Life Cycle Assessment of Biofibres Replacingglass Fibres as Reinforcement in Plastics

Resources, Conservation and Recycling

33 (2001) 267287

Life cycle assessment of biofibres replacingglass fibres as reinforcement in plastics

T. Corbiere-Nicollier a,*, B. Gfeller Laban a, L. Lundquist b,Y. Leterrier b, J.-A.E. Manson b, O. Jolliet a

a Laboratory of Ecosystem Management (GECOS-EPFL), Swiss Federal Institute of Technology,CH-1015 Lausanne, Switzerland

b Composite and Polymer Technology Laboratory, LTC-EPFL,Swiss Federal Institute of Technology Lausanne, EPFL, CH-1015 Lausanne, Switzerland

Received 8 December 2000; accepted 18 June 2001

Abstract

This article aims to determine the environmental performance of China reed fibre used asa substitute for glass fibre as reinforcement in plastics and to identify key environmentalparameters. A life cycle assessment (LCA) is performed on these two materials for anapplication to plastic transport pallets. Transport pallets reinforced with China reed fibreprove to be ecologically advantageous if they have a minimal lifetime of 3 years comparedwith the 5-year lifetime of the conventional pallet. The energy consumption and otherenvironmental impacts are strongly reduced by the use of raw renewable fibres, due to threeimportant factors: (a) the substitution of glass fibre production by the natural fibreproduction; (b) the indirect reduction in the use of polypropylene linked to the higherproportion of China reed fibre used and (c) the reduced pallet weight, which reduces fuelconsumption during transport. Considering the whole life cycle, the polypropylene produc-tion process and the transport cause the strongest environmental impacts during the usephase of the life cycle. Since thermoplastic composites are hardly biodegradable, incinerationhas to be preferred to discharge on landfills at the end of its useful life cycle. The potentialadvantages of the renewable fibres will be effective only if a purer fibre extraction is obtainedto ensure an optimal material stiffness, a topic for further research. China reed biofibres arefinally compared with other usages of biomass, biomaterials, in general, can enable a threeto ten times more efficient valorisation of biomass than mere heat production or biofuels fortransport. 2001 Elsevier Science B.V. All rights reserved.

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* Corresponding author. Tel.: +41-21-693-5768; fax: +41-21-693-3739.E-mail address: [email protected] (T. Corbiere-Nicollier).

0921-3449/01/$ - see front matter 2001 Elsevier Science B.V. All rights reserved.

PII: S0921 -3449 (01 )00089 -1

T. Corbiere-Nicollier et al. / Resources, Conseration and Recycling 33 (2001) 267287268

Keywords: Renewable raw materials; Biofibres; Biomaterials; Environmental life cycle assessment; Fibrereinforced; Composites; Low-density materials; Transport pallets

1. Introduction

A life cycle assessment (LCA) is performed on two different plastic composite foran application to plastic transport pallets. After a short introduction, the goaldefinition and scooping, the inventory and the impact assessment, the results arediscussed.

1.1. Background

Towards development of sustainable biomass usage, one must first better under-stand the fundamental loops and processes of the material life cycle. The extraction,use and disposal of materials indeed have substantial environmental and economicimplications. In many cases far more material is extracted and translocated thanwhat is actually used in the end product itself. An optimal material technology has,therefore, to consider resource consumption and the amount and the quality ofwaste material during the entire life cycle. Moreover, the sustainability of a specifictechnology is determined to a large extent by the pollutant emissions to theenvironment during the manufacture of a product, its use and the waste treatmentat the end of its useful life.

Most of the objects of every-day life have a much shorter lifetime than theirconstituents. Through increased material efficiency and loop closing, resourceconsumption and environmental emissions can be reduced. For that, Lundquist etal. (1999) define three main possibilities: Use of renewable resources. Reuse of products and recycling of materials, including their energy content. Increase in the product durability.

The use of China reed (Miscanthus sinensis) as the reinforcing fibre in plasticsinstead of the more common glass fibre conforms to the first possibility. Moreover,this replacement reduces the environmental impact of the product transport palletwithout using end-of-pipe technologies. This corresponds to what sustainabledevelopment wants to achieve. The large number of criteria impinging on theimplementation of various kinds of loop-closing structures implies, however, trade-offs between technological, environmental and socio-economic requirements. Forexample, the addition of renewable resources can seriously limit the number oftimes a material can be recycled. Furthermore, cultivation, extraction and treatmentof renewable materials are clearly not environmentally neutral, as they may involvethe use of hazardous chemicals in the form of fertilisers as well as refinery andprocessing chemicals.

