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Technology and Environment 1989. Pp. 23~9. Washington, DC National Academy Press. Industrial Metabolism ROBERT U. AYRES We may think of both the biosphere and the industrial economy as systems for the transformation of materials. The biosphere as it now exists is very nearly a perfect system for recycling materials. This was not the case when life on earth began. The industrial system of today resembles the ear- liest stage of biological evolution, when the most primitive living organisms obtained their energy from a stock of organic molecules accumulated during prebiotic times. It is increasingly urgent for us to learn from the biosphere and modify our industrial metabolism, the energy- and value-yielding pro- cess essential to economic development. Modifications are needed both to increase reliance on regenerative (or sustainable) processes and to increase efficiency both in production and in the use of by-products. In this chapter, mass flows for key industrial materials of environ- mental significance, and the waste emissions associated with them, are reviewed along with the environmental impact of the waste residuals; eco- nomic and technical forces driving the evolution of industrial processes; long-range tendencies in the development of the industrial metabolism; and some applications of "materials-balance" principles to provide more reliable estimates of outputs of waste residuals. The Appendix contains theoretical explorations of the biosphere and the industrial economy as materials-transformation systems and lessons that might be learned from their comparison. Before presenting the main analytic framework, it is useful to begin with some positive examples of how industrial metabolism can shift in the direction of increased efficiency in materials flows and waste streams. It 23

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24 ROBERT U LYRES has been justly remarked that the history of the chemical industry is one of finding new uses for what were formerly waste products (Multhauf, 1967~. One of the most interesting early examples of such an innovation was the Leblanc process (the predecessor of the Solvay process) for manufacturing sodium carbonate circa 1800. As a raw material, it made use of sodium sulfate, an unwanted by-product of the eighteenth-centu~y process for manufacturing ammonium chloride (sal ammoniac). Sal ammoniac was used for cleaning metals and as a convenient source of ammonia, but sodium sulfate had no use. The Leblanc process reduced sodium sulfate to sodium sulfide by heating it in a furnace with charcoal. This, in turn, was heated with calcium carbonate (chalk), which induced a reaction producing the desirable sodium carbonate and a new waste product, calcium sulfide (Multhauf, 1967~. Meanwhile, the market for ammonium chloride failed, so sodium sulfate had to be produced in the same complex by reacting sulfuric acid with common salt. This yielded hydrogen chloride (hydrochloric acid) as another by-product. In this case, the hydrochloric acid quickly found a practical use in the manufacture of chloride of lime as a bleach for the rapidly growing textile industry. The other waste product, calcium sulfide, was not successfully used until the 1880s, as a source of sulfur for the manufacture of sulfuric acid. One of the most important waste products of the early nineteenth century was coal tar, which was generated in large amounts by gasworks making "town gas" for illumination. It was a systematic search for useful by- products, initiated by German chemists, that resulted in the creation of the modern organic chemical industry. The synthetic aniline dyes introduced after 1860 were all essentially derived from chemicals obtained from coal tar. Phenolic resins, aspirin, and the sulfa drugs are later examples of derivatives. Until recently, even natural gas was regarded as a by-product of petroleum production. Although it was used almost from the beginning as a fuel for refinery processes and illumination in local areas, much of it was wasted by "flaring" (indeed, this is still true in remote areas of the, world). It had no significant chemical uses until World War II, when natural gas became the feedstock for producing ethylene, and thence butadiene and styrene, the major ingredients of synthetic rubber. Chlorine is a final example. It is manufactured jointly with sodium or sodium hydroxide (lye) by electrolysis of salt or brine. When this process was introduced In the 1890s, it was the sodium hydroxide that was wanted for a variety of purposes, including petroleum refining and soap manufacturing. At the time, chlorine was a low-value by-product, which was luckily available for use in municipal water treatment The development of a number of valuable chlorine-based organic chemicals (e.g., the most

