Aula 7 Eco-seleção e ferramenta de eco-auditoria ... aula 7 selemat - PMT2051.pdf · CES EduPack...

Mike AshbyDepartment of Engineering

University of Cambridge

© M. F. Ashby, 2011For reproduction guidance see back page

This lecture unit is part of a set created by Mike Ashby to help introduce students to materials, processes and rational selection.

The Teaching Resources website aims to support teaching of materials-related courses in Design, Engineering and Science. Resources come in various formats and are aimed primarily at undergraduate education.

Aula 7Eco-seleção e ferramenta de

eco-auditoria

Análise de ciclo de vida

Sustentabilidade e eficiência de material:

eco-design

1PMT 2501 – Seleção de Materiais e Análise de Falhas - 2011

M. F. Ashby, 2011PMT 2501 – ANÁLISE DE FALHAS E SELEÇÃO DE MATERIAIS, 2011,COMPILADO POR PROF. CESAR R. F. AZEVEDO

Outline

� Material consumption and life-cycle

� Eco-audits and the audit tool

� Strategy for materials selection: eco-design

� LCA - problems and solutions

Motivation• Humans use materials and energy on a colossal scale• Making materials accounts for about 30% of all global energyconsumption – most derived from fossil fuels• Dependence on imported fossil fuel caries economic and securityrisks for some countries• Continued release of carbon to atmosphere carries risk• Responsibility to seek to minimize energy / carbon aspects ofmaterial and process selection .


Material production

Concern 1: Resource consumption, dependence

96% of all material usage

20% of all globalenergy

• the consumption of steel exceeds, by a factor of ten, that of all other metals combined• the combined consumption of polymers begins to approach that of steel..

• the consumption of hydrocarbon fuels (oil and coal) is about 9 billion tonnes per year


Material production


• The consumption of wood exceeds that of steel even in tonnes per year and since it is a factor of 10 lighter, if measured in m3/year, wood totally eclipses steel..

•The biggest consumption are for the materials of the construction industry.




Material production


• The biggest consumption is of concrete, which exceeds that of all other materials combined. The other big ones are asphalt, bricks and glass.

•The biggest consumption are for the materials of the construction industry.




Carbon to atmosphere

Concern 2: Energy consumption, CO2 emission

20% of allcarbon toatmosphere

Carbon release to atmosphere caused by the production of materials is estimated by theembodied energy of the material (energetic matrix). If you want a big change in thecontribution of material production to the C problem, we should focus on these materials.


Life cycle analysis (LCA)

ISO 14000 and PAS 2050 of the International StandardsOrganization defines a family of standards for environmentalmanagement systems. ISO 14000 contains the set ISO 14040,14041, 14042, 14043, 14047, 14048 e 14049 published between1997 and 2003, prescribing broad procedures for conductingthe four steps of an LCA:• setting goals and scope• inventory compilation• impact assessment• interpretation.

The standard is an attempt to bring uniform practice andobjectivity into life-cycle assessment and its interpretation,but implementation is burdensome and expensive.

PAS (public available specification) 2050:2008 - Specificationfor the assessment of the life cycle greenhouse gas emissionsof goods and services


The product life-cycle: phases

LandfillCombust

Resources

Emissions and waste

Life cycle

assessment (LCA)


Typical LCA output: Al cans

Aluminum cans, per 1000 units• Bauxite 59 kg

• Oil fuels 148 MJ

• Electricity 1572 MJ

• Energy in feedstock 512 MJ

• Water use 1149 kg

• Emissions: CO2 211 kg

• Emissions: CO 0.2 kg

• Emissions: NOx 1.1 kg

• Emissions: SOx 1.8 kg

• Particulates 2.47 kg

• Ozone depletion potential 0.2 X 10-9

• Global warming potential 1.1 X 10-9

• Acidification potential 0.8 X 10-9

• Human toxicity potential 0.3 X 10-9

Life cycle assessment (LCA)

Roll up into an“eco-indicator” ?

