Industrial metabolism theory and policy robert u ayres
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Industrial Metabolism: Theory and Policy Robert U. Ayres. Summary: Patrick Wilkinson Critique: James Silva. Overview. Introduction to Industrial Metabolism The Materials Cycle Measures of Industrial Metabolism Policy Implications of the Industrial Metabolism Perspective.

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Industrial Metabolism: Theory and Policy Robert U. Ayres

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Industrial Metabolism:Theory and PolicyRobert U. Ayres

Summary: Patrick Wilkinson

Critique: James Silva


  • Introduction to Industrial Metabolism

  • The Materials Cycle

  • Measures of Industrial Metabolism

  • Policy Implications of the Industrial Metabolism Perspective

Introduction to Industrial Metabolism

  • Definition: “the whole integrated collection of physical processes that convert raw materials and energy, plus labor, into finished products and wastes in a (more or less) steady-state condition.”

  • Metabolism: Analogous to the process of a living organism

    • Takes in food for self/storage and excretes wastes.

  • Differences:

    • Organisms reproduce themselves, specialized, change over long period of time.

    • Firms produce products or services, not specialized, can change quickly

The Materials Cycle

  • Closed cycles are self-sustaining with no external sources or sinks and are in steady state.

  • Open cycles are unsustainable, using materials without replenishing sources.

    • Must stabilize or will ultimately fail

  • The Biological cycle is a closed cycle, while our industrial cycle is an open cycle.

The Material Cycle

  • “Industrial system of today”: Unsustainable

    • Can this stabilization be obtained with a “technological ‘fix’”?

    • If so, how?

    • If not, how long will the current system last?

  • Biological system

    • Has not always been a closed system

    • “Responded to inherently unstable situations (open cycles) by ‘inventing’ new processes (organisms) to stabilize the system by closing the cycles.”

  • Time scales

    • Biological system took billions of years

    • Industrial system does not have that much time

Measures of Industrial Metabolism

  • Recycling and dissipative loss are the “fates” of all waste materials

  • There are 3 classes of materials use

    • Those that are recyclable under present technology and cost

    • Those that are recyclable, but not under present tech. and cost

    • Those that are not recyclable

  • For the industrial system to function as a closed cycle, it must recycle or reuse nearly all materials

Measures of Industrial Metabolism

  • Examples of dissipative use: Class 3 materials

    • Sulfur

    • CFC’s

    • Ammonia

    • Phosphoric acid

    • Chlorine

      • Although can be classified as class 2 when used in plastics and solvents

Measures of Industrial Metabolism

  • Potentially recyclable materials

    • Are they being recycled and reused?

    • Recycle (reuse) vs. Dissipation of a material shows how far sustainability is from being reached

Policy Implications of the Industrial Metabolism Perspective

  • Industrial metabolism is “holistic” in theory

    • All interactions are considered together resulting in the best for the system as a whole

  • Short term solutions and policies, however, are being enforced

    • Such policies are usually more harmful and costly in the long run

    • Ex.’s Pollution and coal as a fuel

      • Air and water pollution reduced, but land disposal increased

      • Clean coal technology could extend coal as fuel, but effects of byproducts extended as well


  • Sulfur Example

  • Comparison: human vs. natural

  • Material Source vs. Material Path

  • A more “holistic view”

Sulfur Example

  • Example of Dissipative use

    • Nearly all sulfur mined is dissipated or discarded

    • Mostly used for sulfuric acid – used in non-recyclable chemicals

    • Thus sulfur mainly falls into the third category

  • But… plaster-of Paris

Comparison: human vs. natural

  • Where is the natural to compare with the anthropogenic?

  • What are the percentages referring to?

  • “In all cases, with the possible exception of nitrogen, the anthropogenic contributions exceed the natural flows by a considerable margin.”

    • Really?

Comparison: human vs. natural (Can you interpret this?)

Material Source vs. Material Path

  • Should be less concerned with how much of something is left than with what path used material takes

    • How much oil/steel/etc. is left to be extracted from natural sources is not a good measure of evaluation for industrial processes

    • A better way is to quantify how much recycling of material is going on: What do we do with what we use?

A more “holistic view”

  • Defines it more by what it is not

    • Contrasts with “narrowly conceived or short-run (myopic) ‘quick fix’ policies”

      • Longer pipelines for sewage

      • Air vs. water vs. land

  • Not an in-depth application paper

    • Less than 15 pages

  • The industrial system of tomorrow…?


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