Life Cycle Assessment on Central Softening of Drinking ... · This project is carried out as a part...

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Life Cycle Assessment on Central Softening of Drinking Water in Copenhagen

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DTU Management

In co-operation with

Københavns Energi A/S

http://www.man.dtu.dk/�

http://www.ke.dk/portal/page/portal/Forside/Forside�

http://www.dtu.dk/�

Life cycle assessment on drinking water in Copenhagen

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Preface

This project is carried out as a part of the course “42372 - Lifecycle assessment of products and systems” at DTU during the fall semester of 2009.

Prior to the project a Life cycle Check was carried out. It gave an initial assessment of the product system and the outcome has been used in this report.

Københavns Energi and Niels Winther from Teknologisk Institut are gratefully acknowledged for helping out with data and knowledge about water systems and lime scale effects. Also a special thank to Alexis Laurent from DTU management for good supervision.


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Abstract

The study described in this report is a Life Cycle Assessment (LCA) of the consequences of softening the household drinking water in the municipality of Copenhagen.

Three different scenarios for softening of drinking water are used in this case study in order to compare the degree of softening with the environmental improvement potential.

The aim of the study is to see whether there is an environmental improvement when softening the household drinking water in Copenhagen and if the softening degree is of importance for the magnitude of a possible environmental improvement.

The results of the study show that there is an environmental improvement when softening the water within the system boundaries of this product system. The environmental improvement is found within the categories environmental impacts, toxicity and resource consumption according to the EDIP method for life cycle assessment. All impact categories shows an environmental improvement, except for ozone depletion. The study also shows that the negative environmental effects are reduced proportional to the reduced degree of hardness.

Keywords: LCA; central softening of household drinking water; reducing lime scale effect; environmental improvement; EDIP


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Table of Contents

1 Introduction .................................................................................................................................. 7

1.1 Background ............................................................................................................................ 7

1.2 Aim of project ........................................................................................................................ 9

2 LCA Theory .................................................................................................................................. 10

2.1 What is a LCA? ..................................................................................................................... 10

2.2 Goal definition ..................................................................................................................... 12

2.3 Scope definition ................................................................................................................... 13

2.3.1 The object of the assessment and the functional unit ................................................ 13

2.3.2 Reference product ....................................................................................................... 13

2.3.3 Defining the boundaries............................................................................................... 13

2.3.4 Definition of time scope ............................................................................................... 14

2.3.5 Definition of technological scope ................................................................................ 14

2.3.6 Geographical scope ...................................................................................................... 14

2.4 Inventory ............................................................................................................................. 14

2.4.1 Data format .................................................................................................................. 14

2.4.2 Data collection ............................................................................................................. 15

2.4.3 Calculation model ........................................................................................................ 15

2.5 Impact assessment .............................................................................................................. 16

2.5.1 Impact potentials ......................................................................................................... 16

2.5.2 Normalization ............................................................................................................... 17

2.5.3 Weighting ..................................................................................................................... 17

2.6 Uncertainty and sensitivity analysis .................................................................................... 18

2.6.1 Uncertainty .................................................................................................................. 18

2.6.2 Sensitivity analysis ....................................................................................................... 18

3 Gabi software .............................................................................................................................. 19

3.1 Cradle-to-grave analysis in GaBi .......................................................................................... 19

4 Comparison of central softening of drinking water in Copenhagen .......................................... 20


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4.1 Water system ...................................................................................................................... 20

4.2 Technical details of softening water ................................................................................... 21

4.3 Goal and scope .................................................................................................................... 22

4.3.1 Goal .............................................................................................................................. 22

4.3.2 Scope ............................................................................................................................ 23

4.4 The three scenarios ............................................................................................................. 28

4.4.1 Scenario 1 – 20 odH ...................................................................................................... 29

4.4.2 Scenario 2 – 14 odH ...................................................................................................... 29

4.4.3 Scenario 3 – 8 odH ........................................................................................................ 30

4.5 Inventory ............................................................................................................................. 30

4.5.1 General ......................................................................................................................... 30

4.5.2 Softening reactor at waterworks ................................................................................. 31

4.5.3 Washing machine ......................................................................................................... 33

4.5.4 Dishwasher ................................................................................................................... 35

4.5.5 Coffee machine ............................................................................................................ 37

4.5.6 Boiler ............................................................................................................................ 40

4.5.7 Soap for personal hygiene ........................................................................................... 42

4.5.8 Other relevant issues for the inventory ....................................................................... 44

4.6 Results of impact assessment ............................................................................................. 46

4.6.1 Environmental impacts ................................................................................................ 46

4.6.2 Toxicity impacts............................................................................................................ 48

4.6.3 Resource consumption ................................................................................................ 49

4.7 Discussion of the results ...................................................................................................... 53

4.7.1 Environmental impact .................................................................................................. 53

4.7.2 Toxicity ......................................................................................................................... 53

4.7.3 Resources ..................................................................................................................... 54

4.7.4 Working environment .................................................................................................. 54

4.7.5 Uncertainty- and sensitivity analysis ........................................................................... 55

4.7.6 A critical viewpoint of the LCA ..................................................................................... 61

5 Conclusion ................................................................................................................................... 62

6 References .................................................................................................................................. 63


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7 Appendices ................................................................................................................................. 66

7.1 Appendix – List of assumptions ........................................................................................... 66

7.2 Appendix – GaBi plans ......................................................................................................... 69


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1 Introduction

1.1 Background

In Denmark the drinking water supply is almost solely based on groundwater abstraction. A consequence of this is that the drinking water in certain areas of the country is hard or very hard. The degree of hardness arises from the chalk aquifer where the ground water is abstracted. The hardness of water relates to the content of calcium and magnesium and is often given in the unit German degrees of hardness, odH. One odH correlates to 10 mg dissolved calcium oxide (CaO) per litre or 7.19 mg magnesium oxide (MgO) per litre. In Figure 1 the hardness of groundwater in Denmark is shown.

