Diesel Inventory Improvemen

for Regulatory Development

Planning and TechSupport DivisionNovember 18, 2010
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Outline

 Emissions Inventory Development  Truck and Bus Rule Inventory Off-Road Rule Inventory Conclusion
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What is an emissions invento

 An estimate of current and future air po

emissions

 Combines emissions measurements w

on the population and operating characof different types of vehicles

 Methods and data sources improve ov

Introduction
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How are future emissions forecas

 Current emissions are adjusted for gro

regulation requirements – Forecasted economic trends – New technology penetration

Introduction
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What types of data sources are us

 Engine emission test data  Academic research  Agency program information Market reports and industry surveys ARB surveys and field studies Economic forecasts 

Introduction
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What’s different with in-use ru

 New engine standards focus on manuf In-use rules focus on fleets owned and 

operated by individual businesses

 Requires understanding the nature of i

fleets and their operations

Introduction
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Truck and Bus Inventory

 Comprehensive update in 2008  Latest update is for 

recession impacts

 Other refinements
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Inventory Updates

 Comprehensive 2008 update – Addressed variety of fleet categories – Incorporated new methods and data 2010 update for recession – Adjusted economic assumptions – Other refinements

Truck and Bus Inventory
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Inventory Update Public Proce

 First workshop discussing updates Apr 6 inventory workshops in 2007 and 200 9 inventory workshops in 2009 and 201 Stakeholder participation Inventory data and models available to 

Truck and Bus Inventory
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Recession Impact

 Emissions reduced by 25%  Impact of recession based on fuel sale Agrees well with fuel estimates

Truck and Bus Inventory
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Use of Economic Forecasts 

 Evaluated latest near-term forecasts  Forecasts from UCLA, UOP, CA Depa

Finance, Beacon Economics, Energy Information Administration, CongressioBudget Office, and others 

 Focus on 2014 

Truck and Bus Inventory
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Economic Recovery Scenario

 Faster scenario assumes eight year re

period

 Slower scenario assumes no return to 

previously anticipated levels 

 April report to Board used average sce Average scenario consistent with UCLA 

UOP transportation forecasts

Truck and Bus Inventory
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Scenarios ForecastinActivity

Truck and Bus Inventory
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Scenarios ForecastinActivity

Truck and Bus Inventory
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Scenarios ForecastinActivity

Truck and Bus Inventory
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Truck and Bus Inventory Scenarios Forecastin

Activity
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Scenarios ForecastinActivity

Truck and Bus Inventory
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Other Refinements

 Applied 2008 statewide methods to dev

regional estimates

 Reduced out-of-state vehicle miles trav

California

 Reduced emission rate estimates for o

vehicles

 Overall these changes reduce emissio

about 10 percent

Truck and Bus Inventory
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Results of PM2.5 Invento

Truck and Bus Inventory

05

1015202530

2010 2014 

Statewide PM2.5 Tons per Day

OriginalRecessionRecession + Re

25%
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Recent Public Comments

 Comments – Use a slow recovery scenario – Limit lifetime mileage to 600,000 miles – Reduce annual mileage assumptions  Based on review of the data staff conc

current inventory estimates are approp

Truck and Bus Inventory
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How was lifetime mileage upd

 Refers to the cumulative miles traveled 

truck category over a lifetime

 Fleet average value used in calculation Emission rates increase with use 2008 inventory used values greater tha

million 

 Updated inventory average lifetime mil

800,000

Truck and Bus Inventory
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ARB Response to Lifetime Mileag

Comment

 Two approaches to estimating lifetime 

– EPA approach suggests lifetime mileag

1,000,000 miles – Survey approach suggests 650,000 mi

 800,000 miles is an appropriate mid-po

lifetime mileage estimate

Truck and Bus Inventory
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Evaluating Lifetime M

Estimates

Truck and Bus Inventory
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Evaluating Lifetime M

Estimates

Truck and Bus Inventory
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Evaluating Lifetime M

Estimates

Truck and Bus Inventory
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Evaluating Lifetime M

Estimates

Truck and Bus Inventory
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How is annual mileage used?

 Inventory includes estimates of annual 

based on vehicle age

 Emissions are the product of annual m

emission rates

 Reducing mileage attributed to older, d

vehicles would further reduce emission

 2008 inventory included annual mileag

adjustments

Truck and Bus Inventory
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ARB Response to Annual Mileage Comment

 Staff compiled more than 11,000 recor

US Census surveys, ARB surveys, and Bond, Moyer programs. 

 Data are available to the public Results support ARB estimates

Truck and Bus Inventory
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Revised Off-Road Rule Invent

 Updated for 2007 

Rulemaking 

 Significant updates to 

inventory methods using new data

 Effect of recession 

incorporated 
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Inventory Updates

 Rule inventory completed in 2007 – Started with EPA and ARB methods – Updated key inventory estimates with indu

studies, market reports – Supplemented with ARB surveys of indust

 2010 inventory improvements – New data reported through regulatory proc

– Comparison to fuel-based estimates – Impact of recession

In-Use Off-Road
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Inventory Update Public Proce

In-Use Off-Road

 Public workgroup meetings starting in 2 3 inventory workshops in 2006 Executive Officer Hearing March 2010 Meetings with stakeholders in 2010 8 inventory workshops in 2010 All inventory data and models available 
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Sources of New Information

 Off-Road rule reporting database Database of financed equipment sales 

California

 Manufacturer provided engine downloa ARB 2008-2009 engine testing Revised human population forecasts Updated employment data and forecas

In-Use Off-Road
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Key 2010 Updates 

 New methods and data – Equipment population – Hours of use – Load factors  Recession impact

In-Use Off-Road
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Equipment Population Update

 National survey data used in original e Now California reporting data is used  Current equipment population is reduc

195,000 to 145,000 

In-Use Off-Road
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Hours of Use Update

 Prior estimates based on industry mark

reports and studies

 New California reporting data used  On average activity is reduced 50% fro

previous estimates

 New data reflects both 2007 and 2009 

levels

In-Use Off-Road
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Load Factor Update 

 National study used in original inv Revised inventory uses data colle

from industry, ARB testing and acstudies

 New load estimates are 30% lowe Revision consistent with recent stu

other categories

In-Use Off-Road
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Recession Impact and Foreca

 Original rule inventory based on 2005 d

continued growth forecasts 

 Recession reduced emissions by 50% 

peak levels 

 Revised emissions forecast

In-Use Off-Road
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In-Use Off-Road Scenarios Forecastin

Road Activity
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In-Use Off-Road Scenarios Forecastin

Road Activity
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In-Use Off-Road Scenarios Forecastin

Road Activity
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In-Use Off-Road Scenarios Forecastin

Road Activity
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Results of PM2.5 Inven

Update

In-Use Off-Road
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Comparison to Fuel Sales 

 Fuel sales used to evaluate new estim Only total off-road sales are reported  Revised inventory based on reported a Updated fuel use is generally consisten

other estimates 

In-Use Off-Road
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Summary of Inventory Update

 Trucks and Buses – Revised inventory reduced 35% in 2010 d

primarily to recession

 Off-Road – Revised inventory reduced 80% in 2010; h

recession and half due to new information

 Both inventories consistent with fuel sa

estimates

 Inventory models and documentation a

to the public
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Conclusion 

 Truck/Bus and off-road emissions are l

than anticipated in the SIP

 Provides a margin for economic relief i

– Equal to 62 tons/day in South Coast – Equal to 40 tons/day in San Joaquin Valle

 Meeting federal air quality standards re

the cleanest technologies for all source