Life Cycle Assessment
of flax fibre
for the reinforcement of composites
Nilmini Dissanayake,
John Summerscales, Stephen Grove and Miggy Singh
Content
 Flax
 Life Cycle Assessment (LCA)
 goal and scope
 system boundaries
 Life Cycle Inventory analysis (LCI)
 3 scenarios
 energy
 Environmental Impact Classification Factors (EICF)
 Life Cycle Impact Assessment (LCIA) - results
 Conclusions
Flax
• Linum usitatissimum
• temperate zone plant
• flax – grown for fibre
linseed – grown for seed oil
• sown in March-May in UK
• life cycle of the plant
45-60 day vegetative period
15-25 day flowering period
30-40 day maturation period
Why Flax ?
• flax is the
most agro-chemical intensive
bast fibre used as reinforcement
• other bast fibres may be “greener”
provided yield/hectare and
performance/durability are satisfactory
Growth stages
• Life cycle of the flax plant consists of
• a 45 to 60 day vegetative period,
• a 15 to 25 day flowering period and
• a maturation period of 30 to 40 days
• From J A Turner “Linseed Law” BASF (UK) Limited, 1987
via http://www.flaxcouncil.ca/images
UK harvest
Flax: from plant to fibre
• tillage and growth
• harvest (combining or pulling)
• retting
(dew-, wet-, stand- or enzyme-retting)
– enzymes (e.g. pectinase digests pectin binder)
• decortication/scutching
(hammer mill, fluted rollers, willower)
• cleaning (removal of shive)
• carding (brushing/combing aligns fibres)
> sliver
• spinning (twisting binds fibres)
> yarn/filament
Life Cycle Assessment (LCA)
Goal and
Scope
Definition
Inventory
Analysis
Impact
Assessment
Interpretation
Goal and Scope
 To determine the sustainability of natural fibres
as reinforcement in polymer matrix composites
(referenced to glass fibres)
 Cradle-to-factory gate
• agricultural operations (from ploughing to harvest)
• fibre extraction operations (retting and decortication)
• fibre preparation operations (hackling and carding)
• fibre processing operations (spinning or finishing)
 The functional unit : “one tonne of flax fibres
for reinforcement in polymer matrix composites”
(assumes Eflax = 42 GPa  equal specific modulus)
 Co-products allocated burdens only for post-separation handling
System Boundaries
seed, fertiliser,
pesticides, diesel
machinery
diesel, machinery,
water
electricity
Crop Production
Dry, green flax stems
Retting
Dry, retted flax
Scutching
Scutched long fibre
electricity
Hackling
SLIVER
electricity, water
Wet Spinning
YARN
atmospheric emissions,
emissions into water,
co-products and waste
Life Cycle Inventory (LCI)
Three scenarios linking
different tillage and retting methods:
1. No-till & water retting
- minimum impact?
2. Conservation till (chisel) & stand/dew retting
- average impact?
3. Conventional till (mouldboard) & bio-retting
- maximum impact?
Tillage Methods
Mouldboard plough
Chisel plough
Pass with no soil tillage
0
100
200
300
400
Energy consumption in ploughing MJ/ha
500
600
Fibre Processing
Bio-retting
Dessicant
Stand/Dew retting
Retting +
Scutching
Water retting
0
20
40
60
80
100
Energy consumption in retting & subsequent
scutching process GJ/tonne of yarn
< Sliver
100
90
80
70
60
50
40
30
20
10
0
Crop
Production
Retting
Scutching
Hackling
< Yarn
Mass loss during the production
Spinning
Remaining mass as a % of green stems at each
stage of the production
Scenario-1
Scenario-2
Scenario-3
LCI results – energy consumption
90
80
70
60
50
40
30
20
10
0
Scenario-1
Scenario-2
Scenario-3
Energy use in the production of flax sliver
(GJ/tonne)
Energy consumption - breakdown
Scenario 1- Sliver (54 GJ/tonne)
4%
9%
17%
Agricultural operations
Fertiliser/pesticides
1%
Warm water retting
Scutching
69%
Hackling
LCI results – energy consumption
90
80
70
60
50
40
30
20
10
0
Scenario-1
Scenario-2
Scenario-3
Energy used in the production of flax yarn
(GJ/tonne)
Energy consumption - breakdown
Scenario 1- Yarn (80GJ/tonne)
Agricultural operations
6%
Fertiliser/pesticides
30%
Warm water retting
Scutching
49%
2%
12%
1%
Hackling
Spinning
Energy consumption
Mat .. sliver
GJ/t
Glass fibre mat
54.7
No-till & water retting
54.4
Conservation & stand retting
113
