The sustainability of our environment and the energy we use to support society are dominant concerns across the globe. Rising concentrations of carbon dioxide in the atmosphere and shrinking availability of petroleum from secure sources have led to focused efforts on policy and technology solutions.
Against this larger backdrop, the global automotive fleet of roughly 700 million cars represents a significant source of CO2. By some estimates, 14 percent of global CO2 emissions are from transportation—with cars making up the lion's share. As such, reducing vehicle fuel consumption and related tailpipe emissions are vital to combating climate change and lessening our reliance on foreign oil.
The aluminum content in cars and light trucks reached an all-time high of 8.6 percent of average vehicle curb weight in 2009, continuing almost 40 years of uninterrupted growth in North America. The main driver behind aluminum's success is the environmental advantages the high-strength, low-weight, infinitely recyclable metal provides. As a result, it is no surprise that in a recent study by Ducker Worldwide LLC, Troy, Mich., auto industry experts ranked aluminum use as a top option and "very significant" in meeting the federally mandated fuel economy improvements of 40 percent by 2020.
It's well accepted that lighter vehicles can minimize both the fuel consumption and carbon emissions associated with their use. In fact, a 5- to 7-percent fuel savings can be realized for every 10-percent weight reduction by substituting aluminum for heavier steel. In terms of curbing greenhouse gas (GHG) emissions, each pound of aluminum replacing two pounds of iron or steel in a car or truck can save a net 20 pounds of CO2 equivalent emissions over the typical lifecycle of a vehicle.
According to the International Aluminium Institute, London, the aluminum content of vehicles manufactured in 2006 alone will lead to potential global savings of approximately 154 million tons of CO2-equivalent GHG emissions and an energy savings equivalent to about 16 billion gallons of crude oil over the life of the vehicles. If you extend using aluminum to reduce the weight of the world's transportation fleet (including cars, trucks, trains, planes and sea-going vessels), the potential exists to reduce GHG emissions by 660 million tons annually, or close to 9 percent of all global, transportation-related GHG emissions.
When considering how automotive material choices impact total energy use related to GHG, it's important to note that a vehicle's true lifecycle covers three discrete phases production, use and end-of-life.
In terms of total impact on the environment from all three phases, it would be misleading to simply consider the energy used during the production phase alone. That is why the U.S. Automotive Materials Partnership reports that the energy required to produce aluminum is small relative to the energy used by a vehicle over its lifetime. Given aluminum's incredibly high recycling rates, its environmental footprint is even smaller than one might initially realize.
The aluminum industry is already the world's largest user of renewable energy, with more than 55 percent of primary aluminum globally produced from hydropower; that number jumps to more than 70 percent from hydroelectric sources in North America. Specific to recycling, more than 55 percent of the aluminum used on North American vehicles is recycled. Better still, recycled aluminum takes 95 percent less energy to produce than primary aluminum. And as further evidence of aluminum's infinite recyclability and durability, more than 70 percent of all the aluminum ever produced is still in use today.
Today, automakers are hyperconscious of these environmental issues and they are breaking new ground with redesigned vehicles and high-tech powertrains to meet the challenge. Plug-in hybrids like the Chevy Volt and full electrics like the Nissan Leaf are poised to revolutionize the auto industry and the very makeup of the vehicles we all drive. Generally, these need new fuel-saving powertrains, which come with an added cost. As the cost of powertrains goes up, the value of lightweighting vehicles, regardless of their powertrains, also increases since it requires less energy to move a lighter vehicle. In fact, for some types of electric vehicles, replacing heavy steel with aluminum actually reduces the total cost of the car because fewer batteries are needed to move the lighter vehicle.
It is well known that diesel and hybrid powertrains provide better fuel economy over standard internal combustion engines, but at an increased cost to the consumer. In addition, advanced powertrains have a payback period of several years compared with gasoline engines at equivalent vehicle performance. Add in aluminum and the new, lighter platform on its own typically costs more—at least upfront—than a current platform. However, by reducing the weight of the vehicle, the power requirements can be correspondingly reduced, leading to a more affordable powertrain and vehicle. The fuel savings gained offsets the additional cost of the platform and powertrain within one to four years. As a result, aluminum's value proposition in the automotive sector is increasing nearly as fast as its usage.
Almost everyone agrees that we must reduce GHG emissions in automotive applications and reduce our dependence on foreign oil. Yet both must be done in such a way that it won't bankrupt automakers or consumers. For this, there is no silver bullet. The answer, instead, lies in a holistic solution consisting of safe and smart design, lightweighting and advanced powertrains that offer real-world solutions to today's challenges of meeting the promise for a better tomorrow.
Randall Scheps is chairman of the Aluminum Association's Aluminum Transportation Group and marketing director of ground transportation for Alcoa Inc.