The US auto industry’s shift toward lighter weight vehicles through greater use of aluminium is now in high gear with 2015 pick-up trucks rolling into dealer showrooms sporting as much as 350 pounds more of the metal than last year.

Automakers are racing to satisfy new 54.5mpg corporate average fuel-efficiency (CAFE) targets for 2025. Automobile manufacturers report plans to use more aluminium in doors, hoods and other parts beginning in the next few years, including plans for aluminium-bodied pickups. There has been a global surplus of aluminium the past nine years, but the shift raises questions about supply. In the near term, demand is projected to grow at an average annual rate of almost 6% a year through 2018.

“The more aluminium that is recycled, the better the aluminium supply picture, especially in the near term, while the industry waits for new primary production to come on stream,” says Tony Palermo, program manager, metallurgy, for Linde LLC in North America. Linde LLC is a member of The Linde Group, a leading global industrial gases and engineering company, which offers proprietary oxyfuel heating technology that can help improve the productivity and energy efficiency of aluminium production from recycled feedstock sources that will be increasingly critical to meet burgeoning demand.  

Aluminium is about one-third lighter than steel, but costs about 2-3 times as much per pound. Yet a 10% reduction in weight means about a 7% improvement in fuel economy for the life of the average vehicle. Initial raw material costs are less important on vehicles with higher sticker prices. And because heftier vehicles like SUVs, pickup trucks and luxury sedans can shed pounds more easily in a material switch, they can be critical to strategies to improve fleet economy.

A new survey of automakers by Ducker Worldwide, commissioned by the Aluminium Transportation Group, projects the use of aluminium for NAFTA-produced vehicles to grow from 350 pounds per vehicle in model year 2015 to 547 pounds per vehicle in 2025. That equates to an overall market volume of 6.9bn pounds now to 10.8bn pounds in 10 years — a 56% increase.

Sheet aluminium for auto and truck bodies remains the top growth area for the auto industry, though aluminium castings are finding their way into a growing list of automotive components.  Aluminium currently enjoys about a 73% share, by weight, of the casting market in 2015 vehicles.

Aluminium Boost

Analysts indicate aluminium-cast parts manufacturers are increasingly engaging in vertical integration to ensure a continuous supply of raw materials. That means construction of smelters to increase secondary production from recycled content, as well as boosting downstream production of finished aluminium-based products.

Traditionally, primary and secondary production operations have run side-by-side so that recycled content could be added to the primary operation to increase the casthouse output.  In 2007, Linde documented a 60% increase in aluminium remelting capacity and a 50% reduction in fuel consumption in such a 130,000 metric tonne per year facility in Norway using Linde Low-Temperature Oxyfuel (LTOF) technology.

However, primary aluminium production has been scaled back in the US in recent years, and most secondary aluminium plants have lower production capacities and start at or close to 100% solid material in the charge, Palermo says. “With high levels of solid charge materials, you need to either add more energy or improve the energy efficiency of your process - or both to maintain, let alone increase, melting capacity.”

Linde LTOF (Low-Temperature Oxyfuel) technology addresses this problem by replacing air-fuel combustion with oxyfuel combustion that is characterized by low flame temperatures. Lower flame temperatures result in more uniform heating and lower thermal NOx generation while continuing to reap the benefits of energy efficiency and increased radiative heat transfer efficiency typically attributed to oxyfuel combustion.

According to the US Environmental Protection Agency (EPA), about 1.7 million tons of aluminium were used to make durable goods such as appliances and automobile parts in 2012. While more than half of aluminium beverage cans are recycled, most back into cans, the EPA does not calculate recycled automotive aluminium in measures of waste generation, recycling or disposal.

Linde provides industry-leading portfolio solutions for the ferrous and non-ferrous metallurgy industries, ranging from gases and equipment to process consulting and services.