Conventional & bio-retting
119
Continuous fibre … yarn
GJ/t
Glass fibre
31.7
No-till & water retting
80.4
Conservation & stand retting
142
Conventional & bio-retting
148
Energy consumption
Energy source
% in UK
% in France
Coal/Solid fuels
25.8
5
Natural Gas
47.7
14
-
33
Nuclear
18.0
40
Renewables
6.6
6
Other
1.9
2
Oil
UK: http://www.decc.gov.uk/en/content/cms/statistics/fuel_mix/fuel_mix.aspx
France: http://ieepa.org/news/Other/20100917174353200.pdf
Environmental Impact Classification Factors
From Adisa Azapagic (and ISO 14047)
1. Acidification Potential (AP)
2. Aquatic Toxicity Potential (ATP) – ecotoxicity
3. Eutrophication Potential (EP) - nitrification
4. Global Warming Potential (GWP) - climate change
5. Human Toxicity Potential (HTP)
6. Non-Renewable/Abiotic Resource Depletion Potential (NRADP)
7. Ozone Depletion Potential (ODP)
8. Photochemical Oxidants Creation Potential (POCP) – smog
Draft BS8905 adds “land use”
EICF definitions I
•
Acidification Potential (AP)
consequence of acids (and other compounds which can be transformed into acids)
being emitted to the atmosphere and subsequently deposited in surface soils and water
•
Aquatic Toxicity Potential (ATP) – ecotoxicity
based on the maximum tolerable concentrations
of different toxic substances in water by aquatic organisms
what about insects and birds ?
•
Eutrophication Potential (EP) – nitrification
the potential of nutrients to cause over-fertilisation of water and soil
which in turn can result in increased growth of biomass
•
Global Warming Potential (GWP) - climate change
caused by the atmosphere's ability to reflect some of the heat radiated from the earth's surface:
reflectivity is increased by the greenhouse gases (GHG) in the atmosphere
relatively difficult to quantify climate change
EICF definitions II
•
Human Toxicity Potential (HTP)
persistent chemicals reaching undesirable concentrations in each of the three elements of the
environment (air, soil and water) leading to damage to humans, animals and eco-systems
•
Non-Renewable/Abiotic Resource Depletion Potential (NRADP)
depletion of fossil fuels, metals and minerals
•
Ozone Depletion Potential (ODP)
potential for emissions of chlorofluorocarbon (CFC) compounds
and other halogenated hydrocarbons to deplete the ozone layer
•
Photochemical Oxidants Creation Potential (POCP) – summer smog
related to the potential for VOCs and oxides of nitrogen to generate photochemical or summer smog
Environmental Impact Classification Factor
Ploughing
Sowing
Water
Herbicides
Pesticides
Fertiliser
Dessication
Harvest
Rippling
Retting
Decortication
Hackling
Carding
Spinning
:
Land clearance
Environmental Impact for Flax fibre
Acidification Potential (AP)
Aquatic Toxicity Potential (ATP)
Eutrophication Potential (EP)
Global Warming Potential (GWP)
Human Toxicity Potential (HTP)
Non-Renewable/Abiotic Resource Depletion (NRADP)
Ozone Depletion Potential (ODP)
Photochemical Oxidants Creation Potential (POCP)
Noise and Vibration
Odour
Loss of biodiversity
Very High Effect
Low Effect
No Effect
See also http://www.netcomposites.com/downloads/03Thurs_Summerscales.pdf - slide 15
Life Cycle Inventory Analysis (LCI)
INPUTS
Materials
Value (per tonne of yarn)
Seed
Fertilisers: Lime
Ammonium nitrate
Triple superphosphate
Potassium chloride
Pesticides
Diesel (using no-till & water retting)
Electricity
423 kg
2445 kg (4GJ)
444 kg (25 GJ)
400 kg (6GJ)
305 kg (3 GJ)
9 kg (2 GJ)
5 GJ
36 GJ
OUTPUTS
Yarn
Co-products : Short Fibres
Shive
Dust
Coarse plant residues
Direct Emissions : CO2
NH3
N2O
NOx
SO2
1000 kg
4497 kg
7104 kg
2824 kg
2304 kg
9334 kg
68 kg
14 kg
6 kg
3 kg
Life Cycle Impact Assessment
– LCIA methodology
In the impact assessment interpretation of the LCI data,
Environmental impact potential,
where: Bjx = burden (release of emission j
or consumption of resource j per functional unit)
ec1 = characterisation factor for emission j
continues …
Non-renewable/abiotic resource depletion potential
is calculated using :
Where: Bj = burden
(consumption of resource j per functional unit)
ec1 = estimated total world reserves of resource j.
