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A study was conducted by the California Air Resources Board to investigate the effects that altitude has on in-use heavy-duty diesel truck smoke opacities. The understanding of these effects may allow for the establishment of a high altitude opacity standard for diesel trucks operating at or above altitudes of 5800 feet. During a three-week study, 170 heavy-duty diesel trucks were tested at an altitude of 5,820 feet using a test procedure consisting of rolling acceleration and snap idle tests. Eighty-four (84) of these trucks were recaptured and retested at an altitude of 125 feet. Results from a regression analysis indicates that, on average, truck smoke opacities increased by 23 opacity points when tested at altitudes near 6000 feet. Possible high altitude cutpoints and failure rates are also discussed.

California is considering adopting an enhanced Inspection and Maintenance (I&M) program (commonly referred to as Smog Check II) beginning with the 1996 calendar year. This program will utilize a targeting scheme to identify vehicles likely to be high emitters and send these vehicles to centralized testing facilities. The remaining fleet of vehicles will be sent to decentralized testing facilities. At these facilities, vehicles will be subjected to steady state loaded mode dynamometer based tests. Simultaneously, all 1996 and later model year passenger cars, light- and medium-duty trucks sold in California will be equipped with an On-Board Diagnostic (OBDII) system. This system is designed to monitor critical emission related components and activate a Malfunction Indicator Light (MIL) when a failure or a drift in calibration is likely to cause emissions to exceed 1.5 times the vehicle certification standards.

In recognizing the potential for large, damaging impacts from climate change, California enacted Executive Order S-03-05, requiring a reduction in statewide greenhouse gas (GHG) emissions to 80% below 1990 levels by 2050. Given that the transportation light-duty vehicle (LDV) segment accounts for 28% of the state's GHG emissions today, it will be difficult to meet the 2050 goal unless a portfolio of near-zero carbon transportation solutions is pursued. Because it takes decades for a new propulsion system to capture a large fraction of the passenger vehicle market due to vehicle fleet turn-over rates, it is important to accelerate the introduction of these alternatives to ensure markets enter into early commercial volumes (10,000s) between 2015 and 2020. This report summarizes the results and conclusions of a modeling exercise that simulated GHG emissions from the LDV sector to 2050 in California.

Heavy-duty vehicles account for approximately 30 percent of the oxides of nitrogen (NOx) and 65 percent of the particulate matter (PM) emissions from the entire California on-road fleet, despite the fact that these vehicles comprise only 2 percent of the same. To meet legislative mandates to reduce excess smoke emissions from in-use heavy-duty diesel-powered vehicles, the Air Resources Board (ARB or Board) adopted, in December 1997, amendments to the regulations governing the operation and enforcement of the Heavy-Duty Vehicle Inspection Program (HDVIP or the “roadside” program) and the Periodic Smoke Inspection Program (PSIP or the “fleet” program). The initial roadside program was adopted in November 1990 in response to Senate Bill (SB) 1997 (stat. 1988, ch. 1544, Presley), and enforced from 1991 to 1993. It was suspended in October 1993, when the Board redirected staff to investigate reformulated fuels issues.

Two additive blends proposed for improving the flame luminosity in neat methanol fuel were investigated to determine the effect of these additives on the exhaust emissions in a dual-fueled Volkswagen Jetta. The two blends contained 4 percent toluene plus 2 percent indan in methanol and 5 percent cyclopentene plus 5 percent indan in methanol. Each blend was tested for regulated and unregulated emissions as well as a speciation of the exhaust hydrocarbons resulting from use of each fuel. The vehicle exhaust emissions from these two fuel blends were compared to the Coordinating Research Council Auto-Oil national average gasoline (RF-A), M100, and M85 blended from RF-A. Carter Maximum Incremental Reactivity Factors were applied to the speciated hydrocarbon emission results to determine the potential ozone formation for each fuel. Toxic emissions as defined in the 1990 Clean Air Act were also compared for each fuel.

While most studies addressing the fuel effects are based on the Federal Test Procedure (FTP), there are limited studies investigating the fuel effects outside FTP test conditions. In this study, we investigated the differences in exhaust emissions from California Phase 1 to Phase 2 reformulated gasoline over a wide range of speed and ambient temperatures. Eleven catalyst equipped passenger vehicles were tested. The vehicles were comprised of three fuel delivery system configurations, namely, three from carburetor (CARBU), three from throttle body injection (TBI), and five from multi-port fuel injection (MPFI) group. Each vehicle was given 60 tests with the combination of two reformulated fuels: Phase 1 (without oxygenates) and Phase 2 (with oxygenates), three temperatures (50, 75, and 100 °F), and ten speed cycles (average speed ranges from 4 mph to 65 mph).

