Material flow analysis

Material flow analysis (MFA) (also referred to as substance flow analysis (SFA)) is an analytical method to quantify flows and stocks of materials or substances in a well-defined system. MFA is an important tool to study the bio-physical aspects of human activity on different spatial and temporal scales. It is considered a core method of industrial ecology and urban metabolism. Typical applications of MFA include the study of material, substance, or product flows across different industrial sectors or within ecosystems. MFA can also be applied to a single industrial installation, for example, for tracking nutrient flows through a waste water treatment plant. Examples for policy-relevant applications of MFA include the determination of material use indicators for different societies and the assessment of strategies for improving the material flow systems in form of material flow management. Since 1990, the number of publications using material flow analysis as main method of investigation has grown steadily. Major journals that publish MFA-related work include the Journal of Industrial Ecology, Ecological Economics, Environmental Science and Technology, and Resources, Conservation, and Recycling.[1]

Description of the method

Motivation

Human needs such as shelter, food, transport, or communication require materials like wood, starch, sugar, iron and steel, copper, or semiconductors. As society develops and economic activity grows, production, use, and disposal of the materials employed increases to a scale where unwanted impacts on environment and society cannot be neglected anymore, neither locally nor globally. Material flows are at the core of local environmental problems such as leaching from landfills or oil spills. Rising concern about global warming put a previously unimportant waste flow, carbon dioxide, on top of the political and scientific agenda. Moreover, the gradual shift from traditional to urban mining in developed countries requires a detailed assessment of in-use and obsolete stocks of materials within human society. Scientists, industries, government bodies, and other organisations therefore need a tool that complements economic accounting and modelling. They need a systematic method to keep track of and display stocks and flows of the materials entering, staying within and leaving the different processes in the anthroposphere. Material flow analysis is such a method.

Basic principles

MFA is based on two fundamental and well-established scientific principles, the systems approach and mass balance. [2] [3] The system definition is the starting point of every MFA study.

System definition

An elementary MFA system without quantification.
A more general MFA system without quantification.

An MFA system is a model of an industrial plant, an industrial sector or a region of concern. The level of detail of the system model is chosen to fit the purpose of the study. An MFA system always consists of the system boundary, one or more processes, material flows between processes, and stocks of materials within processes. Exchange between the system and its environment happens via flows that cross the system boundary. Contrary to chemical engineering, where a system represents a specific industrial installation, systems and processes in MFA can represent much larger and more abstract entities as long as they are well-defined. The explicit system definition helps the practitioner to locate the available quantitative information in the system, either as stocks within certain processes or as flows between processes.

MFA system descriptions can be refined by disaggregating processes or simplified by aggregating processes.

Next to specifying the arrangement of processes, stocks, and flows in the system definition, the practitioner also needs to indicate the scale and the indicator element or material of the system studied. The spatial scale describes the geographic entity that is covered by the system. A system representing a certain industrial sector can be applied to the USA, China, certain world regions, or the world as a whole. The temporal scale describes the point in time or the time span for which the system is quantified. The indicator element or material of the system is the physical entity that is measured and for which the mass balance holds. As the name says, an indicator element is a certain chemical element such as cadmium or a substance such as CO2. In general, a material or a product can also be used as indicator as long as a process balance can be established for it. Examples for more general indicators are goods such as passenger cars, materials like steel, or other physical quantities such as energy flows.

MFA requires practitioners to make precise use of the terms 'material', 'substance', or 'good'. We refer to the definitions given in chapter 2.1 in the book by Brunner and Rechberger,[4] one of the main references for the MFA method.

A typical MFA system with quantification.

Process balance

One of the main purposes of MFA is to understand the metabolism of the elements of the system. Unlike purely economic accounting, MFA also covers non-economic waste flows, emissions to the environment, and stocks of obsolete products. The process balance is a first order physical principle that turns MFA into a powerful accounting and analysis tool. The processes in the system determine which balances apply. For a process ‘oil refinery’, for example, one can establish a mass balance for each chemical element, while this is not possible for a nuclear power station. A car factory respects the balance for steel, but a steel mill does not.

