Life Cycle Analysis of Glass vs. Polycarbonate

Sidelights

Natalie HenryJaymie Meliker Mike Turnbull

Melissa Vernon

April 14, 1999

Agenda

• Goals• System Overview• Life Cycle Costs • Impacts - Energy, Solid Waste, Air, Water• Drivers• Summary• Recommendations

Goal

• Evaluate two automobile sidelight systems• Sidelight = all windows except windshield

• Polycarbonate: – 40% lighter than glass– 200 times more resistant to shatter

• Glass:– scratch resistant

System Overview

Data Sources:

– Eco-profiles of the European Plastics Industry: polycarbonate

– Life Cycle Inventories for Packaging: packaging glass

Assumptions

• Packaging glass data equivalent to flat glass

• PC does not need scratch resistant coating • Equivalent mfg, recycling practices in

Europe & US• Identical mechanisms for window function

during use phase

Polycarbonate Flow DiagramAutomotive Assembly

Sidelight ProductionPC ManufacturingAcquisition, Refining & Processing of Raw

Materials

Coke

Natural Gas

Coal, Oil or Gas

Sodium Bisphenol A Production

Package & ship pellets

Cut pellets

Polymerisation: Chemical reaction

of inputs

Extrusion

Phosgene production

Injection mold pellets

Assemble sidelightsSilkscreen

ceramic frit

Package & ship sidelight

Glass Flow DiagramAcquisition, Refining & Processing of Raw

Materials

Sidelight Production Automotive Assembly

Glass Manufacturing

Draw glass over molten

tin

Cut glass

Package & ship glass

Annealing lehr: Cool glass

Melting furnace

Limestone

Carbon

Cullet

Package & ship sidelight

Silkscreen ceramic frit

Bending lehr: Shape glass

Assemble sidelights

Silica (sand)

Dolomite

Soda Ash

Limestone

Salt cake

Rouge

Cut and drill holes in glass

Mix raw materials

Vehicle of Study• Vehicle: Chevy Express G Van• Total surface area of sidelights = 51 sq ft• Useful life of van = 110,000 miles• Fuel Economy = 16.4 mpg

Life Cycle Costs

Polycarbonate Glass

Cost ofsidelights

$156.06 $25.50

Gasolinecosts

$51.73 $86.22

Landfill costs $1.39 $2.31

TOTAL $209.18 $114.03

Energy Consumption: Per Vehicle

03,0006,0009,000

12,00015,000

Matl.Acquisition

& Mfg

Use End of Life Total

Life Cycle Phase

Ener

gy (M

J)

Glass

PC

Solid Waste: Per Vehicle

020406080

Matl.Acquisition &

Mfg

Use End of Life Total

Life Cycle Phase

Mas

s (k

g)

Glass

PC

Air Emissions: Per Vehicle

0

200

400

600

800

CO2 CO

Mas

s (k

g)

Glass

PC

Air Emissions: Per Vehicle

0

5

10

15

20

Lead Aromatic HCs and Organo-Halogens

Mas

s (g

)

Glass

PC

Air Emissions: Per Vehicle

01000200030004000

NOX ParticulateMatter

SOX

Mas

s (g

)

Glass

PC

Wastewater: Per Vehicle

0

2

4

6

8

Wastew ater

Vol

ume

(m3 )

Glass

PC

Water Emissions: Per Vehicle

0

5000

10000

15000

20000

Chlorine Dissolved Solids

Mas

s (g

)

Glass

PC

Energy, Solid Waste, Water Emissions Summary

Glass PC SignificanceEnergy 0 0 Resource

DepletionSolid Waste - + Landfill VolumeWaste Water: Volume + - Volume Cl + - - Toxic/Carcinogen Metals + - Toxic Dissolved Solids - + Decrease O2 Suspended Solids - + Decrease O2

Air Emissions Summary

Glass PC SignificanceCO2 - + Global WarmingMethane + - Global WarmingCO - + ToxicNOx - + Ground level OzoneHydrocarbons - + Ground level OzonePM + - ToxicSO2 + - Acid RainAromaticHydrocarbons

+ - - Carcinogen

Organo-halogens

+ - - Carcinogen

Lead - + ToxicCFCs + - Ozone Depleting

Key DriversManufacture Use End of Life

Environmental Reduce toxicityof raw materials

Increaserecyclability

Performance Avoid scratching Avoid scratchingReduce noise

Cost Reduce cost ofraw materials

Legal Clean Air ActClean Water Act

ANSI/SAE Z26.1 RCRA

Environmental Recover energy Increase fueleconomy

Increaserecyclability

Performance Decreasecracks, flaws

Increasepassenger safety

Cost Increase fueleconomy

Legal Clean Air ActClean Water Act

ANSI/SAE Z26.1 RCRA

PC

Gla

ss

Summary of Results

Glass• Lower environmental

impact in Mfg phase• Lower total:

– Particulate matter– SO2

• Lower total cost

Polycarbonate• Lower environmental

impact in Use phase• Lower total:

– NOx & HC– Solid waste– CO– Lead in air emissions

Overall: Neither product system is more environmentally friendly

Recommendations

PC Manufacturers• Reduce manufacturing

costs• Improve scratch

resistant coating• Develop single unit for

sidelight & encapsulation

Glass Manufacturers• Reduce/recover

energy used in manufacturing

• Increase recycled content from 15% to 50%

Overall: Improve mpg of automobile End of life material recovery and recycling

Questions & Answers