Life Cycle Analysis of Hemp Textile Yarn

Transcription

1 INRA Institut National de la Recherche Agronomique French National Institute for Agronomy Research Unité Mixte de Recherche INRA-AGROCAMPUS Sol, Agronomie, Spatialisation 65, rue de Saint Brieuc CS Rennes Cedex, FRANCE Life Cycle Analysis of Hemp Textile Yarn Comparison of three hemp fibre processing scenarios and a flax scenario Lea Turunen Hayo van der Werf This report is a result of the European Union project HEMP-SYS - Design, Development and Up-Scaling of a Sustainable Production System for HEMP Textiles: an Integrated Quality SYStems Approach; Contract No QLK5-CT Version of 31 May 2006

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3 Abstract In the recent past, there has been a revived interest in natural textile fibres other than cotton. Within the framework of the project HEMP-SYS - Design, Development and Up-Scaling of a Sustainable Production System for HEMP Textiles: an Integrated Quality SYStems Approach, the present study aimed to quantify major impacts associated with the production of hemp yarn using a Life Cycle Analysis (LCA) methodology and to compare the impacts of hemp yarn to those of flax and cotton yarn. For the evaluation of the impacts of hemp crop production, a generic Central-European scenario was sketched, based on hemp production practices in Hungary and France. The flax crop scenario was based on production practices in France, Belgium and the Netherlands. For hemp fibre processing, traditional warm water-retting according to current production practices in Hungary was treated as a reference. Three scenarios were compared to the reference: 1) Bio-retting: hemp green scutching followed by water-retting using selected bacteria, 2) BabyHemp, based on desiccation and stand-retting of pre-mature hemp, 3) dew-retting of flax. The yarn production stage, employing the wet ring spinning technology, was largely same for all four scenarios. Overall, neither of the alternative scenarios was unambiguously better than the reference. The environmental impacts of the hemp reference scenario and the flax scenario were very similar, except for pesticide use (higher for flax) and direct water use (higher for hemp). Bio-retting had higher impacts than the reference scenario for climate change and energy use, due to higher energy input in the fibre processing stage. BabyHemp had higher impacts than the reference scenario for eutrophication, land occupation (both due to its low yield) and pesticide use. Comparison with cotton was difficult due to lack of comparable data, but for the crop production stage hemp performs clearly better than cotton with respect to pesticide use and water use. However, during the fibre processing and yarn production stages hemp requires more energy, resulting in higher impacts. In general, a reduction of the environmental impacts associated with the production of hemp yarn should give priority to a reduction of eutrophication in the crop production phase and of energy use in the fibre processing and yarn production stages. Finally, technological development, in particular aiming at the reduction of labour requirements, seems essential for the successful production of hemp textiles in Europe. Key words: environmental impact, fibre processing, flax, hemp, Life Cycle Assessment, yarn production

4 1 INTRODUCTION HEMP TEXTILE CHAIN HEMP ESSENTIALS LIFE CYCLE OF HEMP TEXTILES METHODOLOGY METHODOLOGY IN GENERAL SCOPE OF STUDY SYSTEM BOUNDARIES AND ALLOCATION PRINCIPLES CHARACTERISATION FACTORS LIFE CYCLE INVENTORY PROCESS DESCRIPTIONS AND DATA CROP PRODUCTION AND HARVEST Crop production Processes and data Emissions associated with crop production Harvest BabyHemp FIBRE PROCESSING Overview of fibre processing Traditional warm water-retting scenario Processes and data Emissions from retting Bio-retting scenario Processes and data Emissions from bio-retting BabyHemp scenario YARN PRODUCTION Processes and data Emissions from bleaching and spinning FLAX IN GENERAL CROP PRODUCTION AND HARVEST FIBRE PROCESSING AND YARN PRODUCTION COTTON IN GENERAL CULTIVATION AND HARVESTING FIBRE PROCESSING AND YARN PRODUCTION LCA STUDIES ON COTTON RESULTS OF THE IMPACT ASSESSMENT IMPACTS FOR HEMP AND FLAX SCENARIOS Eutrophication Climate change Acidification Energy use...40

5 7.1.5 Land, pesticide and direct water use SCENARIO VARIATIONS DISCUSSION COMPARISON OF THE SCENARIOS FOR IMPACTS AND YIELD Bio-retting relative to warm water-retting scenario BabyHemp relative to warm water-retting scenario Bio-retting scenario relative to BabyHemp Hemp versus flax Hemp versus cotton ENVIRONMENTAL HOT SPOTS OF THE HEMP SCENARIOS In general Warm water-retting Bio-retting BabyHemp CONCLUSIONS AND OUTLOOK...53 REFERENCES...55 PERSONAL COMMUNICATIONS...61 APPENDIX A: DETAILED HEMP CROP PRODUCTION INVENTORY APPENDIX B: DETAILS OF THE FLAX SCENARIO APPENDIX C: DETAILED FLAX CROP PRODUCTION INVENTORY APPENDIX D: ADDITIONAL DATA CONCERNING PROCESS INPUTS APPENDIX E: INVENTORY CROP PRODUCTION APPENDIX F: INVENTORY FIBRE PROCESSING APPENDIX G: INVENTORY YARN PRODUCTION APPENDIX H: COMPARISON OF TRANSFORMATION EFFICIENCIES AND YARN YIELDS

