Assessing Impacts of Water Use along Product Life Cycles

162 Pages·2014·11.66 MB·English

by  Markus Berger

Water Footprint – Assessing Impacts of Water
Use along Product Life Cycles

vorgelegt von
M.Sc. / Dipl.-Ing. (FH) Markus Berger

Fakultät III Prozesswissenschaften
der Technischen Universität Berlin
zur Erlangung des akademischen Grades

Doktor der Ingenieurwissenschaften
‒ Dr.-Ing. ‒
genehmigte Dissertation

Promotionsausschuss:
Vorsitzender: Prof. Dr. Martin Jekel
Gutachter: Prof. Dr. Matthias Finkbeiner
Prof. Dr. Stefanie Hellweg

Tag der wissenschaftlichen Aussprache: 16. Dezember 2013

Berlin 2014
D 83

Acknowledgement
Acknowledgement
“This dissertation would not have been possible without the support of many people.” 7,820 Google
hits show that this is a default sentence in the acknowledgement section of many dissertations – and
now I know why… There are a lot of people whom I would like to thank for their support and
assistance throughout the last years – and especially during the last weeks.
First of all, I wish to thank my supervisors Prof. Dr. Stefanie Hellweg and Prof. Dr. Matthias Finkbeiner
for their valuable feedback and the help they provided. A very special thank goes to you Matthias, for
supporting me with your knowledge, experience, and Long Island Ice Tea with hardly any coke…
Furthermore, I would like to thank Annekatrin Lehmann for reading the first draft of this doctoral
thesis and the detailed feedback she provided. Thanks a lot also to all co-authors of the journal
publications upon which this dissertation is based. I am very grateful for the time, efforts, and
feedback you dedicated to this work. In particular the data provided by Ruud van der Ent and
Stefanie Eisner have been very important for the innovations presented here. As important as these
datasets has been the help of Korbinian Brochnow who taught me how to process them in the GIS
calculations. Moreover, the support provided by our project partners, especially by Dr. Jens Warsen
and Dr. Stephan Krinke from Volkswagen, are highly acknowledged as they enabled the first water
footprint study of industrial products. A big thank you goes to my colleague Vanessa Bach with whom
I had the pleasure to collaborate in all the water footprint projects during the last years ranging from
cows to seawater desalination plants. Furthermore, I wish to thank all colleagues from the Chair of
Sustainable Engineering for supporting me with feedback and ideas as well as with coffee and
chocolate.
A very special thank is extended to my mum, Ursula Berger, who spent her holidays proofreading this
entire dissertation, with the exception of the acknowledgement – which is likely to be full of
mistakes…
Finally, the biggest thank you goes to my family: Inga and Emil. Three lines in an acknowledgement
section can hardly express the great support you provided and the sacrifices you made. Sorry for
spending too many evenings in front of a computer rather than with you on a playground and thank
you for giving me the strength to finish this work. Mops!
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Abstract
Abstract
Freshwater scarcity is a relevant problem for more than 1 billion people around the globe. Therefore,
the analysis of water consumption along the supply chain of products is of increasing relevance in
current sustainability discussions. This thesis aims at enhancing the concept of water footprinting by
reviewing and applying various water footprint approaches, identifying methodological challenges,
and developing a novel water footprint method.
In a comprehensive literature review more than 30 water footprint methods, tools, and databases
have been identified and discussed. The scopes of water footprint approaches differ regarding the
types of water use accounted for, the distinction of watercourses, the inclusion of quality aspects,
and the consideration of temporal and regional aspects such as water scarcity and sensitivity of
population or ecosystems. As the most advanced methods require the highest resolution inventory
data, the trade-off between precision and applicability needs to be addressed in future database and
method developments.
As most of the water accounting and impact assessment methods have hardly been applied in
practice, in this work a selection of methods has been tested in various case studies. Representing
the first water footprint study of complex industrial products, water consumption and resulting
impacts have been analyzed along the life cycles of Volkswagen’s car models Polo, Golf, and Passat.
Based on inventory databases freshwater consumption throughout the cars’ life cycles has been
allocated to material groups and assigned to countries according to import mix shares or location of
production sites. By means of these regionalized water inventories, consequences for human health,
ecosystems, and resources have been determined by using recently developed impact assessment
methods. Water consumption along the life cycles of the three cars ranges from 52 – 83 m3/car.
More than 95% of the water is consumed in the production phase, mainly resulting from producing
iron, steel, precious metals, and polymers. Results show that water consumption occurs in 43
countries worldwide and that only 10% is consumed directly at Volkswagen’s production sites.
Impacts on health tend to be dominated by water consumption in South Africa and Mozambique,
resulting from the production of precious metals and aluminum. Consequences for ecosystems and
resources are mainly caused by water consumption of material production in Europe.
Based on the review and case studies, methodological challenges in water footprinting have been
identified and potential solutions have been presented. A key challenge is the current definition of
water consumption according to which evaporated water is regarded as lost for the originating
drainage basin per se. Continental evaporation recycling rates of up to 100% within short time and
length scales show that this definition is not valid and needs to be revised. Also the inclusion of land
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Abstract
use effects on the hydrological balance is questionable as land transformation often leads to higher
water availability due to locally increased runoff. Unless potentially negative consequences, like
flooding or water logging, and adverse effects on the global water cycle are considered, water credits
from land transformation seem unjustified. Most impact assessment methods use ratios of annual
withdrawal or consumption to availability to denote regional water scarcity. As these ratios are
influenced by two metrics – withdrawal and availability – arid regions can appear uncritical if only
small fractions of the little renewable supplies are used. Besides neglecting sensitivities to additional
water uses, such indicators consider neither ground nor surface water stocks which can buffer water
shortages temporally.
In addition to methodological challenges it has been discussed whether the water footprint should
be a volumetric or impact oriented index. Authors favoring volumetric indicators claim that global
freshwater appropriation is more important than regional impacts, easier to determine, and less
error-prone than putting complex ecological interaction into mathematical models. However, as 1 m³
of water consumption in Mexico does not compare to 1 m³ of water consumed in Canada, water
footprints need to consider regional impacts in addition to volumes. As shown in an example,
volumetric water footprints can be misleading without additional interpretation because numerically
smaller footprints can cause higher impacts.
Tackling the shortcomings of existing water footprint methods, the water accounting and
vulnerability evaluation (WAVE) model has been developed. On the accounting level, atmospheric
evaporation recycling within drainage basins is considered for the first time, which can reduce water
consumption volumes by up to 33%. Rather than predicting impacts, WAVE analyzes the vulnerability
of basins to freshwater depletion. Based on local blue water scarcity, the water depletion index
(WDI) denotes the risk that water consumption can lead to depletion of freshwater resources. Water
scarcity is determined by relating annual water consumption to availability in more than 11,000
basins. Additionally, WDI accounts for the presence of lakes and aquifers which have been neglected
in water scarcity assessments so far. By setting WDI to the highest value in (semi-)arid basins,
absolute freshwater shortage is taken into account in addition to relative scarcity. This avoids
mathematical artefacts of previous indicators which turn zero in deserts if consumption is zero. As
illustrated in a case study of biofuels, WAVE can help to interpret volumetric water footprint figures
and, thus, promotes a sustainable use of global freshwater resources.

