WorldAutoSteel (www.worldautosteel.org)—the automotive organization consisting of member companies of the International Iron and Steel Institute—is undertaking its fifth vehicular automotive research project, the “Future Steel Vehicle,” which is predicated on demonstrating the benefits of lightweight steel bodies combined with alternative powertrains (e.g., hybrid, electric, fuel cell). The engineering study for the project is being performed by EDAG Engineering + Design’s facility in Auburn Hills, MI (www.edag-us.com).
One of the reasons behind the work is to show that when it comes to greenhouse gas (GHG) emissions over the lifecycle of a vehicle, steel is beneficial.
To that point, Jody Shaw, manager, Automotive Marketing, United States Steel Corp. (www.ussteel.com), explains that there has been a study on that subject conducted at the University of California-Santa Barbara by Dr. Roland Geyer of the Donald Bren School of Environmental Science and Management. Specifically, Dr. Geyer was looking at the lifecycle GHG emissions, with the lifecycle including raw material extraction, material production, production, use and maintenance, and disposal or, in the case of steel, recycling. The comparison was made with aluminum, advanced high-strength steel (AHSS), as well as with conventional steel.
Note well that the target here is lifecycle, not just the in-use portion of a vehicle. If it is just a matter of looking at the use phase only—the driving—then aluminum, Shaw admits, is responsible for reduced GHG emissions, with AHSS coming in second and conventional steel third. Lighter weight cars are generally responsible for fewer emissions than comparable but heavier ones. “But are we measuring the right thing?” Shaw asks, indicating that the focus on the use phase is insufficient, even though that is often what is considered—at least so far. Arguably, more awareness of the potential problems associated with GHG emissions will result in greater consideration of all aspects of the impact of motor vehicles.
When the material production is considered, then steel really comes into its own. That is, the average kilograms of CO2 equivalent emissions per kilogram of material is 2.3 to 2.7 for conventional or AHS steel, but 13.9 to 15.5 for aluminum. This represents the energy-intensiveness of producing the aluminum. As Shaw points out, it is a lot easier to separate iron and oxygen than aluminum and oxygen. So even though aluminum can have an edge as regards just the car or truck in operation, when adding in the emissions associated with making the materials, the results are different.
Shaw points out that one of the considerations that needs to be taken into account as alternative powertrains are deployed—powertrains that are more efficient and produce lower emissions—is what the GHG emissions are associated with the vehicle. That is, if you have a hybrid-powered vehicle with comparatively low GHG emissions out of the tailpipe, then the GHG emissions associated with the materials used to produce that vehicle have, as a percentage, a higher effect on the overall GHG emissions on the vehicle throughout its lifecycle. The use phase is one thing. The entire existence of the vehicle is another. Steel begins to be a whole lot more attractive when it is considered holistically.—GSV