Figure 1 -- hardness of drinking water in Denmark (Geus, 2009)

In Copenhagen water is abstracted from the neighbouring municipalities and transported to the citizens of the Capital. Figure 2 shows where the water comes from. The water utility for providing water to the city is Copenhagen Energy (Energi, 2009). The company is responsible for the abstraction of water, treatment of water and deliverance to the household where the water is consumed or used.


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Figure 2 - Areas for abstraction of groundwater by Copenhagen Energy (Københavns Energi, 2009)

It is found that the hardness of the drinking water in Copenhagen spans from 17 to 23 odH. In the rest of the report an average value of 20 odH is used for the hardness of the drinking water.

In the household the consumers experience the high hardness of the water by a corresponding high consumption of chemicals and cleaning agents for removing lime scale, detergents for washing and dishes, soap for personal hygiene and also an increased consumption of energy needed for heating or boiling water due to scaling and subsequent insulation of the heating element. These disadvantages of hard drinking water result in environmental impacts which have not been tried quantified yet for the water system of Copenhagen.

Central softening is implemented in several countries e.g. in Holland, where drinking water is softened in order to reduce the corrosion potential for the pipe lines, which ensures lower content of heavy metals in sludge (Hofman, et al., 2007). In Denmark the main benefit is assumed to be found in the households as reduction of the above mentioned disadvantages of the hard drinking


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water. However, although softening may reduce several environmental impacts, chemical use and energy consumption by the softening technologies may lead to other impact on the environment.

1.2 Aim of project

The aim of the project is to evaluate whether it is environmentally beneficial to introduce central softening of drinking water in Copenhagen.

To make this evaluation Life cycle assessment (LCA) is used. The application of LCA has so far been limited in water supplies despite it can provide an integrated evaluation of many very different parameters within environmental and climate aspects and is thus an excellent decision support tool also for water systems.

In a LCA of central softening of drinking water the softening process at the water work poses the expected negative effects as the softening process includes building of a reactor, use of chemicals and is a rather energy requiring process.

The expected positive effects of softening drinking water are experienced further downstream the water distribution system in the households. These effects are being evaluated in this study trying to calculate the environmental benefits of softening water in Copenhagen in terms of the effects of:

- Reduced energy consumption for washing, dishwashing, brewing coffee and heating water,

- Longer life time of household machines compared to today where the water is hard - Reduced use of cleaning agents for removing lime scale from household machines,

water taps and shower surfaces - Less use of soap and shampoo for washing , hair and body - Less energy consumption in pumps due to less scaling effect of distribution pipes

Three different scenarios for softening of drinking water are selected in order to compare the optimal degree of softening evaluating the environmental benefits by the use of LCA. The first is the reference scenario, which is the drinking water of today without softening; the second scenario is drinking water softened to a hardness of 14 odH; and the third scenario considers drinking water softened to 8 odH. The scenarios are described more detailed in chapter 4.

The lifecycle assessment of the 3 scenarios provides the platform for decision making regarding the environmental benefit by introducing softening of drinking water in Copenhagen - and to what degree of hardness softening should be considered from an environmental viewpoint.


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2 LCA Theory

2.1 What is a LCA?

Life cycle assessment (LCA) is a methodology used to identify the environmental and social impacts related to a product, service or system from a holistic standpoint that incorporates all known potential environmental impacts and follows the product, service, process or system during its lifetime, from cradle to grave.

“Cradle to grave” means that the life cycle includes all known processes in the stages of extraction of raw materials, transport, manufacturing, packaging, distribution, use and disposal, as seen in Figure 3. This type of holistic analysis has gained increasing interest within the EU and in many other parts of the world (among others USA and China) and life cycle thinking has become an integral part of many strategies and regulations within development of products, services, processes and systems.

Another term is “cradle to gate” and this is used when the LCA only includes life cycle stages from the extraction of raw materials to when the product is distributed to the consumers. The reason for using this way of making a LCA is often, that it is not known how and for how long the product is being used by the consumers (and what is happening with the product after use) and therefore it is not possible to get proper data and information about these last phases of the lifecycle (Hedal, et al., 2009) (Danish-EPA, 2007).

Figure 3 - Structure of the life cycle assessment (Rosedi, 2009)


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In the EU and USA the “cradle to grave” principles are these days developed to a new paradigm called “cradle to cradle”, where the development of products and buildings is using raw materials that can be used again and again in “end of life cycles” and thereby eliminate the production of waste by using end of life products to generate new product development (Nielsen, 2009), but in this study a classical way of performing LCA has been used, that is. “the cradle to grave”-way.

There are different guidelines for how to carry out an LCA but in this study the EDIP method is used. This method is in agreement with SETACS general guidelines for the content of a life cycle assessment and is normally used by Danish LCA practitioners (SETAC is the Society of Environmental Toxicology and Chemistry). The core of the EDIP method is valid for most applications even though the method originally is designed for product development (Hauschild, et al., 1997).

The LCA method is described in the ISO standards 14040 and 14044. An LCA study consists of four phases as shown in Figure 4 giving the life cycle assessment framework. These four phases are:

- Goal and scope definition - Inventory analysis - Impact assessment - Interpretation

The main purposes of the goal and scope definition phase are to clarify the purpose of the study, what it can and cannot be used for, the product system studied and its boundaries. In the inventory analysis phase, data on the inputs and outputs of the processes included in the system are collected or calculated. On the basis of this inventory, the potential environmental impacts are assessed and finally the results are interpreted. Carrying out an LCA is by definition an iterative process where the above mentioned four phases are repeated several times. This method makes the results more trustworthy (Jerlang, et al., 2001)

When the LCA is done and the results are shown, there are many ways to use the results such as:

- Product development and improvements - Strategic planning - Public policy planning - Marketing - Others e.g. benchmarking with other products (within the company or from

competitors).

This is shown in Figure 4.


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Figure 4 - Phases in a Life Cycle Assessment (ISO-14040, 2006)

LCA is increasingly being used as a decision-support tool, and the application of the method has shifted from scenarios examining the current situation to those examining the consequences of change. The former is called attribution LCA and includes average data on each unit process within the whole life cycle. The latter, called consequential LCA, focuses on examining all known consequences of a change, including unit processes that are significantly affected by the change, irrespective of whether they are within or outside the life cycle.