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INDUSTRIAL METABOLISM TABLE 1 Mass of Active Materials Extracted Commercially in the United States, 1960-1975 (million tons) Year Material1960196519701975 Food and feed crops267295314403 (excluding hay) Meat, fish, and dairy products82858584 Cotton, wool, hides, and tobacco5544 Timber (who moisture basis)256267271249 Fuels (coal, lignite, oil, gas)9901,1761,4581,392 Ores(Fe, Cu. Pb, Zn)400435528460 Nonmetallics2ooa24Oa266255 Total2,2~a2>ooa2,9262,847 25 - aEstimated value. NOTE: Vegetable material harvested directly by animals has been omitted for lack of data, along with some obviously minor agricultural and horticultural products. Figures for metal ores exclude mine tailings and gangue removed to uncover ore bodies. Inert construction materials such as stone, sand, and gravel have also been omitted. Inert materials account for enormous tonnages, but undergo no chemical or physical change except to the extent that they are incorporated in concrete or paved surfaces. The table also excludes soil and subsoil shifted during construction projects or lost by erosion. SOURCE: U.S. Bureau of the Census (1960 1975~. common industrial solvents and refrigerants, pesticides, herbicides, and plastics such as polyvinyl chloride) actually reversed the position. By the l950s and 1960s, chlorine was the primary product and sodium hydroxide was the less valuable by-product. MASS FLOWS AND WASTE EMISSIONS Our economic system depends on the extraction of large quantities of matter from the environment. Extraction is followed by processing and conversion into various forms, culminating in products for "consumption." The U.S economy extracts more than 10 tons of "active" mass per person (excluding atmospheric oxygen and fresh water) from U.S. territory each year. Of the active mass processed each year, roughly 75 percent is mineral and "nonrenewable," and 25 percent is, in principle, from renewable (i.e., biological) sources as shown in Bible 1. Of the latter, much is ultimately discarded as waste, although much of it could (in principle) be used for energy recovery. It is difficult to estimate the fraction of the total mass of processed

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26 ROBERT U LYRES active materials that is annually embodied in long-lived products and capital goods (durables). None of the food or fuel is physically embodied in durable goods. Most timber is burned as fuel or made into pulp and paper products. At least 80 percent of the mass of "ores" consists of unwanted impurities (more than 99 percent in the case of copper). Of the final products made from metals, a large fraction is converted into "consumption goods," such as bottles, cans, and chemical products, and "throwaway" products such as batteries and light bulbs. Only in the case of nonmetallic minerals (if inert materials are ignored, as before) is as much as 50 percent of the mass embodied in durable goods (mainly Portland cement used for concrete and clays used for bricks and ceramics). The annual accumulation of active materials embodied in durables, after some allowance for discard and demolition, is probably not more than 150 million tons, or 6 percent of the total. The other 94 percent is converted into waste residuals as fast as it is extracted. Combustion and carbothe~mic reduction processes are the major sources of atmospheric pollutants today but by no means the only important ones; nor is the atmosphere the only vulnerable part of the environment. From a broader environmental perspective, the production and dispersal of thousands of synthetic chemicals many new to nature, and some highly toxic, carcinogenic, or mutagenic- and the mobilization of large tonnages of toxic heavy metals are of equally great concern. The complexity of the problem Is too great to permit any kind of short summary. However, two points are worthy of emphasis. First, as noted above, most materials "pass through" the economic system rather quickly. That is to say, the transformation from raw material to waste residual takes only a few months to a few years in most cases. Long-lived structures are very much the exception, and the more biologically "potent" materials are least likely to be embodied in a long-lived form. The second point is that many uses of materials are inherently dissipa- tive (Ayres, 1978~. That is, the materials are degraded, dispersed, and lost in the course of a single normal use. In addition to food and fuels (and additives such as preservatives), other materials that fall into this category include packaging materials, lubricants, solvents, flocculants, antifreezes, detergents, soaps, bleaches and cleaning agents, dyes, paints and pigments, most paper, cosmetics, pharmaceuticals, fertilizers, pesticides, herbicides, and germicides. Many of the current consumptive uses of toxic heavy met- als such as arsenic, cadmium, chromium, copper, lead, mercury, silver, and zinc are dissipative in the above strict sense. Other uses are dissipative in practice because of the difficulty of recycling such items as batteries and electronic devices. Bibles 2 and 3, which summarize estimates of emission coefficients for various heavy metals by use category and annual emissions attributable to

