4

Materials

Man tends to be conscious of products . . . but also tends to take the materials in products for granted. Nylon is known far better in stockings than as the polyamide engineering material used to make small parts of automobiles.

National Academy of Sciences,

Materials and Man's Needs, 1974

With the rise of modern industrial economies in the nineteenth century, the use of raw materials has grown at an explosive rate. Over the past 100 years, the world's industrial production increased more than fiftyfold (see Rostow, 1978, pp. 48–49). Some anthropogenic materials released to the environment far exceed natural release rates. In many instances today, human activities match the scale of fundamental natural processes. Almost half of the plant material fixed by photosynthesis over the earth's surface is taken or transformed by humans (Vitousek et al., 1986); humans fix almost as much nitrogen in the environment as does nature, mainly because of artificial fertilizers (Graedel, 1989); and the rate at which humans release carbon into the atmosphere—7 to 8 billion tons per year—is about 7 percent of the total natural carbon exchange between the atmosphere and the oceans (Bolin, 1979).

These high-level consumption trends suggest that the problem of continuing the damage that material extraction and processing impose on the environment is graver than the problem of resource depletion, an issue of wide concern in the 1970s. Oil provides an instructive example: Rising levels of carbon dioxide in the atmosphere and associated global warming concerns may raise the environmental cost of using oil to prohibitive levels before the world runs out of oil. Early stages of industrial activities, such as the mining of ores and the refining and reduction of metals from ores, have a more severe impact on the environment than later stages such as manufacturing and use of products. The current focus of materials management, however, is on life-cycle environmental considerations. This requires taking into account environmental factors across all stages in the lifetime of a product or process.

The workshop participants generally agreed that environmental risks posed by increased material flows can be addressed by improving industrial efficiency and by substituting less damaging materials for those currently used. From an industrial ecology perspective, change requires understanding what materials are involved and how they flow throughout an industrial system.

PERSPECTIVES

Trends in Materials Technology

GREGORY EYRING

Increasing variety, increasing efficiency, and increasing complexity characterize the dramatic changes materials have undergone in the twentieth century. Technological advances and economic pressures have driven the change. Often new materials have offered environmental benefits over the materials they replaced. The changes in materials use also present difficult trade-offs if a choice is to be made solely on the basis of environmental considerations.



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Industrial Ecology: U.S.-Japan Perspectives 4 Materials Man tends to be conscious of products . . . but also tends to take the materials in products for granted. Nylon is known far better in stockings than as the polyamide engineering material used to make small parts of automobiles. National Academy of Sciences, Materials and Man's Needs, 1974 With the rise of modern industrial economies in the nineteenth century, the use of raw materials has grown at an explosive rate. Over the past 100 years, the world's industrial production increased more than fiftyfold (see Rostow, 1978, pp. 48–49). Some anthropogenic materials released to the environment far exceed natural release rates. In many instances today, human activities match the scale of fundamental natural processes. Almost half of the plant material fixed by photosynthesis over the earth's surface is taken or transformed by humans (Vitousek et al., 1986); humans fix almost as much nitrogen in the environment as does nature, mainly because of artificial fertilizers (Graedel, 1989); and the rate at which humans release carbon into the atmosphere—7 to 8 billion tons per year—is about 7 percent of the total natural carbon exchange between the atmosphere and the oceans (Bolin, 1979). These high-level consumption trends suggest that the problem of continuing the damage that material extraction and processing impose on the environment is graver than the problem of resource depletion, an issue of wide concern in the 1970s. Oil provides an instructive example: Rising levels of carbon dioxide in the atmosphere and associated global warming concerns may raise the environmental cost of using oil to prohibitive levels before the world runs out of oil. Early stages of industrial activities, such as the mining of ores and the refining and reduction of metals from ores, have a more severe impact on the environment than later stages such as manufacturing and use of products. The current focus of materials management, however, is on life-cycle environmental considerations. This requires taking into account environmental factors across all stages in the lifetime of a product or process. The workshop participants generally agreed that environmental risks posed by increased material flows can be addressed by improving industrial efficiency and by substituting less damaging materials for those currently used. From an industrial ecology perspective, change requires understanding what materials are involved and how they flow throughout an industrial system. PERSPECTIVES Trends in Materials Technology GREGORY EYRING Increasing variety, increasing efficiency, and increasing complexity characterize the dramatic changes materials have undergone in the twentieth century. Technological advances and economic pressures have driven the change. Often new materials have offered environmental benefits over the materials they replaced. The changes in materials use also present difficult trade-offs if a choice is to be made solely on the basis of environmental considerations.