As defined by Adisa Azapagic et al (2003, 2004) in Polymers, the Environment
and Sustainable Development and Sustainable Development in practice –
case studies for engineers and scientists
Life Cycle Impact Assessment (LCIA)
For the production of flax sliver
40
ATP
GWP
30
ODP
20
10
0
HTP
AP
POCP
No-till & water
retting
Conservation &
dew retting
Conventional &
bio-retting
EP
continues …
Life Cycle Impact Assessment (LCIA)
For the production of flax yarn
40
GWP
30
ATP
ODP
20
10
No-till & water retting
Conservation & dew
retting
0
HTP
AP
Conventional & bioretting
POCP
EP
No-till/water-ret flax vs glass fibres…
50
GWP
No-till
Yarn & water retting
(yarn)
40
HTP
30
ODP
20
No-till
Sliver& water retting
(sliver)
GlassFibre
Glass
10
0
POCP
AP
EP
GF data from Sustainability at Owens Corning – 2008 Summary Progress Report
However ….
• our analysis uses
100% burden to long fibre
• economic apportionment:
If long fibre = 10% weight at 90 p/kg
and short fibre/dust = 90% at 10p/kg,
then burdens on long fibre halved
• if mass apportionment (indefensible?),
then long fibre burden reduced to ~10%
A Le Duigou et al, JBMBE, 2011.
• environmental impact analysis on
French flax fibers using
different underlying assumptions
to Dissanayake et al for UK fibers
concluded that
“without the allocation procedure
the results from the two studies
would be similar.”
Le Duigou vs Dissanayake key differences
• UK plants desiccated at mid-point flowering
but French plants allowed to set seed
• UK yield only 6000 kg/ha
but French yield 7500 kg/ha at harvest
• UK study excluded
photosynthesis and CO2 sequestration
• Higher level of nuclear power in the French energy mix
• UK study allocated all burdens to fiber
French study allocated on mass of product and co-products
This study did not address:
• sequestration of CO2
• use phase – assumed comparable to glass
• disposal – flax could be composted
but degradation leads to
“biogas [which] is typically 60-65% methane,
35% carbon dioxide and a small amount of
other impurities” [Jana et al, 2001]
S Jana, NR Chakrabarty and SC Sarkar, Removal of Carbon Dioxide from Biogas for Methane
Generation, Journal of Energy in Southern Africa, August 2001, 12(3).
This study did not address:
• glass fibres are inert
• natural fibres burn GJ/tonne*
– Flax (Top-F)
– Hemp (Strick H)
– Jute (Wingham)
– Jute (Virk)
16.36±0.05
17.20±0.24
17.46±0.14
17.75±0.17
• but that will release the sequestered CO2
* Parr 1356 bomb calorimeter
data by Adam Smith
However …
• long flax fibre could be
a by-product/co-product
if flax grown for seed (Ω3 health food)
• … but more difficult
to separate fibre from stem
Conclusions I
 no-till and water retting scenario
• lowest global warming potential
 using bio-retting process
• increased global warming
• reduced eutrophication, acidification and toxicity
 fibre mass as % green flax stems
• 5% in bio-retting
• 4% in water retting
• 2% in dew retting
 the embodied energies for flax (no-till agriculture):
54 GJ/tonne for sliver (55 GJ/tonne for glass mat)
80 GJ/tonne for yarn (32 GJ/tonne for continuous glass)
Burdens from …
minimum < average < maximum
• no till < conservation agriculture
< mouldboard plough
• organic fertiliser < agro-chemicals
• biological control of pests
< pesticides
• water- < dew- < bio-retting
• sliver < spun yarn
Conclusions II
 the validity of the “green” case for substitution
of glass fibres by natural fibres is dependent on
the chosen reinforcement form, associated
processes and allocation of burdens
 no-till with water retting is identified as
the most environmental friendly option
 conservation agriculture, organic fertiliser and
biological control of pests
will improve environmental credentials of flax
PhD thesis as free download:
http://pearl.plymouth.ac.uk/
handle/10026.1/483
Thank you for your attention.
Any questions?
http://www.fose1.plymouth.ac.uk/sme/acmc/lca.htm