When quantifying MFA systems either by measurements or from statistical data, mass other process balances have to be checked to ensure the correctness of the quantification and to reveal possible data inconsistencies or even misconceptions in the system such as the omission of a flow or a process. Conflicting information can be reconciled using data validation and reconciliation, and the STAN-software offers basic reconciliation functionality that is suitable for many MFA application.[6]

Examples for MFA applications on different spatial and temporal scales

MFA studies are conducted on various spatial and temporal scales and for a variety of elements, substances, and goods. They cover a wide range of process chains and material cycles. Several examples:

Historical development

Recent development

Relation to other methods

MFA is complementary to life cycle assessment (LCA) and input-output (I/O) models. Some overlaps between the different methods exist as they all share the system approach and to some extent the mass balance principle. The methods mainly differ in purpose, scope, and data requirements.

MFA studies often cover the entire cycle (mining, production, manufacturing, use, waste handling) of a certain substance within a given geographical boundary and time frame. Material stocks are considered explicitly in MFA, which makes this method suitable for studies involving resource scarcity and recycling from old scrap. The common use of time series (dynamic modelling) and lifetime models makes MFA a suitable tool for assessing long-term trends in material use.

See also

References

  1. ↑ http://www.journals.elsevier.com/resources-conservation-and-recycling/
  2. ↑ Marina Fischer-Kowalski, The Intellectual History of Materials Flow Analysis, Part I, 1860-1970, Journal of Industrial Ecology 2(1), 1998, pp 61-78, doi:10.1162/jiec.1998.2.1.61.
  3. ↑ Marina Fischer-Kowalski, The Intellectual History of Materials Flow Analysis, Part II, 1970-1998, Journal of Industrial Ecology 2(4), 1998, pp 107-136, doi:10.1162/jiec.1998.2.4.107.
  4. 1 2 3 4 5 6 Brunner, P.H.; Rechberger, H. (2004). Practical Handbook of Material Flow Analysis. Lewis Publishers, New York. ISBN 1-56670-604-1.
  5. ↑ IUPAC, Compendium of Chemical Terminology, 2nd ed. (the "Gold Book") (1997). Online corrected version: (2006–) "chemical element".
  6. ↑ http://www.stan2web.net/
  7. ↑ Baccini and Bader 1996, 'Regionaler Stoffhaushalt' (Regional metabolism), Spektrum Akademischer Verlag, Heidelberg (Germany), ISBN 3-86025-235-6
  8. ↑ Baccini P. & Brunner P.H. (2012). Metabolism of the Anthroposphere, Analysis, Evaluation, Design. 2nd Edition, The MIT Press, Cambridge, MA. ISBN 9780262016650
  9. ↑ 'Predicting future emissions based on characteristics of stocks', Ecological Economics, 2002, 41(2), 223-234.
  10. ↑ "Wuppertal Institute". Retrieved 3 July 2011.
  11. ↑ Schmidt-Bleek MIPS: Ein neues ökologisches Maß, 1994
  12. ↑ "UNEP". Retrieved 3 July 2011.
  13. ↑ "IPCC". Retrieved 3 July 2011.
  14. ↑ "Accounting in the EU". Retrieved 3 July 2011.
  15. ↑ "Accounting in Japan" (PDF). Retrieved 3 July 2011.
  16. ↑ "World Resources Forum". Retrieved 3 July 2011.
  17. ↑ Nakamura, S.; Kondo, Y. (2009). Waste Input-Output Analysis. Concepts and Application to Industrial Ecology. Springer. ISBN 978-1-4020-9901-4.
  18. ↑ "materialflows.net". Retrieved 3 July 2011.
  19. ↑ Daniel B. Müller, Stock dynamics for forecasting material flows--Case study for housing in The Netherlands, Ecological Economics 59(1), 2006, pp 142-156, doi:10.1016/j.ecolecon.2005.09.025.
  20. ↑ "3R in Japan". Retrieved 3 July 2011.

Further reading

External links

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