The practical application of LCA may be placed along a continuum from strictly consequential to strictly attributional, and both approaches are accepted within the ISO LCA standards. The consequential approach is best suited to studies which compare two products or processes. Since the present study is a comparative LCA, the consequential approach has been the primary focus. The attributional approach is, however, still practiced internationally, also for comparative studies.

2.2 Goal definition

The goal and scope definition defines together the purpose of the study and describes the structure of the product in the given study.

The goal definition describes what the intention of the product scenario is, e.g. what the reason is for carrying out the study including the decisions that the study is meant to support and the environmental impact that the decisions can lead to. It is important here to mention what the study can be used for, what it cannot be used for and who the intended receiver of the results from the study is (Hauschild, et al., 1997).


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The goal definition also mentions the interested parties in the study, who the target group is and what the results are meant to be used for (ISO 14041) (Hedal, et al., 2009).

2.3 Scope definition

The scope definition presents the function and the boundary of the product system.

2.3.1 The object of the assessment and the functional unit

The basis of the function of the product system studied is to define the object of the assessment and the functional unit which is a quantitative measure of the function, the amount and the time in which the function is valid (Jerlang et al 2001).

In this way the functional unit must contain both a qualitative description of the service provided by the product system and a quantification of the service. The reason for this is that it makes it possible to compare quality level, amount and duration of different product services.

2.3.2 Reference product

In order to represent a way to provide a service one or more reference products must be chosen. The reference product must form the basis on which the company wishes to establish the LCA.

2.3.3 Defining the boundaries

In order to specify the processes and systems which are included in the LCA it is also necessary to define the boundaries of the product system. It is often a good support to illustrate this with a diagram or flow chart showing exactly the phases and stages of the life cycle. This yields an overview of the interrelationships of elements included in the LCA (all products and processes being affected by the product system must be discussed no matter if they are included in the LCA or not).

Some elements are often left out of the LCA for different reasons. This could be because of lacking data, insignificant impact or other reasons. It is always crucial to explain what has been left out and why. (Hauschild, et al., 1997) (Hedal, et al., 2009)


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2.3.4 Definition of time scope

The time horizon for which the decisions based on the study are to apply must also be stated and the period of time must be divided into the different phases of the product life for which the LCA concerns or for which it acts as a reference.

2.3.5 Definition of technological scope

The technological level to be represented in the product system under assessment must also be stated. The most important technological trends for processes and parameters in the product system must be investigated.

2.3.6 Geographical scope

The geographical scope of the product system must be described. This means that it must be stated where in the world the stages of the product system occur. Where are the materials coming from and where do the processes take place?

2.4 Inventory

When the boundaries for the product system are set and the goal and scope is defined, the inventory is launched. The inventory is split into three parts; the actual data collection is the central part, where all relevant processes for the concerned product lifecycle are collected. Before data collection one needs to state the data format and after the data collection one needs to have a calculation model, where the data are transparently presented.

2.4.1 Data format

Defining the data format is about developing a procedure for data collection, which is used throughout the project and it ensures that there is a common unit for comparable processes. For example all transport is chosen to be expressed in km*loaded weight combined with type of transport, e.g. lorry, truck, ship. This pre-stage data collection includes consideration and requirements of data type and source including general data vs. product specific data. These considerations are visualized in Table 1, where typical requirements for product specificity in the data collection are seen. Product-specific data is either measurements of the concerned product or data from the manufacturer. Site-specific data are processes coming from localities of which the product system is in contact, but not product-specific. General data comes from processes that are similar to the one concerned, but is neither product- or site-specific.


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Table 1 - Typical picture of requirements for specificity of data

Required data specificity

Extraction of raw materials

Materials production

Product manufacture

Use

Disposal Transport Energy systems

Product-specific

X x x x

Site-specific x x X x x x

General x x x x x x

When co-products are produced or recycling is part of the product life cycle, allocation must be considered. If allocation cannot be avoided, allocation keys must be defined. Allocation is often needed in complex products or when manufacturers produce various products of different type.

2.4.2 Data collection

Dependent on the size of the product system, data collection can be massive and will entail time-consuming work. The data can be gathered from different sources, which can be divided into four parties;

- Expert knowledge centres - Authorities - Associations of material producers and companies - Private companies

Different data collection methods are used to cover all processes. Usually one starts by electronic literature information retrieval, which has become increasingly more useful. For specific data one often needs to do a questionnaire at contractors and suppliers. Sometimes processes are basic and can be calculated from basic physics and chemistry. If data collection cannot be totally covered by any of these methods, one will have to do measurements to get the missing data.

2.4.3 Calculation model

Data on the collected processes is probably given for different amount of material, so in order to be able to get the right impact the processes should be expressed for the functional unit, which is


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defined in the early stage of the life cycle assessment. Fortunately software is developed to do the modelling of the results, but one still needs to understand the process to interpret the results.

2.5 Impact assessment

An impact assessment is vital for the interpretation of the inventory and can be done in different ways. This report is based on the EDIP97-method (Hauschild, et al., 1997) that divides the impacts into three general categories, which are environmental impacts, resource consumption and impact on the working environment. Each category suggests different assessment criteria for the impact assessment and is based on environment conditions.

