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Resource Flow Analysis

ScottMatthews12-712 / 19-622Lecture 8

Administrative Issues

HW 3 Graded (avg 45)

HW 4 Due Wednesday

Project Updates Only 5 groups submitted plans last

week

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Recap of Last Time

Ecological footprint Relevant metric (equiv land use) Concerns/issues about data and

assumptionsGallery show

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Mass Balance

Fundamental principle of engineering / environmental engineering (law of conservation of mass)

Commoner: “everything must go somewhere”

Physical quantitiesEnergyCalories, etc.

Relevant: stocks and flows, ins and outs

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5Source: USGS

Material (Resource) Flow Analysis

Has existed for 100 years, but formalized as a modeling technique more recently Tool to link impacts with material uses Simple: materials book-keeping Complex: dynamic flow analyses

Inevitably an IN=OUT issue Is this trivial? Is it relevant? Do others realize? We tend to underestimate complexity – i.e.

simple materials in fact very complex flows

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MFA – Definition (Brunner)

A systematic assessment of stocks and flows of a material at a given space/time

Connects sources and pathways with sinks, intermediate flows

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Basic Plan for an MFA

Begin building a simple IN=OUT modelStart assembling IN, OUT flow data

Are there many more relevant IN, OUT flows?Is there a substantial stock or sink?

Do we have sufficient data to quantify them?Continue iterating as data and time allowWhen done, summarize as many disaggregate

stocks and flows as possible Typically express results “over life cycle”

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9Source: Brunner

10Source: USGS “MFA and Sustainability”

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12Source: Yale STAF Project

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Cadmium USGS Report

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Postel (1996) - Water

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Computers

What Data do we have?

What data do we need?

Can we do a “good enough” job?

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Group exercise

Split into groupsTry to do computer MFA for 2008

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18Source: USGS, Obsolete Computers, “Gold Mine,” or High-Tech Trash? Resource Recovery from Recycling

Policy Relevance of MFA

Can we track natural versus anthropogenic flows? JIE paper – Cadmium – only way to reduce is to

eliminate inflow But inflow is byproduct of Zinc; either need to

eliminate zinc production or cut off co-product Structure of such studies – and construction of the

stock/flow models – yields insightsCan we learn more about connections

between stocks and flows, our activities?

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MFA Issues

Data / methods are largest barriers (conceptually simple otherwise)

What about uncertainty?

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Sankey Diagrams

Generally used for Energy flow analyses

Implicit assumptions The diagrams concern quantity sizes that are related to

a period in time or to a functional unit, such as a product unit.

The quantity scale is proportional (i.e., twice the quantity is represented by an arrow that is twice as wide).

Inventories are not taken into account (i.e., there is no stock formation).

An energy or mass balance is maintained.

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23Source: WRI, http://www.wri.org/image/view/9529/_original

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Lead Flows 1970 (USGS)

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Lead Flows 1993

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To Dos

HW 5 coming Wednesday. Start tracking your expenses AND your

general “material/resource” flow starting tomorrow am. Will need to for HW.

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