� Full LCA expensive, and requires great detail and skill – and even then is subject to uncertainty

Resource consumption

Emissionsinventory

Impactassessment

ISO 14040 series

PAS 2050

� How are CO2 , CO, NOx and SOx productions to be balanced against resource depletion, toxicity or ease of recycling when choosing a material? This question has lead to efforts to condense the eco-information about a material into a single measure or eco-indicator, giving the designer a simple, numeric ranking.


Eco-audit for design

The first step is to develop an eco-audit tool that isapproximate, but retains sufficient power to differentiatebetween alternative choices.

A spectrum of levels of analysis exist, ranging from asimple eco-screening to a full Life Cycle Assessment,with overheads of time and cost.

In between lie methods that are less rigorous but fast...

The strategy for guiding design has 3 steps, detailed here and on the next frames.



The second step is to select a single measure of eco-stress. On one point there is some internationalagreement: the Kyoto Protocol of 1997 committed thedeveloped nations that signed it to progressively reducecarbon emissions, meaning CO2.

In the UK the focus is more on reducing energyconsumption, but since this and CO2 production areclosely related, they are nearly equivalent. Thus there isa certain logic in basing design decisions on energyconsumption or CO2 generation.




Need: Fast Eco-audit with sufficient precision to guide decision-making

� Distinguish life-phases of components in terms of energy

consumption and equivalent CO2 emissions

600

400

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100

0

-100

Ene

rgy

(MJ)

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-2

C0 2

equi

v (k

g)

This is the life-energy and life-CO2

(as prescribed in ISO 14040 and PAS 2050)These are potential benefits

(could be recovered at end of life)



The third step is to separate the contributions of each ofthe phases of the life of a component becausesubsequent action depends on which is the dominantone.• If it is that a material production, then choosing amaterial with low “embodied energy” (defined on a laterframe) is the way forward.• If it is the use phase, then choosing a material to makeuse less energy-intensive is the is the right approach –even if it has a higher embodied energy (example: car).



Fast

eco-audit

Eco-aware design: the strategy (1)

The stepsAnalyse

results, identifypriorities

Explore

options with “What if..”s

600

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200

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0

-100

Ene

rgy

(MJ)

Initial design

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400

300

200

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0

-100E

nerg

y (M

J)

What if ..

Different material?


Fast

eco-audit


The stepsAnalyse


Use CES to

select new Materials and/or Processes

Recommend

actions & assesspotential savings

Explore


600

400

300

200

100

0

-100

Ene

rgy

(MJ)

Use eco-audit toidentify

design objective

Minimize:

• material in part

• embodied energy

• CO2 / kg

Material

Minimize:

• process energy

• CO2/kg

ManufactureMinimize:

• mass

• distance

• transport type

TransportMinimize:

• mass

• thermal loss

• electrical loss

Use

Select:

• non-toxic materials

• recyclable materials

End of life

Look at the first three steps


The CES Eco-audit tool

User interface

� Bill of materials

� Manufacturing process

� Transport needs

� End of life choice

User inputs

Eco database

� Embodied energies

� Process energies

� CO2 footprints

� Unit transport energies

� Recycling / combustion

Data from CES

Eco audit model

Outputs(including

tabular data)


Typical record showing eco-properties


The simple Audit tool: Levels 1, 2 and 3

Add record

Eco Audit

Synthesizer

Options….

^ 1. Material, manufacture and end of life

v 2. Transport

v 3. Use

v 4. Report

1 Component 1 Cast iron 30% 2.4 Casting Recycle

1 Component 2 Polypropylene 0% 0.35 Molding Landfill

Name Choose

material from CES DB tree

Enter

mass

Set recycle

content 0 – 100%

Choose

process

Choose end-of-

life path

How

many?


CES EduPack materials

tree

Material and process energy / CO2

Component name Material Process Mass (kg) End of life

Component 1 Aluminum alloys Casting 2.3 Recycle

End of lifeoptions

• Reuse

• Refurbish

• Recycle

• Combust

• Landfill

Component 2 Polypropylene Polymer molding 1.85 Landfill

Component 3 Glass Glass molding 3.7 Reuse

Total embodied energy Total process energy Total mass Total end of life energyAvailable processes

• Casting

• Forging / rolling

• Extrusion

• Wire drawing

• Powder forming

• Vapor methods


Transport

Transport stage Transport type Distance (km)