In order to provide optimal environmental solutions, Gutzwiller et al. (1998)carried out a first comparison of the use of China reed instead of glass fibre in

T. Corbiere-Nicollier et al. / Resources, Conseration and Recycling 33 (2001) 267287 269

plastics, using estimated physical properties of China reed. Lundquist et al. (1999)investigated further the technical feasibility of this replacement in plastic transportpallet. The physical properties of China reed fibre being better known, a morerealistic analysis can be performed. Based on the results of these investigations, thisnew study analyses if the use of China reed instead of glass fibre in plastics isadvantageous from an ecological point of view. It also identifies key environmentalparameters, production and use of each material. A plastic transport pallet is theapplication used for the comparison of the two types of plastic composites, enablingone to perform sensitivity analysis on the influence of the lifetime transportdistance.

1.2. General approach and existing studies

To this end a comparative LCA was carried out. The LCA method is anenvironmental assessment method, which focuses on the entire life cycle of aproduct from raw material acquisition to final product disposal ISO (1998). Thisassessment is structured in four parts (see Fig. 1): The goal definition, which defines the aim and the scope of the study as well as

the function and the functional unit of the studied product. The inventory, which lists pollutant emissions and consumption of resources per

functional unit. The impact assessment, which assesses the environmental impact of the pollu-

tants emitted during the life cycle. The interpretation, which allows one to interpret the results and to estimate the

uncertainties.The present study relies on data and methods of various LCAs of renewable and

non-renewable materials, the LCA of biomaterials performed by Jolliet et al. (1994)showed that environmental friendly is different from natural and that materialdensitymass of material satisfying service requirements is a key factor for bothtechnological and environmental optimisation, specially in case of long distancetransport. Within the European concerted action on harmonisation of environmen-

Fig. 1. General scheme for life cycle assessment.


tal life cycle assessment for agriculture, Audsley et al. (1997) developed a system-atic approach to LCA of agriculture production. Jolliet et al. (1997) and Wolfen-berger et al. (1997) studied M. sinensis used for heat production compared withother renewable materials. Landtechnik Weihenstephan (1995) and Dinkel et al.(1996) developed LCA for different renewable materials.

For the plastic components of the transport pallet, Koppen et al. (1994)performed an LCA of glass fibre for insulation purposes. Detailed LCA data forplastics have recently been updated and published in the BUWAL database(Haberstatter et al., 1998). Based on these earlier works, this paper develops thespecific case of M. sinensis biofibres and presents results according to the fourphases of LCA, finally comparing the obtained performances to earlier studies.

2. Goal definition and scoping

2.1. Goals

The present study concentrates on the comparison of China reed biofibres usedinstead of glass fibre as reinforcement in plastics, with transport pallets as the endproduct. It specifically aims: To determine if the use of China reed instead of glass fibre as reinforcement in

plastics is advantageous from an ecological point of view. To identify key environmental parameters and phases in the whole life cycle of

transport pallets. To study various disposal scenarios of the transport pallets (incineration, dis-

charge and recycling) in order to optimise environmentally this part of the lifecycle.

To investigate the sensitivity of the LCA results to different factors, such asproduct lifetime, resin fibre content and total transport distance.

2.2. Functional unit and system boundaries

The functional unit is defined as a standard transport pallet satisfying servicerequirements (transport of 1000 km per year) for 5 years.

It is useful to provide some specific information on M. sinensis. In Switzerland,the production of China reed is mainly used for energy production, but some smallenterprises promote its use as reinforcement for compression and injection mouldedthermoplastic composites. China reed is a C4 perennial grass, which grows veryquickly due to a particularly efficient photosynthesis (Werner and Kohler, 1994).For this reason the plants grow to a height of approximately 4 m during fivesummer months, producing 1720 tonnes of biomass per ha per year. In the stem,fibre rich bundles are distributed throughout the cross section, with a higher densitytowards the surface. The China reed fibre is obtained through a simple grinding andsieving process with a yield of 70%. The remaining 30% are grinding residues, whichare presently used as landfill.


