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

Flax, Hemp, Jute, Kenaf and Nettle fibres
Glossary of fibre/textile terms
Suppliers of natural fibres

Environmental issues

• Depletion of soil nutrients/fertiliser
• Competition from weeds/herbicides
• Competition from animals/pesticides

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:

• "natural fibre production requires less than 10 percent of the energy used for production of PP fibres (around 90 GJ/tonne)".
• the total energy input for jute fibre cultivation (excluding field labour, retting and decortication) was calculated at 3.75-8.02 GJ/tonne when grown by numerous small farmers utilising labour and animal power with limited use of agrochemicals and machinery.
• the energy input from inorganic fertilisers, based on the energy content of the substance and the energy required for production, transport, storage and application is 17 MJ/kg for potassium (K), 26 MJ/kg for phosphorous (P) and 128 MJ/kg for nitrogen (N).
• the energy input from pesticides, based on the energy content of the substance and the energy required for production, transport, storage and application is 320-476 MJ/kg for fungicides, 461-568 MJ/kg for insecticides and 467-622 MJ/kg for herbicides.

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.

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 reference [8].
Note 3: There is a Table of CO₂ emissions for a broader range of materials at http://www.tech.plym.ac.uk/sme/mst324/MST324-05 Azapagic.htm#CO2.

Cunliffe, Jones and Williams [9] have published data for the calorific value of pyrolysis gas derived from various composite materials (Table 2).

Economic issues

The Stern Review [10] 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 following percentages:

• Agricultural subsidies (Single Payment Scheme and Fibre Processing Aid)
• Dependence on the weather
• Market price vs other producers

Technical issues

• Degradation of fibre properties during harvest and subsequent processing
• Wide variations in properties between batches of fibre
• Resistance to deterioration in moist conditions

References

1. Aquatic eutrophication in England and Wales: a proposed management strategy, Environment Agency Consultative Report, December 1998.
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
   Technical manual: design for lifestyle and the future, http://www.yourhome.gov.au/technical/fs52.html accessed 13 November 2008 at 11:34.
5. Textiles Online: Waste minimisation in the textiles industry, http://www.e4s.org.uk/textilesonline/content/6library/report5/1_waste_minimisation.htm accessed 21 December 2007 at 15:57 (not available on 13 November 2008!).
6. Table of Embodied Energy Coefficients, Centre for Building Performance Research (NZ), http://www.vuw.ac.nz/cbpr/documents/pdfs/ee-coefficients.pdf, accessed 16 December 2006 at 16:40.
7. J Diener and U Siehler, Okologischer vergleich von NMT-und GMTBauteilen, Die Angewandte Makromolekulare Chemie, 1999, 272(1), 1–4.
   (cited in SV Joshi, LT Drzal, AK Mohanty and S Arora, Are natural fiber composites environmentally superior to glass fiber reinforced composites?, Composites Part A: Applied Science and Manufacturing, 2004, 35(3), 371-376.
8. 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.
9. AM Cunliffe, N Jones and PT Williams, Pyrolysis of composite plastic waste, Environmental Technology, 2003, 24(5), 653-663.
10. 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

• Jan E.G. van Dam and Harriëtte L. Bos, The Environmental Impact of Fibre Crops in Industrial Applications, http://www.fao.org/es/esc/common/ecg/343/en/Environment_Background.pdf, accessed 22 December 2006 at 12:09.