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Industrial Ecology: U.S.-Japan Perspectives Increasing Variety A century ago, U.S. industry used only about 20 elements of the periodic table; today, virtually all 92 naturally occurring elements are used. Recent developments in materials technology are impressive in terms of both breadth and ingenuity. High-performance ceramics and composites, high-temperature superconductors, conductive plastics, diamond films, and “smart” materials are just a few examples of materials that did not exist until only recently. In the future, the impacts of these “ engineered” materials may be overshadowed by a variety of biologically derived materials for applications such as artificial skin, superabsorbants, dispersants, and packaging. These materials could be made nontoxic, renewable, biodegradable, and biocompatible. These developments illustrate the great dynamism of materials technology, and suggest both new challenges and opportunities for improving environmental quality. Increasing Efficiency New processing technologies, more sophisticated materials, and improved product design have resulted in more efficient use of materials. For example, an office building constructed with 35,000 tons of steel today required 100,000 tons 30 years ago. Glass bottles and aluminum cans weigh 30 percent less than they did 20 years ago. This general decline in materials intensity (which has been accompanied by a corresponding decline in energy intensity) of products is one component of a broader phenomenon called “dematerialization.” 1 The trend toward increasing materials efficiency contributes to environmental quality, since it suggests that economic growth need not necessarily be accompanied by increased resource use and waste generation. Increasing Complexity Statistics concerning materials consumption do not capture a more subtle change that has potentially important environmental consequences —the trend toward increasing complexity of materials use. Advances in chemistry, material science, and joining technology have made it possible to combine materials in new ways (e.g., fiber-reinforced composites and anticorrosion coating on metals) to meet performance specifications more cheaply. This creates products with complex material composition. The makeup of a modern snack-chip bag, for example, shows complex materials use and benefits. The combination of nine extremely thin layers and seven different materials produces a lightweight package that meets a variety of needs (e.g., preserving freshness, preventing tampering, providing information). The use of so many different materials effectively inhibits recycling. On the other hand, the package has waste prevention attributes; it is much lighter than an equivalent package made from a single material and provides a longer shelf life, resulting in less food waste. Virtually every product, from the automobile to the tennis racket, exhibits this increasing complexity of materials use. Implications of Materials Trends The central conclusion from this review of materials trends is that environmental considerations for use of material in designing products are multidimensional concepts that extend over the entire life cycle of a product. With technologies available to create new materials and combine conventional materials in new ways, manufacturers as well as consumers are faced with more choices than ever. Increasingly, these choices involve environmental dilemmas. Energy-efficient compact fluorescent lightbulbs, for example, contain mercury, a toxic heavy metal. In cases such as this, trade-offs will be required not only between traditional design objectives and environmental objectives, but among environmental objectives themselves: for example, waste prevention versus recyclability, or energy efficiency versus toxicity. In general, every design will have its own set of environmental pluses and minuses. In the context of the industrial economy, it is not easy or simple to establish absolute conclusions about what materials choices are “good” or “bad” for the environment. Some choices are urgent and compelling, such as avoiding the use of chloroflurocarbons, which are linked to depletion of the earth's protective ozone layer. But in most cases, materials choices will depend on specific products, production networks, and local geographical and technological factors. Trends in materials use suggest the following conclusions: New (and emphatically nonnatural) materials technologies can lead to remarkable efficiencies and environmental benefits. These benefits may come from surprising directions, including research not initiated for environmental purposes. Use of nonrenewable materials (e.g., plastics) is not necessarily bad. Their use can often yield waste prevention benefits in relation to their alternatives. Use of complex and nonrecyclable materials is not necessarily bad. In general, recycling-oriented environmental policies do not adequately account for waste prevention opportunities with complex materials.