2.5.1 Impact potentials

The amount of one raw material used for a product system is an impact potential. The duration of exposure for processes above a certain level of impact on the working environment is also an impact potential. These figures are already given in the inventory and are ready for further handling. The environmental impact potentials for the emissions are not directly given in the inventory, but they must be calculated for each assessment parameter. The impact potential can be understood as the impact expressed in a reference unit of each assessment parameter. Common environmental impact assessment parameters are:

- Global warming (GWP) - Nutrient enrichment - Stratospheric ozone depletion - Photochemical ozone formation - Acidification - Waste - Eco-toxicity - Human toxicity

Actual calculation of environmental impact potentials is thus only necessary for the emissions’ impacts for each impact category. For each category there are different ways of calculating the environmental impact potential (EP), but the common purpose is to come up with an equivalency factor (EF) to the reference substance and then multiply the amount of substance in concern with the equivalency factor to get the environmental impact potential. The equivalency factor is already given for common emissions. The EDIP97-method where all individual emissions are summed for every impact category uses the formula:


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𝐸𝐸𝐸𝐸(𝑗𝑗) = �𝐸𝐸𝐸𝐸(𝑗𝑗)𝑖𝑖 = �(𝑄𝑄𝑖𝑖 ∙ 𝐸𝐸𝐸𝐸(𝑗𝑗)𝑖𝑖)

In the EDIP method the environmental impact potential is abbreviated EP, quantity of substance is Q and the substance’s equivalence factor for the given impact category j is EF. The emission of a substance is i.

2.5.2 Normalization

The units for impact potential depend on the reference substance and are not the same for the various impact categories, i.e. for global warming the impact potential posses the unit of g CO2-equivalent and for nutrient enrichment g NO3

--equivalent.

The purpose of the normalization step is to make environmental impacts, resource consumption and impacts on the working environment comparable. Instead of having various units of impact potentials due to the different assessment parameters a common unit of person equivalency (PE) is obtained. One PE is the fraction of the society’s total emissions for each person, which makes the results easier to interpret. One person reserve (PR) is the unit used for resource consumption, which expresses the amount of raw material an average citizen consumes annually.

The normalization reference is the resource consumption and impacts that society imposes on the environment and the working environment each year. Thus the results will show how big a part of the annual resource consumption and emissions the product in concern will exhaust.

2.5.3 Weighting

When impacts are normalised they are comparable, but to make interpretation even easier, a weighting factor is introduced, which is multiplied with the normalised values. The weighting factor expresses the seriousness of the assessment category; the more serious the higher a weighting factor. Scientific, political and normative considerations determine these factors. E.g. scarce resources have higher weighting factor than available resources and fatal accidents have higher weighting factor than non-fatal accidents.


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2.6 Uncertainty and sensitivity analysis

When doing a life cycle assessment the use of generalised and assumed data is inevitable; the uncertainty and sensitivity analysis are performed to assess how these generalisations and assumptions affect the final result.

2.6.1 Uncertainty

The uncertainty analysis is divided into three main parts:

The modelling of the product system Values for environmental impacts of the concerned processes Assessment factors based on local and global data for a pre-defined period of time

These three parts correspond to uncertainty analysis of scope definition, inventory and impact assessment. Changes in data for each part result in different results; the variation of the results is thus the basis for the uncertainty analysis.

2.6.2 Sensitivity analysis

Key figures of the product system are identified to see how they affect the final result. The key figures will be based on assumptions, which to some degree can be considered rough estimations. The uncertainty of key figures constitutes the sensitivity. To assess the importance of the key figure values for the final result, changes for key figure values are inserted in the calculations and the influence is assessed.


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3 Gabi software

In order to calculate and evaluate the different impacts considered in a LCA study, a huge amount of calculations has to be performed. Moreover, the normalisation and weighting factors needed add a new dimension to the complexity of the task. For these reasons, the use of specialised software for modeling and calculation of system impacts is very helpful.

For the LCA case study presented in this work, the GaBi Software package was employed. In order to apply the EDIP method chosen for the analysis, different databases implemented in the software were used. The main source of data was the PE database, provided by the software owner. In several cases, the Ecoinvent and EDIP databases were used. Whenever possible, the newest and more accurate database was chosen.

3.1 Cradle-to-grave analysis in GaBi

The different stages in the life cycle analysis of the water softening reactor and the other parts of the system affected by the water softening process are conceptualized by several flowcharts. In these charts, each part of the system has associated one or more flows representing different exchanges between stages: masses when referring to material flows, energy flows, and so on. In figure 4 an example of the model is presented:

Figure 5 – GaBi diagram for washing clothes

Figure 5 shows the different stages in the life cycle of the chosen product, including the materials and building stage, as well as the use and disposal stages.


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4 Comparison of central softening of drinking water in Copenhagen

4.1 Water system

The water system which is in focus in this LCA is illustrated in the flow chart in Figure 6. The flow chart represents scenario 2 and 3 as softening is introduced at the waterworks.

Softening of water at waterworks

Use of water in households

Effects in households of soft water:- reduced energy consumption- longer life time of machinery

- reduced use of cleaning agents- less use of detergents, soap and shampoo

Abstracted groundwater

Waste water to sewage system

Output: CaCO3

Input: NaOH, sand,

energy

Figure 6 – flow chart of the processes involved in softening drinking water. The box indicates the system boundaries

The basic scenario is the situation of today where no softening is taking place at the waterworks. This corresponds to the flow chart without the softening process.

The water system includes the processes taking place at the waterworks concerning the softening process, and the effects of the hardness of the drinking water in the households.

At the waterworks the environmental disadvantages of central softening take place since the process requires sodium hydroxide (NaOH), sand and energy. The softening process removes lime scale (CaCO3) from the water and this is considered as a waste product with a value. The lime scale can be used for increasing pH on agricultural land, and therefore needs to be credited in the LCA, see “Inventory, softening reactor at waterworks” for a more detailed description.

In the households the four major water consuming machines are identified as washing machine, dishwasher, coffee brewer and electric water boiler (boiler). When central softening is introduced these machines save energy and require less use of chemicals. Also the amount of chemicals used for removing lime scale is decreased. The use of soap and shampoo for personal hygiene is also lowered due to more efficient effect of fatty acids when CaCO3 is not present in the water.

The effects included in the LCA are summarized in Table 2.


