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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),
OCR for page 87
87
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OCR for page 88
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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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.
Representative terms from entire chapter:
flows accounts
