Consequential Life Cycle Assessment (CLCA) of Replacing Steel with Aluminum in North American Light Vehicles

Vehicle Production and use Emit Greenhouse Gases (GHGs)

Lightweight Materials Cause Greenhouse Gas Trade-Off

Standard Approach: Attributional Life Cycle Assessment

Shortcomings of such GHG accounting:

• How to account for metal recycling

• Timing of emissions

• Fleet effects

• How to model consequences of material substitution

(Better) Alternative: Consequential Life Cycle Assessment

Starting Point: Assumed Aluminum Additions to North American Light Vehicle Production

Summary

• Consequential LCAs of automotive material substitution are feasible and insightful

• Results of presented study are still preliminary (need to select probable scenarios from all plausible ones)

• Replacing automotive steel with aluminum will always lead to an initial increase in GHG emissions

• When GHG payback is achieved (an whether) depends on the assumptions in the model, the most important of which are:

• GHG intensity of aluminum production

• GHG consequences of large increase in automotive aluminum scrap