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Table 2 - Effects of central softening of drinking water included in this LCA

Effect takes place at: Description of the effect: Waterworks Building of the reactor (see Inventory where it is decided to not included due

to the result of the Life Cycle Check) Waterworks NaOH, sand and energy for the use phase of the softening process Waterworks CaCO3 produced during the softening process Households Reduced energy consumption for washing , dishwashing, boiling and heating

water Households Longer life time of household machinery Households Reduced use of cleaning agents for removing lime scale from household

machinery, water taps and shower surfaces Households Less use of soap and shampoo for washing , hair and body

4.2 Technical details of softening water

Copenhagen Energy provided a report concluding that a pellet reactor was an appropriate choice for central softening of drinking water at the waterworks delivering water to Copenhagen. Therefore, the pellet reactor was chosen for the LCA. Also Copenhagen energy provided data on a similar water system in Sweden where the water work “Vombverket” had installed this type of pellet reactor. All data for the softening process in this LCA is based on the factual experiences from “Vombverket” in Sweden

The process in a pellet reactor is shown in Figure 7. Water enters the reactor at the bottom and passes upwards. On its way up the water reacts with the added NaOH and sand making the carbonate of the water react with Ca-ions and precipitate on the surface of grains of sand. The softened water (with less CaCO3) comes out in the top of the reactor and the grains of sand wrapped in CaCO3 settles downwards and can be removed from the bottom of the reactor.


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Figure 7 - A pellet reactor for softening water at a water work (Niras, 2009)

The chemical reaction taking place in the water when NaOH is added is described by this reaction:

Ca2+ + HCO3- + OH- -> CaCO3 + H2O

The lime scale (CaCO3) will precipitate on the grains of sand due to the electrical polarization of the oxides in the sand and the calcium.

4.3 Goal and scope

4.3.1 Goal

The objective of the LCA is to measure and evaluate the environmental impacts (toxicity, resource consumption and environmental impacts) of household drinking water in Copenhagen for 3 scenarios:


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Scenario 1 - Normal hardness at 20 odH Scenario 2 - Water softened to 14 odH Scenario 3 - Water softened to 8 odH

It will be evaluated if there is a change in environmental impacts of softening the water shifting from scenario 1 to scenario 2 and further to scenario 3. These changes will be compiled for each scenario in order to come up with comparable data.

“Drinking water” is a term used for all household water used for e.g. dish washing, washing clothes, drinking water, cooking etc

The LCA can be used for supporting the decision whether to introduce softening of household drinking water by Copenhagen Energy A/S (KE). It does not aim at supporting decisions concerning the health issues of drinking hard versus soft tap water. The LCA does not include a study of taste and smell of the water – it is assumed that it is not changed by softening the water.

The decisions based on this LCA can lead to:

- Introduction of softened drinking water in households supplied by KE and maybe extended to the rest of Denmark.

- Less energy consumption for the use stage of household machines. - Longer life time of household machines compared to today where the water is not

softened. - Less use of cleaning agents for removing lime scale from household machines (dish

washer, washing machine, boiler, coffee machine etc.) and water systems (bath, shower, taps, toilet).

- Less use of soap and shampoo for washing of clothes, hair and body. - Higher price for household drinking water.

4.3.2 Scope

As mentioned earlier the objective of the LCA is to measure and evaluate the environmental impacts of household drinking water in Copenhagen for three scenarios. Scenario 1 with a water hardness of 20 odH, scenario 2 with a water hardness of 14 odH and scenario 3 with a water hardness of 8 odH.

Lowering the degree of hardness of the drinking water requires building of a softening reactor, consumption of sodium hydroxide, sand and energy.


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The effects considered in the household in this study are concentrated on washing machine, dishwasher, coffee machine and boiler - because it is assumed that an average household owns one of each.

The less energy presumed to be used for heating water when using soft water, less use of chemicals for removing lime scale and less use of soap will also be included in our LCA, see Table 2.

The study does not include material or energy needed for abstracting groundwater or transport of drinking water since we in this study assume that these values are similar for each scenario.

4.3.2.1 Primary service for the user

The user will receive drinking water with a lower content of lime scale (CaCO3) leading to a decrease of the environmental impacts arising from washing , dishwashing, coffee brewing, boiling water, cleaning and personal hygiene all requiring more energy, detergents or chemicals when the water is hard.

4.3.2.2 Obligatory properties

The soft water of scenario 2 and 3 will result in two different levels of reduction of the need for energy, detergents (washing and dishwashing), chemicals for removing lime scale and soap.

4.3.2.3 Positioning properties

The consumer will experience a lower purchase of detergents, chemicals for cleaning, and soap. The consumer will also see a drop in expenditures on energy.

4.3.2.4 Functional unit

The supply of softened drinking water as incentive for reducing the lime-scale effects in a household for 1 person in 1 year, equivalent to the supply of 40.88m3.

4.3.2.5 Data to support the functional unit

The coverage of the study is water supply to the 520.000 citizens of Copenhagen. The annual amount of water is 21.25 million m3.


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This study is focusing on drinking water supplied to household, thereby industry is not included. This focus is considered appropriate since there isn't much industry left in the region applied in this study.

4.3.2.6 Reference product:

The reference product is the drinking water of today in Copenhagen, which is incorporated in scenario 1 in the study (see above).

4.3.2.7 System boundaries:

The main processes of softening the drinking water supply can be seen in the flow chart in figure 6. The most important processes are:

- Treatment of water in the reactor - The effects of softened drinking water in the household

4.3.2.8 Temporal scope:

The temporal scope of the system is estimated on the basis of the lifetime of the processing of the drinking water and the construction of the reactor supporting the softening of household drinking water.

The temporal scope of the reactor is 40 years based on experiences from Sweden, where they have the same reactor. So if the reactor is finished in 2011 it will last to 2051.The lifetime of the reactor is the crucial object of the time scope because the reactor is having a long lifetime but is not easy to replace like the household machines for instance.

The lifetime of the household machines is also important. We assume that the lifetime of a coffee machine and a boiler is 7 years and the lifetime of a washing machine 11 years and a dish washer is 10 years for the reference scenario, the life times will change with the water hardness changing.

The lifetime of the household machines might change due to efficiency improvements but we will consider the machines as they are today in relation to how the lifetime of the machines is presumed to change because of lesser scale in the machinery. Therefore the results of the LCA are only valid as long as the machines stay the same.

