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Among on-road motor vehicles, diesel-fueled heavy-duty trucks emit disproportionately high amounts of oxides of nitrogen (NOx) and particulate matter (PM). The trucking industry has taken an active interest in the use of engines powered by liquefied natural gas (LNG) to reduce NOx and PM emissions. However, major barriers exist to widespread use of LNG in trucking applications, including reduced performance and higher initial capital costs compared to diesel-fueled vehicles, as well as a limited fueling infrastructure. To help address these barriers, the California Energy Commission (Commission) joined with the South Coast Air Quality Management District (SCAQMD) and the U.S. Department of Energy's National Renewable Energy Laboratory (DOE/NREL) in cost sharing a program led by the West Coast Transportation Technology Group of Arthur D. Little, Inc. (ADLittle).

Liquefied natural gas (LNG) use as a heavy-duty vehicle fuel is increasing. Current generation high-horsepower natural gas engines used in trucks and buses typically require fuel supply pressures in the range 75 to 120 psig. LNG delivered to the fueling station usually has a saturation pressure of roughly 10 psig. A variety of approaches may be used to provide the required fuel pressure increase. Each approach involves a different on-vehicle fuel system design, and LNG station capabilities must accommodate vehicle fuel system requirements. This paper describes various LNG vehicle fuel system design strategies including key tradeoffs, implications on station requirements, and developmental status. The most commonly used fuel system design receives and stores the LNG in the vehicle tank at a saturation pressure at least equal to the engine fuel supply pressure requirement.

The California Energy Commission is studying key fuel cell vehicle (FCV) infrastructure issues that need to be addressed in the next decade. This paper reports preliminary findings. A survey was conducted of industry experts on FCV technology status and related fuels. The survey includes information on leading FCV fuels, fuel production, quality, safety concerns, and other key areas. Findings indicate proton-exchange membrane FCVs are likely to be commercial by 2004, and likely fuels in the mid- and long-term include gasoline, methanol, natural gas and hydrogen. Conclusions are drawn and recommendations made to aid the state in preparing for this technology.

This paper surveys issues affecting the supply of fuel-grade methanol for the California Energy Commission's alternative fuels demonstration programs and operations by other public agencies such as transit and school districts. Establishing stable and reasonably priced sources of methanol (in particular) and of alternative fuels generally is essential to their demonstration and commercialization. Development both of vehicle technologies and of fuel supply and distribution are complementary and must proceed in parallel. However, the sequence of scaling up supply and distribution is not necessarily smooth; achievement of volume thresholds in demand and through-put of alternative fuels are marked by different kinds of challenges.

California's experience with fuel methanol holds lessons for infrastructure development efforts for other alternative fuels and suggests strategic approaches for developing future infrastructure to serve dedicated vehicles: 1. Vehicle/engine capability to utilize “dedicated” (neat) fuels in a fuel-flexible mode; this requires large investments to meet initially small markets. 2. “Strategic dispersal”, placing stations along primary transportation corridors and in “target areas” determined by proximity to alternative fuel fleets; adopted in the California Enery Commission's M85 network. 3. Massive infrastructure development effort, coupled with the financial depth to persist until fuel throughput reaches economically sustainable levels. This approach may be unstable if tied solely to the fortunes of a single company. 4. “Strategic concentration,” the development of a dense fueling network in delimited areas, allowing the incremental deployment of dedicated fuel vehicles.

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.

Neat methanol fuel (M100) has many advantages for achieving low emission levels as an automotive fuel, but there are several items that require attention before this fuel can replace conventional fuels. One item involves the low flame luminosity of methanol. An extensive literature search and laboratory evaluation were conducted to identify potential additive candidates to improve the luminosity of a methanol flame. Potential compounds were screened based on their concentration, luminosity improvement, and duration of luminosity improvement during the burn. Three compounds were found to increase the flame luminosity for segments of the burn at relatively low concentrations: toluene, cyclopentene, and indan. In combination, these three compounds markedly improved the luminosity of methanol throughout the majority of the burn. The two combinations were 1) 4 percent toluene plus 2 percent indan and 2) 5 percent cyclopentene plus 5 percent indan in methanol.

Possible fuel efficiency improvements of light-duty methanol engines are reviewed in comparison to gasoline engines. This comparison outlines improvements resulting from differences in fuel properties and engine configurations. Methanol engines evaluated included those with higher compression and those using lean-burn, stratified charge. Higher compression yields about a 10 percent improvement over gasoline engines. Lean-burn concepts result in 13 percent increases over gasoline engines operated stoichiometrically. Fuel economy for the California dedicated methanol fleet is evaluated and compared to existing baseline gasoline fuel economy. Data for both carburetted and fuel-injected 1983 Ford Escorts are presented. Fuel economy for the carburetted vehicles used in a variety of fleets ranged from 20.9 to 26.0 mpg on a gasoline equivalent basis.

Emission control options for heavy-duty engines are evaluated for meeting the recently promulgated NOX and particulate standards. Particulate options to meet these standards are evaluated in terms of emissions reduction, cost, and cost effectiveness. Control options include particulate trap, clean diesel fuel (low sulfur, low arontatics), methanol, and gasoline. The cost effectiveness for particulate control range from $3,000/ton to over $18,000/ton. These costs, however, are lower than many stationary measures.

This paper presents forecasts of future California car and truck fuel demand based on projected economic, demographic, and technologic variables. Vehicle stocks and sales are predicted based on changes of these variables. The paper presents several different cases of market-induced, technical fuel economy improvements. Increased fuel efficiency is projected to reduce fuel demand despite growth in income, population, and vehicle miles traveled. Implementation of relatively inexpensive, post-1985 fuel economy improvements is forecast to reduce 2002 fuel demand 9 percent from 1982 levels, assuming a fuel price escalation rate of 3 percent above inflation. An additional 7 percent reduction appears feasible through refinements in existing technology.