates trip generation based on land use, employment, census and car ownership data.