A LIFE-CYCLE MODEL OF AN AUTOMOBILE

The environmental and energy implications of a midsized automobile wer e assessed by performing a life-cycle inventory analysis that emphasiz ed manufacture and use phases. An Economic Input-Output Life-Cycle Ana lysis model was used that produces a large array of indicators of the effects of a product or service on the economy and the environment. Th e analysis corroborates two previous studies that used the conventiona l life-cycle analysis model developed by the Society for Environmental Toxicology and Chemistry (SETAC) (1,2) and EPA (3). The use phase ia more important than the manufacture and disposal phases in terms of en ergy use and environmental discharges. Automobile service is comparabl e to the fuel cycle in terms of discharges of toxic substances. In con trast to a Volkswagen study, tailpipe exhaust and evaporative emission s of hydrocarbons (HC)/volatile organic compounds (VOCs), nitrogen oxi des (NOx), and particulate matter are greater than emissions upstream in the fuel cycle. This difference apparently arises from using on-roa d tailpipe emissions data, rather than emissions data from laboratory tests. The Economic Input-Output model is found useful for quantifying the range of implications of decisions concerning manufacture and use .