The Industrial Ecology Flow Cycle Materials budgets are required to understand where a material goes once it enters the materials flow system –Virgin materials processing –Manufacturing –Use These can be integrated into the total industrial ecology materials cycle

Mass balance around a process: –Inflow must equal outflow: A = D + E + H Product budgets can be developed in the same way Process and Product Budgets New Solvent In Solvent Reservoir A Solvent Wash B Dragout on products C Remains in Product E Evaporates D Solvent Purification F G To waste disposal H

Ensemble Industrial Materials Flows One can model flows of materials worldwide –Water, steel, coal This doesn’t address the fraction lost to productive use Materials flows must be understood in order to develop mechanisms for reducing losses and waste

Industry Budgets Flows within an industry can be determined through research, and drawn using traditional mass balance flow graphs E.g. Fluxes of lead in the world economy

Cradle-to-Grave Budgets and Cycles Materials budgets can also be developed to consider environmental sources and sinks

Industrial Perturbations to Natural Budgets Industrial materials flows may or may not contribute significantly to natural flows One must look at natural biogeochemical cycles, z.B. –Nitrogen –Phosphorous –Chlorine

Evolution of Industrial Materials Historically, improved standard of living brings an increased use of materials –z.B. in the US in the 20 th century, population increased three-fold while materials use increased ten-fold If the developing world achieves improved standard of living in the same way as the US, we get results such as shown in the next slide

Materials Consumption Rates and Projections Cement Nitrogen Iron and steel Sand and gravel Potash Salt Copper Phosphate rock Aluminum Synthetic fibers Plastic Factor of increaseProjected World1990 World1990 USCommodity Tg/yr

Applying the Budget Concept Materials and energy flows may be described and analyzed as budgets Analogy: a sink with several faucets & drains –For a small sink, it can be easy to tell whether inputs are in balance with outputs –But for a larger sink, waves may make it harder Basic concepts: –Reservoir, flux, sources, sinks, cycles

Budgets and Cycles: A systems description Type I Systems: –Unlimited Resources  Unlimited Waste –Cellular –Linear Type II Systems: –Energy and Limited Materials  Limited Waste –Constrained biology –Quasicyclic Type III Systems: –Energy  nil –Cooperative biology –Cyclic

The Industrial Process Diagram Four nodes: –Materials Extractor/Grower –Materials Processor/Manufacturer –Materials User –Materials Scavenger Not necessarily sequential Waste is anything that does not add value

Material Extractor or Grower Materials Processor or Manufacturer Materials User or Consumer Scavenger or Waste Processor V I ReRe RmRm RcRc R S RwRw P L M Limited Resources Limited Residues

Quantitative Measures of a Cycle Extracting efficiency Manufacturing efficiency Recovery efficiency Recycling efficiency System efficiency

Extracting Efficiency A function of good extraction technology, high-quality residue streams) If no virgin material is used and no residue is produced, = 1

Manufacturing Efficiency A function of process and product design, and implementation If no manufacturing residue is produced, = 1

Recovery Efficiency A function of product design, government policies, and recycled materials markets If all material is recycled, = 1

Recycling Efficiency A function of “design for disassembly” and government and customer regulations and policies If no recycling residue is generated, = 1

Overall System Efficiency Defined as linear combination: –In a perfect Industrial Ecosystem,  = 1 Overall reuse factor is:

Time Scales in Budget and Cycle Analysis Such systems are inherently dynamic Therefore, for completeness we would also examine temporal terms

Related Areas of Focus Design for Environment (DFE) Environmentally Conscious Manufacturing (ECM)