Fig. 2. System boundaries with primary non-renewable energy consumption (MJ).

The system boundaries are chosen in order to include all the processes necessaryfor the realisation of the system function. All the processes related to manufacture,use and disposal of each type of pallet are taken into account. The process tree isdepicted in Fig. 2. For the China reed reinforced pallet, the production of Chinareed fibre is considered instead of the production of glass fibre. China reed iscultivated and then transported to a depot, where it is ground. The unusable partis put in a bioactive discharge; the fibre is used for the pallet production. During themanufacture, it is necessary to use a compatibiliser to improve the interfacebetween polypropylene and natural fibres. The production of this compatibiliser


(maleic anhydride) is also taken into account in the system. For the glass fibre-reinforced pallet, the following processes are included in the system, productionof glass fibre, polypropylene production, pallet production, use (transporting)and disposal of the pallets.

Detailed assumptions made in the environmental assessment are presented inAppendix A.

2.3. Scenarios

The first type of transport pallet studied is composed of polypropylene andglass fibre (GF pallet). Their lifetime is assumed to be 5 years. The second typeof pallet is composed of polypropylene and China reed fibre (CR pallet). Forthis material, only the mechanical properties of its constituents (i.e. fibre andmatrix) are currently available.

A comparison of the two types of pallets requires that they meet the sameservice requirements. Thus, they must have the same mechanical properties (inthis case stiffness characterised by the E-modulus). A GF pallet weighting 15 kg,containing 42% by weight of glass fibre, which is representative for this applica-tion, was chosen as a basis for comparison (Lundquist et al., 1999). The fibreweight fraction of a CR reinforced composite with equivalent stiffness was calcu-lated using a simple law of mixtures, assuming an optimal contact betweenmatrix and fibre in order to determine the potential of these biofibres. Thispallet weighs 11.8 kg and contains 53% by weight of CR fibre. In practice,remaining parenchyma residues lead to a poor contact between matrix and biofi-bres and thus to a strong decrease in the material stiffness. Further research ispresently carried out to enable a purer extraction of the renewable fibre to takefull advantage of their potential. Both pallets are assumed to be disposed byincineration. This is the reference scenario.

Two alternatives to incineration are considered. On the one hand, a 20%recycling of the GF pallet, on the other hand bioactive discharge. In addition,three sensitivity studies have been performed, analysing variations in lifetime,resin fibre content and use (transport distance), all three compared with thereference scenario.

Table 1Pallet composition, reference scenario

CR palletGF pallet

8.73PP weight (kg) 5.556.27 6.22Fibre weight (kg)

15Total weight (kg) 11.77


3. Inventory

3.1. Method

The inventory is the quantitative description of all emissions and all resourcesused during the life cycle of each pallet type. Inventory calculations were performedbased on Haberstatter et al. (1998) and Frischknecht et al. (1996). A detaileddescription is given by Gfeller Laban et al. (1999). The emissions to air, water andsoil, as well as the renewable and non-renewable raw materials needed during theentire life cycle, are taken into account. The primary non-renewable energyconsumption for each pallet is then calculated on the basis of the inventory, usingthe energy contents proposed by Gaillard et al. (1997).

3.2. Allocation

Other valuable products than pallet use during the 5 years are generated in theconsidered system. During incineration usable energy in the form of heat andelectricity can be recovered. It is possible to take account of these valuable productsby allocating them an environmental load. In this study, the allocation is avoidedby system extension: this means that the heat and the produced electricity replacea quantity of heat and electricity which does not have to be manufactured in theeconomic background system according to ISO Standards (ISO, 1998). In apractical way, they will reduce energy consumption and environmental impacts.Detailed assumptions are given in Appendix A.

Fig. 3. Energy consumption for the glass fibres (GF) and the China reed pallets (CR). The processes thatare not mentioned, GF incineration, PP incineration, pallet transport, pallet use (transport van),compatibiliser manufacture, fibre grinding, fibre in bioactive discharge-are negligible.


4. Results

4.1. Resource depletion

4.1.1. Primary non-renewable energyFig. 3 shows significantly lower primary non-renewable energy consumption for

the CR pallet. The strong primary non-renewable energy reduction is due to threefactors: (a) the substitution of energy requiring glass fibres by the low energynatural fibre production; (b) the indirect reduction in the use of polypropylene(Table 1) linked to the higher proportion of China reed fibres used and (c) thereduced pallet weight, which reduces fuel consumption during transport.

