STATISTICS ON THE RESOURCE FLOWSrequired to produce primary and recycled alu-minum are incomplete on a global basis. Inaddition, there has not been a consensus or quan-titative estimate of future resource flows relatedto aluminum production or the potential avail-ability of less resource-intense end-of-life alu-minum (recycled) metal to meet ever-increasingconsumer and developing nation needs.

A model was developed by Alcoa Inc. (Ref6.1) to provide a quantitative understanding ofhistoric and today’s (year 1950 through year2003) worldwide aluminum mass flows andsystems losses. In addition, current and futureresource requirements and life-cycle inventoryflows were estimated by coupling these globalaluminum mass flows with global, average life-cycle inventory intensity data developed from amajority of producers in a report (Ref 6.2) bythe International Aluminum Institute (IAI) (seealso Chapter 4, “Life-Cycle Assessment of Alu-minum: Inventory Data for the WorldwidePrimary Aluminum Industry” in this book). Themodel was also developed to provide quantita-tive scenario-development capability to deter-mine the positive impact of enhanced recycling,lower resource-intense production, and productusage scenarios. The model and key resultsinformation were developed to be shared with

global aluminum industry technical experts,executives, and external stakeholders to betterunderstand potential paths to more globally sus-tainable aluminum.

Modeling

Modeling of historic and current flows wasbuilt around aluminum product net shipmentsstatistical data provided by governments, suchas the U.S. Geological Survey (Ref 6.3–6.5), orregional aluminum associations, such as theEuropean Aluminum Association, AustralianAluminum Council, the Japan Aluminum Asso-ciation, or the North American Aluminum Asso-ciation (Ref 6.6). The data were gathered,starting in year 1950, into a comprehensivespreadsheet model by year, by region (EuropeanUnion, South America, China, etc.), and inaccordance with the following customer (mar-ket) segmentation:

• Building and construction • Transportation—auto and light truck, aero-

space, and other (heavy trucks, trains, etc.) • Packaging—aluminum containers and other

packaging (foil, etc.) • Machinery and equipment • Electrical—cable and other electrical • Consumer durables • Other (such as aluminum used for propellant

or steel deoxidation)

From the product net shipments, the modelestimates both internal (runaround) aluminum

CHAPTER 6

Material Flow Modeling of Aluminum for Sustainability*Kenneth J. Martchek, Alcoa Inc., Alcoa Corporate Center

*Adapted with permission of International Journal of LifeCycle Assessment from the following article by Kenneth J.Martchek: “Modelling More Sustainable Aluminium: CaseStudy,” International Journal of Life Cycle Assessment,Volume 11 (No. 4), 2006.

Aluminum Recycling and Processing for Energy Conservation and Sustainability John A.S. Green, editor, p 103-107 DOI: 10.1361/arpe2007p103

Copyright © 2007 ASM International® All rights reserved. www.asminternational.org

104 / Aluminum Recycling and Processing for Energy Conservation and Sustainability

facility recycle flows and new (prompt, fabrica-tor) customer recycle flow amounts, based onestimation of average use, yield, and melt lossrates identified in the literature and reviewedand agreed on by a subteam of global aluminumtechnical experts.

This subteam of experts was commissionedby the IAI Global Aluminum Recycling Com-mittee (GARC). Postconsumer (end of productlife) aluminum flows are estimated from prod-uct net shipments in previous years, estimatedproduct lifetimes (worldwide by market byyear), scrap recollection rates (by region bymarket by year), and recovery factors againbased on industry statistics, published litera-ture, and review and agreement by the IAIGARC committee. An illustration of some ofthese data on scrap recovery rates and meltingrecovery efficiency is provided in Table 6.1.

Modeling of future aluminum and resourceflows is based on literature (Ref 6.7, 6.8) andexpert projections of life-cycle inventory inten-sity rates (Ref 6.2, 6.9) and aluminum productshipments by market (currently with a weighted-average compounded annual growth rate of2.5% per year). The availability of recycle flowsto meet these market demands is based onprojected use, yield, melt loss, recovery rates,postconsumer recycling rates, and anticipatedfuture product lifetimes. Primary aluminum pro-duction is then calculated to determine the

market demand for additional primary capacityand resulting resource requirements.