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INDUSTRIAL METABOLISM 27 dissipative uses, make clear the heterogeneity of the materials flows. In some cases the dissipation is slow and almost invisible. For instance, paints (often containing lead, zinc, or chromium) gradually crack, '~weather," and turn to powder, which is washed or blown away. Tires, which contain zinc (and cadmium) salts, are gradually worn away during use, leaving a residue on the roads and highways. Similarly, shoe leather, containing up to 2 percent chromium salts, is gradually worn away to powder during use. Incinerator ash contains fairly high concentrations of heavy metals from a variety of miscellaneous sources, ranging from used motor oil to plastics and pigments. On reflection, many dissipative uses (food and fuel again excepted) are generally seen to be nonessential in the sense that technologies are the- oretically available, or imaginable, that could eliminate the need for them. 1b take one example only: hydroponic agriculture in enclosed, atmospher- ically controlled greenhouses, with genetically engineered pest controls, would eliminate all losses of fertilizers and pesticides to watercourses by way of surface runoff. ENVIRONMENTAL IMPACT OF WASTE RESIDUALS Materials do not disappear after they are used up in the economic sense. They become waste residuals that can cause harm and must be disposed of. In fact, it is not difficult to show that the tonnages of waste residuals are actually greater than the tonnages of crops, timber, fuels, and minerals recorded by economic statistics. Although usually unpriced and unmeasured, both air and water are major inputs to industrial processes and they contribute mass to the residuals-especially combustion products. Residuals tend to disappear from the market domain, where everything has a price, but not from the real world in which the economic system is embedded. Many services provided by the environment derive ultimately from "common property," including the air, the oceans, the genetic pool of the biosphere, and the sun itself. Distortions in the market (i.e., prices) are unavoidably associated with the use of common property resources. Clearly, environmental resources such as air and water have been unpriced or (at best) significantly underpriced in the past. For this reason, such resources have generally been overused.2 As noted, the total mass of waste residuals produced each year by industrial metabolism far exceeds the mass of active inputs derived from economic activities. This is because nearly half of the inputs other than air and water are fossil fuels (hydrocarbons), which combine with atmospheric oxygen and form carbon dioxide and water vapor. The carbon fraction of hydrocarbons ranges from 75 percent in methane to about 90 percent

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28 TABLE2 Consumption-Related Emissions Factors: Heavy Metals ROBERT U LYRES Painting Paint Electron Other Metallic and and Tubes and Electrical Metal usea Coatingb PigmentsC Batteries d Equipment Silver 0.001 0.02 0.5 0.01 0.01 Arsenic 0.001 0 05 0.01 N^. Cadmium 0.001 0.15 05 0.02 N^. Chromium 0.001 0.02 05 N^. N^. Copper 0.005 0 1 N^. 0.10 Mercury 0.050 0.05 0.8 0.20 N^. Lead 0.005 0 0.5 0.01 NA. Zinc 0.001 0.02 05 0.01 N^. N^. = Not applicable. aAlloys or amalgams (in the case of mercury) not used in plating, electrical equipment, catalysts, or dental work. Losses can be assumed to be due primarily to corrosion, except for mercury, which volatilizes. b Protective surfaces deposited by dip coating (e.g., galvanizing), electroplating vacuum deposition, or chemical bath (e.g., chromic acid). The processes in question generally resulted in significant waterborne wastes until the 1970s. Cadmium-plating processes were particularly inefficient until recently. Losses in use are mainly due to wear and abrasion (e.g., silve~plate) or to flaking (decorative chrome trim). In the case of mercu~y-tin "silver" for mirrors, the loss is largely due to volatilization. Paints and pigments are lost primarily by weathering (e.g., for metal-protecting paints), wear, or disposal of painted dyes or pigmented objects, such as magazines. (::opper- and mercury-based paints volatilize slowly over time. A factor of 0.5 is assumed arbitrarily for all other paints and pigments. dIncludes all metals and chemicals (e.g., phosphorus) in tubes and primary and secondary battenes, but excludes copper wire. Losses in manufacturing may be significant. Mercury in mercury vapor lamps can escape to the air when tubes are broken. In all other cases it is assumed that discarded equipment goes mainly to landfills. Minor amounts are volatilized in fires or incinerators or lost by corrosion. Lead-acid batteries are recycled. Includes solders, contacts, semiconductors, and other special materials (but not copper wire) used in electrical equipment control devices, instruments, etc. Losses to the environment are primarily through discard of obsolete equipment to 1andfi11s. Mercury used in instruments may be lost through breakage and volatilization or spillage. in anthracite. Petroleum is intermediate. Every ton of fuel carbon is converted into 3.67 tons of carbon dioxide emitted to the atmosphere.3 It is thought that only about half of this amount remains in the atmosphere, but the carbon dioxide level of the earth's atmosphere has risen over the past century from about 290 parts per million (ppm) to around 344 ppm at present. Although the magnitude of the climatic warming (the "greenhouse