The most significant contributions to the total primary non-renewable energyconsumption for the GF pallet are PP production, glass fibre production, palletmanufacture and pallet use (transporting). For the CR pallet, the same processes-except fibre production-play the most significant role. The natural fibre preparation,transport from the depot to the factory and from the factory to the place of use, aswell as the compatibiliser production, are negligible from an energetic point of view(see details in Fig. 2).

The recoverable primary non-renewable energy by incineration is nearly equal forboth scenarios and is presented in Fig. 3 as contributions to primary non-renewableenergy consumption (see Section 3.2), and has to be deducted from the positive one.

4.1.2. Land useLand use plays a role in every process. Space requirement of the CR pallet is its

weak point. A surface of about 52 m2 of cultivated land is needed for theproduction of one CR pallet.1

4.2. Air, water and soil emissions

The GF pallet life cycle emissions are generally higher than those of the CRpallet (Table 2). In the case of CR pallet, only the agriculture specific pollutantemissions dominate: N2O (nitrogen protoxide) and NH3 (ammonia), both comingfrom the China reed culture. The following substances, maleic anhydride (compat-ibiliser), dimetenamide, glyphosate and pendimethaline (all three used duringculture), are specific to the CR pallet life cycle. Significant emissions of zinc andvanadium linked to the polypropylene production are also noticeable. These heavymetal emissions can have an influence on human health.

In water as well, the CR pallet globally emits less pollutants than the GF pallet(Table 2). Only two substances, phosphate and nitrate are emitted in greateramount during the CR life cycle. This is due to the cultivation stage. Thesesubstances play an important role for surface water eutrophication.

The life cycle of the CR pallet causes higher emissions of heavy metals.

1 http://www.miscanthus.de/anbau.htm


Table 2Emissions of pollutants into air, soil and water for the glass fibre (GF) and the China reed (CR) pallets

CR palletGF palletSubstance Unit

Air emissions5.88x(mg)Maleic anhydride

(g) 84.1Benzo[a]pyrene 57.826.8Cd 32.7(mg)

74.3 54.6(g)CO(kg) 73.1 42CO2

4.92(mg)Cr 8.5328.6(mg)Cu 4536.9xDimethenamide (mg)38.7Glyphosate x(mg)

(mg)H2S 80.6 28.3(g) 4.48 3.65HCl

201(mg)HF 506(mg) 1.48 0.68Hg

Methane 79.4(g) 150(mg) 36.6 24.3Mn

2.2(g)N2O 1.9611.3NH3 0.123(g)

(mg) 142 88.6Ni(g) 497 318NMHC

349513NOx (g)2.27(mg)P 5.19

Particles 35.1(g) 57.5(mg) 195 56.2Pb(mg) x 34.6Pendimethaline

163289SOx (g)0.731V (g) 1.16

Zn 512(mg) 375

Soil emissions264As (g) 447324Cd 33.9(g)

(g) 6.94 268Co(mg) 5.61 5.97Cr

22.50.128Cu (mg)1.32Fe 2.24(g)

(g)Hg 3.54 274(mg) 44.8 26.4Mn

3.04(mg)Ni 0.192(mg) 46.9Pb 34.2

Zn 18.1(mg) 110

Raw material199(kWh)Energy 388

Water emissions607(g) 382Ag

(g) 8.81 3.56Al


Table 2 (Continued)

GF palletUnit CR palletSubstance

7.54(mg) 18.1AsBa 3.09 1.78(g)

266414(mg)BOD80Cd (mg) 123

443702Chloride (g)Cl 120(g) 119

6.8717(mg)Co10.7(g) 6.81COD

670(mg) 406Cr+3

6.4816.3Cr+6 (g)133(mg) 77.9Cu

4.296.55(mg)Cyanide203F (mg) 326

5.0813Fe (g)101Hg (g) 166

1.112.96Hydrocarbons (mg)257(mg) 111Mn

1.53(g) 0.947NH30.00122xNH4+ (kg)

18.7Ni (mg) 46.11531.72Nitrate (g)

18(g) 11.1Oil135(mg) 42.8Pb

83132Phenol (mg)(g) 0.587 1.67Phosphate

18.144.6(mg)Se31.3(mg) 19.7Sulfide

1.01(mg) 0.608TBT1.181.86Zn (g)

Particularly during the agronomic production, heavy metals, such as cadmium,copper, mercury, nickel, zinc and cobalt, are emitted into the soil. Therefore, incontrast to air and water, soil emissions are higher for the CR pallet than for theGF pallet. These heavy metals have negative toxicological effects on the soil faunaand flora.

