Aluminum has been a critical material that let the auto industry meet fuel economy and emissions regulations for decades, and its usage is expected to continue growing as tighter regulations take hold. Its light weight provides significant benefits in improving fuel economy, augmenting the environmental impact that comes when aluminum parts are recycled.
“Aluminum has a great story to tell for environmental issues," said Lloyd “Buddy” Stemple, General Manager at Novelis Specialty Products Group. Stemple’s keynote address at ET ’08, a conference for extrusion technology experts that is held every four years, detailed aluminum’s role in meeting environmental requirements.
Transportation is a key market for aluminum, consuming nearly a third of aluminum used in manufactured goods. The auto industry has a very good record for recovering material for recycling, retrieving roughly 90% when vehicles end their lifetimes. While aluminum in vehicles accounts for only 5 to 10% of the scrap by weight, it represents between 30 and 50% of its scrap value.
Automakers also make extensive use of recycled aluminum. In North America, 57% of the aluminum comes from recycled material. That is below the 63% in Japan but above the 50% of recycled aluminum used in Europe’s cars.
Recycling is not the only way aluminum helps. Most of the emissions and energy consumed over a car’s lifetime comes from the fuel it burns on roadways, not from manufacturing and dismantling. Aluminum’s light weight is making it a more important material in the drive to create more fuel-efficient vehicles.
“In 1973, the average car had 81 lb of aluminum. In 2007, it had 320 lb. Lightweighting through the use of aluminum must be part of the solution going forward as companies strive to meet more stringent regulations," Stemple said.
That's because aluminum is far lighter than the material it routinely replaces. “In the best case, a 50% improvement over steel parts can be achieved," Stemple said.
When a vehicle’s steel body is replaced with aluminum parts, overall weight loss can be greater than the savings from aluminum alone. That’s because engines can be slightly smaller without sacrificing performance.
“One aluminum body went to 649 lb, a 396-lb decrease compared to steel. When they downsized the engine accordingly, they saved a total of 487 lb," Stemple said. Over the vehicle’s lifetime, it will consume far less fuel than the heavier version, he added.
Stemple noted that since 1990, the increased use of automotive aluminum has saved more than 22.2 billion gal (84 billion L) of fuel, according to Energy Information Administration statistics. That is nearly equal to the amount of oil that the U.S. imported from Saudi Arabia in 2007.
These benefits will continue to compound in the years ahead. Using aluminum in cars and light trucks produced in 2006 alone will reduce CO2 emissions by approximately 140 million ton (127 million t) and save 14.5 billion gal (55 billion L) of crude oil over these vehicles’ life cycles.
Lighter weight does not necessarily mean less safety. “It’s a myth that heavier vehicles are safer. Size, not weight, makes vehicles safer. Aluminum can extend crush zones while lowering weight. Aluminum can be designed to fold predictably," Stemple said.
He also noted that recyclability makes aluminum a cradle-to-cradle material, not a cradle-to-grave material. Aluminum has long been one of the most recycled materials, making it quite sustainable. Since Americans first started mining and using aluminum in 1888, a full 73% of the material is still in use, according to Stemple.
Last year, 5 million ton (4.5 million t) of aluminum were recycled. Recycling 1 ton (0.9 t) of aluminum conserves up to 5 ton (4.5 t) of bauxite ore and 14 MW·h of electricity.