introduction to water assessment in gabi...
TRANSCRIPT
Introduction to Water Assessment in GaBi Software
Version 1.0 November 2012
Authors
Dr. Annette Koehler [email protected]
Daniel Thylmann [email protected]
PE INTERNATIONAL AG
Hauptstraße 111 – 113 70771 Leinfelden – Echterdingen Germany
Phone +49 711 341817 – 0 Fax +49 711 341817 – 25
E-Mail [email protected]
Internet www.pe-international.com
Content
1
List of Contents 1 Introduction...................................................................................................................... 2
2 Terminology ..................................................................................................................... 3
3 Water assessment in GaBi Software ............................................................................... 4
4 Quantities of water use, degradative water use and freshwater consumption ................. 6
4.1 Water use ..................................................................................................................................... 6
4.2 Degradative use ........................................................................................................................... 7
4.3 Consumptive use of freshwater (freshwater consumption) ........................................................... 8
5 Assessment of environmental impacts – water footprinting ........................................... 10
6 Literature ....................................................................................................................... 11
List of Figures
Figure 3-1: Water input flows in GaBi Software .................................................................................. 4
Figure 3-2: Water output flows in GaBi Software ............................................................................... 5
Figure 4-1: Fresh water use in GaBi Software ................................................................................... 6
Figure 4-2: Blue water use in GaBi Software ..................................................................................... 7
Figure 4-3: Degradative water outputs in GaBi Software ................................................................... 7
Figure 4-4: Freshwater consumption in GaBi Software ...................................................................... 9
Figure 4-5: Blue water consumption in GaBi Software ....................................................................... 9
Introduction
2
1 Introduction
Freshwater scarcity is recognized as one of the most pressing environmental issues today and in the future.
There is increasing interest in using the GaBi software to assess water use from an LCA perspective. With the
yearly upgrades, GaBi Software always contains complete and consistent water inventory data. The 2012
GaBi 6 upgrade provides additional quantities to allow for easy assessment of water data that are the funda-
mentals for water footprint calculations. It is therefore important to have a correct understanding of the termi-
nology for the GaBi quantities applied. This document provides an introduction to the latest GaBi water as-
sessment terminology and details on how water use and water consumption can be assessed using GaBi
Software.
Terminology
3
2 Terminology
Water use
Water use is understood as an umbrella term for all types of anthropogenic water uses. On an inventory level,
water use equals the measured water input into a product system or process. In most cases water use is
determined by total water withdrawal (water abstraction).
Consumptive and degradative use
Freshwater use is generally differentiated into consumptive water use (= water consumption) and degradative
water use, the latter denoting water pollution:
Freshwater consumption (consumptive freshwater use) describes all freshwater losses on a watershed level
which are caused by evaporation, evapotranspiration from plants (Note: Only water from irrigation is consid-
ered in the assessment of agricultural processes. Consumption of rain water is neglected.), freshwater inte-
gration into products, and release of freshwater into sea (e.g. from wastewater treatment plants located on the
coast line). Therefore, freshwater consumption is defined in a hydrological context and should not be inter-
preted from an economic perspective, so it does not equal the total water use (total water withdrawal), but
rather the associated losses during water use. Note that only the consumptive use of freshwater, not sea
water, is relevant from an impact assessment perspective because freshwater is a limited natural resource.
Degradative water use, in contrast, denotes the use of water with associated quality alterations and describes
the pollution of water (e.g. if tap water is transformed to wastewater during use). These alterations in quality
are not considered to be water consumption.
Note that the watershed level is regarded as the appropriate geographical resolution to define freshwater
consumption (hydrological perspective). If groundwater is withdrawn for drinking water supply and the treated
wastewater is released back to a surface water body (river or lake), then this is not considered freshwater
consumption if the release takes place within the same watershed; it is degradative water use.
The difference between freshwater use and freshwater consumption is highly crucial to correctly quantify
freshwater consumption, in order to interpret the meaning of the resulting values and for calculating water
footprints (see ISO 14046 CD).
