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 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.
Material | Embodied energy (MJ/kg) |
Emissions (tonnes CO2/tonne) |
Water usage (m3/tonne) |
Waste | Incineration | References |
---|---|---|---|---|---|---|
Wood | ||||||
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] | ||||
Fertiliser | ||||||
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 | ||||||
Glass | 12.7 | [4] | ||||
Glass fibre (Owens Corning) | 12,58 | [12] | ||||
Glass fibre (Vetrotex International) | 25.3 | [12] | ||||
Glass fibre (Vetrotex Germany) | 32.0 | [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] | |||
Plastics | ||||||
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] | ||||
Metals | ||||||
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
https://ecm-academics.plymouth.ac.uk/jsummerscales/MST326/MST326-05 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.
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 |
Infrared oven heating | 5.20 | Lacoma et al [30] based on 590 g carbon/PPS part |
Injection moulding (all-electric) | 1.6-3.5 | Hesser et al [31] |
Injection moulding (hydraulic) | 19.0-29.9 | Thiriez et al [32] [23, 33] |
Injection moulding | 11.2/33.7 | DACOMAT |
Machining | 0.22 | Lacoma et al [30] based on 590 g carbon/PPS part |
Preform cutting by abrasive water jay | 1.55 | Lacoma et al [30] based on 590 g carbon/PPS part |
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 |
Robot arm handling | 0.14 | Lacoma et al [30] based on 590 g carbon/PPS part |
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 |
Stamp forming | 9.11 | Lacoma et al [30] based on 590 g carbon/PPS part |
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 [34] |
Vacuum assisted resin infusion (VARI) | 10.2/30.6 | DACOMAT |
Vacuum assisted resin infusion (VARI) | 10.2 | Suzuki and Takahashi [18] |
Recycling | ||
Pre-recycling shredding | 0.09 | Witik et al [35] |
Sieving | 0.125 | Turner et al [36] |
Grinding | ||
glass mat thermoplastic (GMT) | 0.14 | Hedlund-Åström [33] via [15]. |
Grinding (Eco-Wolf GM2411-50 at 800 kg/h) | 0.14 | Job et al [37] citing EXHUME |
Grinding sheet moulding compound (SMC) | 0.16 | Hedlund-Åström [33] via [15]. |
Grinding flax/polypropylene | 0.17 | Hedlund-Åström [33] via [15]. |
Grinding CFRP | 0.27 | Hedlund-Åström [33] via [15]. |
Grinding acrylic-based composites | 0.29 | Cousins et al [38] |
Grinding FRP sandwich | 0.31 | Hedlund-Åström [33] via [15]. |
Grinding (IIT M300 at 29 kg/h) | 4.75 | Job et al [37] citing EXHUME |
Grinding | 5.97-6.77 | Srivastava et al [39] |
Milling | ||
CFRP at 150 kg/h | 0.27 | Howarth et al [40] |
Milling CFRP at 10 kg/h | 2.03 | Howarth et al [40] |
Granulating | ||
Eco-Wolf GM-2411-50 at 800 kg/h | 0.14 | Shuaib and Mativenga [41] |
Wittman ML2201 at 150 kg/h | 0.17-0.27 | Job et al [37] citing EXHUME |
Wittman MAS1 at 30 kg/h | 0.32 | Shuaib and Mativenga [41] |
Wittman MAS1 at 30 kg/h | 0.35 | Job et al [37] citing EXHUME |
Wittman MAS1 at 30 kg/h | 0.37 | Shuaib and Mativenga [41] |
Granulating | 0.5 | Turner et al [36] |
Wittman MAS1 at 1.8 kg/h | 5.53 | Shuaib and Mativenga [42] |
Fluidised bed | ||
optimal conditions to recycle CFRP | 10 | Meng [43 (citing 44), 45] |
low feed rate recycling CFRP | 15-30 | Pickering [46] |
optimal conditions to recycle GFRP waste | 22.2 | Pickering [47] |
Pyrolysis | 23-30 | Job et al [37] |
Pyrolysis | 30 | Witik et al [48] |
High-Voltage Fragmentation (HVF) | ||
"optimally configured HVF" | 16.2-43.2 | Weh [49 via 33] |
HVF with 500 pulses | 17.1 | Mativenga et al [50] |
HVF with 1000 pulses | 35.6 | Mativenga et al [50] |
HVF with 1500 pulses | 60.0 | Mativenga et al [50] |
HVF with 2000 pulses | 89.1 | Mativenga et al [50] |
Dissolution for acrylic-based composites | ||
Dissolution-evaporation-extrusion | 4.0 | Cousins et al [38] |
Thermoplastic blade recycling facility | 15.3 | Cousins et al [38] |
Dissolution-distillation-extrusion | 20 | Cousins et al [38] |
Solvolysis | ||
solvolysis of CFRP waste | 19.2 | Keith et al [51] |
dissolve a CFRP tennis racket | 63-91 | Shibata and Kakagawa [52] |
solvolysis of CFRP waste | 101 | La Rosa et al [53] |
Distillation (within chemical recycling below) | ||
Chemical recycling | 38 | Shibata and Nakagawa [52] |
Some Life Cycle Assessments address a specific composite component rather than a set material or process:
Published data for the calorific value of pyrolysis gas derived from various composite materials are shown in Table 3.
Material | Pyrolysis temperature (ºC) |
Gross Calorific Value (MJ m-3) |
|
---|---|---|---|
Epoxy resin with glass and carbon fibre reinforcement | 350 | 51.1 | Cunliffe et al [55] |
Epoxy resin with glass and carbon fibre reinforcement | 400 | 39.8 | Cunliffe et al [55] |
Epoxy resin with glass and carbon fibre reinforcement | 500 | 42.0 | Cunliffe et al [55] |
Epoxy resin with glass and carbon fibre reinforcement | 600 | 28.9 | Cunliffe et al [55] |
Epoxy resin with glass and carbon fibre reinforcement | 800 | 23.9 | Cunliffe et al [55] |
PET with 50 weight % glass fibre and silane binder | 550 | 7.8 | Cunliffe et al [55] |
Poly(propylene) with 40% glass fibre and silane binder | 550 | 44.7 | Cunliffe et al [55] |
Unsaturated polyester resin with 20-30 weight % glass fibre and silane binder |
550 | 13.0 | Cunliffe et al [55] |
Orthophthalic polyester/glass fibre SMC | 300 | 33.9 | Torres et al [56] |
Orthophthalic polyester/glass fibre SMC | 400-700 | 36.7 | Torres et al [56] |
Vinylester resin with 70% woven glass fibre fabric | 550 | 18.7 | Cunliffe et al [55] |
Economic issues
The Stern Review [57] 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:
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
References
Further reading