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As the owner of the largest non-military vehicle fleet in the world, the United States Postal Service (USPS) has been a pioneer and a leader among all federal agencies in adopting alternative fuel initiatives, continuing to work in cooperation with the vehicle industry to develop new ways to reduce fuel consumption and air pollution. Given that hydrogen can be produced from a variety of energy sources, it is considered by most to be the ultimate energy carrier for relieving the U.S. of its dependence on imported oil. Hydrogen fuel cell vehicles operate via an electro-chemical process that converts pure hydrogen into water and electricity, producing zero emissions and potentially doubling the energy efficiency seen in today's gasoline-powered vehicles. This paper describes the USPS experiences gained during operational testing and evaluation of a hydrogen fuel cell vehicle at Fort Belvoir, Virginia.

Biodiesel has been used to reduce petroleum consumption and pollutant emissions. B20, a 20% blend of biodiesel with 80% petroleum diesel, has become the most common blend used in the United States. Little quantitative information is available on the impact of biodiesel on engine operating costs and durability. In this study, eight engines and fuel systems were removed from trucks that had operated on B20 or diesel, including four 1993 Ford cargo vans and four 1996 Mack tractors (two of each running on B20 and two on diesel). The engines and fuel system components were disassembled, inspected, and evaluated to compare wear characteristics after 4 years of operation and more than 600,000 miles accumulated on B20. The vehicle case history-including mileage accumulation, fuel use, and maintenance costs-was also documented. The results indicate that there was little difference that could be attributed to fuel in operational and maintenance costs between the B20- and diesel-fueled groups.

The United States Postal Service (USPS) operates the largest and most visible civilian vehicle fleet in the world. To accomplish its mission, the Postal Service must have dependable sources of fuel for its 208,000 vehicles. A fleet operation of that size must also constantly seek ways to reduce operating costs, and United States energy policy emphasizes the goal of reducing reliance on petroleum fuels in the highway sector. In furtherance of these goals and that of environmental protection, the USPS also operates the nation's largest fleet of alternative fuel vehicles. The USPS is committed to the continuing expansion of its alternative fuel vehicle (AFV) fleet and has assumed a strong leadership role in the development and deployment of alternative fuel vehicle technologies. This paper provides an overview of the Postal Service's current AFV program and its history.

The technical and economic feasibility of an electric postal delivery vehicle is demonstrated and reported in this paper. Vehicle operational data are collected in a deployment of six prototype electric Long-Life Vehicles (ELLV) at postal sites in Torrance, California and Merrifield, Virginia, beginning in April, 1995. Eight months of data have been collected and are analyzed Extensive design trade studies and analyses are conducted to demonstrate the feasibility of achieving the maximum cost effectiveness of the ELLV Operating costs of the ELLV are compared to its internal combustion engine (ICE) counterpart.

Compressed natural gas (CNG) is being increasingly used as an automotive fuel. This gas is stored in fuel cylinders at pressures up to 3600 psig to maximize the vehicle range. These cylinders must be inspected periodically; hydrostatically and/or visually, which requires removal of the cylinders from the vehicle. An alternative technique termed SLAM (for source location acoustic monitoring) has been used here to inspect cylinders in the US Postal Service fleet. The advantage of the SLAM technique is that the cylinders were inspected without removing them from the vehicles. The inspection was performed during refueling and resulted in minimal vehicle down time. The SLAM technique involves placing sensors on the cylinder surface and measuring the acoustic activity emanating from defects. The SLAM technique captures the total acoustic emission (AE) waveform, unlike other parameter based AE techniques that capture simple measures such as AE counts or hits.