An overview of this system’s temporal scope is seen in table 3.


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Table 3- Average lifetime based on the reactor: 40 years, LCA completed in 2009/ 2010.

4.3.2.9 Technological scope

The most important changes: shifting from “normal household drinking water” to more soft household drinking water with less calcium and less potential of scale deposition. This could reduce the environmental impact by minimizing use of cleaning agents and energy.

The technological level of this system does not require development of new technologies. Reactor and pumps are already available on the market. Chemicals, sand and energy is needed for the reactor but the process is fairly simple. Energy is also needed for the transport of water and the household machines but the electricity is supplied everywhere. And the household machines are also standard equipment.

The energy used for softening the water and for driving the household machines is supplied from the grid. The energy mix is changing in favour of renewable sources. This may influence the conclusion of the LCA, so a further study of this could be done in future work. The goal for the Danish government is that 30 % of all energy comes from CO2 neutral sources in 2025. Today it is approximately 20 % (Energistyrelsen, 2009).


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4.3.2.10 Geographical scope

The water supporting the drinking water of Copenhagen will come from the underground in the eastern part of Zealand, see figure 2.

The chemicals, steel and concrete to build the reactor will come from different places. The chemicals will be produced nearby. The iron in the steel will come from northern Sweden and the chrome will come from China. In Denmark steel will be made out of the iron and chrome. The concrete will come from Denmark.

The energy to support the movements of the water and the use of the reactor and the household machines will come from Denmark – and maybe from Sweden and Norway in times of energy shortage.

In the end the system covers the 520.000 Citizens in Copenhagen and their households.

The disposal of household machines after ended use and waste water from the households will be handled in the vicinity of Copenhagen.

4.3.2.11 Assessment criteria

The assessment of this study is divided into three groups of impacts: Environmental, Toxicity and Resource consumption. Toxicity is actually part of the environmental impacts, but has become extensive and acquired a separate part. Later on in chapter 4.7.4 the working environment will be discussed.

Due to the nature of the water system the categories are chosen as seen in Table 4. The categories in environmental impacts and toxicity are fixed according to the EDIP-method. For Resource consumption minerals and metals are chosen according to the given system. The ones shown are the ones relevant for this water system.

Table 4 - Impact categories relevant in this assessment

Impact category Sub category Primary Sources (process, machine) Environmental impacts Acidification washing, coffee brewing, dish

washing Global warming potential washing, coffee brewing, boiling of

water Nutrient enrichment Soap, washing, coffee brewing Ozone depletion washing, coffee brewing, softening Photochemical oxidant formation, low

NOx washing, boiling of water, coffee brewing

Toxicity Soil chronic toxicity Soap, washing, softening


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Water acute toxicity washing, coffee brewing, boiling of water

Water chronic toxicity washing, coffee brewing, dish washing

Human air toxicity washing, soap, dish washing Human soil toxicity washing, coffee brewing, soap Human water toxicity washing, dish washing, soap Resource consumption Chromium (Cr) washing, softening, dish washing Copper (Cu) washing, dish washing, boiling of

water Lead (Pb) washing, Lignite washing, softening Nickel (NI) washing, dish washing Zinc (Zn) washing Iron (Fe) washing, dish washing, boiling of

water Molybdenum (Mo) washing, soap, boiling of water

4.3.2.12 System boundaries

The system boundaries are shown in figure 6. The main processes are the ones taking place at the waterworks for softening drinking water and the effects of softening in the households. Deliverance of abstracted groundwater, transport of water and sewage treatment is not included in the assessments. This is due to the comparative nature of the LCA, making these processes equal for each scenario, and therefore not included.

The chosen system boundaries are based on studies showing that the most important environmental impacts of softening household drinking water are present during use stage of the reactor and within the changes in the use stage of the household machines. The studies providing us with this information was a Life Cycle Check (LCC) of softened water in Copenhagen and a study from Holland where they have build a reactor with the same purpose (Hofman, et al., 2007).

4.4 The three scenarios

Three different scenarios were chosen in order to evaluate whether central softening of drinking water is environmental beneficial. The scenarios only differ in the extent of central softening at the water work and to which degree of hardness of the drinking water the softening leads to. To do only two scenarios might be sufficient but before modelling in GaBi three scenarios were chosen making it more probable to find the tipping point where the environmental advantages exceeds the disadvantages.

The hardness of the drinking water in the three scenarios was determined before doing any modelling of the softening process. The hardness values were chosen according to expectations on


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effects in the household. The expected levels resulted in the three values of hardness described in Scenarios 1, 2 and 3.

From an environmental view point the disadvantages of the central softening are found at the water work where the softening process takes place. Here chemical, sand and energy consumption is a part of the softening process and all have environmental impacts.

The advantages of the softening process are found in the household as less use of chemicals for removing lime scale when cleaning, less use of detergents for washing and dishes, less use of soap for personal hygiene, less use of energy due to less scaling on heater in household machinery and an extended lifetime of the household machinery.

The advantages and disadvantages are explained in details in the Inventory, where the input or output for each scenario is given for softening reactor at the water work and the household effects of the washing machine, dishwasher, boiler, coffee machine and soap for personal hygiene.

4.4.1 Scenario 1 – 20 odH

The first scenario was chosen as the reference scenario defined as the situation of today where central softening of drinking water does not take place in Copenhagen. This scenario could also be described as a “do nothing” scenario since it does not require any building of a reactor for softening water at the water works or changes in the household due to the effects of the hardness of drinking water.

The drinking water quality staff at Copenhagen Energy provided information about the water today. The hardness of the water lies within a range of 17 to 23 odH resulting in an average of 20 odH. This was chosen as the hardness of the drinking water for scenario 1, which is used as a reference scenario.

Scenario 1 primarily shows the effect in the household of the hardness of the drinking water of today. The effects of lime scaling in the household leading to higher consumption of chemicals for cleaning, use of detergents and soap and also the higher energy consumption due to lime scaling on the heater of different household machines are all incorporated in the results of this scenario.


