Automakers and suppliers have experimented with a variety of materials in their pursuit of weight savings. Aluminum is a perfect example of incurring environmental debts elsewhere in the life cycle for potentially saving weight in the next model year. Smelting 1 ton of aluminum requires more electricity than the average American home uses in an entire year. These factors need to play a role in any comprehensive life cycle accounting but don't show up when the only consideration is weight.
If we're going to talk about the life cycle impacts of automotive materials, then it only makes sense to do so for steel. The North American steel industry has made extensive sustainability strides in recent years. Today's steel has lower energy use and CO2 emissions per ton than aluminum and magnesium, among other automotive materials.
Two recent peer-reviewed studies from the Steel Recycling Institute clearly illustrate that advanced high-strength steel-intensive vehicles had lower or equivalent life cycle emissions than aluminum-intensive vehicles for every class of vehicles tested — sedans, pickups, crossovers, SUVs and alternative powertrain vehicles. And that the use of advanced high-strength steel for large-scale automotive fleet lightweighting results in an immediate and sustained decrease in greenhouse gas emissions associated with production, use and recycling of automobiles, whereas the use of aluminum for lightweighting the same vehicles results in an increase in overall greenhouse gas emissions lasting for several decades.
This is the kind of comprehensive environmental accounting that will drive true sustainability for the automotive industry in the future.
We are encouraged to see the increasing awareness throughout the industry that it's time for automotive environmental accounting to require life cycle considerations and not just tailpipe benefits.