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7 Research Challenges for Material Flows Accounting Chapter 1 notes that attempts to solve increasingly complex sys- temic problems are likely to benefit from enhanced versions of material flows accounts. Consequently, the study and use of ma- terial flows accounting have a substantial need for research in new meth- ods of material flows accounts and analysis. The research needs fall into two broad categories: first, as the development of the material flows ac- counting system progresses, research will facilitate successive improve- ments as the system matures; second, material flows accounts will pro- vide an important foundation and structure for integrating data. These data could be used to support an emerging National Science Foundation (NSF) program focusing on the need for "environmental synthesis to frame integrated interdisciplinary research questions and activities and to merge data, approaches, and ideas across spatial, temporal, and societal scales" (NSF Advisory Committee for Environmental Research and Edu- cation, 2003~. The most common and simplest material flows analysis is one performed for a single geographical region, for a single material, and at a specific point in time, for example, the amount of steel entering the United States in one year. There are, however, a number of types of mate- rial flows accounts that could be developed, each of which has the poten- tial to bring additional insights or to provide additional utility. Few of these extensions of existing standard material flows accounts (primarily in Europe) have been explored extensively by scientists or economists. Nonetheless, it is potentially beneficial to investigate the ways in which they might best be assembled, characterized, and integrated with the more standard types of material flows accounts and the ways in which they 83

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84 MATERIALS COUNT might be made most efficacious. This chapter presents examples of some of these potential extensions to standard material flows accounts and analysis methods and briefly discusses their status and prospects. These examples illustrative, not comprehensive are largely enhancements of the standard material flows accounting structure and, thus, would be ex- pansions of the proposed material flows accounting framework for the United States. They are windows into the future potential of material flows accounting and analysis. SPATIALLY DISCRETE MATERIAL FLOWS ACCOUNTS A spatially discrete material flows account is one that quantifies stocks and/or flows for a specific geographic area and also locates those stocks and/or flows at specific spatial locations within the area. Most current material flows accounts refer to a specific geographical area (usually a country), but not to the spatial locations of the various stocks and flows within that area. Spatial information would help identify opportunities for resource sharing among industrial firms, the development of collec- tion and processing plans for discarded material, and analyses of the po- tential for environmental impacts resulting from material dissipation. As an example of a spatially discrete material flows account, Plate II(a) shows the spatial population in China, coded by density, and Plate II(b) shows the light emitted from energy-utilizing activities in China as monitored by satellite. (Light has been shown to be a fairly accurate mea- sure of total energy consumption; Elvidge et al., 1997~. Plate II(c) com- bines the two images. It is immediately apparent that Hong Kong (bottom, right of center) is using energy at a high rate, more or less consistent with its high population density. In west central China, however, a large popu- lation is using extremely modest amounts of energy. Spatial information on materials and energy utilization not only reveals the current resource use (fossil fuel energy in this case), but also provides a basis for thinking about trends, possible future scenarios, and policy options for the further development of China's energy infrastructure. There are a few other examples of spatially discrete material flows account-related studies. In one, energy use in Osaka has been analyzed spatially (Shimoda et al., 2002~. In another, the stocks of copper in Cape Town, South Africa, have been estimated (van Beers and Graedel, 2003~. A number of geographical information system databases provide plat- forms upon which materials stocks and flows might be studied. These spatially discrete databases include urban water supply systems, locations of residences and industrial buildings, and population densities; they have seen little use thus far for material flows accounting purposes. The construction and analysis of spatially discrete material flows ac-

