global guide d4s07 modulos:Layout 1 18-12-2009 19:31 Page ...d4s-sbs.org/MH.pdf · materials, and...

123

EEccoo--MMaatteerriiaallssMODULEHNNgguuyyeenn XX..HH..,, HHoonnddaa TT..,, WWaanngg YY..,, aannddYYaammaammoottoo RR..,, UUnniivveerrssiittyy ooff TTookkyyoo

1. Basic introduction ofeco-materials

1.1 What are eco-materials

Eco-materials are defined as those materials that enhan-ce the environmental improvement throughout thewhole life cycle, while maintaining accountable perfor-mance (Halada and Yamamoto 2001). Eco-materials playa key role in material science and technology to minimi-ze environmental impacts, enhance the recyclability ofmaterials, and to increase energy and material efficiency.

In North America and Europe, eco-materials areoften called “environmentally-friendly materials” or“environmentally preferable” materials.

1.2 How do eco-materials differ from conventionalmaterials?

One of the most comprehensive definitions for eco-materials was proposed by Professor Yagi in 2000 (Yagi2002). From the view point of material science and engi-neering, an eco-material should pose at least oneamong ten superior properties compared to conven-tional materials. A more detailed explanation of eachsuperior property of eco-material can be found in box1. As a result, there is a very wide range of eco-materi-als developed in various industries such as iron andsteel, electronics, chemicals, paper, construction, textileand polymers. Some examples of commercialized eco-

materials are given in table 1 and in the examples sec-tion.

Eco-materials are those that can contribute toreduction of environmental burden through their lifecycles” (Shinohara 2004). In other words, any materialcould be an eco-material as long as it could satisfy pre-requisites (I) and necessary conditions of eco-materials(II and/or III) (see figure 1). The pre-requisites of eco-materials include the optimization of physical and/orchemical properties and best technical performance (I).The necessary conditions are as follows:> Significant environmental improvements compared toconventional materials (II),> No tradeoff of environmental load through the wholelife cycles, and > If there is a tradeoff, whole life cycle environmentaldata must be available to verify the improvement ofenvironmental performance (III).

It should be noted that the whole life cycle impactsof eco-materials must be considered and be improved.The conditions (II) include six vectors: as 1) greenresource profile; 2) minimal environmental impact dur-ing the material manufacturing process; 3) high produc-tivity in use; 4) minimal hazardous substance; 5) highrecyclability; and 6) high environmental purification effi-ciency. More details of these six vectors are describedin the eco-materials guideline section. An eco-material isnot necessary to meet all these six vectors, but at leastone must be satisfied, while the others should be similar

global guide_d4s07_modulos:Layout 1 18-12-2009 19:31 23

to the refere nce material

Textbox 1> Definition of superiorproperties of eco-materials1> Energy saving ability to reduce total lifecycle energy consumption of a system or device.2> Resource saving ability to reduce the totallife cycle material consumption of a system ordevice.3> Reusability to allow the reuse of collectedproduct as similar functions.4> Recyclability l to allow the use of collectedproduct of material as a raw material.5> Structural reliability to be used on the basicof its reliable mechanical properties.6> Chemical stability to be used over longterm without chemical degradation.7> Biological safety ability to be used withoutcausing negative effects to the ecological system.8> Substitutability to be used as an alternativeof “bad” materials.9> Amenity to ensure the comfort of workingenvironment10> Cleanability to separate, fix, remove anddetoxify a pollutant for environmental treatmentprocess.

2. More backgroundinformation

2.1 The development of eco-materials

A study by Nguyen reported a list of eco-materialsbased on the environmental reports or responsible carereports in 2002 of more than 40 Japanese companiesin several industrial sectors including metals, cement,chemicals, and others (Nguyen, Honda et al. 2003). Atotal of 359 different eco-materials were identified andfurther investigated for the eco-material classification.

