Lightweighting vehicles to improve fuel economy remains the driving force in the design and application of metals and other materials in the automotive industry. But the environmental burden imposed through the entire lifecycle of materials—from manufacturing to use and recovery—is a growing concern for industry as governments across the globe impose stricter regulations to better control and reduce greenhouse gas emissions.
The lightweighting trend itself is unstoppable, especially as small vehicles are desired in many regions of the world, fast-growing emerging economies are creating a middle class that wants to own vehicles, and materials must now be fashioned to handle new fuel sources, such as plug-in batteries.
The steel, aluminum and copper industries all say that the content of each of these metals entering service in a brand-new vehicle typically has already been recycled, thus creating very little emissions in the manufacturing process; is made to last the life of the vehicle without needing replacement; and is virtually 100-percent recyclable when the vehicle is scrapped.
Copper content in North American vehicles ranges from 55 to 68 pounds, according to a market study conducted by the Copper Development Association (CDA), New York. Forecasting that hybrid electric/gasoline-powered vehicles will make up 4 to 6 percent of all vehicles on North American roads within two years, the study estimated that hybrids "will use almost twice as much copper as traditional 14-volt (battery) vehicles," according to Bob Weed, vice president of the CDA's original equipment manufacturing section.
Apart from the needs created by a battery-operated vehicle, the increasing amount of standard electronics—from global positioning satellite (GPS) devices and video screens to iPhone docking stations—all require more wiring.
"Our studies show that the copper content of vehicles is increasing, primarily due to the increase of electrical and electronic components. (That) includes the connectors and terminal components as well as wiring," Weed said.
Aluminum's strength in the lifecycle of automotive materials comes in the use phase, according to Doug Richman, vice president of engineering and technology at Kaiser Aluminum Corp., Foothill Ranch, Calif.
Aluminum production "uses more energy and generates up to three times more CO2 (carbon dioxide) than to create virgin steel, but in the use phase that deficit is now offset," he acknowledged. "In 18 months, the vehicle is breakeven in terms of greenhouse gas savings, and from then on there is a net savings for the rest of the vehicle's life up to 14 years"—the average age of a vehicle when it is scrapped.
Although they perform well in the use phase because they are so light, materials such as magnesium, plastics and composites like carbon fiber perform less well in lifecycle comparisons, Richman said. With magnesium, according to researchers at General Motors Co. and Chrysler Group LLC, one "must drive 80,000 miles before breaking even on CO2 emissions and energy usage," Richman said.
Magnesium recycling rates grew to 53 percent of apparent supply in 2008 from 40 percent in 2004, according to the latest data available from the U.S. Geological Survey.
Approximately 95 percent of all aluminum in a scrapped vehicle is recycled and about 60 percent of the aluminum that goes into making a new car is secondary material, Richman said, noting that melting secondary aluminum uses only 5 percent of the energy needed when smelting new aluminum.
"Right now, folks are paying more attention to the sustainability of vehicle content," said Ron Krupitzer, vice president of automotive applications at the Steel Market Development Institute (SMDI), a division of the American Iron and Steel Institute.
Metal manufacturers and converters have become more focused on sustainability primarily for sound economic reasons—the more metal recovered, the less raw material has to be mined and melted—but also for the sake of environmental stewardship. "The EPA is interested in our carbon footprint," he said.
Steel accounts for 60 to 65 percent of the average North American vehicle's content today, up from about 55 percent 15 years ago, which Krupitzer attributes to the wider application of high-strength lightweight steels. There continues to be even more pressure, he said, "on mass reduction and continued work on strengthening methods and lightweighting."
Krupitzer firmly believes that lighter but highly engineered vehicles are the future and that lightweight high-strength steels will take an even greater share of vehicle content.
"Our basic thinking on lifecycle is simple In making a car, if we reduce the amount of steel by using high-strength steel we reduce carbon and greenhouse gas emissions in making the steel, and the car uses less gasoline, so we're creating lower emissions there," he said. "At the end of the vehicle's life, every pound of steel is recovered and reused. The average recycling rate—pounds retrieved through scrapping and dismantling and remelting of material—is 100 percent, equal to the new steel going into vehicles every year."
The economics of the recycling business "determine the way end-of-life vehicles are processed in the United States," Weed said. Automakers are working on cost-effective solutions that will improve the recycling rates for junked cars and trucks. "Dismantlers are removing those components for which commodity prices make separate processing economical. Similarly, shredding companies choose their technologies to maximize the amount of copper recycled, which also has a positive effect on their revenues," he said.
"The engine that drives recycling in the automotive market is steel," Krupitzer said. "If there weren't a market to retrieve steel, the other metals couldn't be recovered economically."