The analysis of the inventory is not sufficient to rank the different alternatives.An impact assessment is, therefore, needed.

5. Environmental impact assessment

5.1. General description

The environmental impact assessment enables one to evaluate the environmentalimpact of the inventory emissions and extraction. It is composed of three parts, in


the classification, the pollutant emissions are attributed to each impact category orproblem type (greenhouse effect, human toxicity, ecotoxicity, etc.). In the character-isation, the impact of the emissions are weighted and quantified within eachcategory. In the weightings, the relative damage to safeguard subjects generated byeach impact category is assessed. The main assessment method used in this workwas the Critical Surface-Time method (CST95) developed by Jolliet and Crettaz(1997) because it enables to take into account the heavy metals in the soil. Themethods CML 92 (Heijungs et al., 1992), Ecopoints (Braunschweig and Muller-Wenk, 1993), and Eco-indicator 95 (Goedkoop, 1995) were also applied to checkthe reliability of the results obtained with CST 95.

5.2. Characterisation results

5.2.1. Incineration scenariosFor the characterisation step, the CR pallet obtains slightly better results in most

of the impact categories, i.e.: human toxicity, terrestrial ecotoxicity, aquatic ecotox-icity, global warming, ozone depletion, acidification and primary non-renewableenergy consumption. Only for eutrophication does the GF pallet have a betterresult (Fig. 4).

The damage characterisation proposed by the CST95 method enables one togroup impacts relative to the same safeguards, i.e. human health, aquatic, terrestrialecotoxicity global warming and primary non-renewable energy use. Fig. 5 showsthat the CR pallet is better than the GF pallet in all categories.

Fig. 4. Characterisation of incinerated and discharged pallets (GF, glass fibre; CR, China reed),according to CST95.


Fig. 5. Results of the damage characterisation of glass fibre (GF) and China reed (CR) pallets, accordingto CST95 for the incineration scenarios.

The polypropylene plays an important role in the life cycle of both pallet typesfor primary non-renewable energy consumption and emissions, especially duringmaterial production and incineration. A lower polypropylene content of the palletwould thus be favourable from these points of view. The use (transporting) ofpallets plays an important role and increases directly with the transport distance.Furthermore, the glass fibre production generates a significant part of the impactsof the GF pallets.

For CR pallets, the cultivation has a dominant role for the categories humantoxicity, terrestrial ecotoxicity, and eutrophication. This is due to heavy metalemissions to soil and to phosphate emissions to water originating from manure andfertiliser use during China reed cultivation. In this application, applied herbicides(dimetenamide, glyphosate and pendimethaline) have very little influence. A crucialpoint is the crop rotation. It was assumed here that edible crops followed Chinareed, which means that a significant fraction of the heavy metals will enter humandiet. This fraction is null if other long-term non-edible crops followed China reed.

Table 3Results with CML

Unit GF pallet CR pallet CR pallet (% GF pallet)

43Human toxicity kg 1,4 21.2 9.04dichleq./pal.

85Terrestrial ecotoxicity kg 1,4 5250 4480dichleq./pal.

0.6651.09Aquatic ecotoxicity 61kg 1,4dichleq./pal.kg CO2eq./pal. 75.3 40.4 54Greenhouse effectkg 64Ozone formation 0.208 0.133ethyleneeq./pal.kg SO2eq./pal. 66Acidification 0.4320.653

0.06280.0682 92kg PO4eq./pal.Eutrophication51717Energy 1400MJ/pal.


Table 4Results with Ecoindicateurs 95

CR pallet CR pallet (% GF pallet)GF palletUnit

7.11107Carcinogenic 4.48107kg PAHeq./pal. 63substances

1.72103kg Pbeq./pal. 71Heavy metals 2.43103

0.163Winter smog 56kg SO2eq./pal. 0.28940.4 5475.3Greenhouse effect kg CO2eq./pal.

