Oct 08 2007

Behind the Shining: Aluminum’s Dark Side

Carbon dioxide

The industry emits carbon dioxide at each stage of production, from the

mining and processing of bauxite, to the electrolytic refining of alumina,

and the casting of aluminum.

A quintet of Massachusetts Institute of Technology scientists, led by

Jochen Harnish, in a 1999 study titled “Primary Aluminum Production:

Climate Policy, Emissions, and Costs,” found that “the source of electric

energy used for the electrolytic reduction is the single most important

factor influencing total carbon dioxide emissions from primary aluminum

production. The specific emissions of CO-2 vary by a factor of five

depending on whether coal or hydroelectricity is used as a source of power

for the reduction cells.” (Jochen Harnisch, Ian Sue Wing, Henry Jacoby,

Ronald Prins, “Primary aluminium production: climate policy, emissions and

costs,” paper presented at the Kyoto and Montreal Protocols’ Joint Expert

Meeting, Petten, May 1999)

Another study has calculated that the aluminum production cycle, including

mining, processing, refining, and casting, produces about 12 tons of carbon

dioxide per ton of aluminum produced. (R. Huglen and H. Kvande, “Global

considerations of aluminium electrolysis on energy and the environment,

Light Metals 1994, pp. 373-380)

The industry’s International Aluminium Institute has lower carbon dioxide

estimates of 7.4 tons of carbon dioxide per ton of aluminum production

(including 5.8 tons from energy and 1.6 from the electrolytic process).

(IAI, “Aluminium’s Life Cycle,” on website world-aluminium.org, 2000)

The MIT study predicts that CO-2 emissions from the industry will rise from

about 2 billion tons in 1985 to about 3 billion tons in the year 2030. The

more coal that is consumed to power new capacity, the more emissions will

occur. If 75% of new capacity is fueled by coal, then the amount of CO-2

generated per ton of aluminum cast would increase from 12 to 18.3 tons.

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