Keywords: water footprint, water use, water consumption, life cycle assessment, evaporation
recycling, vulnerability

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List of abbreviations
List of abbreviations
A - Availability of freshwater, here: runoff plus upstream inflow
AF - Adjustment factor for groundwater stocks
GWS
A - Surface area of lakes
lake
AoP - Area of protection
AP - Acidification potential
A - Surface area of wetlands
wetland
BIER - Basin internal evaporation recycling
BIER - Basin internal evaporation recycling within 100km
100
BIER - Hydrologically effective basin internal evaporation recycling
hydrol-eff
C - Water consumption
CTA - Consumption-to-availability
DALY - Disability adjusted life years
d - Effective depth of lakes and wetlands
eff
E - Share of withdrawal consumed due to evapo(transpi)ration
EIA - Environmental impact assessment
EP - Eutrophication potential
ER - Evapo(transpi)ration recycling
FW - Freshwater
GW - Groundwater
GWP - Global warming potential
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List of abbreviations
GWS - Groundwater stocks
ISO - International Organization for Standardization
JRC-IES - Joint Research Centre - Institute for Environment and Sustainability
LCA - Life cycle assessment
LCI - Life cycle inventory analysis
LCIA - Life cycle impact assessment
Max-s - Maximum scarcity
Min-s - Minimum scarcity
ODP - Ozone depletion potential
P - Precipitation
PGM - Platin group metals
POCP - Photochemical ozone creation potential
Q90 - Statistical low flow (runoff exceeded with a probability of 90%)
R - Long-term average runoff
SETAC - Society of Environmental Toxicology and Chemistry
SWS - Surface water stocks
T - Availability time horizon of surface water stocks
TDI - Turbo direct injection
UNEP - United Nations Environment Program
USEtox - UNEP-SETAC toxicity model
V - Vapor created in chemical reactions