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INDUSTRIAL METABOLISM 29 Chemical Agri- Nonagri Uses Not cultural cultural Medical, Miscella Metal Embodiedf Embodiedg Uses h Uses i Dental3 neous k Silver 1 0.40 N^. N^. 0.5 0.15 Arsenic N^. 0.05 0.5 0.8 0.8 0.15 Cadmium 1 0.15 NA. N^. N^. 0.15 Chromium 1 0.05 N^. 1 0.8 0.15 Copper 1 0.05 0.05 1 NA. 0.15 Mercury 1 NA. 0.80 0.9 0.2 0.50 Lead 1 0.75 0.05 0.1 NA. 0.15 Zinc 1 0.15 0.05 0.1 0.8 0.15 fuses not embodied in final products include catalysts, solvents, reagents, bleaches, etc. In some cases a chemical is embodied but there are some losses in processing. Losses in chemical manufacturing are included here. Major examples include copper and mercury catalysts (especially in chlorine manufacturing); copper, zinc, and chromium as mordants for dyes; mercury losses in felt manufacturing; chromium losses in tanning,; lead in desulfunzation of gasoline; and zinc in rayon spinning. In some cases, annual consumption is actually loss replacement and virtually all of the material is dissipated. Detonators such as mercury fulminate and lead azide (and explosives) are included in this category. "Uses embodied in final products other than paints or batteries include fuel additives (e.g., tetraethyl lead), anticorrosion agents (e.g., zinc dithiophosphate), initiators and plasticizers for plastics (e.g., zinc oxide), wood preservatives, and chromium salts embodied in leather. Losses to the environment occur when the embodying product is used, for example, gasoline containing tetraethyl lead is burned and largely (lasso) dispersed into the atmosphere. However, copper, chromium, and arsenic are used as wood preservatives and dispersed only if the wood is later burned or incinerated. In the case Of silver (photographic film), it is assumed that 60% is later recovered. Includes agricultural pesticides, herbicides, and fungicides. Uses are dissipative, but heavy metals are largely immobilized by soil. Arsenic and mercury are exceptions because of their volatility. i Biocides used in industrial, commercial, or residential applications. Loss rates are higher in some cases. j Includes primarily pharmaceuticals (including cosmetics), germicides, etc., as well as dental filling matenal. Most uses are dissipated to the environment through wastewater. Silver and mercury dental fillings are likely to be buried with cadavers. k Miscellaneous emissions not counted elsewhere. SOURCE: Ayres et al. (1988~. effect") due to the rising level of carbon dioxide is still quantitatively uncertain, the qualitative impact is likely to be adverse. Carbon monoxide is, of course, toxic to humans and has been impli- cated in health problems among urban populations. It is less well known that carbon monoxide plays an active, and not necessarily benign, role in a number of atmospheric chemical reactions before it is ultimately oxidized to carbon diomde. Inefficient combustion processes convert up to 10 percent

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30 ROBERT U LYRES TABLE 3 Emissions from Consumptive Uses: Heavy Metals, United States, 1980 (metnc tons) Metallic Uses Electrical (E!xcept Protective Coverings Other Coatings Plating Paints Batteries Electrical and and and and Uses, Instru Metal Electrical) Coating Pigments Equipment meets, etc. Silver 0.83 a o.o 0.15 0.67 Arsenic 0.04 0.0 0.0 1.97 0.0 Cadmiumb 0.04 136.1 116 7.81 0.0 Chromium 151.80 155.7 6,490 0.0 0.0 Copper c 11,074.00 0.0 0.0 0.0 0.0 Mercury 0.0 0.0 0.0 195.91 1752 Leadc 1,249.00 0.0 48,S00 8,510.00 0.0 Zinc 514.00 8,778.0 77,750 63.00 0.0 bIncluded in first column. cl979. 1977. SOURCE: Ayres et al. (1988). Of fuel carbon into carbon monoxide; carbothermic reduction of iron ore and other metals generates even higher percentages. However, the average percentage over all processes is much smaller. Actual emissions of carbon monoxide to the atmosphere in the United States were about 110 million tons in 1970 (mostly from automobiles and trucks), with a carbon content of 47 million tons. Emission controls reduced the net output of carbon monoxide in 1980 to about 85 million tons (U.S. Environmental Protection Agency, 1986~. The discovery of chlorofluorocarbons (CFCs) in the stratosphere has raised an even more frightening prospect: ozone depletion (see Glas, this volume). In apparent confirmation of this phenomenon, an "ozone hole" has recently appeared in the stratosphere over Antarctica. This "hole" has reappeared each spring for several years and seems to be growing (Clark, 1987; Miller and Mintzer, 1986~. Chlorofluorocarbons are chemically inert gases, discovered in 1928 and produced since the 1930s mainly as refrigerants and solvents and for "blowing" plastic foams (see Friedlander, this volume). The major use is for refrigeration and air conditioning. In most uses, CFCs are not released deliberately, but losses and leakage are inevitable. The problems revealed so far may be only the beginning. If (perhaps it is better to say "when") the ozone level in the stratosphere is depleted, the effect will be to let more of the sun's ultraviolet radiation through to