2.2 Eco-material classification

Some authors have been tried to classify eco-materialsfrom the view point of life cycle concept. New develop-ment of materials or eco-materials should be viewed inthe full context of sustainability. This classificationmethod of eco-materials was based on the four sustain-able principles: (i) ”cyclic” materials; (ii) materials forecology and environmental protection; (iii) materials forsociety and human health; and (iv) materials for energybased on the two main criteria as their sources andfunctions. These four main categories were then classi-fied further to ten sub-categories (see table 1).

GGrreeeenn rreessoouurrcceess pprrooffiillee

This aspect is related to both the new resource andrecycling stages. The main question is if “materials arefrom resources of green resource profile” (Shinohara 2004).Four major issues for this aspect are including:> Reducing use of non-renewable resources;> Substituting non-renewable by well-managed renew-able natural resources;> Reducing use of renewable natural resources, and> Increasing use of recycled resources.

124

Figure 1 ___ Conceptual model of eco-materialswithin the context of material science

global guide_d4s07_modulos:Layout 1 18-12-2009 19:31 Page 124

125

Figure 2 ___ Classification model for eco-materials

Table 1 ___ Some examples of eco-materials which are currently commercialized in Japan


Several quantitative indicators could be used includ-ing total material requirement (TMR), material intensity(MI), ecological footprint (EF), and ratio of recycledmaterials used.

PPrroodduuccttiioonn pprroocceessss ooff mmiinniimmaalleennvviirroonnmmeennttaall iimmppaaccttss

This aspect is related to four life cycle stages includingmaterial manufacturing, product manufacturing, recy-cling, and waste disposal. The main question is if “mate-rials are fabricated, disposed of and recycled through theprocess of low environmental impact” (Shinohara, 2004).Seven major issues for this aspect are:> Reducing CO2 emission at material manufacturingprocess;> Reducing emissions of pollutants at material manufac-turing process;> Increasing production yield;> Reducing energy and input materials at product man-ufacturing process;> Reducing energy and input materials at recyclingprocess;> Reducing energy and input materials at waste dispos-al stage, and > Saving the landfill area.

Quantitative indicators for this aspect could includethe CO2, SOx, NOx emission, energy consumption, andmaterial productivity.

HHiigghh pprroodduuccttiivviittyy

This aspect is related to the consumption stage of thewhole life cycle of materials. The main question is if“materials can exhibit high productivity in the applied prod-uct” (Shinohara 2004). Major issues in this aspect are:> Reducing energy and input material at consumptionstage, and> Enhancing reuse and longevity of materials and prod-ucts.

Quantitative indicators in this aspect could be ener-gy and material efficiency during the consumption stage.

MMiinniimmaall hhaazzaarrddoouuss ssuubbssttaanncceess

This aspect is related to the material manufacturing, col-

lection and recycling stages. The main question is if“material could reduce emission of hazardous chemical sub-stances from the product and waste” (Shinohara 2004).Major issues are:> Reducing use of hazardous or potentially hazardoussubstances, and> Establishing a collection system for hazardous chemi-cal substances from used products.

Quantitative indicators of this aspect could be totalamount of hazardous substances used and released inthese life cycle stages. Information of hazardous sub-stances could be obtained using a pollutant release andtransfer register (PRTR) approach.

HHiigghh rreeccyyccllaabbiilliittyy

This aspect is related to the material manufacturing andrecycling stages. The main question is if “material couldcontribute to efficiency recycling” (Shinohara 2004). Majorissues in this aspect are:> Increasing ratio of recycled resources,> Enhancing separation and recovery ability of otherproducts,> Establishing a closed-loop recycling system, and> Enhancing a open-loop recycling system.

Quantitative indicators for this aspect could be theratio of recycled over virgin material.

HHiigghh eennvviirroonnmmeennttaall ttrreeaattmmeenntteeffffiicciieennccyy

This aspect is related to the consumption stage. Themain question is if “material can increase efficiency of envi-ronmental treatment or purification process” (Shinohara,2004). Major issues of this aspect are:> Purifying volatile organic compounds (VOCs) or sick-house syndrome organic compounds in the living envi-ronment,> Removing hazardous substances in contaminatedenvironment (air, water, and soil), and> Removing hazardous substances from exhaust gas.