The second scenario was designed as a scenario with a medium effect of softening. After the softening process at the water work the drinking water is 14 odH which is characterized as rather hard water. This is a range of water hardness where advantages of softening is expected to be found in the household, but it is not probable that the advantages exceeds the disadvantages of


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the softening process at the water work (chemicals, sand and energy needed to operate the central softening system).


In the third scenario a softened drinking water with 8 odH was chosen. This water is characterized as soft water and here it is most probable that advantages of central softening of drinking water found in the household exceed the disadvantages found at the waterworks.

4.5 Inventory

In this chapter the different products of the system are to be analyzed and how their different life cycle phases (materials, production, use and disposal) perform. All the GaBi plans which have been made on the inventory can be seen in the appendix.

4.5.1 General

The data collection has been rather extensive since the data had to be gathered from various sources due to the different household machines. Copenhagen Energy provided data on the softening process but the benefits of softening water found in the household was collected from wherever it was found reliable and possible. The data is kept as objective and reliable as possible; meaning that data primarily is gathered from scientific or expert sources. Table 5 shows from where the data originates. Especially the use phase is based on data from various sources. Also the level of data specificity is shown in Table 5.

Table 5- Data reference

Product life cycle stage and process type

Data specificity Data source type

Comments

Product specific

Site Specifik

General 1 2 3 4 5

Raw material extraction X X X Materials Production X X X Product Manufacturing X X Use X X X X X Disposal X X X Transport X X Data source type: 1) Measurements 2) Computation (from mass balance considerations and input data for the process in question) 3) Extrapolation of data from similar process type or technology 4) Extrapolation of data from different process types or technologies 5) Unknown source or qualified estimate


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Some of the references are rough estimates made from valid data in order to simplify the calculations and to restrict the magnitude of the report. This was inevitably due to lack of validated.

Regarding transport of the household machines, it has been left out. It should be noted though that by extended lifetime of a household machines the frequency of how often a new machine have to be imported will decrease. This would result in a lower environmental impact from the transport.

On the other hand, when calculating energy consumption for the household products it is assumed that all of the consumption is raised due to lime scale on the heating element, though it is only the energy consumption of the heating element. The energy consumption of the heating element will obvious make up the biggest part.

4.5.2 Softening reactor at waterworks

Before the LCA was performed in GaBi a Life Cycle Check (LCC) was performed. The LCC showed that the building stage of the softening reactor was insignificant since the impacts per person were extremely low. Therefore the building stage including materials and energy needed for the softening reactor has been left out in the LCA. The use stage is much more consuming since softening of water requires a lot of chemicals (NaOH), sand and energy. A flow chart of the softening processes included in this LCA is shown in Figure 8:

Figure 8 - flow chart of the processes evaluated for the softening reactor at the waterworks in this LCA.

The CaCO3 (lime scale) is a waste product of the softening process. However, it becomes a co-product, because of its value for the agriculture as it can be used for increasing pH of agricultural


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land. In Sweden the lime scale from “Vombverket” is used for increasing pH in lakes (Vombverket, 2009), but for Denmark it is more likely to credit the waste product for use on agricultural land.

4.5.2.1 Production

Since the LCC concluded that the building of the pellet reactor for softening was insignificant it was not included in the LCA. Therefore there is no data for the production stage.

4.5.2.2 Transport

Transport of NaOH and sand to the waterworks for the softening process is included in the LCA. An average distance of 200 km is assumed. Also the transport of lime scale to the agricultural land is included and an average distance of 150 km is assumed. The data is shown in Table 6.

For data on energy used for transporting goods data from note 9 (from the course “LCA of products and systems”) is used. It is assumed that the NaOH, sand and CaCO3 are transported by lorry since it most likely will originate from within the country.

4.5.2.3 Use

As seen in Figure 7 showing the use stage of a softening process sodium hydroxide (NaOH), sand and energy is required. The process creates lime scale which must be removed continuously. The data from “Vombverket” (Vombverket, 2009) has been converted to fit the size of Copenhagen and are shown in Table 6:

Table 6 - Data for the LCA of the use stage of the softening reactor for each of the three scenarios. The functional unit (FU) is the given products portion per person a year.

Scenario 1, 20 odH Scenario 2, 14 odH Scenario 3, 8 odH

NaOH 0 1,98 kg/FU 3,95 kg/FU

Sand 0 0,37 kg/FU 0,74 kg/FU

Transport of sand and NaOH to the waterworks

0 0,47 MJ/FU 0,94 MJ/FU

Produced CaCO3 0 6,96 kg/FU 13,92 kg/FU


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Transport of Ca CO3 0 1,10 MJ/FU 2,19 MJ/FU

Energy consumption for the softening process

0 18,69 MJ/FU 18,69 MJ/FU

The energy consumption for the softening process is assumed the same for scenario 2 and 3. This is due to the fact that energy is used for pumping water into the pellet reactor and making the water move upwards. Energy consumption is assumed not to be affected by the amount of sodium hydroxide and sand.

4.5.2.4 Disposal

Since the building stage of the reactor for softening water is not included in this LCA due to the conclusions of the LCC there will not be considered disposal for the building materials. The experience from Sweden assumed that the lifetime of the reactor will be close to 30 years. The disposal of the waste product lime scale (CaCO3) is considered in the previous chapter as it is a part of the use stage.

4.5.3 Washing machine

The different processes in a washing machines lifetime this LCA will consider can be seen in the flow chart below,Figure 9. The selection processes have been based on several considerations and assumptions which will be described in the following section with the data found and used for the LCA.

Production(Extraction of raw

materials and manufactoring og washing machine

Use of washing machine for 1 year

Recycling and inceneration of the washing machine

Figure 9 - Flow chart of the processes evaluated for the washing machine in this LCA


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4.5.3.1 Production

The production of the washing machine implies several different materials; both resources which have a long supply time and scarce resources, the data for a typical washing machine of 65 kg (WRAP, 2009) can be seen in Table 7.