6 1 INTRODUCTION Ever since Eve ate the apple, clothing and textiles in general have been indispensable parts of our human existence. These days, textile manufacture and retail are a big business, as the lifetime of a product is determined not so much by its wearability than by ever changing fashion trends. Cotton and synthetic fibres, 48% and 45%, meet most of the worldwide textile demand (WWF, 1999). Both are associated with considerable environmental problems: Synthetic fibres deplete non-renewable fossil resources, while contemporary cotton cultivation is characterised by high water requirements and use of substantial amounts of fertilisers and pesticides. Furthermore, cotton cultivation is restricted to sub-tropical climates (Pimentel et al., 1991; WWF, 1999). Under the paradigm of sustainable development, alternatives are looked for. There is an increasing recognition that a shift towards non-cotton natural fibres could contribute greatly to the sustainability of the textile industry. In the European context, alternative fibre crops such as hemp and flax are also interesting because they grow well Europe wide, while cotton thrives only on the most southern edge of the continent. Furthermore, fibre crop cultivation is compatible with the recent EU agricultural policy promoting a switch from food to non-food crops. In November 2002, a comprehensive EU-funded 3-year study called HEMP-SYS was launched under the thematic programme: Quality of life and management of living resources of the 5th Framework (Amaducci, 2003). One of the main objectives of the project is to promote the development of a competitive, innovative and sustainable hemp textile industry in the EU by developing an improved, ecologically sustainable production chain for high quality hemp fibre textiles (HEMP-SYS, 2002). Within the framework of the project, the present study aimed to quantify major impacts associated with the production of hemp textiles using the life cycle analysis (LCA) method, in order to generate propositions for modifications of the production chain, leading to reduced impacts. The study compared the impacts of hemp to those of flax and cotton. In practice, the analysis was carried out up to and including the production of yarn; the functional unit was 100 kg of bleached yarn, which is also used as a unit of comparison between the alternative fibres. 4

7 2 HEMP TEXTILE CHAIN 2.1 HEMP ESSENTIALS Hemp (Cannabis sativa L.) is an annual plant, with a rigid, woody stem, which varies from 150 to 550 cm in height. The leaves are characteristically palmate with 7 to 9 leaflets (Sankari, 2000). The fibre of commercial interest is derived from the stem. Hemp (as well as flax) is a bast fibre plant, which means that the fibres are extracted from the outer part of the plant stem, called bast (Ebskamp, 2002). The inner part of the stem consists of woody core. A single bast fibre cell (fibril) is mm in length (Sankari, 2000). Fibres are tightly joined together by hemicelluloses, pectins and lignins and thus form fibre bundles, whose theoretical length may extend to the entire plant height (Sankari, 2000). The hemp industry uses these fibre bundles, called technical fibres, as a raw material. Normally, for simplicity, the term hemp fibre refers to technical fibres, not to individual fibre cells. Isolation of the technical fibres from the plant stem requires several steps and yields three valuable fractions: long fibres (the product of interest for this study), short fibres and shives (broken woody core). Use of hemp for textiles is not a new invention, but rather a rediscovery. Hemp (along with flax) was an important source for textile yarns until the 18th century. It is often mentioned that Levi Strauss made his first jeans from hemp cloth. European hemp production, especially for textile applications, declined to close to zero after World War II for several reasons: large scale production of cotton, high labour costs compared to the developing countries, the appearance of synthetic fibres, and drug policies. The last few decades have shown a revived interest in hemp as a renewable resource. Hemp has been praised by some as a true wonder crop. The potential of hemp as an attractive crop for sustainable fibre production was pointed out in the early 1980 s (Hanson, 1980). A study by van der Werf et al. (1995), among others, proved most claims of early hemp advocates to be true and concluded that hemp is indeed an agronomically attractive crop. Hemp can supply high fibre yields, requires little or no pesticide and suppresses weeds and some major soil-borne diseases. Thus, it has been concluded that hemp manifestly fits into organic/sustainable farming systems (van der Werf et al., 1996). Hemp can be easily incorporated into current cropping systems. It is commonly grown in rotation with winter wheat. Gorchs and Lloveras (2003) report that farmers consider it an excellent break crop for wheat for several reasons. Hemp is effective in suppressing weeds, thus leading to reduced herbicide costs for the following crop. Hemp leaves the soil in excellent condition, allowing direct drilling for the subsequent winter wheat. They also report a significant yield increase in a wheat crop grown after hemp in comparison to wheat grown in monoculture. In the EU, a marked increase in hemp cultivation has taken place during the past few years, but the total area planted to hemp is still modest: ha in 2003 (EU-15) (Eurostat, 2004). Several bast fibre based industries are operating in the European Union: hemp is used in speciality papers (e.g. cigarette papers), technical textiles (e.g. twine, rope, geotextiles), car parts (e.g. dashboards), and building materials (insulation materials) (Sankari, 2000). However, fibre production in the European context, with high labour costs, can only be truly profitable if the 5

8 raw material can be transformed into high added-value products. Textiles are a good example of such an application. 2.2 LIFE CYCLE OF HEMP TEXTILES A cradle to grave life cycle of hemp (or another natural fibre) textiles in coarse resolution is depicted in Figure 1. CROP PRODUCTION Production and supply of energy carriers (e.g. electricity, diesel) FIBRE PROCESSING YARN PRODUCTION Waste water treatment FABRIC PRODUCTION Production of fertilisers, pesticides, chemicals, machines etc. FINISHING TEXTILE MANUFACTURE Solid waste management Transport RETAIL USE RECYCLING DISPOSAL Figure 1. The main stages of the life cycle of (hemp) textiles. The white boxes are within the scope of this study (the life cycle stages following yarn production, and solid waste management were not included). 6

