Building the Material Flow Networks of Aluminum in the 2007 U.S. Economy

Based
on the combination of the U.S. economic input-output table
and the stocks and flows framework for characterizing anthropogenic
metal cycles, this study presents a methodology for building material
flow networks of bulk metals in the U.S. economy and applies it to
aluminum. The results, which we term the Input–Output Material
Flow Networks (IO-MFNs), achieve a complete picture of aluminum flow
in the entire U.S. economy and for any chosen industrial sector (illustrated
for the Automobile Manufacturing sector). The results are compared
with information from our former study on U.S. aluminum stocks and
flows to demonstrate the robustness and value of this new methodology.
We find that the IO-MFN approach has the following advantages: (1)
it helps to uncover the network of material flows in the manufacturing
stage in the life cycle of metals; (2) it provides a method that may
be less time-consuming but more complete and accurate in estimating
new scrap generation, process loss, domestic final demand, and trade
of final products of metals, than existing material flow analysis
approaches; and, most importantly, (3) it enables the analysis of
the material flows of metals in the U.S. economy from a network perspective,
rather than merely that of a life cycle chain.