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RESEARCH CHALLENGES FOR MATERIAL FLOWS ACCOUNTING 85 counts must be explored for a number of sample materials and locations. Urban areas are probably the most beneficial places to begin because they are major reservoirs of in-use materials and because supporting geo- graphic information is often available. Two approaches might be taken: (1) "top-down" (i.e., taking higher-level spatial data and distributing it spatially by some protocol), and (2) "bottom-up" (i.e., taking representa- tive spatial data on a locally distributed basis and assembling them by some protocol for the entire region or nation). Research using both ap- proaches is needed. MATERIAL FLOWS ACCOUNTS OF LINKED SYSTEMS A substantial complexity in material cycle analyses arises if two or more cycles are closely coupled that is, if a change in stocks or flows, for example, in the cycle of one chemical species significantly influences the cycle of another. In such cases, accounting approaches that treat the cycles as completely independent will not capture the complexity of the actual situation. Cycles can be coupled in two different ways: by source and by use. The cycles of carbon dioxide and methane are source coupled, for ex- ample, since the combustion of fossil fuels produces both gases. Alterna- tively, the cycles of carbon and nitrogen are use coupled, since plant growth is related to carbon dioxide as a source of carbon for leaf produc- tion and to deposited nitrogen as a fertilizer. A technological example of a source-coupled system is that of zinc and lead. Geological processes of zinc and lead ore formation have strongly coupled the sources of these two metals. The principal ore min- eral containing zinc, sphalerite (ZnS, 67 percent zinc), accounts for 90 per- cent of zinc production. Sphalerite is usually found in association with galena (PbS), the principal source of lead, as at Mount Isa in Australia, one of the world's largest zinc deposits. Here the ore occurs as finely dis- seminated bands of galena and sphalerite, often with some pyrite (FeS2), in the host rock, and typically contains 6.5 percent zinc and 5.7 percent lead. Since zinc and lead commonly occur together, the production of one is closely coupled to that of the other. In addition, cadmium atoms fre- quently substitute for those of zinc in sphalerite, and the processing of that ore is the leading source of commercial cadmium. One way in which material cycle coupling occurs in use is when two or more metals are combined into an alloy such as bronze (copper and tin), inconel (copper and nickel), or stainless steel (iron, nickel, and chro- mium). Additional use coupling occurs in the copper-zinc system when more complex brass-like alloys are made. The brass-lead coupled system is used in castings for plumbing fixtures (which is now being phased out

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86 MATERIALS COUNT in favor of other, lead-free alloys) and the screw-machine stock used in large quantities to make fasteners. In the case of natural systems, a modest amount of attention has been given to the coupling of carbon and nitrogen, as mentioned above. For anthropogenic systems, virtually no attention has been paid to identifica- tion and analysis other than the recognition that coupled cycles exist. Few materials have cycles that are substantially independent, yet there is little in the way of analytical approaches to linked cycles. A few studies of such cycles should be undertaken to begin the development of tools for their analysis. DYNAMIC MATERIAL FLOWS ACCOUNTING Dynamic material flows accounting examines changes in stocks and flows rather than the stocks and flows themselves. Dynamic material flows accounts look to historical information on materials generation and use to study trends over time. The data requirements are substantially greater than for traditional material flows accounts since time histories must be generated and analyzed. The flow of stocks of polyvinyl chloride plastic from use to waste management over time is the subject of a demonstration model for a dy- namic material flows account conducted by Kleijn et al. (2000~. In this work, the rate of generation of discards of polyvinyl chloride plastic was modeled using different assumptions of inflow and lifetime relative to different uses (Figure 7.1~. The rate can differ substantially depending on the values of relevant variables, few of which are currently monitored. If such data are routinely available, planning for recycling, energy recovery, and disposal could be undertaken with significantly increased confidence. Another area in which dynamic flow information would be useful is in evaluating the effects of initiating a large new use of a material or of discontinuing an existing large use. An example of the challenges in this regard is presented by the use of platinum in catalytic converters for auto- mobiles. Regulations in North America and elsewhere, designed to re- duce the emissions of smog-forming chemicals, mandated the use of cata- lytic converters by the mid-1970s (Hegedas and Gumbleton, 1980~. Because each converter contains several grams of platinum group metals, a new demand for these metals emerged, doubling their production from virgin ores in less than a decade. It took some 20 years for converters to become ubiquitous in the countries where regulations existed (Grubler, 1998), and the supply system was able to ramp up sufficiently to meet the demand. The situation remains uncertain at this point because increased requirements in greater number of countries coincide with possible major uses of platinum group metals in electronic circuits (Gediga et al., 1998),