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List of abbreviations
Verband der Automobilindustrie e.V. (German Association of the
VDA -
Automotive Industry)
V - Volume of dams and reservoirs
dam
VR - Synthetically created vapor recycling
WaterGAP - Water – a Global Assessment and Prognosis
WAVE - Water accounting and vulnerability evaluation
WBCSD - World Business Council for Sustainable Development
WC - Water consumption
WC - Effective water consumption
eff
WDI - Water depletion index
WF - Water footprint
WFN - Water Footprint Network
WHYMAP - World-wide Hydrogeological Mapping and Assessment Programme
WSI - Water stress index
WTA - Withdrawal to availability
WULCA - Water use in life cycle assessment (working group)
WW - Waste water
x - Length of basin
α Runoff fraction
λ - Average local length scale of evaporation recycling
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Table of content
Table of content
Acknowledgement ................................................................................................................................... iii
Abstract ................................................................................................................................................... iv
List of abbreviations ................................................................................................................................ vi
Table of content ...................................................................................................................................... ix
1 Introduction ..................................................................................................................................... 1
2 Review of water footprint methods ................................................................................................ 4
2.1 Overview of water footprint methods, databases, and tools ................................................. 4
2.2 Comparison of water footprint methods, databases, and tools ............................................. 6
3 Application and comparison of water footprint methods in industrial case studies ...................... 9
3.1 Water footprint of a car manufacturer’s production site (Daimler) ....................................... 9
3.2 Water in the copper production chain (EuroCopper) ............................................................. 9
3.3 Water footprint of seawater desalination plants (Siemens) ................................................. 10
3.4 Water footprint of a flow regulator (Neoperl) ...................................................................... 10
3.5 Water Footprint of passenger cars (Volkswagen) ................................................................. 11
3.5.1 Background .................................................................................................................... 11
3.5.2 Methodology ................................................................................................................. 11
3.5.2.1 Determination of water consumption ...................................................................... 11
3.5.2.2 Top-down regionalization of water inventories ........................................................ 12
3.5.2.3 Sensitivity analysis ..................................................................................................... 14
3.5.2.4 Impact assessment .................................................................................................... 15
3.5.3 Results and discussion ................................................................................................... 16
3.5.3.1 Inventory ................................................................................................................... 16
3.5.3.2 Impact assessment .................................................................................................... 19
3.5.3.3 Comparison between cars ......................................................................................... 20
3.5.3.4 Sensitivity analysis ..................................................................................................... 21
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Table of content
3.5.3.5 Comparison to other environmental interventions .................................................. 22
4 Challenges and potential solutions in water footprinting ............................................................. 25
4.1 Inventory challenges ............................................................................................................. 25
4.1.1 Definition of freshwater consumption .......................................................................... 25
4.1.2 Aggregation of different types of water consumption ................................................. 27
4.1.3 Consideration of green water consumption ................................................................. 27
4.2 Impact assessment challenges .............................................................................................. 28
4.2.1 Challenges of midpoint scarcity indicators ................................................................... 28
4.2.1.1 Absolute vs. relative freshwater scarcity .................................................................. 29
4.2.1.2 Sensitivity to additional water withdrawal ............................................................... 29
4.2.1.3 Withdrawal vs. consumption based scarcity indicators ............................................ 30
4.2.1.4 Annual vs. monthly water scarcity ............................................................................ 30
4.2.1.5 Determination of water availability .......................................................................... 31
4.2.2 Consideration of water quality ...................................................................................... 31
4.2.3 Dealing with environmental credits .............................................................................. 32
4.2.4 Challenges of endpoint impact assessment methods ................................................... 32
4.3 Volumetric or impact oriented water footprints? ................................................................. 33
5 The water accounting and vulnerability evaluation model – WAVE ............................................. 38
5.1 Water accounting model ....................................................................................................... 38
5.2 Vulnerability evaluation model ............................................................................................. 41
5.3 Application of WAVE in a case study on biofuels .................................................................. 45
5.4 Discussion of the WAVE model ............................................................................................. 47
5.4.1 Scope of WAVE .............................................................................................................. 48
5.4.2 Water accounting model ............................................................................................... 48
5.4.3 Vulnerability evaluation model ..................................................................................... 50
5.4.4 The quality corrected risk of freshwater depletion ....................................................... 52
5.4.5 Uncertainties in WAVE and sensitivity analysis ............................................................. 52
x