Stage 1 32 tonne truck 350

Stage 2 Sea freight 12000

Table of transport types: MJ / tonne.kmCO2 / tonne.km

Transport energy

Transport CO2


Use phase – static mode

Energy input and output

Power rating

Usage

Usage

Fossil fuel to electric

days per year

hours per day

1.2 kW

365

0.5

Energy conversion path

Fossil fuel to heat, enclosed system

Fossil fuel to heat, vented system

Fossil fuel to electric

Fossil fuel to mechanical

Electric to heat

Electric to mechanical (electric motor)

Electric to chemical (lead-acid battery)

Electric to chemical (Lithium-ion battery)

Electric to light (incandescent lamp

Electric to light (LED)

Total energy and CO2 for use

W

kW

MW

hp

ft.lb/sec

kCal/yr

BTU/yr


Bottled water (100 units)

Fossil to electric 0.12 kW 2 days 24 hrs/day

Use - refrigeration

� 1 litre PET bottle with PP cap

� Blow molded

� Filled in France, transported 550 km to UK

� Refrigerated for 2 days, then drunk

Number Name Material Process Mass (kg) End of life

100 Bottles PET Molding 0.04 Recycle

100 Caps Polyprop Molding 0.001 Recycle

100 Water 1.0

Transport

14 tonne truckStage 1 550 km


The output: drink container

The audit reveals

the most energy and carbon

intensive steps…

… and allows rapid

“What if…”

Material Manufacture Transport Use

End of life

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-4

-6

Car

bon

(kg)

100% virgin PETwith recycling

PET Glass ?


End of life

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300

200

100

0

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-200

Ene

rgy

(MJ)



Change the materials

Fossil to electric 0.12 kW 2 days 24 hrs/day

Use - refrigeration

� 1 litre glass bottle with aluminum cap

� Glass molded

� Filled in France, transported 550 km to UK

� Refrigerated for 2 days, then drunk

Transport

14 tonne truckStage 1 550 km

Number Name Material Process Mass (kg) End of life

100 Bottles PET Molding 0.04 Recycle

100 Caps Polyprop Molding 0.0001 Recycle

100 Water 1.0

Soda glass Glass mold 0.45

Aluminum Rolling 0.002


Glass bottle replacing PET


End of life

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-6

Car

bon

(kg)



End of life

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Ene

rgy

(MJ)



End of life

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600

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200

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rgy

(MJ)

Change of scale

100% virgin glasswith recycling


End of life

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50

40

30

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10

0

-10

-20

-30

Car

bon

(kg)

Change of scale

100% virgin glasswith recycling

The glass bottle requires almost twice as much energy and emits twice as much carbon and the PET bottle, largely because of its much greater mass.


Use recycled PET instead of virgin PET?

Material Manufacture Transport Use End of life

12

10

8

6

4

2

0

-2

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-6

Car

bon

(kg)

100% recycled PETwith recycling

100% recycled PETwith recycling


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Ene

rgy

(MJ)



End of life

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(MJ)


End of life

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Car

bon

(kg)


The material energy consumption and CO2 emisssiondecrease significantly by using recycled PET. The end of life credit, however, is lower…


Combust instead of recycle


End of life

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10

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-6

Car

bon

(kg)



End of life

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200

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rgy

(MJ)



End of life

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300

200

100

0

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rgy

(MJ)

100% virgin PET with combustion


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10

8

6

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0

-2

-4

-6

Car

bon

(kg)

100% virgin PET with combustion

There is a small energy-credit at end of life by combusting instead of recycliing the PET bottle, but this combustion creates a large carbon emission lower…


Ship by air freight, refrigerate 10 days


Disposal

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10

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Car

bon

(kg)

100% virgin PETwith truck transport

Material Manufacture Transpt Use

Disposal

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50

40

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Car

bon

(kg)

100% virgin PETwith air freight

Change of scale

Material Manufacture Transpt Use

Disposal

1000

800

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200

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rgy

(MJ)

Change of scale

100% virgin PETwith air freight


Disposal

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300

200

100

0

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-200

Ene

rgy

(MJ)

100% virgin PETwith truck transport

The transport phase now dominates the energy consumption andCO2 emissions due to the use of air freight.The use phase has also increased and now it is comparable withthat of the material… so don´t store drinks in the fridge unlessthey are needed….


