 |
 |
Light Duty Truck and SUV Material Studies Show Steel Lighter on the Environment than Aluminum Over Total Vehicle Life
DETROIT, Nov. 19, 2014 – WorldAutoSteel released findings today of two new case studies that examine the effect that various automotive materials can have on total life cycle Greenhouse Gas (GHG) emissions for Light Duty Truck and Sport Utility Vehicle (SUV) classes. The studies, which conduct a Life Cycle Assessment (LCA) of each vehicle class, showed that Advanced High-Strength Steel (AHSS) materials used for lightweighting lowered total life cycle emissions, as well as decreased fuel consumption.
The case studies used the Automotive Materials Energy and GHG Comparison Model (UCSB Model), developed by Dr. Roland Geyer of the University of California Santa Barbara Bren School of Environmental Sciences. The case studies investigated whether or not an AHSS-intensive design would result in fewer emissions than an aluminum-intensive design, compared to a conventional steel baseline, when looking at the entire vehicle life, from material production and manufacturing, to fuel production, vehicle use and vehicle end-of-life recycling and disposal.
“Numerous iterations of the model were conducted using a range of input parameters to simulate the many possible conditions a vehicle might see,” said Russell Balzer, Technical Director, WorldAutoSteel. “In each vehicle’s best performance (lowest emissions) case, the steel design showed decreased total life cycle emissions over the aluminum vehicle by 3% for the Light Duty Truck, and 5% for the SUV.” To put this into a fleet perspective (annual production of 700,000 trucks; 200,000 SUVs), if both vehicles were manufactured in AHSS this equates to approximately 1.7 million metric tonnes total emissions savings over the aluminum-intensive vehicles.
The UCSB Model also projects fuel savings by considering driving cycles, engines, fuel types, effects of lightweighting and other factors that impact fuel usage. The Model results showed that fuel consumption was not substantially decreased when substituting aluminum for steel. The AHSS and aluminum designs reduced structural* weight by 25%, and 35%, respectively. For both the truck and SUV cases, the AHSS designs were within 70 kg of the aluminum weight savings. The data showed that owners of an aluminum-intensive Light Duty Truck can expect to visit the fuel station four less times over the entire life of the vehicle (assuming a 26-gallon tank and 12-year lifetime) than the AHSS-intensive truck owner, or a savings of 1/3 of one fuel fill up per year. The aluminum SUV driver can expect to save about three visits to fill up over the entire vehicle life, or 1/4 of one fuel fill up per year less than steel. At U.S. average fuel prices (US$4.00/gal.), that is a consumer cost savings of about US$25 – $35 per year.
From a lightweighting perspective, the efforts to lower weight with aluminum to reduce fuel consumption resulted in an increased environmental footprint overall at a potential cost of three times that of steel. “On a life cycle basis, the AHSS-intensive vehicles produce fewer emissions than the aluminum-intensive one,” said Balzer. “Steel performs better in these vehicle cases because the primary production of steel, including AHSS, produces seven to 20 times fewer emissions than other materials such as aluminum, magnesium and carbon fibre reinforced plastics. The point is that setting emissions reduction goals based on lightweighting technologies without a thorough understanding of their life cycle impact makes it impossible to know whether or not the emissions reduction goals are actually being met.”
WorldAutoSteel believes a life cycle approach to vehicle emissions regulations will foster the approaches needed to truly reduce automotive industry emissions.
“Without a lifecycle approach to auto emissions, automotive designers can be forced into solutions that end up merely shifting the environmental impact, not reducing it,” said Balzer. “Regulations need to support a holistic big picture approach, from start to finish; otherwise, they will continue to lead automakers into approaches that may result in some fuel consumption savings but that can, in the end, lead to the unintended consequence of increased total vehicle emissions.”
Life Cycle Assessment (LCA) is a methodology that considers a vehicle’s entire life cycle, from the point where raw material is taken from the ground and the vehicle is built (manufacturing), to the time while the car is driving down the road and burning fuel (use or driving), to the point where it is hauled to the scrap yard and all of its recyclable content is removed and the rest disposed (end of life recycling and disposal).
The UCSB model is designed to quantify the energy and GHG impacts of automotive material substitution on a total vehicle life cycle basis, under a broad range of conditions and in a completely transparent fashion. The model methodology has been peer-reviewed by members of the LCA community and the aluminum industry.
You can download and review the complete case studies by clicking these links or the links at upper right: Light Duty Truck and SUV. The UCSB model, including a comprehensive User Guide, also is available for free download at www.worldautosteel.org.
* Structural weight reduction for truck body structure, doors, hood, and truck bed; for SUV body structure, doors, hood, liftgate, suspension, and subframe