Composites Design and Manufacture (Plymouth University teaching support materials)
Natural Fibres - environmental, technical and economic issues.
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CAUTION: For the purpose of the Sustainable Composites pages, the materials described are those from natural sources, without prejudice to the results of any future Quantitative Life Cycle Analysis (QLCA) which may (or may not) make the case for these materials being more environmentally-friendly than equivalent systems manufactured from man-made fibres and synthetic resins.  The inclusion of any specific system here is not an endorsement of that product: potential users will need to fully consider each system in the context of their specific technical requirements.

The value of Eco-System Services

Environmental issues

The Environment Agency has issued a consultation document on aquatic eutrophication in England and Wales [1].  Around 70% of the nitrogen input to inland surface waters is estimated to come primarily from agriculture, then precipitation and urban run-off respectively.  The remaining 30% was from sewage effluent and industrial discharges.   Agricultural activities (livestock and fertilisers) release 44% of the phosphorus present in surface waters, putting the UK third amongst 16 EU/EFTA nations.  Most UK farms operate on the basis of an annual phosphorus surplus, as this is normal agricultural practice across Europe.

The environmental impact of natural fibres in industrial applications has been reviewed by van Dam and Bos [2].  They include quantitative data [Table 1] and suggest that:

In the ADAS review and analysis of the breeding and regulations of hemp and flax varieties available for growing in the United Kingdom [3] they note "that if changes are to be made to hemp & flax varieties that affect the agronomic requirements of the crops (e.g. higher N inputs to hemp in particular), then careful consideration is needed of how this might affect the perception of an environmentally benign, or even beneficial, status that hemp and flax currently enjoy.  Stakeholders promote the perceived environmental advantages (of hemp in particular) as a key selling point".

Embodied energy

Embodied energy is the energy consumed during the production of a material at all stages from acquisition (growing or mining), conversion processes (manufacturing) through to product delivery (including transport) and hence is a significant component of the lifecycle impact of that material.
BEWARE: "Embedded energy" may sound similar but has a specific different meaning as the amount of energy that can be recovered by e.g. combustion.

Table 1:
Some quantitative data for the environmental impacts of various materials and processes (note that an empty cell in the table does NOT imply no significant effect !)
 Material  Embodied energy
(tonnes CO2/tonne)
Water usage
Waste Incineration  References
 Air dried sawn hardwood 0.5         [4, 6]
 Kiln dried sawn hardwood 2.0         [4, 6]
 Kiln-dried sawn softwood 1.6 [6]-3.4 [4]         [4, 6]
 Glue-laminated timber 4.6 [6]-11.0 [4]         [4, 6]
 Ammonium nitrate (33.5% N) 90-121 2.3-7.1       [7]
 Urea (46% N) 52-112 0.9-4.0       [7]
 Ammonia (82% N)   1.5-2.6       [7]
 Single superphosphate {21% P) 61.9 -0.2-1.1       [7]
 Triple superphosphate (48% P) 16.5-63 -0.4-1.1       [7]
 Potassium chloride (60% K) 16.8 0.583       [7]
 Natural fibres            
 Natural fibre (china reed)         yields 8.3 MJ/kg [2]
 Jute fibre cultivation (excluding field labour, retting and decortication) 3.75-8.02 -2.4 [Note 1]       [2]
 Wet decortication (sisal and henequen) 2.0   100 100 m3 water and biomass   [2]
 Flax fibre non-woven mat 9.6         [2, 8]
 Woollen and worsted: spinning and winding frames 10.8-12.8         [5]
 Woollen and worsted: spinning (ring frame) 18.7-28.6         [5]
 Wool (NZ merino on-farm energy use)  14.8-53.4         [9]
 Wool (NZ merino dry top landed in China) 48.1-76.6         [9]
 Cotton yarn 180         EcoInvent
 Cotton fabric 143         [6] 
 Bamboo 2.58 0.13       [10]
 Viscose 169         EcoInvent
 Silk (sericulture in India) 1843         [11]
 Glass 12.7         [4]
 Glass fibre 13-32         [12]
 Float glass 15.9         [6]
 Fibreglass insulation 27.9 [13]-30.3 [6]         [6, 13]
 Fibreglass reinforcement mats 54.7       demands 1.7 MJ/kg [2, 8]
 Carbon fibre            
 Recycled carbon fibre 10.8-36         [14] via [15]
 Recycled CF/PP 15         [15]
 Recycled CF/Epoxy 33         [15]
 CF/PP part 155         [15]
 Carbon fibre 183-286         [12]
 CF/Epoxy part 234         [15]
 Virgin carbon fibre 198-594         [14] via [15]
 Polyacrylonitrile-based (PAN) carbon fibre 286–704 22.4–31       [16, 17, 18]
 Carbon nanofibre (CNF) 654–1807 70–92       [19]
 Polypropylene 24.2         [15]
 Polyhydroxyalkanoates (PHAs) 59–107 0.7–4.4       [20-22]
 Polyester resin 63-78         [12]
 Polypropylene 64 [6], 73.4 [22], 84.3 [2] 2.0-7.5   5.5 ton/tonne   [2, 6, 23]
 Epoxy resin 76-137 4.7-8.1       [12, 15, 18, 23, 24]
 Polypropylene fibres 86 [EcoInvent], 90 [2]       yields 21.5 MJ/kg EcoInvent, [2]
 Plastics - general 90         [4]
 Steel (virgin) 32         [6]
 Steel (recycled) 10.1         [6]
 Stainless steel 110-210         [12]
 Aluminium (virgin) sheet 170 [4]-199 [6]         [4, 6]
 Aluminium alloys 196-257         [12]
 Aluminium (recycled) sheet 14.8         [6]

