Steel is reinventing itself to lower the Green House Gas (GHG) output of cars and trucks at little or no additional cost to automotive manufacturers or consumers.
We know that climate change is a critical issue. Whether you believe in global warming or not, actions to reduce energy use and negative effects on the environment are important. Continued success across industries including transportation is contingent on improving environmental performance. On a global basis, automotive steel is reinventing itself and is helping to reduce automotive greenhouse gas emissions (GHG).
New grades of Advanced High Strength Steel from steel companies around the globe provide lighter, optimised body designs that enable improved vehicle crashworthiness, improved fuel economy and lower total greenhouse gas emissions. So how does Advanced High Strength Steel compare to conventional steel? AHSS such as Dual- Phase, Transformation Induced Plasticity (TRIP) and Martensitic Steels provide unique characteristics because they have very high strength, and yet can be easily formed to make complex automotive parts.
For a typical 5-passenger compact vehicle, evidence shows that replacing former conventional steel designs with optimised AHSS designs will, on average, gain:
• 25 per cent reduction in body structure weight
• 9 per cent reduction in the vehicle weight
• 5.1 per cent reduced fuel consumption
• 5.7 per cent reduced lifecycle GHG emissions
And, all this is accomplished with little or no increase in manufacturing costs. The advantages of AHSS in meeting auto makers' goals are well recognised by the design community and have been incorporated into nearly every new vehicle design. Steel makes up more than 50 per cent of today's vehicles and is the predominant material of vehicle body structures. Today, it is a common practice for a high percentage of the body structures to be manufactured using AHSS. And because of this, AHSS has become the fastest growing material in automotive body structures, which is helping reduce GHG emissions.
One of the challenges concerning automotive emission regulations is to achieve the intended control without creating unintended consequences or unexpected results. Climate change and energy concerns prompt more aggressive fuel economy or tailpipe emission regulations. Of course, fuel economy or tailpipe emissions are important factors, but, all phases of the vehicle's life-from materials production through the end-of-life disposal of the vehicle-should be considered in order to get a complete picture of the vehicle's impact on the environment. Many of you are familiar with Life Cycle Analysis, or Life Cycle Assessment (LCA). In the automotive industry, LCA has only recently become a subject that is broadly discussed (Figure 1). We feel strongly that both approaches-tailpipe emission regulations and life cycle analysis have usefulness in looking at the issue.
A recent study by Dr Roland Geyer at the University of California, Santa Barbara, developed a very good comparison model for use in evaluating GHG emissions related to automotive materials. The model provides a well-documented methodology for evaluating different material choices when designing automobiles. The model demonstrates that, in many cases, choice of low-density materials may lead to increased GHG emissions during the production phase of a vehicle, which may more than offset reductions during the vehicle's use phase that are achieved by small amounts of mass reduction.
An LCA approach assists auto makers in evaluating and reducing the total energy consumed and the lifetime GHG emissions of their products. The regulations that are based only on the vehicle use-phase may encourage the use of GHG-intensive materials that help in manufacturing lighter weight components, but they end up with the unexpected result of increased GHG emissions during the vehicle's total life cycle. A full life cycle assessment methodology reveals that the production of alternative materials like aluminum, magnesium and plastics, require much more energy, and contribute 5 to 20 times more GHG emissions per kg than steel (Figure 2). This means that during the production stages, an alternative material vehicle will load the environment with significantly more GHG emissions than that of a steel vehicle.
In Figure 3, using the University of California LCA comparison model, we show an AHSS vehicle (represented by the blue line) and an aluminium vehicle (represented by the yellow line). Notice that the aluminium vehicle creates less GHG emissions during the vehicle use phase because it is slightly lighter. However, the aluminium vehicle releases a significantly higher level of GHG emissions during the material production phase. The two bars at the right side of the Figure 3 represent the total life cycle emissions of an Advanced High Strength Steel-intensive vehicle (blue bar) and an aluminium-intensive vehicle (yellow bar). Use-phase only regulations can lead auto manufacturers to select GHG-intensive materials that may improve the use phase but leave the total life cycle greenhouse gas emissions unchecked. In other words, these regulations lead to unintended consequences or wrong choices from the planet's point of view.
