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A 1979 8V-71 model DDC two-stroke diesel transit bus engine was tested using ignition-improved methanol and ethanol. The testing was conducted using the Environmental Protection Agency heavy duty engine transient test procedure. The methanol and ethanol fuels were found to have very similar combustion characteristics and required the same percentage of ignition improver (7.5 volume percent) to obtain similar peak cylinder pressures and rates of pressure rise as were observed using diesel fuel. Emissions increased rapidly as the percentage of ignition improver was reduced below the optimum determined. Ignition-improved methanol and ethanol can greatly reduce fuel-produced particulate emissions with the trade-off of a small increase in total unburned fuel emissions. Carbon monoxide emissions were found to be dependent on stoichiometry only and not fuel type.

The Maryland Mass Transit Administration (MTA) is demonstrating the use of liquefied natural gas (LNG) as a cost-effective and low emission transit bus fuel. The potential advantages of LNG as a transit bus fuel relative to using compressed natural gas (CNG) include lower fuel system weight, smaller volume required for the fuel system components, shorter time required for refueling and lower refueling facility cost, more uniform and higher fuel quality, and less demand on utility gas line flow limits. The LNG storage and dispensing system must be engineered in conjunction with the LNG fuel system on the bus to achieve fast, reliable and safe refueling. This paper describes the LNG storage and dispensing system designed and built to support the Maryland MTA demonstration of LNG transit buses.

The New York State Energy Research and Development Authority (NYSERDA), under its Alternative Fuels for Vehicles Fleet Demonstration Program (AFV-FDP), monitored the operation of 31 compressed natural gas (CNG) transit buses divided among five transit properties in New York State. The CNG buses were delivered in 1992 and have accumulated over 3.73 million kilometers (2.32 million miles) of operation through September 1995. Data collected included fuel consumption, maintenance histories, acceleration, driveability, and emissions. Several of these buses experienced problems with defective pressure relief valves though no accidents resulted from these failures. During the period of operation, various upgrades and learning experiences have contributed to improved operations and lower emissions, though variations in emissions were observed due to drift in fuel system calibration.

The New York State Energy Research and Development Authority (NYSERDA), under its Alternative Fuels for Vehicles Fleet Demonstration Program (AFV-FDP), established a demonstration of light-duty dedicated propane vehicles operated by the New York State Office of Parks, Recreation and Historic Preservation (OPRHP). The fleet of five converted trucks began operation in 1993 with the cooperation of the New York Propane Gas Association, which provided the propane systems, and Texaco Research & Development which funded annual emissions testing. The vehicles accumulated 122,000 kilometers (76,000 miles) of operation on propane during the demonstration. Data were collected on fuel consumption, driveability, acceleration, maintenance, and emissions. This paper reports on the transition to propane fuel operations, the findings of the emissions tests, and the service and support experiences during the demonstration.

The New York State Energy Research and Development Authority (NYSERDA), under its Alternative Fuels for Vehicles Fleet Demonstration Program (AFV-FDP), established a number of light-duty CNG vehicle fleet demonstrations throughout New York State to collect data from CNG vehicle operation. The majority of the vehicles were converted from gasoline operation to bifuel1 operation, though dedicated CNG vehicles (new and converted) were also included. Pickups, vans, station wagons, and sport utility vehicles were all represented. The vehicles were tracked for mileage accumulation and service experience, and emissions were measured using the Federal Test Procedure. The types of CNG fuel system technologies represented were mechanical open-loop (MOL), mechanical closed-loop (MCL), electronic single-point injection closed-loop (ESPCL), and electronic multipoint injection closed-loop (EMPCL).

This project demonstrates the use of M85 as an alternative fuel for vehicle operation. The fleets chosen for this demonstration experienced driving conditions typical for most vehicles, i.e., interstate highways and suburban traffic. Four generations of flexible fuel vehicles (FFVs), the 1986 and 1989 Ford Crown Victoria and the 1991 and 1993 Ford Taurus, were used in individual fleet operation. The demonstration spanned a period of over seven years from 1988 through 1995 and approximately 220 vehicle-years of M85 FFV operational data were collected. These data were analyzed to create a comprehensive knowledge base for fuel economy, emissions, driveability, acceleration, maintenance and wear characteristics of FFVs. A comparison of the overall performance of these vehicles with conventional gasoline vehicles was made. Important experience in the design, construction and maintenance of M85 refueling facilities was obtained over the duration of this project.

The Maryland Mass Transit Administration conducted an LNG transit bus demonstration in Baltimore, Maryland. A refueling facility was constructed and maintenance facilities were modified to provide support for the demonstration. During the demonstration operational data were collected on the buses and facilities. Problems encountered with the vehicle LNG fuel systems are reviewed and discussed. This paper summarizes the findings and operation of the LNG fleet during the demonstration and projects future LNG vehicle and operational costs.

With more and more fleet vehicles being converted to compressed natural gas operation, concerns have arisen about the safety of their fuel systems and the need for regulations to ensure safe operation. The potential for widespread operation of vehicles using compressed natural gas adds urgency to these concerns. Most of the safety concerns revolve around the high-pressure storage and fuel lines present in existing systems. Specific items in question are: the need for high-pressure automatic fuel cutoff switches, vehicle disablement during refueling, the need for methane sensors, cylinder specifications and venting requirements, location of refueling points, and system crash-worthiness. This paper examines these concerns.

The natural gas fuel delivery infrastructure required to support a fleet of vehicles large enough to displace 2 million bbl/day of petroleum consumption was estimated. The number and types of vehicles required to use this amount of natural gas was defined based on operational characteristics and technical feasibility. Existing natural gas pipeline and storage capacity was assessed and additions estimated. Natural gas refueling stations to serve the natural gas vehicles defined were estimated. The total cost of the natural gas infrastructure additions was estimated. The institutional and infrastructural barriers to widespread use of natural gas were identified and lead times to overcome them were estimated.