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Industrial Ecology: U.S.-Japan Perspectives The dynamic nature of materials technology and the trend toward complexity seem certain to make a knowledge-intensive approach (such as life cycle assessment) to materials use more difficult and expensive in the future. Primary-Resource Industries YUMI AKIMOTO The changing trends in materials use are occurring in an era when the free use of the great oceans and wilderness as waste dumping grounds for industrial society is increasingly limited. This presents industry with an urgent need to find its own sinks or buffers for environmentally sustainable development. In this respect the rapid emergence of a waste management industry can be said to be a natural consequence. Before sophisticated facilities and systems are created for the sole purpose of waste management, however, consideration should be given to existing production lines for recycling and using waste as resources. Primary industries are underutilized for this purpose. In fact, primary-resource industries have been targeted by some environmentalists as material- and energy-intensive and among the most destructive to the environment. Each year the production of virgin materials (those newly extracted from natural resources) damages millions of hectares of land, destroys millions of trees, and produces billions of tons of solid waste. It also pollutes air and water to a degree exceeded only by the production and use of energy—much of which is generated to extract and process materials (Young, 1991). Mining is energy-intensive and entails moving large amounts of materials. Energy is required to cover the endothermic reactions of extracting the metals. In separation and purification, energy is used to lower the entropy. Primary-resource industries supply materials such as the cement, steel, aluminum, and copper that are the basic ingredients used in a variety of industry sectors, including construction and manufacturing. The value added to materials by these industries, however, is relatively low when compared with the manufacturing processes that use the materials. Thus, in primary-resource industries, the volume of materials and energy handled by one factory is overwhelmingly greater than that of sectors lower down. However, with growth in the scale of material flows in industrial ecosystems, primary industries may serve as recycling sinks for other, smaller-scale processes. The higher the entropy of process materials, the greater its value as the recycling sink. Over the past two decades, the Japanese cement industry has successfully processed various waste materials and recycled goods. The cement industry, which handles a large amount of materials at high temperature and manufactures products of relatively high entropy, provides an effective means of recycling many industrial waste products. Calcium-bearing wastes (in place of limestone), silicate- or alumina-containing products (as an alternative to clay), and wastes rich in iron oxide are prime materials that can be recycled in cement kilns. Other products that can be used in cement kilns include mud, sand, and slag, which contain calcium, aluminum, and iron as main ingredients. The high temperatures of 1,500°C in the kiln facilitate energy recovery from waste that contains water or organic compounds. “Bota”—waste from coal extraction—contains inorganics that can be used in cement manufacture and also provides the calories to fuel operations. Other materials that can substitute for fuel include used tires, waste kaoline from oil refineries, waste paint, and other waste oils. At the final stage of cement production, clinker is mixed with gypsum. Natural gypsum can be replaced with a by-product of gas desulfurization operations. Instead of accepting only those recyclable wastes that would not affect the quality of the end product, new products with characteristics not available in common cement can be created by using recycled materials. Blast furnace cement and fly-ash cement are good examples. The Japanese cement industry, over the past 20 years, has used waste from several diverse industry sectors as shown in Table 2. Of the 99 percent of blast furnace slag recycled in Japan, 60 percent, or 15.6 million tons per year, is recycled to cement kilns. Three-quarters of the fly ash produced in coal power plants, about 1.6 million tons per year, is recycled as cement, while the rest is sent to landfills. Half the used tires generated annually in Japan, about 400,000 tons, are recycled for reuse, while 37 percent are used as a source of energy. Of these tires, 40 percent are burned in cement kilns. “ Bota,” huge heaps of coal wastes once common in coal mining areas, are gradually disappearing through the use of this waste in cement. This type of recycling has benefited various industry sectors. However, potential use of primary-resource industries for closing the loop on material flows is not fully understood. The use of cement and metal smelting industries as sinks for waste from other industries has great potential for minimizing waste from an industrial ecology perspective. There are differences between the United States and Japan in how cement kilns are used to recycle material

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Industrial Ecology: U.S.-Japan Perspectives TABLE 2 Sources of Waste Used in the Japanese Cement Industry Industry Source Waste as Resource in Cement Kiln Power generation (Coal-fired) Fly ash from coal-fired plants, stack gas desulfurized gypsum (Crude oil fired) Fly ash from oil-fired plants, stack gas desulfurized gypsum Coal mining “Bota” (coal wastes) Steel refining Blast furnace slag, pig iron furnace slag, electric furnace slag, converting furnace slag Nonferrous refining Copper slag, iron concentrate, stack gas desulfurized gypsum Metals manufacturing Casting sand waste, waste wire covering Oil refining Oil cokes, catalyst residue, used kaoline Chemicals Automobile tires, waste paint, waste oil, stack gas desulfurized gypsum Papermaking Paper sludge, incineration ash of pulp sludge Food oil Used kaoline, waste oil Sugar manufacturing Waste sugar dregs Beer brewing Used diatomaceous earth Construction Waste earth from construction and recover energy from the wastes of other industries. The total amount of waste recycled in American kilns is equivalent to that recycled in one large Japanese enterprise. The share of “recycled cement” (slag cement, flyash cement, pozzolan cement) production in the United States is 0.8 percent, compared with 18 percent in Japan. It is often assumed that the more vertically integrated Japanese industry structure made it easier to build linkages among the primary, mining, and manufacturing industries to use waste as resources. For example, Mitsubishi, with its cement kilns and smelters, is part of the larger diversified Mitsubishi web of industrial activities, which can feed back into the cement kilns and smelters. However, while that may help, evidence suggests that the keiretsu (alliances among industries) were not a requisite for such linkages, nor did they guarantee success. First, it has been only two and one-half years since the cement and metal sectors have been amalgamated in Mitsubishi, while slag recycling has been going on for more than a decade. Second, recycling is not restricted to the keiretsu, nor does being a member of the keiretsu provide an incentive to recycle. This is illustrated by the following examples: Pulp sludge from paper mills: Mitsubishi Materials recycles sludge or ash from sludge of Oji, Jujo, and Daishowa (firms that are not part of the keiretsu), while negotiations with Mitsubishi Paper Company to offer the same service have not yielded much progress. Automobile fluff: Mitsubishi Materials has yet to process automobile fluff from Mitsubishi Motors, while it recycles automobile fluff from Matsuda, Daihatsu, Nissan, and Hino. Blast furnace slag and fly ash: This constitutes a large portion of what is recycled by the company, but its sources of the waste are outside of Mitsubishi or the keiretsu. There are also several similarities and differences between U.S. and Japanese cement manufacturers. The cement business in Japan, as in the United States, is not monopolized or centralized but is diversified among 20 producers. In the United States, recyclable material is generally traded through the materials market or waste exchanges. In Japan, however, information about recyclables circulates through a more informal information exchange mechanism, including discussions among individuals. For example, Japan does not have a market for waste oil—the Japanese chemical companies take responsibility for the waste they generate and process it in their own plants, seldom putting it on the open market. Profit motivates American cement producers to process hazardous waste. In Japan, on the other hand, the incentive is opportunities to increase market share that can result from the give-and-take relationship with customers. Generally, recycling does not pay even if a nominal charge is levied, but the activity is seen as creating a good marketing climate. DISCUSSION Szekely observed that R&D expenditures highlight another major difference between American and Japanese primary industries. Unlike U.S. companies, most Japanese resource manufacturers operate their own research laboratories and are eager to promote joint projects to solve common problems, particularly environmental problems. Akimoto surmised that many of the differences between approaches in the two countries could be attributed to the fact that the oil price shocks of the 1970s had a profound effect on Japan. Energy recovery from waste was an important strategy to conserve fuel. In addition, he noted that Japan has a limited amount of land and industries are located near large communities. The Japanese industry is therefore under the scrutiny of local communities and has had to be responsive to community concerns about the environment.