Note 1: Use of non-fibre material as fuel and of leaves to improve soil fertility are not accounted.
Note 2: A more comprehensive table of embodied energies can be found at Franklin Associate [13].
Note 3: There is a Table of CO2 emissions for a broader range of materials at Azapagic.htm#CO2.
Note 4: The ICE database: embodied energy and carbon is a free database for building materials.

Various authors have published summary data on unit energies for composites processing and recycling as shown in Table 2.  Piotrowska and Piasecka [25] used LCA to analyse the materials and consumables generated as post-production waste from wind power blade plants.  Eight forms ofwaste were considered: fiberglass mat, roving fabric, resin discs, distribution hoses, spiral hoses with resin, vacuum bag film, infusion materials residues and surplus matter.  Eco-indicator 99 and CED (Cumulative Energy Demand) were used to inform recommendations for the post-use management of wind power plant blades and to make the manufacturing process more sustainable development and to move towards a closed-cycle economy.

Table 2:   Unit energies for composites processing  [12, 15, 26]
DACOMAT (Damage Controlled Composite Materials) data as onsite energy/primary energy
Process Process energy (MJ/kg) Source
Autoclave moulding 21.9 Song et al [12]
Autoclave moulding 22.3/66.8 DACOMAT
Cold press 11.8 Suzuki and Takahashi [18]
Cold press 11.8/35.4 DACOMAT
Compression moulding 7.2-15.9 Das [28]
Compression moulding 11.4/34.3 DACOMAT
Glass fabric manufacturing 2.6 Stiller [29]
Filament winding 2.7 Suzuki and Takahashi [18]
Filament winding 2.7/8.1 DACOMAT
Hand lay-up 19.2/57.7 DACOMAT
Injection moulding
1.6-3.5 Hesser et al [30]
Injection moulding (hydraulic) 19.0-29.9 Thiriez et al [31] [23, 32]
Injection moulding 11.2/33.7 DACOMAT
Preform matched die 10.1 Suzuki and Takahashi [18]
Preform matched die 10.1 DACOMAT
Prepreg production 40.0 Suzuki and Takahashi [18]
Prepreg 40.0/120.1 DACOMAT
Pultrusion 3.1 Suzuki and Takahashi [18]
Pultrusion 3.1/9.3 DACOMAT
Sheet moulding compound 3.5-3.8 Suzuki and Takahashi [18] [16]
Sheet moulding compound 3.5/10.5 DACOMAT
Spray up 14.9 Suzuki and Takahashi [18]
Spray up 14.9/44.8 DACOMAT
Liquid composites moulding (LCM) processes)    
Resin transfer moulding (RTM) 12.8/38.4 DACOMAT
Resin transfer moulding (RTM) carbon fibre 12.8 Suzuki and Takahashi [18]
Resin transfer moulding (RTM) glass fibre 11.6 Dai et al [33]
Vacuum assisted resin infusion (VARI) 10.2/30.6 DACOMAT
Vacuum assisted resin infusion (VARI) 10.2 Suzuki and Takahashi [18]
