Introduction to Water Assessment in GaBi Software

Version 1.0 November 2012

Authors

Dr. Annette Koehler a.koehler@pe-international.com

Daniel Thylmann d.thylmann@pe-international.com

PE INTERNATIONAL AG

Hauptstraße 111 – 113 70771 Leinfelden – Echterdingen Germany

Phone +49 711 341817 – 0 Fax +49 711 341817 – 25

E-Mail info@pe-international.com

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

10

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

11

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)