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INDUSTRIAL METABOLISM Chemical _Biocidal Consumer Poison Uses Industrial Uses, Nonagri Catalysts, Additives, Agriculturalcultural Medical, Reagents, Extenders, Pesticides,Pesticides Dental, Explosives,Photography, Herbicides, (Except Pharma- Miscel etc.etc. Fungicides Medical) ceutical laneousTotal _ 7.648 0 0 15; 0.4560 492.00 2,950 5,901 19.70 09,364 029 0 0 0 0.98290 1,297.03,890 0 1,038 0 2,141.0011,659 4,222.00 1,560 0 0 015,452 412.10 16 236 8.36 6.96893 OO O O 0 1,329.0056,900 2,508.018,622 188 251 1,003.00 0109,670 31 the earth's surface. One likely impact on humans is a sharp increase in the incidence of skin cancer, especially among whites. The ecological impact on vulnerable plant or animal species cannot be estimated, at present, but could be severe. Methane, oxides of nitrogen (NO=), and sulfur oxides (SO=) are other residuals that have been seriously implicated in climatic or ecological effects. All three are generated by fossil fuel combustion, as well as other industrial processes. Like carbon monoxide, carbon dioxide, and the CFCs, they can be considered as metabolic products of industry. Methane is released in natural gas pipelines, petroleum drilling, coal mining, and several kinds of intensive agriculture (especially rice cultivation or cattle and sheep farming). Nitrogen oxides are also coproducts of combustion. In effect, at high temperatures, some of the atmospheric nitrogen is literally "burned." Nitrogen oxides are implicated in many atmospheric chemical reactions (including those that create smog) and eventually oxidize to nitric acid, which contributes to acid rain. In the stratosphere, where nitrogen oxides are decomposed by ultraviolet radiation, atomic nitrogen also contributes to the destruction of ozone. Finally, oxides of nitrogen are "greenhouse gases" that contribute to climatic warming (Miller and Mintzer, 1986~. Sulfur oxides are generated by the combustion of sulfur-containing fuels-especially bituminous coal-and by the smelting of sulfide ores. Most copper, lead, zinc, and nickel ores are of this kind. In principle, sulfur can be recovered for use from all these activities, and the recovery rate is rising. However, the costs of recovery, especially from coal-burning electric power plants, are still far higher than the market value of the potential products (e.g., dilute sulfuric acid). Hence, for the present,

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32 ROBERT U LYRES calcium sulfites and sulfates-as well as SOc-constitute a waste residual that must be disposed of. This is also true of fly ash.4 These examples show that although today's industrialized economic system may be in rough equilibrium in terms of supply and demand rela- tionships, it is far from equilibrium in thermodynamic terms. Enormous quantities of fossil fuels and high~uality minerals are extracted each year to drive the economic engine. The economic system is stable somewhat in the way a bicycle and its rider are stable: if forward motion stops, the sys- tem will collapse. Forward motion in the economic system is technological progress. EVOLUTION OF INDUSTRIAL PROCESSES It is generally accepted by economists that the mechanism that normally drives the evolution of industrial processes is technological innovation. The primary incentive for taking risks appears to be economic. A new process that saves one link in the chain between raw materials and finished ma- terials or final goods can usually be justified through savings in materials and energr inputs or capital requirements, if not both. Moreover, process technology is inherently easier to protect from piracy than product tech- nology. As noted, most chemical products are intermediates used in the production of other chemicals. Thus, final products result from chains, or sequences, of processes with an overall energy conversion efficiency that is the arithmetic product of the conversion efficiencies at each stage.5 If the typical chain has three steps, each of which has a conversion efficiency of 0.7, the overall conversion efficiency of the chain is about 0.34. A four-step chain would have an overall efficiency of around 0.24. That is, the available energy embodied in the final product might be somewhere between 25 and 35 percent of the available energy of the original feedstocks. Because primary feedstocks are essentially indistinguishable from fuels, efficiency improvements translate directly into cost savings. Clearly, a powerful long-term strategy for improving overall effective- ness in production is the development of new processes to shorten these process chains, bypassing as many intermediates as possible. In other words, one would like to be able to produce final products such as polyethylene or synthetic rubber directly from first-tier intermediates or even from primary feedstocks such as ethane and propane.6 Biological organisms differ from industrial organizations in that they are able to build complex molecules directly from elementary building blocks with relatively few intermediates. Thus, biotechnology offers a long-term prospect of radically higher produc- tion efficiencies and correspondingly lower costs (U.S. Office of Technology Assessment, 1982~. Another long-term strategy for increasing effectiveness is better use of