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88 MATERIALS COUNT in fuel cells (Appleby, 1999), or in batteries (Dyer, 1999). Should any of these situations occur, platinum supplies for catalytic converters would once again become problematic. Uses of materials demonstrate price elas- ticity in some cases that is, a rapid increase in the price of a material in use inspires a shift to a cheaper material. Prices are not simply signals of abso- lute scarcity; they more often reflect shorter-term conditions such as the rate of economic growth, tariffs or other trade barriers, or political or so- cial instability. Thus, where a simple substitution (e.g., plastic for metal) is available, price elasticity drives substitution. Where the application is highly dependent on a specific material (e.g., platinum group metal cata- lysts), price signals are reflected only weakly and over long time periods as far as substitution is concerned. Dynamic material flows data are currently available only opportunis- tically and generally only for the early stages of resource cycles. As noted in earlier chapters, the U.S. Geological Survey, for example, has good dy- namic data for mining and processing of metals, but not in general for manufacturing or waste management. It would be advisable to conduct a few investigations of comprehensive dynamic cycles in order to evaluate how challenging it would be to gather such data routinely and how much value might arise from their efforts. MULTILEVEL MATERIAL FLOWS ACCOUNTS A multilevel material flows account is one that is carried out in such a way that more than one level (e.g., state, country, and region) is treated as part of a single analysis. Individual material flows analyses have been conducted almost entirely at a single spatial level. This approach strongly resembles the tendencies in biological ecology to restrict one's studies to a single temporal and spatial level, for example this season's vernal pools or half-hectare ecosystems or landscapes, thus avoiding the challenges of studying "how the signatures of actions at one level manifest themselves at levels higher and lower" (Levin et al., 1997, p. 334). In financial ac- counts, multilevel approaches (at city, state, and federal levels, for ex- ample) are not uncommon and have demonstrated much value in under- standing and relating otherwise uncorrelated information. In material flows accounts there is also evidence that these multilevel issues are im- portant, perhaps even crucial. Environmental, resource, and technology issues clearly intersect at different levels, as when energy use in rural Ala- bama contributes to the potential for global climate change or when the rate of extraction of metal ores is dramatically changed by population migration to rapidly evolving cities. The stocks and flows project at Yale University has recently completed a contemporary copper cycle on several spatial levels (Graedel et al., 2003).

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RESEARCH CHALLENGES FOR MATERIAL FLOWS ACCOUNTING 89 The work treats in detail four stages of resource life: extraction and pro- cessing, fabrication, use, and end of life. The data set consists of cities (2 examples), countries (61 examples), regions and continents (9 examples), and the world. Assessments for 14 types of copper use are followed for each country and then aggregated to regional and global scales. As an example of the results, comparative annual rates of copper en- tering use in Asian countries around 1994 are shown in Plate III(a). It is of interest to note that the rates are identical for China and lapan at 1,200 gigagrams of copper per year, far higher for those two countries than for any others. South Korea and Taiwan have annual rates that are roughly equivalent at around 400 gigagrams of copper per year, about one-third of those of China and lapan. The rates for Malaysia and Hong Kong are a factor of two lower still. Several countries group around annual use levels of about 20 to 100 gigagrams of copper per year. Results for the same parameter on a regional basis are shown on the world map in Plate III(b). These rates of use, like those of individual coun- tries, reflect both domestic production and product imports. Asia's rate is the highest, but it is not much greater than those of Europe and North America. The rates for all other regions are less than 10 percent of those of the top three. This early example of the development of a multilevel material flows account is promising, but clearly represents work in progress. It is advis- able to explore multilevel material flows accounts for a number of differ- ent materials systems and locations in order to gauge their potential use- fulness. The topic remains a potentially rich area for research leading to substantial practical applications. MATERIAL FLOWS ACCOUNTS OF NATURAL SYSTEMS Material flows accounts can, in principle, be constructed for any sys- tem, whether or not the system contains human agents. For example, one could think of nutrient, carbon, or energy flows accounts for natural eco- systems as examples of material flows accounts of natural systems. This type of accounting has, in fact, been popular and useful in ecosystem ecol- ogy (Lindeman, 1942; Hannon, 1973~. The fact that material flows accounts can be constructed for any system also makes them good candidates for comprehensive analysis of linked natural and human systems (e.g., Isard et al., 1972~. The most common type of natural system material flows ac- count has been the type that traces a single element though the various compartments of the system. For example, nitrogen, carbon, phosphorus, and other elemental "budgets" or accounts have been constructed for a wide range of ecosystems at multiple scales from small microcosms to the entire Earth.