1.05103kg ethyleneeq./pal. 5.56104 53Ozone formation

0.411 630.653Acidification kg SO2eq./pal.0.0682kg PO4eq./pal. 0.0632 93Eutrophication

717 51Energy MJ/pal. 1400

The methods CML (Table 3) and Eco-indicator 95 (Tables 4 and 5) generallyconfirm the results obtained with CST95, except for the eutrophication category(Gfeller Laban et al., 1999). These methods give a better score to the CR pallet alsoin this category, because they consider that NOx emissions contribute to eutrophi-cation, whereas CST95 considers that only phosphate emissions contribute toeutrophication in Europe (European lakes are generally P-limited). These NOxemissions originate from PP production and from the use phase (transporting),which are higher for the GF pallet. The Ecopoints method provides a totalecological load expressed in Ecopoints. The improvement with the CR pallet isclear and reaches 30%.

Table 5Comparison of potential energy savings obtained by different uses per ha of biomass production

SourcePotential for energyRaw renewable materials Substitutedsavings (GJ/ha)product

2500 Present studyGlass fibreChina reed, transportpallet 100 000 km pallet

1200 Present study and GfellerChina reed, transport Glass fibrepalletpallet 5000 km Laban et al. (1999)

300750 Dinkel et al. (1996)Starch based polymers foils (LDPE)polyethylenefoils

Wolfenberger et al. (1997)China reed for packing Polystyrene 600700chips chips

200240 Wolfenberger et al. (1997),China reed for heat Oil for heatLandtechnik Weihenstephanproductionproduction(1995)Landtechnik WeihenstephanRapes biofuel 4060Diesel fuel(1995)Wolfenberger et al. (1997)110120Rapes biofuel+heat Diesel fuel+oil

production for straw


5.2.2. Comparison between discharge and incinerationFig. 4 also presents the comparison of the different end-of-life scenarios:

Bioactive discharge obtains a better score for human toxicity and terrestrialecotoxicity, because it emits fewer heavy metals to the atmosphere comparedwith incineration. The polypropylene incineration is the main source of heavymetal emission. As the pallets are hardly biodegradable in the case of bioactivedischarge, the heavy metals are mobilised in the soil. For the greenhouse effect,bioactive discharge apparently emits less CO2 than incineration, since wastedecomposition in bioactive discharge in the considered interval (Haberstatter etal., 1998) is incomplete less than 5% degradation in a 150-year-period. Once aninfinite period of time is considered, the CO2 emissions would be comparable.The greenhouse effect would be even higher if CH4 is emitted instead of CO2.

For all other categories the score is better for incineration. Especially for aquaticecotoxicity, bioactive discharge has a high impact. On the one hand, for theemission of cadmium, which is soluble and toxic in water (Haberstatter et al.,1998). On the other hand, incineration contributes to energy production and thusto a reduction in the emissions of the mean European Grid.The impact category land use is not considered in detail in this work. This

category would be unfavourable to bioactive discharge, since it would occupy alarger surface than incineration.

In summary, disposal of the pallets by bioactive discharge is not a better solutionthan incineration. The problem of air pollutants in incineration is just delayed. Inaddition pollution of the water ecosystem increases.

5.2.3. RecyclingRecycling of pallets offers several advantages, it avoids emissions due to pallet

disposal and reduces emissions during component production. In practice, the

Fig. 6. Energy consumption as a function of the recycling rate for the glass fibre (GF) and the Chinareed (CR) pallets.


recycling level for thermoplastic composites amounts approximately, to 20%(Lundquist et al., 1999). As the technical feasibility of recycling is presentlyunknown for the composite containing China reed fibre, this material has beenconsidered with and without recycling.

For all categories but human toxicity, a recycling level of 20% was not sufficientfor the GF pallets to match the low environmental impact of the CR palletswithout recycling. Fig. 6 shows tendencies. The recycling level should be signifi-cantly higher than 40% (Gfeller Laban et al., 1999) to reach the break-even point,level that is not reachable in present practice.

If both the GF pallet and the CR pallet are recycled, the difference between thetwo pallets decreases as the recycling rate increases.

