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Federal standards that mandate improved fuel economy have resulted in the increased use of lightweight materials in automotive applications. However, the environmental burdens associated with a product extend well beyond the use phase. Life cycle assessment is the science of determining the environmental burdens associated with the entire life cycle of a given product from cradle-to-grave. This report documents the environmental burdens associated with every phase of the life cycle of two fuel tanks utilized in full-sized 1996 GM vans. These vans are manufactured in two configurations, one which utilizes a steel fuel tank, and the other a multi-layered plastic fuel tank consisting primarily of high density polyethylene (HDPE). This study was a collaborative effort between GM and the University of Michigan's National Pollution Prevention Center, which received funding from EPA's National Risk Management Research Laboratory.

A life cycle inventory (LCI) study evaluates the environmental performance of the ULSAB-AVC (UltraLight Steel Auto Body - Advanced Vehicle Concepts) vehicle product system. The LCI quantifies the inputs and outputs of each life cycle stage of the ULSAB-AVC PNGV-gas engine vehicle (998 kg) over the 193,000 km service lifetime of the vehicle. The use phase of the ULSAB-AVC PNGV-diesel engine variant (1031 kg) is also quantified. The data categories measured for each life cycle phase include resource and energy consumption, air and water pollutant emissions, and solid waste production. The ULSAB-AVC LCI study is based on the methods, model and data from the 1999 study by the United States Automotive Materials Partnership (USAMP), a consortium within the United States Council for Automotive Research. This model was modified to represent the ULSAB-AVC PNGV-gas engine vehicle for each life cycle phase as well as the use phase of the PNGV-diesel engine variant.

Sampling and analysis methods for unregulated exhaust constituents are discussed. Emission results for more than fifteen exhaust constituents from both gasoline- and diesel-powered automobiles are presented. It is shown that the catalytic converter substantially lowers the emission rates of aldehydes, benzene, benzo(a)-pyrene, hydrogen cyanide, and nitrogen dioxide. However, under certain rich-malfunction conditions, small increases in hydrogen sulfide, carbonyl sulfide, hydrogen cyanide, and ammonia occur. Particulate emissions are the primary concern for diesels since other unregulated emissions occur at the same low levels as from gasoline-powered vehicles. It is concluded that although steady improvements in chemical analysis technology have led to the detection of more and more minor impurities in exhaust, none of these substances are emitted at concentrations that can be considered dangerous.

Reports published by Gulf R&D Co. and Battelle Columbus Laboratories under contract to the Coordinating Research Council's APRAC project group CAPE-24 were reviewed. Both studies failed to verify the accuracy of polynuclear aromatic hydrocarbon (PNA) emission measurements from heavy-duty diesel engines. Thermal decomposition and chemical reactions of the PNA occur in raw exhaust at temperatures above 500°F. Therefore, pipes which transfer exhaust to dilution tunnels can significantly reduce the apparent emission values. Dilution tunnel conditions have comparatively little effect on PNA measurements. However, vapor traps are required behind particle filters to assure complete collection of 4-ring PNA compounds. Guidelines are presented for controlling and testing sampling systems for accurate PNA emission measurements.