Light duty gasoline vehicles (LDGV) are estimated to contribute 40% of the total on-road mobile source tailpipe emissions of particulate matter (PM) in California. While considerable efforts have been made to reduce toxic diesel PM emissions going into the future, less emphasis has been placed on PM from LDGVs. The goals of this work were to characterize a small fleet of visibly smoking and high PM emitting LDGVs, to explore the potential PM-reduction benefits of Smog Check and of repairs, and to examine remote sensing devices (RSD) as a potential method for identifying high PM emitters in the in-use fleet. For this study, we recruited a fleet of eight vehicles covering a spectrum of PM emission levels. PM and criteria pollutant emissions were quantified on a dynamometer and CVS dilution tunnel system over the Unified Cycle using standard methods and real time PM instruments.

Chrysler, Ford, General Motors, the U.S. Environmental Protection Agency (EPA) and the California Air Resources Board (CARB) have collaborated over the past two years to develop an efficiency test for mobile air conditioner (MAC) systems. Because the effect of efficiency differences between different MAC systems and different technologies is relatively small compared to overall vehicle fuel consumption, quantifying these differences has been challenging. The objective of this program was to develop a single dynamic test procedure that is capable of discerning small efficiency differences, and is generally representative of mobile air conditioner usage in the United States. The test was designed to be conducted in existing test facilities, using existing equipment, and within a sufficiently short time to fit standard test facility scheduling. Representative ambient climate conditions for the U.S. were chosen, as well as other test parameters, and a solar load was included.

The Automotive Industry/Government Emissions Research CRADA (AIGER) has been working to develop a new methodology for the direct determination of nonmethane hydrocarbons (DNMHC) in vehicle testing. This new measurement technique avoids the need for subtraction of a separately determined methane value from the total hydrocarbon measurement as is presently required by the Code of Federal Regulations. This paper will cover the historical aspects of the development program, which was initiated in 1993 and concluded in 2002. A fast, gas chromatographic (GC) column technology was selected and developed for the measurement of the nonmethane hydrocarbons directly, without any interference or correction being caused by the co-presence of sample methane. This new methodology chromatographically separates the methane from the nonmethane hydrocarbons, and then measures both the methane and the backflushed, total nonmethane hydrocarbons using standard flame ionization detection (FID).

The current refrigerant in mobile air conditioning (AC) systems, HFC-134a (also known as R134a), is a potent greenhouse gas (GHG) with a global-warming potential (GWP) of 1300. Its emissions from 2009 and subsequent model-year (MY) light-duty vehicles may be regulated under the terms of a law (Sec. 43108.5, Health and Safety Code) adopted in California in 2002. To support regulation development, we have estimated direct emissions of HFC-134a from vehicular AC systems in California by a novel, three-prong method that uses: 1) data on the consumption of HFC-134a by California commercial fleets, 2) surveys of vehicle owners on AC system repair incidence, and 3) data on repair incidence among California commercial fleet vehicles. Although these sources do not report direct emission rates of HFC-134a, the data reflect actual leakage integrated over long periods from vehicles in all stages of useful life.

A novel in situ method was performed for measuring emissions and fuel consumption of transport refrigeration units (TRUs). The test matrix included two fuels, two exhaust configurations, and two TRU engine operating speeds. The test fuels were California ultra low sulfur diesel and gas-to-liquid (GTL) diesel. The exhaust configurations were a stock original equipment manufacturer (OEM) muffler and a Thermo King pDPF™ diesel particulate filter. The two TRU engine operating speeds were high and low, as controlled by the TRU user interface. Test results indicate that GTL diesel fuel reduces all regulated emissions at high and low engine operating speeds. Separately, the application of a Thermo King pDPF reduced regulated emissions, in some cases almost entirely. Finally, the application of both GTL diesel and a Thermo King pDPF reduced regulated emissions at high engine operating speed, but with an increase in oxides of nitrogen (NOx) at low engine speed.

The Environmental Protection Agency (EPA) is developing emission standards for nonroad spark-ignition engines rated over 19 kW. Existing emission standards adopted by the California Air Resources Board for these engines were derived from emission testing with new engines, with an approximate adjustment applied to take deterioration into account. This paper describes subsequent testing with two LPG-fueled engines that had accumulated several thousand hours of operation with closed-loop control and three-way catalysts. These engines were removed from forklift trucks for characterization and optimization of emission levels. Emissions were measured over a wide range of steady-state points and several transient duty cycles. Optimized emission levels from the aged systems were generally below 1.5 g/hp-hr THC+NOx and 10 g/hp-hr CO.

When the California Air Resources Board (ARB) adopted automotive exhaust emission standards for Super Ultra-Low-Emission Vehicles (SULEV), new challenges were encountered for accurately measuring exhaust emissions. This is especially true for measuring NMOG emissions (NMHC and carbonyls) where the SULEV standard is 0.010 g/mi. One of the challenges in accurately measuring NMHC emissions is to find a clean sample bag material that has no or very low outgassing of hydrocarbons. Tedlar, the bag material commonly used for exhaust emission sampling, has been found to emit N,N- dimethylacetamide (DMAc), which interferes with hydrocarbon measurements and can contribute to significant error in SULEV hydrocarbon emission measurements. Several fluorocarbon materials were tested for hydrocarbon (HC) outgassing and carbon dioxide (CO2) permeation. The materials include Tedlar, Baked Tedlar, KynarFlex 2750, Baked KynarFlex 2800, Teflon FEP, TFM TFE, Tefzel, and Halar.

