A LCA case study of hand washing
with liquid and bar soap
Kasja Witlox, Regula Keller, Niels Jungbluth ([email protected])
Margrit-Rainer-Strasse 11c, CH-8050 Zurich, +41 44 940 61 32, http://www.esu-services.ch
Goal and methodology
Soap production
As part of an introductory course in
Life Cycle Assessment (LCA), at ESUservices in Zurich, this case study analysis
and compares the life cycle " from cradleto-grave" of liquid- and bar hand soap. We
studied the following processes:
Soap is produced through a process called saponification. Fatty acids in fats/oils are hydrolysed with a base such as NaOH to produce a fatty acid salt (soap) and glycerol.
O
O
R
O
O
3R
+ 3NaOH
+ HO
R
ONa
O
OH
HO
O
R
O
1 The production of 1 kg liquid hand
soap from rape seed oil and NaOH,
packaged in a PET dispenser.
1.5
1.0
0.5
0.0
[3] Ramachandran, H., Amirul, A. (2013) ’Evaluation of unrefined glycerine
pitch as an efficient renewable carbon resource for the biosynthesis of novel
yellow-pigmented P(3HB-co-4HB) copolymer towards green technology‘ , in
Biotechnology and Bioprocess Engineering, vol.18, no.6, pp. 1250-1257
Processes
Rape seed oil
Tallow
Fatty acids
NaOH, 50% in H2O
Tap water
Chemical plant
Electricity, MV
Heat
Lorry transport
Rail transport
Disposal, inert waste
Waste water
0.4
0.2
0.0
Vegetable Animal
Bar soap production
Liquid soap production
• The production of animal soap results in a lower climate impact/kg soap because
animal fat is considered a waste product
• The climate impact of bar soap is higher because it requires more raw materials.
7
6
Processes
Liquid soap
Bar soap
Transport
Tap water, 10°C
Paper
Waste water
5
4
3
2
1
0
Bar
kgCO2e/1000 washing cycles
12
Processes
10
Liquid soap
Bar soap
Transport
Tap water, 40°C
Tap water, 10°C
Paper
Waste water
8
6
4
2
0
Liquid
Bar
Washing hands, [T=10°C]
Liquid
Washing hands, [T=20°C]
b.
24
1.4
Processes
20
Liquid soap
Bar soap
Transport
Tap water, 40°C
Paper
Waste water
16
12
8
4
0
Processes
1.2
Liquid soap
Bar soap
Distribution
PET bottle
HDPE foil
Lorry transport
1.0
0.8
0.6
0.4
0.2
0.0
Bar
c.
kgCO2e/1000 washing cycles
Liquid soap from vegetable oil and bar soap from animal fat. a-c: Hand washing at
different temperatures d: Soap at the supermarket.
We used generic data from the ecoinvent
V2.2 database and literature data [1, 2, 3].
The software tool SimaPro 8 developed by
PRé Consultants is used to model the LCA
for both types of soap.
[2] Koehler, A., Wildbolz, C. (2009) ’Comparing the Environmental Footprints of
Home-Care and Personal-Hygiene Products: The Relevance of Different LifeCycle Phases‘ , in Environ. Sci. Technol, vol.43, no.22, pp. 8643-8651
Glycerol
0.6
Vegetable Animal
Data and tools
[1] Escamilla, M. et al (2012) ’Revision of European Ecolabel Criteria for Soaps,
Shampoos and Hair Conditioner‘ , in Tech report
kgCO2e/kg soap
2.0
a.
Literature
Processes
Rape seed oil
Tallow
Fatty acids
NaOH, 50% in H2O
NaCl, brine
Chemical plant
Electricity, MV
Heat
Lorry transport
Rail transport
Disposal, inert waste
Waste water
kgCO2e/kg soap
The aim of this LCA is to describe in
what way and how much the above enumerated processes affect the climate expressed in kgCO2 equivalent over a period of 100 years. Therefore we used the
method that describes the impact on climate, based on IPCC 2013. The system
geographical boundary is Switzerland.
For each goal we include energy use,
transport to retailer and waste management. For bar soap, the purification of tallow and glycerol is not included. For the
comparison we include the home transport
of the hand soap by the consumer and drying hands with paper tissues.
Soap
A comparison between soap production from animal fat and soap from vegetable oil.
kgCO2e/1000 washing cycles
3 The comparison of 1 to 2 expressed in 1000 hand-washing cycles. (2.3g liquid soap+0.64l water/ cycle, 0.35g bar soap+0.91l water/cycle [2])
Lye
Results & conclusion
kgCO2e/kg soap
2 The production of 1 kg bar hand
soap from tallow and NaOH,
wrapped in foil and with glycerol as
co-product,.
Fatty acid
Liquid
Washing hands, [T=40°C]
Bar
d.
Liquid
Supermarket
• During the soap life cycle, the consumer phase shows the highest climate impact.
• In the consumer phase water T(◦ C) matters; washing hands with cold water results
in a higher climate impact for liquid soap because more soap is wasted per washing
cycle; washing hands with warm water means a higher climate impact for bar soap
because more water is wasted per washing cycle.[2]
• PET packaging has a higher climate impact than HDPE foil, here mainly due to a
higher weight.