Automobile recycling in the United States: Energy impacts and waste generation

摘要

Changes in the trends in the material composition of domestic and imported automobiles and the increasing cost of landfilling the non-recyclable portion of automobiles (automobile shredder residue or ASR) pose questions about the future of automobile recycling in the United States. In response to these challenges, new and innovative approaches to automobile recycling are being developed. This paper presents the findings of a recent study to examine the impacts of these changes on the life cycle energy consumption of automobiles and on the quantity of waste that must be disposed of. Given the recycle status quo, trends in material composition and the viability of recycling the non-metallic components of the typical automobile are of secondary importance when compared to the energy consumed during the life of the automobile. The energy savings resulting from small changes in the fuel efficiency of a vehicle overshadow potential energy losses associated with the adoption of new and possibly non-recyclable materials. Under status quo conditions, the life cycle energy consumed by the typical automobile is projected to decrease from 599 million Btus in 1992 to 565 million Btus in 2000. Energy consumed during the manufacture of the typical car will increase from about 120 to 140 million Btus between 1992 and 2000, while energy used during vehicle operation will decrease from 520 to 480 million Btus. This study projects that energy saved at the recycle step will increase from 41 million Btus in 1992 to 55 million Btus in 2000. This study also investigated the energy impacts of several potential changes to the recycle status quo, including the adoption of technologies to retrieve the heat value of ASR by incineration and the recycle of some or all thermoplastics in the typical automobile. The study estimates that under optimistic conditions —i.e., the recycling of all thermoplastics and the incineration with heat recovery of all remaining ASR —about 8 million Btus could be saved per automobile —i.e., an increase from about 55 to 63 million Btus. In the more realistic scenario —i.e., the recycling of easy-to-remove thermoplastic components (bumper covers and dash-boards) —the potential energy savings are about 1 million Btus per vehicle. It is estimated that the annual quantity of ASR in the United States could be reduced from about 5 billion pounds to as little as 1 billion pounds of ash if all ASR is incinerated. Alternatively, ASR quantity could be reduced to about 4 billion pounds if all thermoplastics in automobiles are recycled. However, in the case of recycling only thermoplastic bumper covers and dashboards, the quantity of ASR would be reduced by only 0.2 billion pounds. A significant reduction or increase in the size of the ASR waste stream will not in itself have a large impact on the solid waste stream in the United States.