9 This study focussed on the first three main stages of the life cycle, i.e. on the yarn production chain. The first stage in this chain is crop production. In the fibre processing stage the fibres are extracted from the stem and transformed to raw material for yarn and subsequently fabric production. Each of the main production stages comprises many smaller, successive operations, i.e. each sub-system contains a chain of unit processes. There are many alternative production techniques and methods and, if sketched in more detail, a standardised textile production chain does not exist. Hemp is grown in several parts of Europe. At the other end of the yarn production chain, techniques and know-how exist to spin hemp long fibre into yarn. The stage in between, the fibre processing, is for the moment the bottleneck of the hemp textile production chain. At present traditional fibre processing of hemp is at the same technological stage as 50 years ago. As this technology is labour intensive, it is only viable for low labour-cost countries (e.g. Hungary, Romania, China). For the Western-European context, an optimum processing method is still to be found. Garment production from yarn onwards might seem a straightforward sequence of weaving, cutting of fabric and sewing the pieces together. In the modern world, however, the story is much more complicated, even for a basic garment like a T-shirt. A wide variety of treatments exists to modify the qualities and/or appearance of the textiles. The resources of this study did not allow us to delve into the complexity of textile finishing, and therefore the LCA was carried out up to and including the yarn (see Chapter 4). Nevertheless, below, the main processes of the garment production and the rest of the life cycle, as well as their environmental significance are outlined. This hopefully helps a reader to get a more complete picture over the life cycle. The quantitative contribution of the individual life cycle stages (Figure 1) to most of the environmental impacts is poorly documented. For energy consumption, a provisional estimation is that the consumption in the first three stages (crop production, fibre processing, yarn production) is of the same order of magnitude as the consumption in the subsequent three stages (fabric production, finishing, textile production) (Pulli, 1997). However, the energy consumption in the Use phase is estimated to be approximately three times higher (Pulli, 1997; Blackburn and Payne, 2004). Fabric production There are two main methods for creating apparel fabric from yarn: weaving and knitting. Weaving involves the interlacing of yarns at right angles (e.g. denim jeans, blouses). Knitting involves looping the yarn or yarns around and through one another (e.g. T-shirt, pull-over) (Seagull and Alspaugh, 2001). Energy consumption plays a significant role in both operations, as they are mechanical processes. The figures can differ significantly from one mill to another (Table 1), amongst others because energy consumption per kg of cotton increases strongly with the fineness of the yarn. Alternative techniques and weaving machines also differ greatly in their energy requirement (Weber, 1998). Needless to say, knitting has its own energy requirements. Apart from energy use, weaving involves another environmental concern: prior to the actual weaving, the warp 1 is sized, i.e. sizing agents are applied to the warp in order to lubricate and protect it during weaving. The main sizing agents are either based on native polysaccharides or fully synthetic polymers. The type of sizing agent applied varies according to the fibres processed, the weaving technique etc. Furthermore, sizing agent formulations are usually 1 The warp are the threads which are held along a loom while other threads are passed across them. 7

10 mixtures of various substances; additional auxiliaries may also be present in the sizing mixtures. The sizing agents are later removed by the finisher in a desizing process, which results in a high chemical oxygen demand (COD) load in the wastewater (EC, 2003). Table 1. The variability of energy consumption for three phases of the (cotton) textile chain (modified from Weber, 1998). Production phase Energy consumption (MJ/kg cotton) Spinning (yarn production) Weaving Finishing Finishing Finishing is a term used to refer to all the different treatments that aim to modify the aspect of the yarn or fabric, bringing added comfort, style and functionality. The term is somewhat misleading, since the finishing processes are not necessarily the last steps in cloth manufacture. They can indeed be positioned at different stages of the production process (Figure 2). FINISHING PROCESSES pretreatment, dyeing, printing, functional finishing, washing, drying, etc. FIBRE PROCESSING Loose fibres YARN PRODUCTION Yarn FABRIC PRODUCTION Fabric Figure 2. Finishing processes in relation to the textile chain (modified from EC, 2003). The finishing processes include pre-treatment, dyeing, printing, functional finishing and coating; washings and dryings are also involved. Textile finishing cannot be defined as a standard sequence of treatments, but rather is a combination of unit processes that are chosen, depending on the requirements of the final user. The details of all the finishing options are not given here, but the following description of cotton pre-treatment serves to illustrate the complexity of the issue. The purpose of the pre-treatments is to prepare the fibre/fabric for dyeing. For example, cotton pre-treatment includes normally various, mostly wet, operations: singeing = removing the protruding surface fibres by passing the fabric through a gas flame desizing = removing sizing compounds from woven fabric previously applied to the warp scouring (also known as boiling-off or kier boiling) = extraction of impurities present on the raw fibre or picked up at a later stage mercerising (with tension/caustification/ammonia mercerising) = different techniques/ methods, carried out to improve tensile strength, dimensional stability and lustre of cotton bleaching = an obligatory step when the fibre has to be dyed in light colours 8