Here we illustrate two case study examples of life cycle assessment using the University of California Santa Barbara comparison model. These case studies are based on automotive body structure materials for a 5-passenger compact vehicle with a gasoline internal combustion engine. As you see in the three bars at the left-hand side of Figure 3, going from conventional steels to optimised AHSS results in 25 per cent mass reduction of the body structure and 9.3 per cent reduction of the total vehicle weight. If you go from an AHSS vehicle to an aluminum design, you achieve a further mass reduction of 11 per cent in the body structure.
Next, move to the three bars on the right-hand side of the slide. The UCSB model calculates total life cycle GHG emissions for the same vehicle using difference materials - conventional steel, AHSS, and aluminum. Compare the orange bar on the right with the blue bar on the right. This is the situation of 'steel re-inventing itself ' and replacing former steel materials and design with new steel materials and design. The effect of 25 per cent mass reduction in the body-in-white is to reduce CO2 equivalent or GHG emissions in both the material production and use phase so that the vehicle's total life cycle emissions are reduced by 5.7 per cent. It should also be pointed out that this steel re-invention is accomplished at little or no additional cost. Now, compare the aluminum bar on the right - which shows an optimised aluminum design compared with the orange AHSS bar. Even with some additional mass savings achieved with aluminum, the increase of CO2 equivalent (GHG) emissions from the material production phase more than offsets the reductions due to somewhat lighter weight in the use phase. The vehicle's total life cycle emissions are increased by 2.6 per cent. To add insult to injury, this environmental burden also comes with a significant cost increase.
Although material decisions to achieve vehicle mass reduction are important, the impact of material production on life cycle emissions are relatively small compared to total emissions, as you see in the left-hand two bars of this baseline comparison between an AHSS intensive vehicle and an aluminum intensive vehicle. As we move to the right with the comparison bars, you see that significant improvements in reducing automotive GHG emissions will not be made by material substitution alone. The other comparison bars show the impact of changing automotive technologies on GHG emissions.
The use of advanced powertrains (such as hybrids), more efficient fuels (such as grain and cellulose ethanol), and improved driving cycles, can result in a dramatic reduction in the use phase emissions. As other technologies that improve vehicle GHG emissions are implemented in mainstream vehicle designs, the emissions from material production becomes relatively more important in the total life cycle. This places greater emphasis on selecting low GHG-intensive materials such as steel. For example, compare the first and last two bars in Figure 4. When new technologies are utilised, GHG emissions from the materials production phase grow in relative proportion from 9-23 per cent of the total because the use-phase emissions are reduced.
As the global automotive steel continues to re-invent itself, WorldAutoSteel also wants to position steel for the future. To that end, WorldAutoSteel has begun a multi-million dollar new initiative called Future Steel Vehicle. This new initiative will develop steel auto body concepts that address alternative powertrains such as advanced hybrid, electric, and fuel cell systems. The goal of the research is to demonstrate safe, light weight steel bodies for future vehicles that reduce GHG emissions over the entire life cycle. Future Steel Vehicle will consist of three phases over as many years: a Phase I will include an Engineering Study; Phase II will develop Concept Designs; and Phase III will build Demonstration Hardware. WorldAutoSteel commissioned EDAG Engineering and Design AG, headquartered in Fulda, Germany to complete the first phase Engineering Study. Development work will be based at EDAG's facility in Michigan. Phase I will examine changes affected by new powertrain systems that may radically change the structure of automobiles and will provide input for Phase II design concepts.
Future Steel Vehicle is the fifth in a series of global auto steel research projects that have been undertaken by the global steel industry. The previous four - UltraLight Steel Auto Body, known as ULSAB, UltraLight Steel Auto Closures, Suspensions, and ULSAB-AVC (Advanced Vehicle Concepts), represented over sixty million dollars in steel industry investment. These programs demonstrated the application of new steel grades, design techniques and manufacturing technologies that significantly reduced vehicle weight while improving safety and performance, and maintaining affordability.
Future Steel Vehicle focusses on radical change in the future and is further evidence of the steel industry's commitment to solutions that benefit the environment, automakers and end consumers.
Edward G Opbroek is director of WorldAutoSteel-the Automotive Group of the International Iron and Steel Institute. He was the former director of the ULSAB (UltraLight Steel Auto Body) and ULSAB-AVC (Advanced Vehicle Concepts). He has extensive experience in product development, application engineering, steel production operations management, and marketing/sales with AK Steel Corporation and Armco Steel in the fields of construction and automotive products. He holds a Masters Degree in Business Administration from the University of Missouri.