Pre-recycling shredding 0.09 Witik et al [34]
Sieving 0.125 Turner et al [35]
Grinding glass mat thermoplastic (GMT) 0.14 Hedlund-Åström [32] via [15].
Grinding (Eco-Wolf GM2411-50 at 800 kg/h) 0.14 Job et al [36] citing EXHUME
Grinding sheet moulding compound (SMC) 0.16 Hedlund-Åström [32] via [15].
Grinding flax/polypropylene 0.17 Hedlund-Åström [32] via [15].
Grinding CFRP 0.27 Hedlund-Åström [32] via [15].
Grinding FRP sandwich 0.31 Hedlund-Åström [32] via [15].
Grinding (IIT M300 at 29 kg/h) 4.75 Job et al [36] citing EXHUME
Grinding 5.97-6.77 Srivastava et al [37]
Milling CFRP at 150 kg/h 0.27 Howarth et al [38]
Milling CFRP at 10 kg/h 2.03 Howarth et al [38]
Granulating Eco-Wolf GM-2411-50 at 800 kg/h 0.14 Shuaib and Mativenga [39]
Wittman ML2201 at 150 kg/h 0.17-0.27 Job et al [36] citing EXHUME
Wittman MAS1 at 30 kg/h 0.32 Shuaib and Mativenga [39]
Wittman MAS1 at 30 kg/h 0.35 Job et al [36] citing EXHUME
Wittman MAS1 at 30 kg/h 0.37 Shuaib and Mativenga [40]
Granulating 0.5 Turner et al [35]
Wittman MAS1 at 1.8 kg/h 5.53 Shuaib and Mativenga [40]
High-voltage fragmentation 4 Weh [41]
Pyrolysis 23-30 Job et al [36]
Pyrolysis 30 Witik et al [42]
Distillation (within chemical recycling below) 38 Shibata and Nakagawa [43]
Chemical recycling 63-91 Shibata and Nakagawa [43]

Published data for the calorific value of pyrolysis gas derived from various composite materials are shown in Table 3.

Table 3:  Calorific value of pyrolysis gas derived from various composite materials
 Material Pyrolysis
temperature (ºC)
Gross Calorific
Value (MJ m-3)
 Epoxy resin with glass and carbon fibre reinforcement 350 51.1 Cunliffe et al [44]
 Epoxy resin with glass and carbon fibre reinforcement 400 39.8 Cunliffe et al [44]
 Epoxy resin with glass and carbon fibre reinforcement 500 42.0 Cunliffe et al [44]
 Epoxy resin with glass and carbon fibre reinforcement 600 28.9 Cunliffe et al [44]
 Epoxy resin with glass and carbon fibre reinforcement 800 23.9 Cunliffe et al [44]
 Poly(ethylene terephthalate) with 50 weight % glass fibre and silane binder 550 7.8 Cunliffe et al [44]
 Poly(propylene) with 40% glass fibre and silane binder 550 44.7 Cunliffe et al [44]
 Unsaturated polyester resin with 20-30 weight % glass fibre and silane binder 550 13.0

Cunliffe et al [44]

 Orthophthalic polyester/glass fibre SMC 300 33.9 Torres et al [45]
 Orthophthalic polyester/glass fibre SMC 400-700 36.7 Torres et al [45]
 Vinylester resin with 70% woven glass fibre fabric 550 18.7 Cunliffe et al [44]