126


2.3 Eco-materials examples

EEccoo--cceemmeenntt ((II..AA))

Eco-cement is a product of Taiheiyo CementCorporation. This eco-cement is manufactured usingmunicipal wastes as its substitute for raw materials. Themunicipal waste can be used as raw materials for eco-cement in two different ways, in the form of incinerat-ed ash, and in the form of municipal sludge. In the eco-cement, approximatetly 50% of municipal wastes hasreplaced the cement raw materials (table 2). Quality of

eco-cement is similar toordinary Portland cement.

Use of eco-cement hastwo benefits, reducing nonrenewable raw materialextraction and reducingthe waste released to theenvironment. A life cycleassessment result of eco-cement indicated thatCO2 emissions arereduced up to 50%, energy consumption is reduced upto 89%, and prolongation of landfill could save up to

30000 yen per square meter (Taiheiyo, 2003).

MM--WWoooodd22 ((II..BB))

M-Wood2 is a syntheticwood blend product com-bining various types ofplastics (polyvinyl chlorideor polypropylene) withwood chips. The woodcomposition in this materi-al is about 51-55% or less(by weight). The othercomponents consist of about 25-30% of plastic wastessuch as polypropylene trays, automobile bumpers, agri-cultural PVC, and less than 20% of pigments and addi-tives which are normally used in olefin resins. The pro-duction of this M-Wood2 will not produce any VOCs. Inaddition, 100% recycled materials are used for the pro-duction of M-Wood2. Furthermore, the testing phasereported that M-Wood2 could be recycled 10 times

127

Table 2 ___ Raw materials in eco-cement andPortland cement

TABLE3 ___


without losing its characteristics. M-Wood2 has superior characteristics compared to

normal wood, such as ease to process, light, naturalcolor and pattern. The material which is used PP resincan be incinerated without any formation of dioxin.Some material characteristics of M-Wood2 areexplained below.

Water resistance: Water absorption coefficient (%)(The weight change rate is due to water absorption. Thegreater the value is, the easier to absorb water).

Weather resistance: The time span of outdoor homeproducts of general wood is normally about 10 years.The deterioration of wood material is due to rain andultraviolet radiation. However, M-Wood2 is proved tobe more weather resistant than normal wood.

Heat resistance: polyvinyl chloride has self-extinguish-ing properties.When M-Wood2 is produced by mixingwood chip with PVC, the material will also has thischaracteristic. PP M-Wood2 will have the same heatresistance property with natural wood.

Abrasive resistance: M-Wood2 is proven to be more

abrasive resistance than natural wood as shown in table 5.ZZAAMM ((II..CC))

ZAM is a zinc-aluminum-magnesium high-corrosion-resistance hot-dip coated steel sheet. It is a three-layercoated steel sheet. The first two corrosion protectivelayers are magnesium-zinc and a zinc-aluminum withmagnesium. Its flat section is 10 to 20 times more cor-rosion-resistant than conventional Zn steel and 5 to 8

128

Table 4 ___ Water resistance property of M-Wood 2

Table 5 ___ Flooring abrasion proof test (as formethod of exam in JIS flooring conformity)


times more corrosion resistant than Zn-5% Al steel, andits cut end has greater corrosion resistance than previ-ous coated steel sheets.

Its high corrosion resistance and hence longer lifecontributes to waste reduction, resource conservation,and energy saving. It eliminates coating process afterforming, and contributes to environmental protection.(ZAM won the 2000 Nikkei prize for superior productand service (Nihon Keizai Shimbun award).

CCeerraaCCaatt™ ((IIII..AA))

This material is a ceramichoneycomb catalyst carri-er use for exhaust gaspurification and energy-saving heat reservoirs. Thisceramic honeycombresembles a bee’s nest with its many chambers separat-ed by thin walls and is capable of a variety of functionsdepending on the materials used and the cell structure.Materials that can be used in high-temperature environ-ments include alumina (Al2O3), mullite(3Al2O3"2SiO2) and cordierite (2MgO "2Al2O3"5SiO2).