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So MATERIALS COUNT In addition to single-element material flows accounts, multielement (or multicommodity) material flows accounts have also been constructed for natural systems (Costanza et al., 1983) and for linked natural and hu- man systems (e.g., Patterson, 2002~. These studies have shown the feasi- bility and utility of constructing multicommodity material flows accounts that can address the interdependences among commodities. A major limitation in constructing material flows accounts for natural and linked human-natural systems (as with all material flows accounts) is the difficulty and expense of assembling the data on all the intersector exchanges. In natural systems (unlike human systems) the entities in- volved cannot report to a central authority on their activities and instru- ments, and monitoring networks must be constructed to measure mate- rial and energy exchanges directly in the field. Given the growing importance of ecological concerns, these kinds of monitoring networks are nevertheless becoming more widespread. The NSF-funded long-term ecological research network of research sites is one example, as is the pro- posed national ecological observatory network. The data collected via these ongoing sites could be integrated into ongoing material flows ac- counting efforts for natural and human-natural systems to yield signifi- cant new insights. Coupling material and energy flows data, including emissions to air, land, and water, with biological and physical information could help fo- cus public policy making on the following key issues, which concern people and governments: (1) climate change, (2) the environment, (3) biodiversity (flora and fauna), (4) public health, and (5) quality of life (and the economy). Focusing on these key issues, the following bullets para- phrase the action items of the Sixth Community Environment Action Programme (European Parliament and Council of the European Union, 2002~: Climate change has emerged as an important outstanding chal- lenge hinging on anthropogenic impact, primarily because of energy pro- duction and consumption. National and worldwide initiatives have evolved to curb global warming, but good data and indicators derived from analyses of data will ultimately guide the initiatives and be used to formulate global agreements on climate change. On a national and global scale, public policy initiatives on the pro- tection, conservation, restoration, and sometimes development of the functioning of natural systems, natural habitats, and wild flora and fauna have to be informed with good data and derived indicators, and they will be pursued with the aim of halting desertification and the loss of biodiversity, including the diversity of genetic resources.

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RESEARCH CHALLENGES FOR MATERIAL FLOWS ACCOUNTING 91 Ultimately, better resource efficiency and resource and waste man- agement systems will be founded on more sustainable production levels and consumption patterns, thereby decoupling the use of resources and the generation of waste from the rate of economic growth and aiming to ensure that the consumption of renewable and nonrenewable resources does not exceed the carrying capacity of the environment. The H. I. Heinz III Center for Science, Economics, and the Environ- ment report on The State of The Nation's Ecosystems (H. I. Heinz III Center for Science, Economics and the Environment, 2002) provides "a blueprint for periodic reporting on the condition and use of ecosystems in the United States," aimed at informing public policy making with scientifi- cally sound and unbiased data and analyses. It structures reporting of indicators across six different ecosystems, defined on the basis of land cover (i.e., coasts and oceans, farmlands, forests, fresh waters, grasslands and shrublands, and urban and suburban areas). Indicators focus on sys- tem dimensions (extent, fragmentation, and landscape pattern), chemical and physical conditions (nutrients, chemical contaminants, and physical conditions), biological components (plants and animals, biological com- munities, and ecological productivity), and human use (food, fiber, and water as well as other services, including recreation). While identifying data gaps (data are adequate to support national reporting for 58 of 103 indicators, and data are considered complete for only 33 of the 58 indica- tors), the report defined "what should be measured, counted and reported so that decision makers and the public can understand the changes that are occurring in the American landscape." A material flows accounting system would be a significant source of data for the full development of indicators across ecosystems. SUMMARY AND FINDINGS Clearly the research agenda for material flows accounting and mate- rial flows analysis is rich and exciting, and further development would likely enhance the traditional materials accounting structure and its re- lated analytical outputs in useful ways. Indeed, with financial accounting as a model, it appears virtually impossible to contemplate a materials ac- counting program that does not include such activities. The focus of this chapter has been on research challenges in material flows accounting. As with all research, the most useful outcomes cannot be predicted. It is apparent, however, that the research will benefit from accounting systems that provide information on cycle linkages (e.g., re- porting copper and copper alloys in separate categories rather than as one merged category). Similarly, the development of multilevel material flows

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92 MATERIALS COUNT accounts (e.g., individual states, the United States as a whole, North America as a whole) will provide the basic information from which re- search can generate new analytical approaches and new conclusions. Ma- terial flows accounts are good candidates for comprehensive analysis of linked natural and human systems. Monitoring networks would need to be constructed to measure directly material and energy exchanges in the field. The committee concludes that a comprehensive material flows accounting program requires a research component that explores tools and analytical ap- proaches to studying stocks and flows that vary over space and time, that treats multiple organizational levels, and that explores the complexities and benefits of cycles linked by nature, by technology, or by a combination of the two. The com- mittee recommends that relevant government agencies support research related to material flows accounting.