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Industrial Ecology: U.S.-Japan Perspectives Frosch noted that from an industrial ecology perspective it is necessary to think about whether there are ways to connect different processes that produce waste, different plants, and different industries into a naturally operating web. Examples of this type of linking are commonly associated with the chemical and petrochemical industries, which characteristically think about their processing in terms of turning as much as possible of what they produce, including waste materials, into useful products. One implication of this approach is the constant search for new uses for waste materials. Another is the shifting of manufacturing processes, products, and materials so that the ensemble minimizes waste and cost. For example, one might even think of changing to a more expensive manufacturing process if it meant shifting from a waste material that must be disposed of to a waste material for which there might be a customer, such as a cement kiln or metal smelter. In the United States, about 1 percent (3–4 million tons) of hazardous wastes are incinerated by 20 commercial incinerators and 29 cement or other types of industrial kilns around the country (Schneider, 1993). This practice is under scrutiny, however, as public opposition to incineration rises. Workshop participants agreed on the need to develop more fully current linkages between industries to promote the use of wastes from one manufacturing process as resource material for another. The practice should be encouraged as long as the waste is handled in environmentally appropriate ways at these facilities. There are concerns that boilers, furnaces, and cement kilns in the United States are generally operated under less rigorous environmental requirements than commercial incinerators. This concern has also led to a temporary freeze on the development of new hazardous waste incinerators. In Japan, effective use of cement (and other industrial) kilns as environmental technologies suggests that the kilns of resource industries can be used for environmental benefits to reduce waste from other industries. Improvements in technology or operational procedures may be needed to ensure safe handling of hazardous wastes. Efforts should be made to implement better practices at kilns instead of dismissing them outright as a nonviable technology. Szekely suggested that academia could be involved in joint research with resource industries to develop any new technologies that may be needed. NOTE 1. The term “dematerialization” is often broadly used to characterize the decline over time in weight of the materials used in industrial end products (Herman et al., 1989, p. 50). REFERENCES Bolin, B. , ed. 1977 . The Global Carbon Cycle . New York : Wiley . Graedel, T. E. , and P. J. Crutzen . 1989 . The changing atmosphere . Scientific American 261(3) : 58–68 . Herman, R. , S. A. Ardekani , and J. H. Ausubel . 1989 . Dematerialization . Pp. 50–69 in Technology and Environment , J. H. Ausubel and H. E. Sladovich , eds. Washington, D.C. : National Academy Press . Schneider, K. 1993 . Administration to Freeze Growth of Hazardous Waste Incinerators . New York Times, 18 May 1993 , p. A9 . Vitousek, P. M. , P. R. Ehrlich , A. H. Ehrlich , and P. A. Matson . 1986 . Human appropriation of the products of photosynthesis . Bioscience 36(6) : 368–373 . Young, J. E. 1991 . Discarding the Throwaway Society . Washington, D.C. : Worldwatch Institute .