Recently, more and more strict regulation on theexhaust gas emission from diesel engines has been

introduced worldwide. Installation of exhaust gas con-trolling systems has two constraints, removal of partic-ulate matters (PM) and NOx while maintaining theengine system. Normally, exhaust gas control systemwill reduce the performance of engine. The ceracatmaterial produced with world class technology enablesmore than 95% removal of PM while minimizing pres-sure loss in the control system. Some of characteristicsof Ceracat are shown in table 6.

FFoolliiuumm® -- PPhhoottooccaattaallyysstt ccooaattiinngg aaggeenntt ((IIII..BB))

Folium is a titanium diox-ide photocatalyst coatingagent which is used inbuilding (external andinternal wall, transparentglass), and transportation(car body, roads). The Folium will help to protect envi-ronment byreducing the concentration of formaldehydeand CO2 in the atmosphere under the exposure of UVradiation. Immediately after exposure to ultraviolet lightirradiation, formaldehyde concentration is decreasedsharply to almost zero in about 20 minutes.

129

Table 6 ___ Properties of Ceracat™ for exhaust gasfilter


In addition, the use of titanium oxide as anti-bacteriacould dramatically reduce the contamination of bacteriasuch as colon bacillus (Escherichia col) andStaphylococcus. An anti-bacteria effect test reported thatafter 24 hours, the Coliform and Staphylococcus counthave fallen to less than 10 while the untreated samplesshown about millions counts from coliform and thou-sand counts for Staphylococcus.

Another function of Folium is to protect the coat-ed surface from dirt: A folium-coated surface will beable to remain clean, while a non coated surface willbecome dirty and deteriorate. The mechanism of thisfunction is shown in the figure.

TTooyyoottaa SSuuppeerr OOlleeffiinn PPoollyymmeerr ((IIII..CC))

One method to reducethe total weight of a vehi-cle is to replace steel byother materials such asaluminum or plastics asmuch as possible withoutreducing the safety. Car bumpers and interiors are nowmade of plastic. Recently, Toyota Company introducedtheir TSOP (Toyota Super Olefin Polymer) which hadexcellent recyclability in their car bumper.The TSOP isa polypropylene based blend material. The bumpercould reduce plastic use by 18-30% compared to thetraditional plastic bumper with similar safety properties.At the moment, TSOP is used in a wide range of interi-or and exterior parts in Toyota cars such as the newmodel of Corolla.

VVoollaattiillee oorrggaanniicc ccoommppoouunnddss--ffrreeeeaaddhheessiivveess ((IIIIII..AA))

These adhesives are freefrom all VOC (volatileorganic compounds)including formaldehyde,toluene and xylene as sick-building syndrome gases.Two types are available:one for film installation and the other for wood andpaper. These have outstanding adhesiveness and durabil-ity equivalent to the best conventional products.

BBoonnee--CCeerraamm ((IIIIII..BB))

Boneceram is a highlyprocessable apatite hydrox-ide bone substitute materi-al which plays an active rolein medical fields. This mate-rial has an excellently bio-compatible property tohuman tissue. The materialis so highly processable that it could be made into com-plicated shape to fit to specific part. Boneceram is nowessential for orthopedic surgery and brain surgery.