Sustainability

http://www.iom3.org/events/sustainability

“Sustainable development is development that meets

the needs of the present without compromising the

ability of future generations to meet their own needs”

Report of the Brundtland commission of the UN, 1987

There are five families of natural resources available to us: energy,minerals (fuels as well), land, water and air.

All except minerals have a renewable component and so can be drawnupon indefinitely provided they are managed. Minerals are a finiteresource, but a large one sufficient to meet present needs, but aconcern for the future.

At present we get only 8% of our energy from renewable energy,relying instead on the mineral reserves of oil, coal and gas.


Sustainability

http://www.iom3.org/events/sustainability

Making materials uses lots of energy. The materials enter the supplychain and are processed into products. At the end of the product lifethe material may be:• rejected to landfill;• combusted for energy;• re-circulated through the supply chain via recycling;• re-manufactured;• re-used.

Material efficiency means maintaining sufficient material stockmaterial to meet present needs, while minimizing new inputs ofminerals, energy and biomass. “Conservation” here has a doublemeaning: conserving mineral, energy and biomass resources andconserving the material stock currently in circulation.


Eco-informed design

The materials life-cycle

The drivers for eco-design

• Focus on carbon footprint by governments• Legislation (Carbon taxes)• Incentives (Subsidies, concessions)• Doing more with less = $$$

Eco-informed design?

• 80% of eco-impact tied in at design stage...

• Build-in eco at the design stage!


Resume: the audit

� But when we did “what if’s” we were guessing

� Do better? Be systematic. Identify the critical phases and optimise them!

600

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Ene

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(MJ)

Mat

erial

Man

ufa

ctu

reTra

nsport

Use

Dis

posa

l

EoL

cre

dit

600

400

300

200

100

0

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rgy

(MJ)

Mat

erial

Man

ufa

ctu

reTra

nsport

Use

Dis

posa

l

EoL

cre

dit

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Mate

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Manuf

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ort

Use

Dis

posa

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EoL

cred

it

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Mate

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Manuf

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Use

Dis

posa

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EoL

cred

it

Energy CO2, eqiv



Fast

eco-audit

The stepsAnalyse


Use CES to

select new Materials and/or Processes

Recommend

actions & assesspotential savings

Explore


600

400

300

200

100

0

-100

Ene

rgy

(MJ)

Use eco-audit toindentify

design objective

Minimize:

• mass

• distance

• transport type

TransportMinimize:

• mass

• thermal loss

• electrical loss

Use

Select:

• non-toxic materials

• recyclable materials

End of life

Minimize:

• material in part

• embodied energy

• CO2 / kg

Material

Minimize:

• process energy

• CO2/kg

Manufacture


Example: Eco-selection for a fizzy drink bottle


End of life

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rgy

(MJ)


The initial audit

Improve green credentials of bottle

Design brief

Translation

Constraints

� Transparent / translucent

� Able to contain pressure

Objective

� Minimize embodied energy

of bottle material


Modelling the bottle: Cylindrical pressure vessel

ytRp

σ<=σ� Circumferential stress

� Find material with largest.lowest embodied energy ρ

σ

m

y

H

� Embodied energy per unit area of wall

y

mm

HRpHtE

σ

ρ=ρ=

Embodied energy /

kg of material

� Compare with material with lowest cost, seek largest

ρ

σ

m

y

CPrice / kg of material

free variable: t


Minimizing embodied energy Bio-polymers are colored

green

Selection to minimize embodied energy

PLA meets the constraints at lowest embodied energy

First apply constraints, then use index to optimize choice

ρ

σ

m

y

H


Minimizing material cost

Selection to minimize cost

PET meets the constraints at lowest cost

Bio-polymers are colored

green

ρ

σ

m

y

C

Why there are so few bottles made of PLA? What can be done to revert this situation?


Material efficiency


Material efficiency

Engineering solutions

Legislation Life style

Aula 7 Eco-seleção e ferramenta de eco-auditoria ... aula 7 selemat - PMT2051.pdf · CES EduPack...

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