California Gasoline Predictive Models, and CARBOB Model Development
This page last reviewed September 25, 2008
|CaRFG3 Predictive Model Development Process|
|The California Air Resources Board is currently in the process of developing a new CaRFG3 Predictive Model. This page contains information about fuel/vehicle emission studies, vehicle emissions inventory, permeation, MIR factors, and other related information to the development of the CaRFG3 Predictive Model.|
ARB Staff has released a preliminary draft of the Predictive Model.
Five recently released fuel/vehicle emission studies have been added to the current California Phase 3 Reformulated Gasoline Predictive Model database:
ARB staff is updating the methodology used to develop temperature and relative humidity profiles. These new profiles will be developed to represent meteorological conditions for the California 8-hour ozone standard. These profiles will not be part of vehicle emissions inventory model (EMFAC), but will be used to estimate vehicle emissions by technology group to update the Predictive model.
The need for a study of the permeation effects of ethanol became apparent when in late 1999 California banned the use of MTBE in gasoline. With this ban, which became effective starting in year 2004, ethanol became the only oxygenate approved for use in California gasoline. California must quantify the permeation effects of ethanol because California's statutes require that any increase in fuel emissions be off-set with a similar reduction from other sources. Therefore, the Board directed staff to report on the potential for hydrocarbon emissions increases associated with increased motor vehicle fuel system permeability resulting from the blending of ethanol into California gasoline.
From late 2002 to June 2004, the study was conducted by Coordinating Research Council (CRC) sponsored by the California Air Resources Board. The results of this study would assist the stockholders and the State of California to evaluate the emission benefits as well as the CaRFG 3 Gasoline Program. In January 2005, a second phase of the permeation study was initiated to test higher ethanol content fuels.
Copies of both reports and the supporting data are also available from the Coordinating Research Council.
ARB staff is releasing updates to specific reactivity values complied using the updated MIR values from the list adopted by ARB in 2003. The draft 2006 MIR list was presented for consideration by the reactivity subgroup and there was consensus on its use in the 2006 draft Predictive Model. This new 2006 draft MIR list is presented below. The 1998 and 2003 MIR lists are also provided below for reference.
Using the 2006 draft MIR list, staff has calculated average reactivity values for evaporative and exhaust emissions for speciated data from in-use testing of California compliant fuels at the ARB El Monte laboratory. The data sets include:
In March 2006, ARB staff released a draft modeling analysis for assessing the potential air quality impacts of increased permeation VOC emissions relative to reduced CO emissions for California vehicles using ethanol gasoline. This document describes the problem to be addressed, previous related work, and the air quality modeling results. It is not intended to estimate the air quality impact of ethanol vs. MTBE gasoline.
|Current CaRFG3 Predictive Model|
|Procedures for Using the California Model for California Reformulated Gasoline Blendstocks for Oxygenate Blending (CARBOB) (PDF - 68k) - Adopted April 25, 2001|
|Motor Vehicle Emission Testing Option|
|- California Procedures for Evaluating Alternative Specifications for Gasoline Using Vehicle Emissions Testing (PDF - 84k) - Amended April 25, 2001|