Validity Checks. There are two validitychecks in the model:

• Comparison of estimated postconsumer andnew scrap by year with published values byyear. (This check is informational becausepublished values for global recycled metalare considered to be incomplete.)

• Comparison of the estimated market demandfor primary aluminum by year with pub-lished primary production by year

Figure. 6.1 shows the aluminum productionthat is estimated by the model to have beenrequired for the years 1970 to 2003, based onproduct net shipments less postconsumer and

Met

ric to

ns×1

03

45,000

40,000

35,000

30,000

25,000

20,000

15,000

10,000

5,000

01970 1980 1990 2000 2010 2020

Estimated/predicted

Reported

Fig. 6.1 Estimated versus reported worldwide primary production

Table 6.1 Example of global average worldwidecollection (recycle) rates and melting recoveriesby market

Collection, % Collection, %Market 1990 2000 Melting recovery, %

Buildings 69 70 96Autos and 75 75 96light trucks

Aerospace 76 75 96Other transport 76 75 96Containers 61 59 85 (net of 4 cycles/yr)Packaging––foil 13 16 30Machinery 40 44 96Electrical cable 45 51 96Electrical other 30 33 96Consumer durables 20 21 96

Chapter 6: Material Flow Modeling of Aluminum for Sustainability / 105

new recycle flows and system losses. This isshown to be in fairly good agreement withreported worldwide primary aluminum produc-tion for the years 1970 to 2003. Required pri-mary aluminum production is then projected tothe year 2020, with assumptions about eachmarket segment growth rates, postconsumerscrap collection rates, and anticipated recover-ies based on latest trends.

Key Results

The model assessment of global aluminummass flows is shown schematically in Fig. 6.2.

The size (area) of the circles illustrates relativevolume of flows. In year 2003, recovered post-consumer and new customer recycled metalsupplied 33% of the global aluminum industry’sproduct net shipment supply.

An estimated 516 million metric tons ofaluminum, approximately 73% of all of thealuminum ever produced, is contained in cur-rent transportation, cable, and building productinventory (in service), as illustrated in Fig. 6.3.The model also projects future product inven-tory volumes by market segment to year 2020.

Additional key results also included systemlosses, such as aluminum packaging lost in

Values in millions of metric tons

Primaryaluminum27.4

Recycled

Metal losses1.4

Al inskimmings1.2

Ingots56.2

Internalscrap15.0

Newscrap6.9

Oldscrap7.0

Fabricated andmanufactured products55.0

Finishedproducts33.1

Oxidized inapplication0.8

Landfill

516.1Net addition: 200319.0

Underinvestigation

Total productsin use 2003

Fig. 6.2 Global aluminum mass flows for the year 2003

Met

ric to

ns×1

03

1,000,000

900,000

800,000

700,000

600,000

500,000

400,000

300,000

200,000

100,000

0

Other (e.g., destructive uses)Consumer durablesElectrical–otherElectrical–cableMachinery and equipmentPackaging–other (foil)Packaging–cansTransportation–otherTransportation–aerospaceTransportation–auto and light truckBuilding and construction

1990 1995 2000 2005 2010 2015 2020

Fig. 6.3 Worldwide aluminum product inventory by market

106 / Aluminum Recycling and Processing for Energy Conservation and Sustainability

landfills or metal oxidized to aluminum oxidewhen used as a propellant or for deoxidizingsteel melts. The model also provides an assess-ment of past, current, and projected energy andemissions intensity of aluminum semifabricatedshipments, as illustrated in Fig. 6.4, based onthe latest assessment of average greenhouse gas(GHG) emissions intensity for aluminum proc-esses (Ref 6.9).

On average, worldwide aluminum productsare becoming less GHG intense on a per-ton-shipped basis due to two reasons:

• Increase in the percent recycled metal rela-tive to primary metal. Only 5% of the energyand GHG emissions is required to producealuminum ingot compared to primary (baux-ite/Al2O3/electrolysis) aluminum.

