CALIFORNIA AIR RESOURCES BOARD
Auditorium, First Floor
400 "P" Street
November 14, 1991
91-10-1 Public Hearing to Consider the Adoption of 001
Revisions to the Designation of Areas in
California as Attainment, Nonattainment, or
Unclassified for State Ambient Air Quality
91-10-2 Public Hearing to Consider Amendments to 050
Regulations Regarding the Calculations and Use
of Reactivity Adjustment Factors for Low-Emission
Vehicles and the Adoption of Initial Reactivity
Adjustment Factors for Passenger Cars and Light-
Duty Trucks Certifying to Transitional Low-Emission
Vehicle Exhaust Emission Standards.
91-10-3 Public Meeting to Consider Research Proposals: 129
Proposal Number 1916-165 entitled "Development of
Species Profiles for Emissions from Selected
Combustion Sources," submitted by Energy and
Environmental Research Corporation, for a total
amount not to exceed $98,719.
Proposal Number 1870-165 entitled "A Collaborative
Owens Lake Aerosol Study," submitted by the University
of California, Davis, for a total amount not to
ITEM NO.: 91-10-2
Public Hearing to Consider Amendments to Regulations Regarding
the Calculation and Use of Reactivity Adjustment Factors for Low-Emission
Vehicles and the Adoption of Initial Reactivity
Adjustment Factors for Passenger Cars and Light-Duty Trucks
Certifying to Transitional Low-Emission Vehicle Exhaust Emission
The staff recommends that the Board adopt the proposed reactivity
adjustment factors for passenger cars and light-duty trucks
certifying to transitional low-emission vehicle standards which
operate on methanol ("M85"), compressed natural gas ("CNG"), and
liquefied petroleum gas ("LPG"). The staff also recommends that
the Board adopt the proposed regulatory amendments regarding the
calculation and use of reactivity adjustment factors.
Following a September 28, 1990, hearing, the Board adopted the
Low-Emission Vehicles and Clean Fuels regulations which
established emission standards for low-emitting light- and
medium-duty vehicles. These include standards for transitional
low-emission vehicles ("TLEVs"), low-emission vehicles, ultra-low-emission
vehicles, and zero-emission vehicles. The standards
reflect the relative impact on ozone formation of different
vehicle/fuel systems by applying reactivity adjustment factors
("RAFs") to the measured non-methane organic gas ("NMOG") exhaust
mass emissions of the vehicle.
The regulations contain a protocol by which the Executive Officer
can establish RAFs for representative vehicle/fuel combinations.
Under the protocol, hydrocarbon exhaust speciation profiles are
multiplied by a reactivity scale based on the maximum incremental
reactivity ("MIR") of individual hydrocarbon species. When the
Board acted on the regulations, the staff committed to present
initial proposed RAFs to the Board in the fall of 1991 for
adoption in regulatory form.
Automobile manufacturers have indicated that alternative fuel
TLEVs could be sold in California within the next few years.
These vehicles cannot be certified until the applicable RAFs are
in place, and the establishment of RAFs may influence a
manufacturer's decision to produce an alternative fuel vehicle.
Hence, the adoption of RAFs for alternative fuel TLEVs is needed
at the earliest practicable date.
The Air Resources Board staff is proposing RAFs for M85, CNG, and
LPG TLEVs in the passenger car and light-duty truck class. The
proposed RAFs were developed based on the protocol in the
regulations and updated MIRs. The staff used in-house test data
as well as data acquired from the Auto Oil Air Quality
Improvement Research Program and from Chevron Research and
Technology Company. The proposed RAFs are as follows: 0.36 for
M85, 0.18 for CNG, and 0.50 for LPG.
The staff is also proposing various amendments regarding the
calculation and use of RAFs. The MIRs of individual hydrocarbon
species would be revised to reflect new data and peer review.
The effect of updated RAFs would be clarified, and the gram ozone
potential per gram NMOG for passenger car and light-duty truck
TLEVs operating on conventional gasoline would be established.
SUMMARY AND IMPACTS
Application of the MIR scale was chosen to reflect the conditions
where hydrocarbon control has the greatest impact on ozone
formation. Discussions with industry and the public have raised
concerns regarding the accuracy of the MIR scale for predicting
ozone formation, the limited data base used to calculate RAFs,
the applicability of the RAFs in real world conditions throughout
California, the compounds included in the reactivity
calculations, and the criteria for revising established RAFs and
developing new RAFs.
The adoption of RAFs for TLEVs will not result in additional
costs. By adjusting NMOG emission standards to reflect the lower
ozone-forming potential of M85, CNG, and LPG, development of
TLEVs using these fuels may allow these vehicles to be viable
without the use of the expensive emission control technology
required when conventional gasoline is used.