UUllttrraa--lliigghhtt sstteeeell ffoorr aauuttoommoobbiillee ((IIVV..AA))

In Japan the automobile industry is greatly involved inthe development of eco-materialsincluding steel, non-ferrous and bio-plastics for their “eco-car”. For ener-gy efficiency, some studies indicatedthat a 10% decrease in automobileweight would improve fuel efficiencyby 10-12% . Whole life cycle energyconsumption of apassenger carwas mainly dueto driving (75-80%) and materi-al production,( 1 5 - 2 0 % )(Marukawa and Edwards 2001). In addition, about 75%(by weight) of a car was made of steel. It was obviousthat if the weight of steel was reduced, energy efficiencyof the car would increase. This could be achieved byselecting a high tensile strength steel without any reduc-tion in safety of vehicle. According to Ultra-Light SteelAuto Body (ULSAB) project, a car body could reduce by23% its weight contributing to a 5% weight reduction ofa passenger car (Kawai 2001). High strength steel speci-fications range from 210 to 800 MPa yield strengthswith thickness range from 0.65 mm to 2.0 mm. Furthermore, the use of materials which enable high-efficiencypower generation would also improve the whole lifecycle energy consumption.

130


HHiigghh hhyyddrrooggeenn aabbssoorrbbiinngg aallllooyy ((IIVV..BB))

Hydrogen - ab sorb i n galloys have a comparative-ly short history whichdates back about 20 yearsto the discovery of NiFe,MgNi and LaNi5 alloys.They are capable ofabsorbing hydrogen equivalent to about a thousandtimes of their own volume (or about 3% by mass), gen-erating metal hydrides and also releasing the hydrogenthat they absorbed. More than 65% of hydrogenabsorbed could be utilized. These hydrogen-absorbingalloys combine metal (A) whose hydrides generate heatexothermically with metal (B) whose hydrides generateheat endothermically to produce the suitable bindingenergy so that hydrogen can be absorbed and releasedat or around normal temperature and pressure levels.Depending on how metals A and B are combined, thealloys are classified into the following types: AB (TiFe,etc.), AB2 (ZnMn2, etc.), AB5 (LaNi5, etc.) and A2B

(Mg2Ni, etc.). From the perspective of charge and dis-charge efficiency and durability, the field of candidatemetals suited for use as electrodes in storage batteriesis now being narrowed down to AB5 type alloys inwhich rare-earth metals, especially metals in the lan-thanum group, and nickel serve as the host metals; andto AB2 type alloys in which the titanium and nickelserve as the host metals.

This hydrogen absorbing alloy has several potentialapplications such as heat utilization systems, hydrogenstorage systems, actuators, hydrogen purification equip-ments, nickel-metal hydride secondary batteries, andcatalysts. Recently, Sanyo electric has developed nickel-metal hydride secondary batteries, a portable fuel cellfor notebook computers and a refrigeration systemusing this alloy. Toyota has also developed a new fuel cellsystem which combines with hydrogen-absorbing alloyto make a hydrogen storage device.This promises to bea more efficient, faster charging and farther travellingfuel cell.

131

Table 7 ___


3. Four step approachfor eco-materialselection for eco-redesign and eco--innovation

A conceptual model of eco-material selection guidelinesis illustrated in figure 3. The four steps are defining typeof products, gathering eco-material information, definingproduct requirements, and selecting eco-material. Thisprocess is also considered as a back-casting approach orABCD analysis of TNS (Robert 2002).

3.1 Defining type of products (A)

The first step of the eco-material selection process is todefine product type with a consideration of whole lifecycle concept.

Figure 4 illustrates the four general product typeswith a full consideration of life cycle concepts (Young2002). A type I product normally has a very short lifes-pan and material intensiveness. A single use of packageis a typical example of a type I product. In comparisonto a type I product, a type II product has relativelylonger lifespan, but has more manufacturing-intensive-ness. Notebook computers and digital cameras are typ-ical examples of type II products. In contrast, a type IIIproduct has a comparatively long lifespan. Energy and/orresource consumption during the use phase are themain concerns of type III products. Automobiles andwashing machines are some typical examples of type IIIproducts. The last type of product is that with specialend-of-life or disposal characteristics. Typical examplesof this type of product are disposal diapers and Ni-Cdbattery.