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INDUSTRIAL METABOLISM 33 by-products and wastes. When a process can be justified on the basis of the market for its primely product, by-product sales can be highly profitable. This positive motivation to seek new uses is compounded by the fact that, because of some of the environmental problems already noted, waste generation is being increasingly discouraged by environmental regulation. Moreover, waste disposal is increasingly expensive, and the cost is becoming more uncertain. Firms that buried toxic chemical wastes many years ago in landfills (methods that were regarded as acceptable at the time) are sometimes finding themselves saddled retroactively with heavy costs of digging up the same wastes and disposing of them again in a safer manner. The chemical waste dump used by Hooker Chemical Company at Love Canal, near Niagara Palls, is one example. Meanwhile, suitable sites for disposal of hazardous solid or liquid wastes are becoming scarce.7 Ma- terials that are recovered and reused internally or embodied in marketable products that can be readily and effectively recycled are less likely to cause this kind of problem.8 The incentives for technological innovation in the area of waste re- duction and disposal are not always operating, especially where there are massive market failures. In practice, the "unpaid" environmental damage costs have been deferred and many of them will have to be paid by later generations. But as these costs become larger and more visible, there will be growing political pressure to force the producers and users of fossil fuels (and other materials such as heavy metals) to pay the costs of abat- ing the resulting environmental damages.9 Notwithstanding resistance by energy users, it seems inevitable that in the long run these costs will be added to the prices of fuels and materials. This, in turn, will create sig- nificant economic opportunities for innovations in the area of "low-waste" technologies. EVOLUTIONARY ECONOMICS AND GAIA One view of evolution and probably the most common view among scientists-can be characterized as "the myopic drunkard's walk" The drunkard's walk is not exactly random, but it tends to follow the path of least resistance in the short run. If a mutation or an innovation offers short- term advantages, it will be adopted. In this view, there is no long-range force or tendency to approach a distant goal. I,here is no Aristotelian "final cause." Most scientists tend to regard more teleological theories, including Lovelock's Gala hypothesis ~velock 1988), with skepticism, because of their aroma of mysticism. In the case of biological evolution, indeed, it was difficult for a long time to suggest a likely mechanism whereby short-term advantages to the individual could in some cases be overridden in favor of longer-term benefits

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84 JESSE H. AUSUBEL 10 10-1 Watt INewcomen , Saverv I 10-2 10-3 ~ 1700 1800 1900 2000 Triple Parsons Expansion 1 :.] Fluorescent li a' /~ HT Steam ~Turbine Cornish Tungsten ~` / filament / / ,~~ ~ Prime Movers Cellulose ~ /. t 1 - 50% = 300 yr Filament:/ Edison's ,7 First Lamp/ /:- Paraffin / ~ t 1 - 50% = 80 yr Candle / Mercury Sodium// / Lamp Lamp Lamp / /~ Ammonia Production | At 1 - 50% = 70 yr - Lamps Year 50 to ce 1 .0 0.1 FIGURE 13 Examples of increasing energy efficiency. Prime movers, lamps, and ammonia production are measured as machines or processes for energy transformation according to the second law of thermodynamics. Onginal analyses are by 1~ M. Slesser, University of Strathclyde, Scotland. SOURCE: Marchetti (1983~. is currently more environmentally attractive at the cost of efficiency. A1- though the overall long-term evolution of energy systems appears to be in the direction of both efficiency and environmental compatibility, at vari- ous levels and times the system may not be optimizing for both of these objectives or they may be in conflict. From transportation and energy, let us turn to materials, which figure prominently in the chapters by Herman et al. and by Ayres in this volume. Simple extrapolations of the kind used above have often been troublesome and unsuccessful as aids in projecting consumption of materials. As shown in Figure 14, past projections of demand for certain key materials remind us why studies such as those of Meadows et aL (1972) in the early 1970s foresaw extremely severe problems of both exhaustion of mineral resources and pollution associated with mineral use. What happened to create the gap between the extrapolated trends and realibr? Systems prove to be bounded in a varieW of ways, so that exponential growth does not persist indefinitely. In the case of materials, several factors have been at work, including economic growth rates, shifts in the composition of economies from manufacturing to services, and resource- saving technologies. But most important may be smart engineering that made feasible the substitution of plastics, composites, ceramics, and optical