11 Some of these operations are obligatory only for certain make-ups; some treatments can be combined in a single step (EC, 2003). Potentially, all the above-mentioned steps are employed just in preparation for dyeing; various dyes and dying techniques would require a study of their own. Finishing processes cover also more special treatments such as fireproof, antibacterial etc. finishing. The IPPC BREF (EC, 2003) is a good reference to contemporary textile finishing. The energy consumption and emission levels associated with finishing depend on the type of fibre, the choice of processes, the techniques and the machinery employed. The main environmental issues arising from finishing are emissions to water and energy consumption (Table 1). Emissions to water are of concern, as water is used as the principal medium for removing impurities, applying dyes and finishing agents. The input of chemicals and auxiliaries added at the finishing mills can amount to up to 1 kg per kg of processed textile. Residues in the product are negligible; therefore the bulk is discharged as aqueous effluent. The range of these substances is very extensive: more than 7000 auxiliaries have been listed. Among the products applied during the process, the highest environmental loads arise from salts, detergents and organic acids (in that order). Typical COD loads are in the order of g/kg fibre (EC, 2003). Energy is consumed primarily in raising the temperature of the baths and in drying and curing 2 operations. To this aim steam is normally produced on-site. Electrical energy is required for driving the machinery. The total specific energy consumption is in the range of MJ/kg of finished textile, where the consumption of electricity is about MJ/kg (EC, 2003). Textile manufacture The manufacture of textiles (garments, home textiles etc.) mostly involves cutting the fabric and sewing the pieces. These processes do not involve environmental concerns beyond the use of electricity for the machines. Some textile waste is also produced at the cutting step, but this has been minimised by modern computerised cutting systems. One LCA relevant aspect is the transport of cloth to developing countries, where the labour intensive manufacturing is frequently carried out, and the transport of the ready products back to industrialised countries. Use Use of a garment itself does not affect the environment, but the impacts of maintenance on the life cycle of apparels and textiles are major (Pulli, 1997; Blackburn and Payne, 2004). Domestic laundering is a very frequent task in households and involves use of water and detergents as well as energy for the washing machine and, more and more frequently, also for drying. Blackburn and Payne (2004) calculate that the consumer use accounts for 76% of the energy consumption of a cotton towel over its lifetime. Recycling and disposal Some form of recycling is an important part of the life cycle of textiles. Nearly half of the household textiles are recycled either in their original form or e.g. as cleaning rags before their final disposal (Figure 3). The application of carefully controlled heat to a fabric or garment to cause a reaction in the finishing agents thus fixing it. Finishing agents that require curing include some pigments, easy-care finishing agents, etc. They are applied on the fabric prior to curing, normally by padding. For example, curing permanently sets previously pressed creases in certain wash and wear garments. 9

12 Loss 8% Second hand 10% Landfill 40% Cleaning rags 5% Old clothes, exported 20% Combustion 12% Old clothes, domestic 5% Figure 3. Fate of old household textiles in 1990 (from Weber, 1998). 10

13 3 METHODOLOGY 3.1 METHODOLOGY IN GENERAL Environmental impacts associated with hemp yarn production were evaluated using a method called Life Cycle Assessment (LCA). LCA involves quantifying and evaluating the resources consumed and the emissions to the environment at all stages of the life cycle of a product it encompasses extraction of resources; production of materials, product parts and the product itself; use of the product and its reuse, recycling or disposal (Guinée et al., 2002). After defining the goal and scope of the assessment, the first step is to compile an inventory of the relevant inputs and outputs of a system (the result of this phase is called the Life Cycle Inventory, LCI). In the subsequent Impact Assessment phase, the potential environmental impacts associated with those inputs and outputs are evaluated (ISO,1997). The calculations were elaborated by means of the computer software SimaPro 5.1 (PRé Consultants, Amersfoort, The Netherlands). A normalisation was carried out, i.e. the impact score for each environmental theme was divided by the annual per capita impact score in Europe. Normalisation helps to better understand the relative magnitude for each indicator result of the product system under study (ISO, 2000). 3.2 SCOPE OF STUDY Rather than carrying out a complete LCA over the entire life cycle of hemp textiles, as outlined in chapter 2.2, this study analysed the environmental impacts of the production of bleached, 100% hemp yarn of approximately 26 Nm 3. The functional unit of the study was defined as 100 kg of this yarn. Production of the functional unit was studied from cradle to gate, i.e. emissions and use of resources from agricultural crop production, through fibre processing until the end product were taken into account. Further use of the yarn (for textile manufacture) or its disposal was excluded from the analysis, as sufficient time was not available. Environmental impacts of textile production processes have been studied by Laursen et al. (1997), Pulli (1997) and Blackburn and Payne (2004). The consumer use phase is included in the two latter publications on LCA of a cotton t-shirt and cotton towels, respectively. For the evaluation of the impacts of the crop production phase, a generic Central-European crop production scenario was sketched, based mainly on information on hemp production in Hungary and France. Environmentally relevant parameters did not seem to differ significantly between Hungary and France. Traditional, water-retting based hemp fibre processing (see Chapter 4.2), which has completely disappeared from Western Europe, is still exercised in Eastern Europe, most importantly in Hungary and Romania. The production volumes have greatly diminished in the last decades. Such traditional processing is not directly applicable in Western Europe due to many labour intensive steps, but in Europe it is still the only operational technology used at a large scale for 3 The metric count number (Nm) specifies the yarn thickness/count. The count number in Nm indicates the length in meters of one gram of yarn. Hence a gram of 26 yarn is 26 meters long. The yarn of this count is typically used for example for denim fabric, i.e. jeans. 11

