Duty Vehicles

In addition to very low exhaust emissions, CNG vehicles also have the advantage of no evaporative emissions or running loss emissions9 caused by the fuel. As vehicle exhaust emissions are reduced to meet the most stringent standards, running loss emissions become more important. 

9 Running loss emissions are emissions from the fuel tank during vehicle operation due to heating of the fuel, losses from the evaporative canister, or losses due to permeation of fuel through elastomeric fuel lines. 

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The sum of the downstream costs adds roughly 7.9 cents per Hter (300/gal) and the adjustment of the final cost for an amount of methanol fuel equivalent ia distance driven to an equal volume gasoline involves a multiplier ranging from 1.6 to 2.0, depending on fuel specification and the assumed efficiency for methanol light-duty vehicles as compared to gasoline vehicles. The California Advisory Board has undertaken such cost assessment (11). 

Dedicated Vehicles. Only Brazil and California have continued implementing alcohols in the transportation sector. The BraziUan program, the largest alternative fuel program in the world, used about 7.5% of oil equivalent of ethanol in 1987 (equivalent to 150,000 bbl of cmde oil per day). In 1987 about 4 million vehicles operated on 100% ethanol and 94% of all new vehicles purchased that year were ethanol-fueled. About 25% of Brazil s light-duty vehicle fleet (10) operate on alcohol. The leading BraziUan OEMs are Autolatina (a joint venture of Volkswagen and Ford), GM, and Fiat. Vehicles are manufactured and marketed in Brazil. 

Table 8. California Light-Duty Vehicle Exhaust Emission Standards...

Data from twenty 1989 light-duty vehicles. 

Technical Support Document Revisions to the Malfunction and Diagnostic System Requirements Applicable to 1994 and later New California Passanger Cars, Eight-Duty Trucks, andMedium Duty Vehicles with Feedback Fuel Control Systems (OBD-II), California Air Resources Board, Sacramento, Sept. 14,1989. 

State of California Air Resource Board, California Fuel Evaporative Emissions Standard and Test Procedure for 1970 Model Light Duty Vehicles, April 16, 1968. 

Light-Duty Vehicles and Light -Duty Trucks, Federal Register, Vol. 59, No. 66, April 6, 1994. 

Darrow, K.G., Idght Duty Vehicle Full Fuel Cycle Emissions Analysis Topical Report, Gas Research Institute Report GRI-93/0472 (1994)... 

Borrom-Bird, C. E. (1996). Fuel Cell Commercialization Issues for Light-Duty Vehicle Applications." JournsI of Power Sources 61 33 8. 

Federal Emission Control Requirements for Light-Duty Vehicles... 

SCR for heavy-duty vehicles reduces NOx emissions by 80%, HC emissions by 90% and PM emissions by 40% in the EU test cycles, using current diesel fuel (<350 ppm sulphur) [27], Fleet tests with SCR technology show excellent NOx reduction performance for more than 500000 km of truck operation. This experience is based on over 6 000 000 km of accumulated commercial fleet operation [82], The combination of SCR with a pre-oxidation catalyst, a hydrolysis catalyst and an oxidation catalyst enables higher NOx reduction under low-load and low-temperature conditions [83],... 

Just a few words to explain that in EuroV is that the clean-up strategy adopted by heavy-duty vehicles differs from that chosen by passenger cars. The heavy-duty vehicles have decided to reduce the engine-out particles emission levels and to treat the NOx released in the exhaust line by adopting the SCR-NH3 system. 

The second DeNOx technology, the selective catalytic reduction with ammonia (SCR-NH3) commercially available in heavy-duty vehicles since 2006, seems to present an interesting potential in terms of efficiency, reliability, HC penalties, etc. 

The urea distribution network in Europe, around year 2006, would be limited to one distribution point for a 500 km radius area (heavy-duty vehicles compatibility - data to be checked and actualized), and would not allow a co-fueling strategy whose interests are the simultaneous fuel/urea filling up at the service-station and the minimization of the urea tank volume. Today, it is difficult to anticipate the consequences of EuroV. 

Presently the catalytic selective NOx reduction by ammonia is efficient and widespread through the world for stationary sources. The remarkable beneficial effect of 02 for the complete reduction of NO into nitrogen is usually observed between 200 and 400°C. However, such a technology is not applicable for mobile sources due to the toxicity of ammonia and vanadium, which composes the active phase in vanadia-titania-based catalysts. Main drawbacks related to storing and handling of ammonia as well as changes in the load composition with subsequent ammonia slip considerably affect the reliability of such a process. On the other hand, the use of urea for heavy-duty vehicles is of interest with the in situ formation of ammonia. 

Burke, A.F. and Gardiner, M. Hydrogen Storage Options Technologies and Comparisons for Light-duty Vehicle Applications, Research Report UCD-ITS-RR-05-01, Institute of Transportation Studies, University of California, Davis, 2005. 

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