Aluminum Better than Steel for Automobiles on a Full Lifecycle CO2 Basis

Opting for aluminum over steel in new automobile construction to improve fuel economy is also the best way to reduce energy consumption and carbon emissions, according to a new study by the United States Department of Energy’s Oak Ridge National Laboratory (ORNL).

“As the U.S. works to reduce dependence on foreign oil, promote clean energy and combat climate change, this report definitively documents why aluminum offers the most promise for cutting total automotive-related carbon emissions and energy use,” said ORNL’s Sujit Das, a widely respected expert on product lifecycle assessments.

“This study adds even more evidence that switching car bodies from steel to aluminum is the next logical step for car makers to take in the drive to reduce emissions,” said Randall Scheps, chairman of the Aluminum Association’s Transportation Group (ATG) and automotive marketing director for Alcoa, Inc. “There is already ample evidence that aluminum is a safe, durable and cost effective material for car bodies. Now ORNL has shown that aluminum is better than steel on a full lifecycle CO₂ basis. That is the icing on the cake.”

Highlights from the ORNL study include:

• Reducing vehicle weight with aluminum can result in the lowest total vehicle lifecycle environmental impact – cradle-to-grave – as compared to both traditional and advanced steels.
• An aluminum-intensive vehicle can achieve up to a 32 percent reduction in total lifecycle energy consumption, and up to a 29 percent reduction in CO₂ emissions, compared to a typical vehicle on the road today which uses traditional and high-strength steel in the body construction.
• While a lightweight steel vehicle has a lower production phase environmental impact, those initial gains are erased by higher energy use and carbon emissions during the steel vehicle’s use phase.
• More than 90 percent of automobile energy consumption and carbon emissions occurs during the vehicle’s use phase, with the mining, production and manufacturing phases accounting for just 10 percent or less.
• For an aluminum intensive vehicle, the breakeven point in its use phase for making up the energy consumed during the initial production phase is 9,300 miles – of which most automobiles on U.S. roads would reach in their first year of operation.

The ORNL study modeled a typical 2012 crossover SUV reflective of the average on-the-road vehicle in the U.S. in terms of weight, performance, fuel economy and materials mix of steel, high-strength steel and aluminum. Building on an earlier crossover SUV study by the United States Environmental Protection Agency (Light-Duty Vehicle Mass Reduction and Cost Analysis — Midsize Crossover Utility Vehicle, Aug 2012), ORNL researchers analyzed a baseline SUV (a comprehensive mix of mild and high- strength steel), a lightweight steel vehicle (optimized for maximum use of high-strength and advanced high-strength steel), and a lightweight aluminum intensive vehicle (including currently available body, doors, trunk and hood applications).

“The ORNL environmental report is timely as there is an increasingly loud aluminum buzz in the auto industry right now – and with good reason. Automakers are projecting to double aluminum use within less than a decade as high-volume, all aluminum vehicles move from design studios to showrooms in the not-too-distant future. We already knew aluminum offers great fuel economy, safety and performance advantages, and now it’s proven to be best positioned to cut greenhouse gasses and save energy too,” said Scheps.

The modeling for this study conforms to internationally recognized standard practices (ISO 14040 and 14044). Comparative data sets used in the study were provided directly to ORNL researchers by the U.S. steel and aluminum industries respectively, both sets of which are current, peer-reviewed and publicly available. The Aluminum Association underwrote the effort.

The ORNL study is consistent with an earlier independent study by the magnesium industry which also concluded that aluminum has the smallest carbon footprint of competing materials when examining total lifecycle CO₂ emissions. In addition:

• Using aluminum to reduce vehicle weight across the world’s overall transportation fleet can reduce greenhouse gas emissions by 660 million tons annually, representing 9 percent of transportation-related emissions.
• Recycling aluminum saves 95 percent of the greenhouse gas emissions associated with primary aluminum production, and requires only 5 percent of the energy.
• Nearly 90 percent of automotive aluminum is recovered and recycled.
• Aluminum is infinitely recyclable without degradation to the material.

For access to the full study, facts, and other research about how aluminum builds a better vehicle, visit www.drivealuminum.org, and follow us on Twitter @DriveAluminum.

About Oak Ridge National Laboratory

UT-Battelle manages ORNL for DOE's Office of Science. The Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, please visit http://science.energy.gov/.