From the Field

CONSERVATION BY DESIGN

By Jacqueline Isaacs

If you ask most people their opinion on the environment around them, they will likely maintain that pollution is "bad," and they might be in favor of curbside recycling. If they're particularly conscientious, they might even own a mulching mower to prevent extensive yard waste in landfills. But how can people go beyond simple beliefs that less pollution is better? Is recycling actually a cost-effective or resource-effective strategy for a sustainable environment? Much of the research I have worked on over the past few years has focused on developing tools to help quantify and understand environmental questions.

Whereas the average citizen is unable to answer questions about environmental consequences, manufacturers are increasingly including environmental attributes among the factors for characterizing the success and performance of a product. Environmentally conscious manufacturing initiatives are becoming more common in industry-not only due to impending environmental regulations and liabilities, but also because of the increasing costs of pollution remediation. In addition, companies are discovering the potential for cutting manufacturing costs by preventing pollution. Source reduction, as it's called, is usually cheaper than end-of-pipe pollution abatement.

Furthermore, with "take-back" schemes looming in several countries-which will require companies to take back their products when they wear out-manufacturers are having to think about what comes before and after the manufacturing stage. Choices made at the design stage affect raw material consumption, synthesis, processing, use, reuse, remanufacturing, recycling, and final disposal. Design engineers are becoming aware, more than ever before, that a host of issues needs to be considered before selecting a particular manufacturing process or material. Knowledge of environmental and economic issues at the design stage is invaluable, since seventy percent to ninety percent of the cost and process emissions is determined by the product design.

I first became interested in these issues while working in industry myself. I had begun to wonder how I, as an engineer, could make a societal difference. I wanted my career to take on a broader focus than simply investigating and characterizing materials. I also knew I wanted to do something that could somehow benefit the environment. If my industrial experience had taught me one thing, however, it's that commercialization of new materials and technologies is driven by economics.

At the Massachusetts Institute of Technology's Center for Technology, Policy, and Industrial Development, where I was a researcher, and then at Northeastern, where I joined the engineering faculty in 1995, I have worked to develop spreadsheet-based modeling tools to help assess the environmental attributes and economics of various manufacturing and recycling processes, both existing and under development. These computer models can be useful to calculate the operating and overall costs of manufacturing systems. The models employ clearly defined and verifiable economic and accounting standards and are based on engineering principles and the physics of the manufacturing or end-of-life processes. Perhaps most importantly, the models can be used to determine the prime contributors to processing costs and thereby highlight hidden approaches to cost cutting.

For me, the most interesting application of these modeling tools is in issues related to the automotive industry. The automobile is a highly engineered, sophisticated product that meets stringent reliability, durability, and social requirements. Over the years, its design, manufacture, and operation have demanded increasingly complex technology. The auto industry is extremely competitive and highly regulated worldwide. While today's vehicles are vastly cleaner, more efficient, and less harmful to the environment than those produced twenty years ago, the aggregate effect of all those cars is still an environmental burden, and continued improvement is a challenge.

Car designers have responded to air emission and fuel efficiency mandates in recent years by downsizing vehicles and using new materials and processes. Saturn vehicles use lightweight structural body panels developed by the polymer-composite industry. The body of the Audi A8 is a space frame designed by the aluminum industry to capture the advantages of lightweight aluminum alloys. Steel suppliers have responded by forming a consortium to come up with a new ultralight steel auto body. The competition for materials usage in the automobile is fierce; the stakes are high and the rewards lucrative. Each group of suppliers tries to justify its materials by elucidating the trade-offs among performance, manufacturing costs, and environmental consequences.

My research does not provide a single right answer to the design questions. Rather, the results from my modeling tools allow comparison of the salient environmental and economic attributes for numerous manufacturing scenarios. These methods provide the best means available to allow decision makers to understand the environmental and economic implications of different choices.

People don't usually buy a car for its structural materials, though. The criteria they use include the cost, the design, gas mileage, perhaps-and especially the color. Ironically, the painting process is the major source of environmental pollution in auto manufacturing, generating both air emissions and hazardous wastes. More than eighty percent of all regulated air emissions from assembly plants come from the paint shop. Those emissions can be reduced by changing the paint formulation from solvent-based coatings to waterborne or powder coatings. While these alternative paints can potentially improve the environmental performance of automobile plants, implementing these technologies often means a major capital investment, and there are significant technological challenges to overcome to meet the performance requirements for a Class A finish. And who would buy a car that didn't have that perfect finish? If only consumers weren't so picky.

Ever wonder whether one color of paint on your car affects the environment differently than another? It does. In the days of the Model T, Henry Ford offered any color, so long as it was black. Now, a variety of more exotic colors is available, including those with metallic flakes and mother-of-pearl effects. But there are significant differences in manufacturing cost and environmental emissions among various paint formulations and colors. I was part of a team that evaluated the cost and solvent emissions of three colors: black, white, and red. Our analysis shows that a red basecoat costs the most and generates the most solvent emissions. A black basecoat paint yields significant cost savings and reductions in solvent emissions. (So Henry Ford had the right idea.) The consumer doesn't see these variations in cost, however; no premiums are charged to the customer, per se.

Environmental issues are not usually cut-and-dried problems with simple answers; rather, they are interconnected with many other factors, including technological and economic constraints. Systems models help us understand the trade-offs. An advantage of these models is that they can be developed for any industrial manufacturing setting, and can be used directly by companies, which protects their proprietary concerns. I am currently working on describing the technological, competitive, and environmental trade-offs within the powder metallurgy industry, an auto industry supplier.

These days, I find that I am still asking myself: How can I make a difference? I hope to share my research with students to help them understand the importance of assessing all aspects of engineering design-environmental and economic attributes in addition to technological performance. With a broader understanding of the environmental and economic issues facing industry in manufacturing, these graduating engineers will not only have greater marketability in the workplace, they may also contribute informed decisions to help improve our environment.

Jacqueline Isaacs is an assistant professor in the mechanical, industrial, and manufacturing engineering department.