14 the production of hemp fibre for textiles. So, a reference scenario was defined based on traditional hemp fibre processing in Hungary. The reader should note that in this report the term water-retting is used interchangeably with warm water-retting. For Western European high labour cost conditions, less labour intensive and thus economically more viable fibre processing methods are searched for. At the moment various approaches are being developed side by side. In this study we constructed two alternative scenarios to be compared with the reference scenario. These scenarios are elaborated on in chapter 4.2. Here it is important to mention that, whereas the reference scenario is based on an old, proven technology, the two other scenarios describe technologies/methods that are still at a development stage. The data for these scenarios is based on small-scale pilot production and is therefore provisional, and more uncertain than the data the reference scenario is based on. The yarn production was assumed to employ wet spinning technology, which is commonly used in the production of fine bast fibre yarns. Light bleaching of rove (an intermediary product in yarn production) was included in the analysis. The impacts of yarn production were estimated based on production parameters from the Linificio e Canapificio Nazionale Company, Italy, which is one of the most important bast fibre wet spinning mills in the world. It is not only interesting to compare the environmental impacts of the three different hemp scenarios, but also to see how the impacts of hemp yarn production compare to those of its alternatives. Flax shares many characteristics with hemp (fibre meta-structure and the resulting processing, fibre properties etc.). It is produced in Europe and also advertised as an environmentally friendly crop (low fertiliser and pesticide inputs etc.) (among others Sharma and Van Sumere, 1992; Sankari, 2000; ITL, 2004). We are not aware of any LCA study comparing hemp and flax fibres for textile application or of a study on flax, comparable to our assessment. So, a scenario was defined for fibre flax production and processing. The scenario is based on flax cultivation in France/Belgium/Netherlands, which is at the leading edge of European flax production, and on the common flax long fibre processing methods employed in Europe. There was also a desire to compare hemp with cotton, the most common textile fibre (WWF, 1999). However, available time was not sufficient to construct a cotton production scenario for this study. Thus the comparison will be based on published cotton LCA studies. The comparison will be qualitative rather than quantitative, because the direct comparison of LCA studies is hardly possible, due to different basic assumptions, scope of study and so on. In general, the life cycle stages that are within the scope of this assessment lend themselves well for the comparison of hemp textiles with the flax or cotton equivalents. From yarn onwards the production processes are in principle similar for all the three fibres. As mentioned above, further processing does not depend so much on the fibre (as hemp, flax and cotton are all natural cellulose fibres) as on the desired end product and its qualities. 3.3 SYSTEM BOUNDARIES AND ALLOCATION PRINCIPLES System boundaries differentiate the system under analysis from its environment. General boundaries of the study are given below. Process specific system boundaries, data sources and assumptions are discussed in more detail in the following chapters. 12

15 Capital equipment: Construction, transport from the factory and maintenance of machinery that is directly employed in the production processes were included, with a few exceptions when data was not available (contribution of those machines was estimated to be not very significant). Buildings, however, were not included in the analysis due to lack of data. Possible impacts of storage between various production stages were not taken into account. The machinery used for crop production, fibre processing and yarn production was assigned to three categories, with different production and delivery emissions. The categories are listed in Table 2. The emissions associated with the production, delivery, repair and maintenance of the machines were taken into account based on Gaillard et al. (1997). The impacts were allocated to the relevant processes according to the hours of use compared to the total hours of use over the service life of the machine. Table 2. Machinery classification (modified from Gaillard et al., 1997). Category A B C Description Tractors (95 % steel, 5 % rubber) Harvesters (95 % steel, 5 % rubber) Other machines (100 % steel) Energy requirement (in MJ/kg) for Manufacture Repair/Maintenance Land occupation: Agricultural land occupation was included within the system boundaries, whereas land occupation owing to industrial infrastructure was not. Human labour: The impacts of human labour were excluded. It should be kept in mind, however, that the different production scenarios do require significantly different inputs of human labour. For any socio-economic evaluation or overall decision-making process such differences are highly relevant. Chemicals: The production of chemicals (pesticides, bleaching agents etc.) was taken into account whenever sufficient data was available. However, the effects of pesticides used in crop production on the environment were not assessed. Transport of raw materials and intermediate products were included in the study. On the contrary, the short transports within one processing site (e.g. moving bales around with a forklift) were neglected. Also, intermediate baling of fibres (except baling at field) and other packaging for storage or transport were not considered. 13