Summary
Freshwater Use = consumptive use + degradative use of freshwater = water input of freshwater or total fresh-
water withdrawal on inventory level
Degradative use of freshwater = freshwater released back to watershed, with alteration in quality
Freshwater consumption = freshwater lost to the watershed (water vapor to air1, evapotranspiration, water
incorporated into products, water release to sea)
Freshwater inputs – degradative freshwater outputs (outputs to freshwater and soil environment) = Freshwa-
ter consumption
1 Note that evaporated water is denoted water vapor (elementary flow) in the GaBi inventory system while steam is con-sidered a technical flow (as product output from e.g. steam generation, i.e. valuable substance).
Water assessment in GaBi Software
4
3 Water assessment in GaBi Software
All water flows necessary for calculating water use and freshwater consumption can be found in the GaBi
balance view.
The water input flows can be found under Resources Material resources Renewable resources Wa-
ter (see also Figure 3-1).
Figure 3-1: Water input flows in GaBi Software
Water assessment in GaBi Software
5
The water output flows are depicted in Figure 3-2:
Figure 3-2: Water output flows in GaBi Software
Quantities of water use, degradative water use and freshwater consumption
6
4 Quantities of water use, degradative water use and freshwa-ter consumption
With the 2012 update, the GaBi software contains quantities for water use and water consumption, as defined
and described below.
4.1 Water use
The water input flows in GaBi refer to total water use. In order to quantify total freshwater use, all freshwater
input flows are summed up. As stated above, rain water is important for a complete inventory and thus part of
the total water use and total freshwater use. However, for impact assessments, in general only blue water
(surface and groundwater) is considered, excluding rain water. Normally, the focus lies in freshwater use and
consumption. Sea water is also excluded in this aggregation. Thus, the flow based equations are:
Total freshwater use = total freshwater withdrawal/abstraction
= water (river water) + water (lake water) + water (ground water)
+ water (rain water) + water (fossil groundwater)
Blue water use = Water (ground water) + Water (lake water) + Water (river water) + Water (fossil ground
water)
Accordingly the provided GaBi quantities are defined as in Figure 4-1 and Figure 4-2:
Figure 4-1: Fresh water use in GaBi Software
Quantities of water use, degradative water use and freshwater consumption
7
Figure 4-2: Blue water use in GaBi Software
4.2 Degradative use
Degradative water output: As mentioned above, degradative use takes place when the water used remains
in the same watershed and the quality has been altered. Water emissions to freshwater are assumed to re-
main in the same watershed, so this is the degradative use category (see Figure 4-3).
Figure 4-3: Degradative water outputs in GaBi Software
degradative
water outputs
Quantities of water use, degradative water use and freshwater consumption
8
The water flows that leave waste water treatment plants (river water from technosphere, waste water) can be
found among the outputs. “River water from technosphere, turbined” refers to water use in hydroenergy gen-
eration. Corresponding flows “lake water from technosphere” exist. Please note that river/lake/sea water in the
output refers to the destination of the water released, not to the source.
Degradative use (water pollution, release of contaminants or heat into water bodies) describes changes in
quality which are covered by specific impact categories of LCA (e.g. eutrophication, acidification, ecotoxicity,
assessment of thermal emissions). Methods to assess effects of reduced water availability due to deteriora-
tion in water quality are still in development and in their very infancy. Please contact PE INTERNATIONAL in
case further information is needed.
4.3 Consumptive use of freshwater (freshwater consumption)
As mentioned above, freshwater that leaves the watershed is considered consumed. This is the fraction that is
most interesting as this water is lost to the ecosystem and for downstream users.