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REGULARITIES TV TECHNOLOGICAL DEVELOPMENT 40C 30 20 10 0~ 1950 1960 800 600 Year Steel Aluminum Projected ,, I i 1970 1 980 Projected' ~~M o 1955 19601970 1980 Year 10 Zinc Projected Hi' 1960 1970 1980 Year 85 0.8 10 8 6 4 2 o 1950 1 960 .2 Copper Projected '' Actual 1970 1 980 Year Nickel Projected '' 0.0 _ 1950 1960 1970 1980 Year FIGURE 14 Actual materials consumption for five metals, 195~1985, and projections made in 1970 for 197~1985. SOURCE: Tilton (1987~. materials for metals, that is, the continuing replacement of metals with nonmetals and the associated overall decrease in metal needs. The telecommunications sector provides a vivid example (Figure 15~. In 1955, telecommunications cables were made almost entirely of copper, steel, and lead. By 1984, close to 40 percent of the materials used were plastics. If substitution of lead by polyethylene for cable sheathing had not taken place, consumption of lead by AT&T alone might have reached a billion pounds per year, an amount to create considerable anxiety from the point of view of environment, given the toxic properties of lead. Herman et al. (this volume) have examined the possible "dematerialization" of the .,

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86 JESSE H. AUSUBEL automobile. In considerable part, the phenomenon again has to do with the substitution of plastics for metals, as implied by Figure 16. Overall, there appears to be a decreasing dependence on common metals, perhaps combined with greater need for less common metals (Hib- bard, 1986~. There is also growing use of metals in the form of composites, coatings, films, and artificial structures. As Ayres (this volume) suggests, use of metals in such areas as electronics may dissipate more broadly and rapidly because many of the uses are highly dispersed and thus also entail greater complexity in recycling. The difficulty is that good data are not readily available, and may not exist, to back up such generalizations firmly. In 1976 Goeller and Weinberg sought to develop baseline information for what they termed the "age of substitutability." One of the notions they introduced was that of "demandite," the average nonrenewable resource used by human society. They defined demandite by taking the total extraction in moles of elements such as copper and iron and selected compounds (e.g., hydrocarbons) and computing the average hypothetical chemical composition of one demandite molecule (or average mole percent composition). Goeller and Weinberg excluded renewable resources, such as agricultural products, wood, and water, from demandite but looked at them in another portion of their study. Able 2 shows the result for the United States and for the world, for 1968, the most current year for which Goeller and Weinberg were able to perform the calculation in the mid-1970s. The dominance of hydrocarbon is spiking. It is interesting that in 1968 the United States had a more favorable hydrogen-to-carbon ratio than the world as a whole, partly offsetting from an environmental perspective the fact that U.S. energy consumption is so high. Broadly speaking, the need is apparent for developing and applying concepts like "demandite" on a regular basis. With steady monitoring, such approaches might serve as indicators that would alert us to substitution processes, improving projections and reducing the likelihood of the kind of erroneous projections shown in Figure 14. At a specific level, it is evident that, just as some environmental concerns about metals use may be decreasing, more attention must be given to plastics and paper, as also argued by Herman et al. (this volume) and Ayres (this volume). Although according to one estimate per capita use of materials in the United States remained constant between 1974 and 1985 at about 20,000 pounds per year, use of paper increased by about 25 percent to about 650 pounds, and use of plastics increased by about 40 percent to 180 pounds (Hibbard, 1986~. The latter figure is an obvious and essential part of the explanation for the recent widely reported concerns about the deterioration of environmental quality at beaches in the United States and Europe (see Lynn, this volume).

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88 JESSE H. AUSUBEL 10 - ~8 a) a) 6 - ._ - a) a) 4 2 o O Ward's Data (U.S. Fleet) , ' - Ford Fleet f it, o ~ , O O I 1 1 1 Projected 1960 1970 1980 1990 Model Year FIGURE 16 mends in plastics content of U.S. passenger cars. Included is increased use of plastics in bumped, fuel tanks, air cleaners, and wheel covers, but not in body panels, for which construction in plastic is also increasingly feasible. SOURCE: Gjostein (1986~. In the search for advanced materials, we may be creating materials that are virtually immortal. One wonders, for example, whether the new marvelously strong materials increasingly popular for heavy-duty envelopes are as readily recycled or biodegradable as old-fashioned paper. From an environmental point of view, electronic memory would indeed be a sought-after substitution for paper as a medium for storing information, if it could be made long-lived and reliably reproducible. Also attractive is the notion of replacing packaging itself; food irradiation, for example, may be environmentally desirable if it can significantly reduce the required volume of packaging materials. 1b summarize, there is intriguing evidence of long-term regularities in the evolution, diffusion, and substitution of technologies. Understanding these regularities is of value for both environmental research and man- agement. From numerous illustrations available in transport, energy, and materials it is evident that there is need to increase scrutiny of environ- mental problems and opportunities associated with growth of air transport; increasing reliance on natural gas; and disposal of plastics. Clear possibili- ties exist for the development of illuminating indicators, such as trends in the hydrogen-to carbon ratio and the composition of demandite, connected to technologies and resources that would be valuable in our diagnoses