16 Allocation principles The allocation of environmental impacts, in the case of co-products 4, was based on the economic value, which represents a measure of the incentive for production (Audsley et al., 1997). Economic allocation is not without problems, as the prices of natural fibres fluctuate according to the supply-demand situation, which is affected by many factors ranging from agricultural yield to fashion trends. Nevertheless, economic allocation was chosen over massbased allocation, because long (and short) fibres represent only a small fraction of the stem mass, but they are the major reason for hemp cultivation. For flax it is even more so: 85% of the economic value of a fibre flax crop is generated by the long fibres, that, by weight, represent only 10-20% of the yield (Mallet, pers. comm., 2004). Thus, in our opinion, it only makes sense to allocate the environmental effects to the co-products based on economic value. Published price statistics, which would be the preferred source for price data, were unfortunately not available for hemp. We consulted a number of producers and experts in order to obtain a reliable estimation of the prices for the purpose of this analysis. The prices reflect the situation in It is important for the reader to realise that for the purpose of an economic allocation it is the relative values of the co-products rather than their absolute prices that really matter. Furthermore, the prices of similar products in different scenarios need not be identical, as long as within one allocation step the prices reflect the relative value of the co-products. Data sources At the inventory step the production system under study must be defined in terms of the flows of energy and material entering the system (inputs) and the polluting substances emitted to the environment outside the system boundaries (outputs). This requires appropriate data sources. Project partners provided process- and site-specific data, which was complemented by literature sources. Personal communication with project partners, producers and experts was an irreplaceable source of data for this study. The list of informants is included at the end of the report. 3.4 CHARACTERISATION FACTORS In the Life Cycle Impact Assessment phase, it is first determined which impact categories (environmental themes) will be considered. The impact categories considered in this study are: eutrophication, climate change, acidification, energy use and land occupation. Next, the indicator result for each impact category is determined. This is done by multiplying the aggregated resources used and the aggregated emissions (from the life cycle inventory) of each individual substance with a characterisation factor for each impact category to which it may potentially contribute (Heijungs et al., 1992). Characterisation factors are substance specific, quantitative representations of the additional environmental pressure per unit emission of a substance (Huijbregts et al. 2000). The characterisation factors used in this study are given below for each impact category. 4 A co-product is any of two or more products from the same unit process (ISO, 1998). 14

17 Eutrophication covers all potential impacts of high environmental levels of macronutrients, in particular N and P. Eutrophication potential (EP) was calculated using the generic EP factors by Guinée et al. (2002) in kg PO 4 -eq., NH 3 : 0.35, NO 3 : 0.1, NO 2 : 0.13, NO x : 0.13, PO 4 : 1, N: 0.42, P: 3.06 and chemical oxygen demand (COD): Climate change was defined here as the impact of emissions on the heat radiation absorption of the atmosphere. As recommended by Guinée et al. (2002) Global Warming Potential for a 100- year time horizon (GWP 100 ) was calculated according to the GWP 100 factors by IPCC (Houghton et al., 1996) in kg CO 2 -eq., CO 2 : 1, N 2 O: 310, CH 4 : 21. Acidifying pollutants have a wide variety of impacts on soil, groundwater, surface waters, biological organisms, ecosystems and materials (buildings). As recommended by Guinée et al. (2002) Acidification Potential (AP) was calculated using the average European AP factors by Huijbregts (1999) in kg SO 2 -eq., NH 3 : 1.6, NO 2 : 0.5, NO x : 0.5, SO 2 : Energy use refers to the depletion of energetic resources. Energy use was calculated using the Lower Heating Values proposed in the SimaPro 1.1 method (PRé Consultants, 1997), crude oil: 42,6 MJ/kg, natural gas: 35 MJ/m 3, uranium (in ore): MJ/kg, coal: 18 MJ/kg, lignite: 8 MJ/kg, gas from oil production 40.9 MJ/m 3, wood pellets 17 MJ/kg. Land occupation refers to the use of land as a resource, in the sense of being temporarily unavailable for other purposes due to the growing of crops. This is a quantitative assessment, which does not distinguish quality of land use. In addition to these impact categories that are commonly considered in an LCA study, the use of pesticides was assessed. However, the impacts of pesticides and their metabolites were not taken into account in this study, as appropriate characterisation factors are lacking for many of these substances. The direct water use in processing was also calculated. No characterisation was involved, as we did not intend to transfer this production input into a larger impact category. Average European AP factors take into account regional sensitivity to acidification. The indicator result is expressed in kg SO 2 emitted in Switzerland equivalent, with the AP factor for Switzerland being 1.0. The value of the average European AP factor for SO 2 (1.2) indicates that, on average, Europe is more sensitive to acidifying pollutants than Switzerland. 15

18 4 LIFE CYCLE INVENTORY PROCESS DESCRIPTIONS AND DATA 4.1 CROP PRODUCTION AND HARVEST Crop production Processes and data For the evaluation of the impacts of the crop production phase, a generic Central-European crop production scenario was sketched, based mainly on information on hemp production in Hungary supplied by Iványi, I. (pers. comm., 2004). Additional data sources were van der Werf (2002) and a discussion with French hemp producers (Quinton, S. et al., pers. comm., 2004). There was insufficient data to construct regional or national production scenarios and, in fact, environmentally relevant parameters, such as the amounts of fertiliser and fuel used due to field operations, do not seem to vary significantly across Europe. The hemp crop is assumed to be grown for the stem/fibre only. The investigated crop production scenario is described below. The detailed production inventory is given in Appendix A (see also Appendix E). The field operations preceding hemp production depend on the previous crop, which is commonly winter wheat. Wheat stubble breaking is regarded as part of the wheat production process and thus outside the system boundaries of this study; the first operation included in the analysis is the ploughing of the field, cm deep. Lime application is assumed to take place once every three years. Amounts of fertiliser applied are: 68 kg N, 30 kg P 2 O 5 and 114 kg K 2 O per hectare. According to Good Agricultural Practice, the amount of fertilisation was calculated based on the anticipated crop needs (van der Werf, 2002). Two passes by tractor were assigned for the fertiliser application, i.e. nitrogen is applied separately, while phosphate and potassium applications are coupled. See Appendix D for further details on process input data (energy carriers, fertilisers etc.). Subsequently, the seedbed is harrowed and 55 kg of seed per hectare is sown. The production of the seed for sowing was taken into account, assuming similar inputs to those of the fibre crop, with a few exceptions: amount of seed (25 kg/ha), need for mechanical weed control, harvest of seed with a combine harvester, and a seed yield of 1000 kg/ha (Quinton et al., pers. comm., 2004). Road transport of the seed to the farm over a distance of 300 km was included. Until the harvest there are no further operations. No pesticides are used on hemp. The use of common contemporary agricultural machines is assumed for field operations, despite the fact that the current state of the machinery in some hemp production regions, e.g. Hungary, is not as modern as in Western Europe. Details of machinery are presented in Table 3. The duration of different operations and the fuel use (Appendix A) was based on unpublished data from van der Werf (2004). 16