Economic issues

The Stern Review [46] on the economics of climate change notes that raising the cost of fossil fuel energy will significantly impact on costs and prices in the most carbon-intensive industries.  There are 123 industries assessed.  For profits to remain unchanged with a carbon price of £70/tonne-of-carbon, prices for the top six industries  would have to rise by the percentages shown in Table 4:

Table 4:  Carbon prices required for profits to remain unchanged [45].
Industry Price change to maintain profit
at £70/tonne-of-carbon
Energy as a percentage
of total costs
gas supply and distribution +25% 42.9%
refined petroleum +24% 72.8%
electricity production and distribution +16% 26.7%
cement, lime and plaster +9% 5.0%
fertilisers +4.61% 13.3%
fishing +4.28% 12.8%

Technical issues


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  2. JEG van Dam and HL Bos, Consultation on natural fibres: the environmental impact of hard fibres and jute in non-textile industrial applications, ESC-Fibres Consultation no 04/4, Rome, 15-16 December 2004.
  3. Review and analysis of breeding and regulations of hemp and flax varieties available for growing in the UK, ADAS UK Limited, November 2005.
  4. B Lawson, Building materials, energy and the environment: Towards ecologically sustainable development, RAIA, Canberra, 1996 as echoed in
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  5. Textiles Online: Waste minimisation in the textiles industry, accessed 21 December 2007 at 15:57 (not available on 13 November 2008!).
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  13. Comparative energy evaluation of plastic products and their alternatives for the building and construction and transportation industries, Franklin Associate Limited Final Report for The Society for the Plastics Industry, 1991, as reproduced in Table 3 of Insulation Materials: Environmental Comparisons, Environmental Building News, January/February 1995, 4(1), and replicated in Feature from Environmental Building News (January/February 1995): Insulation Materials: Environmental Comparisons, accessed 15:26 on 03 November 2007.
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  22. M Akiyama, T Tsuge and Y Doi, Environmental life cycle comparison of polyhydroxyalkanoates produced from renewable carbon resources by bacterial fermentation, Polymer Degradation and Stability, 2003, 80(1), 183–194.
  23. S Kim and B Dale, Life cycle assessment study of biopolymers (polyhydroxyalkanoates) - derived from no-tilled corn, International Journal of Life Cycle Assessment, may 2005, 10(3), 200-210.
  24. M Pietrini, L Roes, MK Patel and E Chiellini, Comparative life cycle studies on poly(3-hydroxybutyrate)-based composites as potential replacement for conventional petrochemical plastics, Biomacromolecules, 2007, 8(7), 2210–2218.
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  27. J Rybicka, A Tiwari, PA Del Campo and J Howarth, Capturing composites manufacturing waste flows through process mapping, Journal of Cleaner Production, 15 March 2015, 91, 251-261.
  28. S Das, Life cycle assessment of carbon fiber-reinforced polymer composites, International Journal of Life Cycle Assessment, March 2011, 16(3), 268-282.
  29. H Stiller, Material intensity of advanced composite materials, Results of a study for the Verbundwerkstofflabor Bremen e.V., Wuppertal Institute, 1999.
  30. F Hesser, M Mihalic, BJ Paichl and M Wagner, Injection moulding unit process for LCA: energy intensity of manufacturing different materials at different scales, Journal of Reinforced Plastics and Composites, 2017, 36(5), 338–346.
  31. A Thiriez and T Gutowski, An environmental analysis of injection molding, International Symposium on Electronics and the Environment, IEEE, San Francisco CA, 2006.  MS thesis.
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  41. A Weh [via 32], High voltage pulse fragmentation technology to recycle fibre-reinforced composites, FP7 Project 323454 SELFRAG CFRP Final Report Summary, SELFRAG AG (2015).
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  46. N Stern, The Economics of Climate Change, HM Treasury website, accessed 04 November 2008 at 14:42. Cambridge University Press, January 2007. ISBN-13: 9780521700801.

Further reading

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Created by John Summerscales on 19 June 2006 and updated on 08-Mar-2022 19:03. Terms and conditions. Errors and omissions. Corrections.