Defining the right product type is crucial in D4S andmaterial selection.An eco-material appropriate for oneapplication might not be suitable for another applica-tion. For instance, high tensile strength steel is not

132

Figure 3 ___ Four step model of eco-material selec-tion process

Figure 4 ___ Four general product types with lifecycle concept


appropriate for type II product like digital cameras, asthe lifespan of this product is relatively short (about 2-5 years). Another example is that the use of readilybiodegradable polymers as a construction material isnot appropriate. Renewable material is appropriate fortype I products, while material that is most efficient toprocess is appropriate for type II products. Lightweightor high tensile strength steel should be used for type IIIproducts, while biodegradable or recyclable materialsshould be used for type IV products.

3.2 Gathering eco-materialinformation (B)

The second step in eco-material selection guidelines isto obtain as much eco-material information as possible.In this step, all necessary information on eco-materialsis collected and verified. Necessary information shouldcover all “triple bottom line” aspects, including social,economic and environmental aspects.

The classification and database of eco-materials inprevious sections are among the crucial informationneeded. By studying the information, product designerswould have a better understanding on the state-of-the-art of eco-material development. From then, productdesigners should be able to direct themselves towardssustainability.

In addition to information on eco-material classifica-tion, life cycle impact assessment or eco-efficiency orother similar assessment results of the related materi-als should also be collected. Some assessment resultslike LCA are difficult to obtain, while some others likequalitative assessment are relatively easier to conduct.

Besides environmental and social information, eco-nomic information is also vital information. One of theeconomic issues in material selection is the cost ofmaterial or the market price.The cost of eco-materialscould be influenced by many factors and normally fluc-tuates in the market. Thus collecting cost of materialsshould be carefully carried out.

3.3 Defining product requirements (C)

The third step of eco-material selection process isdefining product requirements. In this step, five main

properties of a particular product including physical,mechanical, electrical, thermal, and chemical propertiesneed to be defined. Information of these propertiescould be found in various sources such as IDEMAT,MATWEB, literature, handbooks, or companybrochures.

Relative importance of each property will depend onthe application. Different classes of material will havedifferent specific properties. Metals, for instance, tend tohave high stiffness and strength while having a high den-sity. Polymers are lower in density with relatively lowstrength and stiffness.Thus defining appropriate productrequirements will ease eco-material selection.

3.4 Selecting eco-materials (D)

The final step in the eco-material selection process is toselect appropriate eco-material for eco-products. In thisstep, eco-material is strategically evaluated and selected.The objective of this step is to optimize the number ofthese product requirements during the product designphase. Several performance metrics or productrequirements will be involved in selecting eco-materials.This step, therefore, requires a multi-criteria optimiza-tion process for eco-material choice.

4. References

> Halada, K. and R. Yamamoto (2001). “The current sta-tus of research and development on eco-materialsaround the world.” MRS Bulletin 26(11): 871-878.> Kawai, J. (2001). Materials and Design. 22: 111-122.> Marukawa, K. and K. L. Edwards (2001). Materials andDesign. 22: 133-136.> Nguyen, X. H., T. Honda, et al. (2003). Classification ofeco-materials in the perpectives of sustainability.Proceedings of eco-design 2003: Third InternationalSymposium on Environmental Conscious Design andInverse Manufacturing, Japan.> Robert, K.-H. (2002). The Natural Step Story. Canada,New Society Publishers.> Shinohara, Y. (2004). Eco-materials guideline project inJapan. Proceedings of the 1st Japan-China Symposiumon Eco-materials, Recycling-oriented Industry and

133


Environmental Management, Suzhou, China.> Yagi, K. (2002). Concept and Development of Eco-materials. Proceedings of International Workshop onEco-materials, Tokyo, Japan, National Institute forMaterials Science.> Young, S. B. (2002). Materials Eco-selection.Proceedings of International Workshop on Eco-materi-als, Tokyo, Japan, National Institute for Materials Science.


global guide d4s07 modulos:Layout 1 18-12-2009 19:31 Page ...d4s-sbs.org/MH.pdf · materials, and...

Documents

Transcript of global guide d4s07 modulos:Layout 1 18-12-2009 19:31 Page ...d4s-sbs.org/MH.pdf · materials, and...