Environmental Costs of Linear
Societies
October 9, 2006
Life Cycle Analysis of Aluminum Cans
• Americans use 102.2 BILLION
aluminum cans/ year (368 per
capita/year)
• We throw away 49.6% of these
cans (50.7 billion!)
• Biggest environmental impact of
this disposal is “upstream” from
the consumer
• Had these cans been recycled
enough energy would have been
saved to supply gasoline to over 1
million cars for an entire year
Aluminum Can Production: Step 1 – Bauxite Mining
• Most bauxite “ore” from
open pit or strip mines in
Australia, Jamaica and Brazil
(99% of US needs is
imported)
• Bauxite mining results in
land clearance, acid mine
drainage, pollution of
streams and erosion
• 5 tons of mine “tailings”
(waste) produced per ton of
bauxite ore removed
• Significant fossil fuel energy
consumed in mining and
transporting bauxite ore
Land Degradation
from mining
For each ton
of useful ore
extracted,
many tons
of “overburden”
have to be
removed in
the process.
For bauxite
ore, the ratio
can be as
high as 5:1.
Mineral ores and metals are shipped all over the world,
consuming vast quantities of energy in the process.
Aluminum Can Production: Step 2 – Alumina Refining
• Bauxite ore is mixed with
caustic soda, lime and
steam to produce a sodium
aluminate slurry
• “Alumina” is extracted
from this slurry, purified
and shipped to smelters
• Leftover “slag” waste
contains a variety of toxic
minerals and chemical
compounds
• Alumina refining process
is also fossil fuel energy
intensive
Refined
alumina
Alumina Refining
Facilities
Aluminum Can Production: Step 3 – Smelting
• Powdered alumina is heated
(smelted) in order to form
aluminum alloy ingots
• Aluminum smelting uses
massive amounts of electricity
(usually from coal)
• One ton of aluminum
production requires energy
equivalent of 5 barrels of oil
(210 gallons of gasoline)
• Aluminum smelting also
produces 7.4 tons of air
pollutants (particulate matter,
sulfur oxides, VOCs) for every
1 ton of aluminum produced
Aluminum Ingots
Aluminum Smelter
Aluminum Can Production: Step 4 – Tertiary Processing
• Aluminum ingots are
melted (requiring more
energy) and are extruded
as sheets
• Finishing process for
rolled sheets involves
several chemicals
(strong acids and bases)
that are toxic
Aluminum Can Production: Step 5 – Finishing/Assembly
• Aluminum sheet is fed into
extrusion tubes and cut into
shallow cups
• Cups are fed into ironing press
where successive rings redraw
and iron the cup. This reduces
sidewall thickness, making a
full length can
• The bottom is “domed” for
strength
• Cans are necked in at the top
and flanged to accept the end
• Little chemical pollution at this
stage, just electricity use
Aluminum Can Production: Step 6 – Filling/Distribution
• Cans are shipped without end
portion to beverage company
• Beverage is injected under
pressure – outward force
strengthens the can
• After filling, can is labeled and
packaged
• Cardboard and plastic is used,
some toxic waste from making
paint and ink used for labels
• Finally, product in the can is
trucked (diesel fuel use) to a
wholesaler/distributor and then
to retailer (multiple trips)
Life Cycle Analysis of an Aluminum Can
• Mining/Extraction of Bauxite – Ship to processing plants
• Primary Processing – Convert bauxite to alumina
• Secondary Processing – Convert alumina to aluminum ingots
(smelting)
• Tertiary Processing – Convert aluminum ingots into
aluminum sheets
• Finishing/Assembly – Convert aluminum sheets into
aluminum cans
• Filling/Distribution – Fill cans with beverage, transport to
distributor/final consumers
• ALL OF THESE STAGES use significant amounts of fossil
fuel energy. MOST OF THESE STAGES generate large
quantities of hazardous and toxic waste products
Aluminum can, used once
Steel can used once
Recycled steel can
Glass drink bottle used once
Recycled aluminum can (65% less energy)
Recycled glass drink bottle
Refillable drink bottle, used 10 times
0
8
16
Energy (thousands of kilocalories)
24
32