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Life cycle assessment of automotive lightweighting through polymers under US boundary conditions

The International Journal of Life Cycle Assessment volume 19, pages 538–545 (2014)Cite this article

Abstract

Purpose

In the transportation sector, reducing vehicle weight is a cornerstone strategy to improve the fuel economy and energy efficiency of road vehicles. This study investigated the environmental implications of lightweighting two automotive parts (Ford Taurus front end bolster, Chevrolet Trailblazer/GMC Envoy assist step) using glass-fiber reinforced polymers (GFRP) instead of steel alloys.

Methods

The cradle-to-grave life cycle assessments (LCAs) for these studies consider a total service life of 150,000 miles for two applications: a 46 % lighter GFRP bolster on the 2010 Ford Taurus that replaced the 2008 steel and GFRP bolster, and a 51 % lighter GFRP running board for the 2007 Chevrolet Trailblazer/GMC Envoy that replaced the previous steel running board including its polymer fasteners. The life cycle stages in these critically reviewed and ISO-compliant LCA studies include the production of upstream materials and energy, product manufacturing, use, and the end-of-life treatment for all materials throughout the life cycle.

Results and discussion

The results show that the lighter GFRP products performed better than the steel products for global warming potential and primary energy demand for both case studies. In addition, the GFRP bolster performed better for acidification potential. The savings of fuel combustion and production during the use stage of a vehicle far outweigh the environmental impacts of manufacturing or end-of-life. An even greater benefit would be possible if the total weight reduction in the vehicle would be high enough to allow for the reduction of engine displacement or an elongation of gear ratio while maintaining constant vehicle dynamics. These so-called secondary measures allow the fuel savings per unit of mass to be more than doubled and are able to offset the slightly higher acidification potential of the GFRP running board which occurs when only the mass-induced fuel savings are considered.

Conclusions

The lightweight GFRP components are shown to outperform their steel counterparts over the full life cycle mainly due to the reduced fuel consumption of the vehicle in the use phase. To harvest the benefits of light weighting to their full extent, it is recommended that the sum of all mass reductions in the design process be monitored and, whenever feasible, invested into fuel economy by adapting the drive train while maintaining constant vehicle performance rather than leveraging the weight reduction to improve vehicle dynamics.

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Notes

  1. For comparison, note that the average distance from the earth to the moon is 238,855 miles (NASA 2012)

  2. The Value-of-Scrap is the difference of a hypothetical 100 % primary BOF (without any scrap inputs) and a 100 % secondary EAF and accounts for the EAF recycling efficiency. Note that all scrap inputs into manufacturing are also assigned a burden using the same worldsteel inventory to avoid double-counting.

  3. (55 % × 11.04 miles + 45 % × 10.26 miles)

  4. (55 % × 25 % + 45 % × 8 %)

  5. Please refer to http://plastics.americanchemistry.com/Education-Resources/Publications/ for details.

  6. This applies likewise to eutrophication potential and smog formation potential (not shown).

  7. Based on total CO2e savings converted to gallons of gasoline using a C content of 0.855 kg C/kg and a density of 0.735 kg/l.

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Authors and Affiliations

  1. PE INTERNATIONAL, Inc., 344 Boylston Street, Boston, MA, 02116, USA

    Christoph Koffler

Authors
  1. Christoph Koffler
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Corresponding author

Correspondence to Christoph Koffler.

Additional information

Responsible editor: Wulf-Peter Schmidt

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Cite this article

Koffler, C. Life cycle assessment of automotive lightweighting through polymers under US boundary conditions. Int J Life Cycle Assess 19, 538–545 (2014). https://doi.org/10.1007/s11367-013-0652-7

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  • DOI: https://doi.org/10.1007/s11367-013-0652-7

Keywords

  • Automotive
  • Design for environment
  • Fuel economy
  • Glass-fiber reinforced polymers
  • Life cycle assessment
  • Lightweighting