19 Table 3. Details of agricultural machinery. Machine Category * Weight Service life Reference (kg) (hours) (ha) Tractor: 4WD, 50 kw A Audsley et al., 1997 Tractor: 4WD, 75 kw A Audsley et al., 1997 Plough: 4-furrow C Audsley et al., 1997 Lime spreader C Unpublished data, van der Werf, 2004 Disc broadcaster: >450 l, 15 m C Audsley et al., 1997 Roller: 5 m C Unpublished data, van der Werf, 2004 Seed drill: 3m C Audsley et al., 1997 Rotary harrow: 3m C Audsley et al., 1997 Mounted crop sprayer: 1000 L, 15 m C Audsley et al., 1997 Cultivator: 2.2 m C Audsley et al., 1997 Blade mower/ Combine harvester: 95 kw B Flake et al., 2000 Pulling machine: 55 kw A Flake et al., 2000 * See Table Emissions associated with crop production Ammonia emissions due to the application of ammonium nitrate fertiliser were estimated according to ECETOC (1994): emission factor (EF) was 0.02 kg of NH 3 -N per kg N applied. The loss of nitrate nitrogen (NO 3 -N) to groundwater was estimated to be 40 kg/ha, which corresponds to a moderate nitrate loss (van der Werf, 2004). Unpublished data from Hungary (Iványi, pers. comm., 2004) strongly suggests that for regions with low summer and autumn rainfall (such as the Hungarian hemp production regions) 20 kg/ha would be a more likely figure. Emissions of nitrous oxide nitrogen (N 2 O-N) were estimated according to Mosier et al. (1998). For direct emissions from soils EF was kg of N 2 O-N per kg N input after the volatilisation of ammonium. For indirectly induced emissions EF was 0.01 kg of N 2 O-N per kg of NH 3 -N emitted and kg of N 2 O-N per kg of NO 3 -N emitted. Emissions of nitric oxide nitrogen (NO X - N) were estimated according to Rossier (1998) at 10% of emissions of N 2 O-N. Run-off of PO 4 -P to surface water was estimated according to Rossier (1998): an EF of 0.01 kg of PO 4 -P per kg of P input from fertilisers was used. Emissions of Cd, Cu, Ni, Pb and Zn to the soil were calculated according to a balance approach, considering input by fertilisers and output via harvested produce. Heavy metal content of fertilisers was based on Rossier (1998). Data on heavy metal uptake of crops is rare. Reference uptake was based on a wheat crop yielding 6800 kg/ha of grain containing 0.12 mg/kg of Cd, 5.9 mg/kg of Cu, 0.22 mg/kg of Ni, 0.2 mg/kg of Pb and 31 mg/kg of Zn (contents based on Audsley et al., 1997 and Baize, pers. comm., 2001). 17

20 4.1.2 Harvest The word harvest refers to the gathering of a crop and usually it is understood to include the operations from mowing the crop to collecting it from the field (if not carried out simultaneously). In this report, however, harvest refers only to the operation of mowing, which leaves the stems on the field. The subsequent operations depend on the chosen fibre processing method, and are thus discussed as part of the Fibre processing sub-system (chapter 4.2). Fibre hemp is harvested just before the end of flowering, normally in August. The crop is mown and laid down on the ground in swaths. For the long fibre production it is important to keep the hemp stems oriented, i.e. parallel, throughout the harvest and further processing. Hemp harvesting in Hungary is actually carried out by a mower that, in addition to cutting, also binds the stems in sheaves (20-30 cm in diameter). We did not have detailed information on this machine and it is expected to be replaced by a newer technology, because at present the harvest requires a significant amount of human labour. A modern harvester that would accommodate the need for stem orientation is still to be developed. Nevertheless, our scenarios assume such a harvester and we will estimate the LCArelevant parameters, e.g. fuel use, emissions, etc., based on a contemporary blade mower (Table 3). More information on different harvesting technologies can be found in Bassetti et al. (1998) and Müssig and Martens (2003), among others. A stem yield of 8 t/ha was assumed (among others, Meijer et al., 1995; Kozłowski et al., 1998). This weight corresponds to dry stems; dry in this context means 14% humidity. The same principle applies to all the stem and fibre weights given in this report BabyHemp The sheer length of the hemp plant explains some of the difficulties concerning its harvest and subsequent handling. In addition, its strong fibres call for a robust cutting equipment at harvest. Most existing bast fibre processing facilities are ill suited for hemp, as they mostly process flax, which is a significantly shorter and more delicate plant. Instead of developing the machinery and processing facilities for hemp, some people have started modifying hemp to suit the existing equipment. In Italy this approach has resulted in a dawning commercial production of BabyHemp (Amaducci, 2005). BabyHemp is grown at high plant density. For the purpose of the analysis, BabyHemp crop production is according to the generic European scenario, with the following exceptions: 100 kg seed is sown per hectare (Amaducci, pers. comm., 2004), and the fertilisation was reduced in proportion to the stem yield. Emissions associated with crop production were calculated as explained in The NO 3 -N loss to groundwater was assumed to be 40 kg/ha, as in the general scenario. The growth of the BabyHemp crop is terminated by herbicide spraying when it is cm tall: 4 kg/ha of both the herbicide Glyphosate and the auxiliary substance ammonium sulphate are used (Amaducci, 2005). The resulting stems are similar in length to flax and thus can be further handled and processed with existing flax machinery. After desiccation BabyHemp stems are pulled, instead of cut. This operation is identical to flax pulling, and a number of firms offer machines for flax harvest. We assume the use of a Depoortere self-propelled machine that pulls 18

