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ES110_10F_LifeCycleAnalysis

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					  Lifecycle Analysis – The
Environmental Costs of Linear
          Societies
  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
For each ton
of useful ore
extracted,
many tons
of “over-
burden”
have to be
removed in
the process.
For bauxite
ore, the ratio
can be as
high as 5:1.
Land Degradation
  from mining
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
Recycling aluminum
cuts out the energy-
  intensive early
    stages of the
      lifecycle
    Aluminum can, used once


    Steel can used once


    Recycled steel can

                                              Glass drink bottle used once



                                Recycled aluminum can (70-90% less energy)


                               Recycled glass drink bottle



            Refillable drink bottle, used 10 times




0               8                        16                      24          32

                    Energy (thousands of kilocalories)

				
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posted:8/8/2012
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