6. Interpretation

6.1. Sensitiity analysis

6.1.1. Pallet life timeThere is presently little information concerning the durability of natural fibre

reinforced composites. For this study, it was assumed that the CR pallet lifetimewas the same as the GF lifetime (5 years). If this lifetime was much shorter than 5years, the number of pallets required to meet the product function (transport of1000 km per year during 5 years) would increase and CR pallets could lose theirenvironmental advantages. Therefore, variations in the primary non-renewableenergy consumption and in the environmental impact were analysed as a functionof the lifetime of the CR pallet. Fig. 7 shows that for the primary non-renewableenergy consumption, the minimal lifetime necessary for the CR pallet to match thescore of the GF pallet amounts to 2.2 years.

As far as the environmental impacts are considered, the minimal lifetime neces-sary for the CR pallet to have an environmental impact lower than or equal to thatof the GF pallet was found to be approximately 3 years (Gfeller Laban et al., 1999).

Fig. 7. Relation between the CR pallet lifetime and primary non-renewable energy consumption.


Fig. 8. Relation between primary non-renewable energy consumption and Youngs moduli for the glassfibre and the China reed pallets.

6.1.2. Plastic compositionThis part of the study considers the changes in the LCA results, considering three

different fibre contents. This sensitivity analysis is especially useful to extrapolatethe results to technical applications other than the transport pallet.

The primary non-renewable energy assessment is more favourable for plasticswith a larger fibre fraction (both for glass fibre or natural fibrem, Fig. 8). Thelargest contribution to the primary non-renewable energy consumption comes, asmentioned earlier, from the polypropylene production. Thus, replacement ofpolypropylene with filler is favourable regardless of it being glass fibre or Chinareed. In the case of transport over longer distances than 5000 km, the substitutionof polypropylene by glass fibre would be unfavourable, because of the higherweight of glass fibre (section below). These results are confirmed in the other impactcategories and for all three disposal strategies, the impact being reduced with ahigher fraction of reinforcing fibres (Gfeller Laban et al., 1999).

6.1.3. Use/transport distanceIn the reference scenario, the considered use phase was restricted to 5000 km in

5 years with a 40 T truck. Fig. 9 represents the variation in primary non-renewableenergy consumption with an increasing transport distance. The relation between theprimary non-renewable energy consumption and the transport distance is consid-ered to be linear. Impacts of the use (transport) phase dominate from 27 000 kmonwards for the CR pallet, and from 38 000 km for the GF pallet.

China reed fibres reduce the pallet weight and, therefore, reduce fuel consump-tion during transport. Compared with glass fibre, China reed fibre leads to areduction in primary non-renewable energy consumption of 2300 MJ at 200 000 kmto 660 MJ for the reference scenario of 5000 km.


Fig. 9. Primary non-renewable energy consumption as a function of transport distance.

For a GF pallet with a long use distance (over 38 000 km in 5 years), an increaseof the glass fibre content is environmentally unfavourable. The glass fibre has athree times higher density than the PP. They are heavier and a larger amount ofprimary non-renewable energy is needed to transport them.

6.2. Source of uncertainties

To perform an LCA, the life cycle of the considered product has to be modelled.Only the most significant processes of the life cycle are taken into account. Theother processes are left aside. To improve this study, the natural fibre palletmanufacturing process should be considered in more detail. Secondly, the data, onwhich this life cycle analysis is based, come from various sources and thus havebeen estimated differently. They do not have the same precision. To increase theprecision of this work, it would be useful to improve the quality of data with apotentially relevant influence on outcomes. Moreover, for some processes, sincedata were not available, it was necessary to use similar products as an approxima-tion. For example, the values for the glass fibre manufacture were estimated withdata for glass wool manufacture.

7. Biofibres compared with other uses of biomass

To verify and extend the results of the present study, it is interesting to compareit with other uses of raw renewable materials, including heat production. Studiesbased on the same database of Frischknecht et al. (1996) were selected for thiscomparison. Table 3 shows that the use of China reed biofibres as a replacement forglass fibres (substitution of 12002500 GJ/ha) enables a four to ten times highervalorisation than a direct combustion of China reed for heat production (substitu-tion of 200240 GJ/ha). The glass fibre substitution is also more efficient than thesubstitution of polypropylene chips (600700 GJ/ha). Generally speaking, China


reed is more efficient than starch based biomaterials, as China reeds are a lowenergy requiring and efficient C4 plants. More generally, Table 3 confirms thatbiomaterials have a much higher substitution potential than the use of biomassfor direct heat production or the production of biofuels for transport. Moreover,the manufacturing of biomaterials can also be combined with heat production atthe materials end-of-life.