Total freshwater consumption is defined as:
Total freshwater consumption = total freshwater use (water input) – total freshwater
release from technosphere (water outputs)
= water vapor (including water evaporated from input products
and including evapotranspiration of rain water from plants)
– water incorporated in product outputs + water (freshwater
released to sea)
Please note that in general only blue water (surface and ground water) is considered. Therefore, rain water is
typically excluded from freshwater consumption and the focus is only on blue water consumption. In detail, the
flow based calculation is:
Blue water consumption = Water (ground water) + Water (lake water) + Water (river water) – Water
(river water from technosphere, cooling water) – Water (river water from technosphere, turbined) –
Water (river water from technosphere, waste water) – Water (lake water from technosphere, cooling
water) – Water (lake water from technosphere, turbined) – Water (lake water from technosphere, waste
water)
Quantities of water use, degradative water use and freshwater consumption
9
The corresponding GaBi quantities are defined as follows in Figure 4-4:
Figure 4-4: Freshwater consumption in GaBi Software
Figure 4-5: Blue water consumption in GaBi Software
Assessment of environmental impacts – water footprinting
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5 Assessment of environmental impacts – water footprinting
The water footprint of a product system is a set of different calculations (see ISO 14046 draft) and should be
used as an umbrella term rather than to communicate a single number. Only results on the level of environ-
mental impact (e.g. after consideration of regional water availability) should be labeled as a water footprint.
The simple aggregation of water on an inventory level represents water accounting and should be expressed
as such and not as a water footprint. Please contact PE INTERNATIONAL for further information on how
further evaluations, including impact assessment of your GaBi water inventories, can be performed.
Literature
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6 Literature
BAYART ET AL.
2010
BAYART, J.; BULLE, C.; DESCHÊNES, L.; MARGNI, M; PFISTER, S.; VINCE, F.; KOEHLER, A. (2010): A FRAMEWORK FOR ASSESSING OFF-STREAM FRESHWATER USE IN LCA. INT J
LIFE CYCLE ASSESS 17(3), PP 304-313
BERGER, FINKBEINER
2010
BERGER, M.; FINKBEINER, M. (2010): WATER FOOTPRINTING: HOW TO ADDRESS WA-
TER USE IN LIFE CYCLE ASSESSMENT?. SUSTAINABILITY 2 (4), 919-944
ISO 14046 (CD) ISO/CD LIFE CYCLE ASSESSMENT -- WATER FOOTPRINT -- REQUIREMENTS AND GUIDE-
LINES. INTERNATIONAL ORGANIZATION FOR STANDARDIZATION.
KOEHLER
2008
KOEHLER, A. (2008): WATER USE IN LCA: MANAGING THE PLANET’S FRESHWATER RE-
SOURCES. INT J LIFE CYCLE ASSESS 13 (6), PP 451-455
PFISTER ET AL.
2009
PFISTER, S.; KOEHLER, A.; HELLWEG, S. (2009): ASSESSING THE ENVIRONMENTAL
IMPACT OF FRESHWATER CONSUMPTION IN LCA. ENVIRON SCI TECHNOL 43(11), 4098–4104.
PFISTER, HELLWEG
2009
PFISTER, S.; HELLWEG, S. (2009): THE WATER “SHOESIZE” VS. FOOTPRINT OF BIOEN-
ERGY. PNAS 106(35), E93-E94
RIDOUTT, PFISTER
2010
RIDOUTT, B.; PFISTER, S. (2010): A REVISED APPROACH TO WATER FOOTPRINTING TO
MAKE TRANSPARENT THE IMPACTS OF CONSUMPTION AND PRODUCTION ON GLOBAL
FRESHWATER SCARCITY. GLOBAL ENVIRONMENTAL CHANGE 20 (2010), 113–120
RIDOUTT, PFISTER
2012
RIDOUTT, B.; PFISTER, S. (2012): A NEW WATER FOOTPRINT CALCULATION METHOD
INTEGRATING CONSUMPTIVE AND DEGRADATIVE WATER USE INTO A SINGLE STAND-ALONE WEIGHTED INDICATOR. INTERNATIONAL JOURNAL OF LIFE CYCLE ASSESSMENT, ONLINE FIRST (2012)