21 one swath at a time (Flake et al., 2000) (Table 3; Appendix B, Table B2). The machine lays the stems parallel in swaths on the ground. 4.2 FIBRE PROCESSING Overview of fibre processing I) Traditional warm water II) Bio-retting scenario III) BabyHemp scenario retting scenario HARVEST HARVEST DESICCATION/ STAND-RETTING DRYING ON THE FIELD B DRYING ON THE FIELD B HARVEST (Pulling) WARM WATER- RETTING GREEN SCUTCHING DEW-RETTING DRYING ON THE FIELD BIO- RETTING DRYING ON THE FIELD B DRYING SCUTCHING SOFTENING SCUTCHING B B B = Material flow = Transport HACKLING B = Baling B = Baling, excluded from the analysis Figure 4. Alternative fibre processing scenarios and their unit processes. Unit processes with the same colour have comparable functions. The unit-processes in perforated boxes are discussed within other subsystems. 19

22 Three fibre-processing scenarios were analysed in this study (Figure 4). Boxes with the same colour present operations with a comparable function. The general purpose of the operations (such as retting and scutching) is explained for the traditional warm water-retting scenario, which is considered as the reference scenario. Scenario specific peculiarities are elaborated on in the description of the respective scenario. The process inventories are included in Appendix F Traditional warm water-retting scenario Processes and data Traditionally (and contemporarily in Hungary and Romania) hemp stems are bound as sheaves of cm diameter at harvest. In order to facilitate drying, the sheaves are lifted into tepee-like formations (Figure 5), each containing about forty sheaves. After about a week, when the water content of the stems has fallen below 15%, the sheaves are assembled into big, loose, rectangular bales for transport from the field. All this is done manually (Iványi, pers. comm., 2004), so we associate no resource use or polluting emissions to it. The baled hemp is assumed to be loaded by a tractor equipped with a front loader into a truck and transported directly to a fibre-processing site over an average distance of 60 km. Longer stem transport distances are not economically viable (Homonyik, pers. comm., 2004; Pfeiffer, pers. comm., 2004; Tofani, pers. comm., 2004). Figure 5. Hemp sheaves drying in tepee-like formation at Hungarohemp. (Photo by Turunen, L., 2004) 20

23 Retting The first process at the fibre processing facility is retting. The purpose of retting (the blue boxes in Figure 4) in general is the decomposition of the pectic substances by which the fibre bundles are attached to the surrounding bark matrix and the woody core. This will facilitate the subsequent mechanical separation of the fibre bundles from the rest of the stem. The warm water-retting process relies on the natural micro-organisms (anaerobic bacteria being the most important), that are present on the plant during the growing season. Warm water-retting provides these organisms with good growth conditions (mainly temperature), in which they multiply rapidly and the retting process functions well. More detailed information on retting can be found e.g. in Sharma and van Sumere, The following description of warm water-retting is based on the actual operational sequence at Hungarohemp Kenderipari és Logisztikai Rt (Hungarohemp, for short), Nagylak, in southeastern Hungary. It is one of the two remaining hemp-processing factories in Hungary; some 30 years ago there used to be around 36 of such factories in the country! (Homonyik, pers. comm., 2004). Unless otherwise mentioned, data is based on a visit to the processing site in August 2004, as well as on personal communication with Attila Homonyik (2004). For retting, loose bales of hemp sheaves are loaded into open concrete retting pools and secured in place with metal bars (Figure 6). Pools are filled with water of about 28 C, which is a mixture of thermal water (47 C) and ordinary well water. The reader should note, that no artificial heating is involved and thus the input of non-renewable energy for heating the retting water is zero. The stem-water mass ratio is 1:14. The stems ret for 5 days. During retting the stem mass loss is about 10%. The fate of the retting liquor and associated emissions will be discussed below. The stems need to be dried after retting, in order to prevent spoilage during intermediary storage. The subsequent scutching process requires the raw material to be dry, too. In the warm water-retting scenario the use of a traditional drying method is assumed, in accordance with the Hungarohemp practice. The retted hemp sheaves are assembled again into tepee stacks on a field next to the retting pools. The operation does not cause significant environmental impact. The drying and moving of the bound sheaves requires a great deal of manpower, though. Thus this drying method is not economically feasible in Western Europe and it is likely to be replaced by other methods in the long run in Hungary too. Hemp is retted either right away after harvest in the autumn, if time/weather allows, or in the following spring/summer. In winter, the air temperature is too low for retting, which takes place in outdoor pools. Before and after retting the stems are stored outdoors in big barn-shaped stacks, called pyramids. During this storage about 10% of the stems are lost due to spoiling. 21