8. Conclusions

The use of China reed fibre as reinforcement in plastics proves to be advanta-geous from an ecological point of view, provided that the CR pallet has aminimum lifetime of 3 years. Generally, and this applies to both pallet types, anoptimisation of the polypropylene production process would bring great advan-tages from both a primary non-renewable energy and an emissions point of view.A reduction of these emissions to the atmosphere, for example due to betterexhaust gas treatment, would have a very positive influence on the environmentalimpacts of both pallet types. Another possible solution would be to replace thematrix material with a natural and biodegradable material.

It is also important to pay attention to the process of pallet disposal. Theenvironmental assessment of the discharge shows that the soluble and toxicheavy metal emission (cadmium) in seepage is the major problem of this disposalmethod. An improvement of the incineration plants exhaust gas treatment effi-ciency, especially the reduction of the heavy metal emissions, would be veryadvantageous for this type of disposal.

As far as the basic recycling scenario is concerned, it was observed thatrecycling has a positive effect, but that a recycling level of 20% was not suffi-cient for the GF pallets to match the lower environmental impact of the CRpallets. To obtain comparable results, it would be necessary to go to extremelyhigh recycling rates, which may be difficult from a technological and logisticpoint of view.

The results of this study could be used as a starting point for the environmen-tal study of other plastics made up of polypropylene and China reed fibre orpolypropylene and glass fibre in order to develop other technical applications.Furthermore, the comparison with other uses of biomass shows that biomaterialshave a much higher substitution potential than the use of biomass for directheat production or the production of biofuels for transport. Higher priority inresearch about the use of biomass should, therefore, be given to biomaterials.

Acknowledgements

The authors would like to thank Genossenshaft Biomasse Technologie,Switzerland for supplying the China Reed used in this study. Pharmacia andUpjohn, Sweden, financially supported this work.


Appendix A. Assumptions

Name of process SourceAssumptions

Gutzwiller et al. (1998)Swiss average rate ofCultivation of Chinamechanization applicationreedof fertilisers according tothe (FAT, LBL)recommendations,probably over-estimatedDistance: 50 km. Type ofTransport of China reed Gutzwiller et al. (1998)lorry: 16 t. Charging rate:40%Consumption ofGrinding of China reed Gutzwiller et al. (1998),

Lundquist et al. (1999)electricity: 50 kWh/t(0.01494 MJ/kg). Lossduring that stage: 30%.Land fill of 30%Distance: 100 km. LorryTransport of China reed Gutzwiller et al. (1998)type: 40 t. Charging rate:fibres50%

Compatibiliser Lundquist et al. (1999)Quantity: 0.0005gMAH/kgPalett

Fabrication of the palett Ignoring additives. Haberstatter et al. (1998)Consume of energy: 800(injection)kWh/t (2.88 MJ/kg)

Transport from the Distance: 100 km. Lorry Gutzwiller et al. (1998)fabric to the user type: 40 t. Charging rate:

50%Use (transporting) of the Two types of transport: Gutzwiller et al. (1998)

palett Van: Distance: 10 km peryear. Type of van: 3.5t. Chargingrate: 30%.Lorry: Distance: 1000 kmper year. Type of lorry:40 t. Charging rate: 50%

Transport between the Same distance as from theplace of use and that fabric to the user:

Distance: 100 km. Lorryof recyclingtype: 40 t. Charging rate:50%

Incineration of pallets


Consumption of energy ofthe UIOM: Heat: 0.24MJtherm/kg. Electricity:0.36 MJelect/kg

ESU (1996)

Bonus of incineration PP Energy recovery: ESU (1996)(PCIPP=30.5 MJ/kg).Heat: 26%. Electricity:10%

Bonus of incineration Energy recovery: Wolfenberger et al.(1997)reed (PCICR=14 MJ/kg).

Heat: 26%. Electricity:10%

Transports which are not explicitly mentioned in this table (for example: trans-port of glass fibres from production to pallet manufacture) are not taken intoaccount in this study as they are negligible from an environmental point of viewcompared to the transport studied above.

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