• Lower emissions from primary aluminumfacilities due to reductions in energy inten-sity and significant reductions in perfluoro-carbon emissions

The results of the model were initially sharedwith the IAI Board of Directors in May 2004.Model development, the GARC expert reviewand contribution, and results of global aluminumflow were described, including a quantitativeassessment of GHG emissions from globalindustry aluminum facilities today (2003) andprojected into the future as a guide to the indus-try’s contribution to climate change effects. Atthat time, the Board requested a “what-if” casescenario that later indicated that industry factoryand indirect emissions from purchased electricitycould be stabilized, despite significant industrygrowth by 2020, based on currently projectedrecycled metal flows and moving all of the globalindustry toward today’s (2003) global benchmarktechnologies and operating best practices.Furthermore, the model indicated that fuel effi-ciency and emissions savings due to additional

aluminum transportation products had thepotential to surpass the global industry’s pro-duction emissions by 2020.

In May 2005, additional model results wereshared with the IAI Board, and they added thefollowing voluntary objective to their list ofsustainable development quantitative goals inrecognition of the ecological and economic valueof enhanced recycling to reduce natural resourceconsumption and life-cycle inventory effects:

“The IAI has developed its SustainabilityMaterial Flow Model to identify futurerecycling flows. The model projects thatglobal recycled metal supply (back to theindustry) will double by 2020 from today’s(2005) level of 6.4 million metric tons. Thealuminum industry will report annually onits global recycling performance.”

The IAI also continues to develop and improvethe model, collect supporting life-cycle inventoryintensity data, and use the scenario capability toquantitatively assess current and future produc-tion paths and sustainable strategies.

REFERENCES

6.1. P.R. Bruggink and K.J. Martchek, World-wide Recycled Aluminum Supply and En-vironmental Impact Model, Light Metals,Proceedings of the 2004 Annual Meeting,March 14–18, 2004 (Charlotte, NC), A.T.Tabereaux, Ed., TMS (The Minerals, Met-als and Materials Society), p 907–911

6.2. “Life Cycle Assessment of Aluminum: In-ventory Data for the Worldwide PrimaryAluminium Industry,” International Alu-minum Institute, London, U.K., March2003; http://www.world-aluminum.org/iai/publications/documents/lca.pdf (accessedJuly 2007)

6.3. P.A. Plunkert, Aluminum: Minerals Year-book, U.S. Geological Survey, U.S. De-partment of the Interior, Reston, Virginia,2001, p 6.1–6.19; http://minerals.er.usgs.gov/minerals/pubs/commodity/aluminum/050401.pdf (accessed July 2007)

6.4. P.A. Plunkert, Aluminum: Minerals Yearbook, U.S. Geological Survey, U.S.Department of the Interior, Reston, Virginia,2002, p 5.1–5.18; http://minerals.er.usgs.gov/minerals/pubs/commodity/aluminum/alumimyb02r.pdf (accessed July 2007)

12

10

8

6

4

2

0

Mto

nne

CO

2-e/M

tonn

e A

l

1950 1990 2000 2010 2020

11.3

9.68.9

7.76.8

Fig. 6.4 Greenhouse gas emissions intensity of aluminumshipments

Chapter 6: Material Flow Modeling of Aluminum for Sustainability / 107

6.5. P.A. Plunkert, Aluminum: Minerals Year-book, U.S. Geological Survey, U.S. Depart-ment of the Interior, Reston, Virginia,2003, p 5.1–5.16; http://minerals.er.usgs.gov/minerals/pubs/commodity/aluminum/alumimyb03.pdf (accessed July 2007)

6.6. “Aluminum Statistical Review for 2002,”The Aluminum Association Inc., Washing-ton, D.C., 2003

6.7. G. Rombach, Future Availability of Alu-minum Scrap, Light Metals, Proceedings ofthe 2002 Annual Meeting and Exhibition,Feb 17–21, 2002 (Washington, D.C.),

W. Schneide, Ed., TMS (The Minerals,Metals and Materials Society), p 1011–1018

6.8. Economics of Aluminium, 8th ed., RoskillInformation Services, London, U.K.,2003

6.9. “Life Cycle Inventory of the WorldwideAluminium Industry with Regard to EnergyConsumption and Emissions of Green-house Gases,” International AluminumInstitute, London, U.K., March 2000; http://www.world-aluminum.org/iai/publications/documents/expanded_summary.pdf(accessed July 2007)