The impact of biodiesel and new generation biofuels on emissions from heavy-duty diesel engines was investigated using a California Air Resources Board (CARB) certified diesel fuel as a base fuel. This study was performed on two heavy-duty diesel engines, a 2006 engine and a diesel particle filter (DPF) equipped 2007 engine, on an engine dynamometer over four different test cycles. Emissions from soy-based and animal-based biodiesel, renewable diesel fuel, and gas-to-liquid (GTL) diesel fuel were evaluated at blend levels ranging from 5 to 100%. Consistent with previous studies, particulate matter (PM), hydrocarbons (HC), and carbon monoxide (CO) emissions generally showed increasing reductions with increasing biodiesel and renewable/GTL diesel fuel blend levels for the non-DPF equipped engine. The levels of these reductions were generally comparable to those found in previous studies performed using more typical Federal diesel fuels.

The California Air Resources Board conducted an extensive field test program to evaluate a vehicle exhaust recirculation system for control of oxides of nitrogen. The system utilized hot exhaust gases from the crossover and included certain modifications to the carburetion, choke, and crank case ventilation system. It was tested on two fleets of automobiles equipped wtih California approved HC and CO emission control devices. The test program involved periodic measurements of exhaust emissions and fuel consumption. The effect of the system on vehicle drivability, engine deposits, wear, and oil deterioration was also studied. The Atlantic Richfield Company, under contract to the Air Resources Board, equipped the vehicles with the recirculation system and performed the final engine inspection.

The use of methanol as a “clean fuel” appears to be a viable approach to reduce air pollution. However, concern has been expressed about potentially high formaldehyde emissions from stoichiometrically operated light-duty vehicles. This paper presents results from an emission test program conducted for the California Air Resources Board (CARB) and the South Coast Air Quality Management District (SCAQMD) to identify and evaluate advanced catalyst technology to reduce formaldehyde emissions without compromising regulated emission control. An earlier paper presented the results of evaluating eighteen different catalyst systems on a hybrid methanol-fueled test vehicle. (1)* This paper discusses the optimization of three of these catalyst systems on four current technology methanol-fueled vehicles. Emission measurements were conducted for formaldehyde, nonmethane organic gases (NMOG), methanol, carbon monoxide, and oxides of nitrogen emissions.

This paper covers work performed for the California Air Resources Board and US Environmental Protection Agency by Southwest Research Institute. Emission measurements were made on four in-use off-road two-stroke motorcycles and all-terrain vehicles utilizing oxygenated and non-oxygenated fuels. Emission data was produced to augment ARB and EPA's off-road emission inventory. It was intended that this program provide ARB and EPA with emission test results they require for atmospheric modeling. The paper describes the equipment and engines tested, test procedures, emissions sampling methodologies, and emissions analytical techniques. Fuels used in the study are described, along with the emissions characterization results. The fuel effects on exhaust emissions and operation due to ethanol content and fuel components is compared.

Gasohol, a blend of 90 percent unleaded gasoline and 10 percent ethanol, has been represented as an alternative to pure gasoline which can reduce the nation’s crude oil dependence. However, a systems analysis of the gasohol production processes indicates that gasohol is increasing rather than decreasing the nation’s dependence on crude oil. Alternative uses of the petroleum and natural gas currently used to manufacture ethanol would reduce the nation’s demand for oil. At the present time, every gallon of crude oil “saved” by substituting ethanol for gasoline results in a need to import approximately two gallons of crude oil. The federal government’s claim that gasohol can reduce the nation’s dependence on imported energy appears, to be based principally on political considerations, but also on the assumption that coal will eventually replace the petroleum and natural gas currently used in the gasohol production wherever possible.

Six laboratories capable of chassis-testing heavy-duty vehicles participated in a crosscheck program designed to compare emissions results from a Ford L-9000. The single-axle vehicle was shipped to each laboratory and tested through a series of UDDS and steady-state cycles. The resulting data were compared statistically using reproducibility and repeatability analyses. Although one lab produced some results that significantly differed from the other five, the remaining labs produced comparable results. TPM, CO and THC were the most variable while NOX and CO2 were most stable. Lab differences included atmospheric and environmental conditions, road-load curve application and drivers. Comparison of steady state and transient tests suggest that driver variability is not a major factor.

The sampling protocol proposed by the international PMP program for determination of particle emissions from clean light-duty vehicles was applied to the emissions from a California heavy-duty trap-equipped diesel truck. CARB is interested in developing opinions about the potential of this new European approach for emission determination and in exploring its utility for use in California. In this exercise, the use of various commercially available instruments for counting and sizing particles in the context of the PMP recommendations are explored. A single vehicle on a chassis dynamometer was exercised over steady-state and transient cycles. Multiple measurements of gaseous, mass, and particle emissions were collected in order to determine statistical significance. The PMP approach yielded particle emission measurements with higher precision and accuracy than the reference mass-based emission measurement.