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REGUI~UTIES IN TECHNOLOGICAL DEVELOPMENT TABLE 2 Average Nonrenewable Resources Used by Man in 1968, ~Demandite~ Atomic Percent Resource United States World CH 2.14 80.22 - CH 1.71 ~ 66.60 SiO 2 11.15 21.17 CaCO3 453 8.1S Fe 1.10 1.45 N 0.76 0.68 O 053 0.4S Na 053 0.45 C1 053 0.45 S 0.23 0.23 P 0.08 0.07 K 0.07 0.07 A 0.11 0.07 Cu. Zn,Pb 0.04 0.04 Mg 0.04 0.04 X 0.08 0.08 NOTE: Here, X represents all other chemical elements: highest in order of demand are Mn, Ba, Cr. F. Ti, Ni, Ar, Sn, B. Br, Zr, others account for less than 100,000 tons per year worldwide or less than 30,000 tons per year in the United States. The term CH refers to the combination of coal, oil, and natural gas, which are all made up of carbon and hydrogen in different ratios. The subscript refers to the average hydrogen-to carbon ratio. SOURCE: After Goeller and Weinberg (1976~. 89 and prognoses of environmental quality. We should not underestimate our technological ingenuity with respect to the environment nor the enormous dimensions of the systems requiring successful application of that ingenuity. ACKNOWLEDGMENTS I would like to thank William Clark Robert Frosch, Arnulf Grubler, Nebojsa Nakicenovic, and Stephen Schneider for sharing many ideas that led to this paper and Hedy Sladovich for research assistance.

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9o JESSE H. AUSUBEL NOTE 1. Mathematically, a logistic function may be denoted by x/(tc -x) = exp( OCR for page 23
REGUI~IES IN 17EC}:INOLOGICAL DEVELOPMENT 91 Marchetti, C, and N. Nakicenovic. 1979. The Dynamics of Energy Systems and the Logistic Substitution Model. RR-79-13. I>xenburg, Austria: International Institute for Applied Systems Analysis. Meadows, D. H., D. Lo Meadows, J. Randets, and W. W. Behrens III. 197Z The Limits to Growth. New York: Universe Books. Montroll, E. W., and W. W. Badger. 1974. Introduction to Quantitative Aspects of Social Phenomena. New York: Gordon and Breach. Montroll, E. W., and N. S. Gael. 1971. On the Volterra and other nonlinear models of interacting populations. Reviews of Modern Physics 43~2~:231. Nakicenovic, N. 1984. Growth to Limits: Long Waves and the Dynamics of Technology. I~enburg, Austria: International Institute for Applied Systems Analysis. Nakicenovic, N. 1985. The automotive road to technological change: Diffusion of the automobile as a process of technological substitution. Technological Forecasting and Social Change 29.309~340. Nakicenovic, N. 1988. Dynamics and replacement of U.S. transport infrastructures. Pp. 175-221 in Cities and Their Vital Systems: Infrastructure Past, Present, and Future. J. H. Ausubel and R. Herman, eds. Washington, D.C.: National Academy Press. National Research Council. 1986. Acid Deposition: Long-Term [Lends. Washington, D.C.: National Academy Press. National Research Council. 1988. Annual Report of the Strategic Highway Research Program (October 31, 1988~. Washington, D.C Olson, S. H. 1971. The Depletion Myth: A History of Railroad Use of Timber. Cambridge, Mass.: Harvard University Press. Reed, H. S., and R. H. Holland. 1919. Ihe growth rate of an annual plant helianthus. Proceedings of the National Academy of Sciences 5:135-144. Schumpeter, J. A. 1939. Business Cycles: A Theoretical, Historical, and Statistical Analysis of the Capitalist Process, Vols. I and II. New York: McGraw-Hill. Stewart, H. B. 1988. Recollecting the Future. Homewood, Ill.: Dow Jones-I'win. Tilton, J. E. 1987. Long-run growth in world metal demand: An interim report. Mineral Economics and Policy Program. Colorado School of Mines. Van Duijn, J. J. 1983. Ihe Long Wave in Economic Life. London: Allen and Unwin. Volterra, V. 1927. Variations and fluctuations in the number of coexisting species. Pp. 6~236 in Ihe Golden Age of Theoretical Ecology 1923 1940, F. M. Scudo and J. R. Ziegler, eds. New York: Springer, 1978.

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The Promise of Technological Solutions

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