Table 7 - Resource list for a washing machine (Haapala, et al., 2008) shared by 2 people

Component No. Material Weigth (kg)

Shell/housing 1 Plastics 11,7

Drum 1 Steel 47,45

Door 1 Glass 1,3

Cord 1 Cu, plastics 0,65

Motor 1 Copper 1,3

Housing 1 Aluminium 2,6

4.5.3.2 Use

It has been assumed, on basis of number from (Statestik, 2009), that all people have access to a washing machine, either they own one or they use a laundry service. This has implied a general assumption that all people use a washing machine. The washing machine has been assumed to have an average lifetime of 11 years if 2 people share one. This has been chosen after finding lifetimes down to 6 years for a cheap washing machine and up to 16 years for an expensive washing machine (Bolius). The lifetime is a variable with the hardness of the water and by lowering the hardness of the water, the lifetime is extended, the extended lifetime in the different scenarios is shown in Table 8.

The energy used for a wash is typically around 1.02 kWh for an energy class A branded washing machine (Wupti, 2009) and it has been assumed that one person washes once a week. The amount of electricity needed for a wash depends on the lime scale on the heating element, as the energy needed increases with 9 % per 1 mm lime scale on the heating element as it has an insulating effect (Teknologisk, 2004). The increased energy use in the different scenarios can be found in Table 8.

The amount of washing powder is also a function of the water hardness; hard the water needs more washing powder. The amount of washing powder used in the different scenarios is an average of several different washing powder companies recommendations based on water


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hardness (Andreasen, et al., 2002). The amount of washing powder needed in the different scenarios is shown in Table 8.

Table 8 - Lifetime, energy use and washing powder use for the 3 scenarios

Scenario Lifetime years

Energy consumption MJ/year per FU

Washing powder kg/year per FU

Scenario 1 - 20dH 11 208,13 5,80 Scenario 2 - 14dH 16 199,53 4,96 Scenario 3 - 8dH 22 190,94 4,11

The consumption of water for a wash is independent of the water hardness and is therefore unnecessary to take into account.

4.5.3.3 Disposal

The disposal of the washing machine will take place in the same country as it is used, in this case Denmark. The different materials in the washing machine is either recycled, metals and glass or incinerated, plastics.

4.5.3.4 Other assumptions

Transport has been left out but it should be noted that by extended lifetime of the washing machine the frequency of how often a new washing machine have to be imported will decrease. This would result in a lower environmental impact for the transport.

4.5.4 Dishwasher

It has been hard to find general data on a dishwasher therefore some rough assumptions have been made in the following part. Figure 10 shows the different stages of the dishwasher’s life cycle that this LCA will consider with regards to the three different degrees of water hardness.


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materials and manufactoring of the

dishwasher

Use of dishwasher for 1 year

Recycling and inceneration of the

dishwasher

Figure 10 - Flow chart of the processes evaluated for the dishwasher in this LCA

4.5.4.1 Production

It has been problematic to acquire general data on the materials used for a dishwasher; it has therefore been assumed that the material composition in percentage is the same as for the washing machine, with exception of the glass which is set to zero. The weight of a dishwasher is 47 kg whereas a washing machine weights 65 kg (WRAP, 2009), the materials used can be seen in Table 9.

Table 9 - Resource list for a dishwasher (Haapala, et al., 2008) shared by 2 people


Shell/housing 1 Plastics 8,46

Inside housing 1 Steel 34,31

Cord 1 Cu, plastics 0,47

Motors 1 Copper 0,94

Housing 1 Aluminium 1,88

4.5.4.2 Use

About 59 % of all people have access to a dishwasher; it is assumed that in average 2 people share a dishwasher in Copenhagen (Statestik, 2009). The life time of a dishwasher depends on the water hardness and the quality of the dishwasher, it has been found to be of an average of 10 years in Denmark. As with the washing machine the energy consumption depends on the lime scale on the heating element which depends on the hardness of the water, a typical energy A rated dishwasher uses around 1.05kWh per wash (Wupti, 2009). As for the washing machine the energy increases with 9 percent per 1 mm of lime scale on the boiler (Teknologisk, 2004). One person does the dishes during a year equivalent to running the dishwasher once a week. The energy use and lifetimes for the 3 scenarios is shown in Table 10.


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Table 10 - Lifetime and energy use for the 3 scenarios for 2 people

Scenario Lifetime years

Energy consumption kWh/yearper person

Detergents kg/year per person

Scenario 1 - 20dH 10 214,25 0,14 Scenario 2 - 14dH 15 205,40 0,13 Scenario 3 - 8dH 20 196,56 0,12

From other LCA’s it has been shown that doing the dishes by hand has at least the same environmental impacts as using a good dishwasher when comparing toxicity impact and energy use (Hauschild, 2009). It has therefore been assumed that one person’s impact regarding energy and detergent use does not have any connection to whether it has access to a dishwasher or not. The detergent consumption does change due to the hardness of the water as does the energy this is shown in Table 10.

4.5.4.3 Disposal

The disposal of the dishwasher will take place in the same country as it is used, in this case Denmark. The different materials used in the dishwasher are either recycled (metals) or incinerated (plastics).


Transport has been left out but it should be noted that by extended lifetime of the washing machine the frequency of how often a new dishwasher have to be imported will decrease. This would result in a lower environmental impact from the transport of dishwashers.

4.5.5 Coffee machine

Impacts, assumptions and considerations regarding the coffee machine are described in the following. In Figure 11 the stages of the coffee machine life cycle taken into account are sketched.


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materials and manufactoring of Coffee machine

Coffee brewing for 1 year

Recycling and inceneration of the

coffee machine

Figure 11 – flow chart of the considered processes in the life cycle of the coffee machine

4.5.5.1 Production

There are various designs of coffee machines and the choice of design for the assessment influences the impacts. In order to achieve values for an average coffee machine, the material specificity is kept low and only basic coffee machine materials are considered. These materials are listed in Table 11.

Table 11 - Resource list for a domestic coffee machine [Wenzel, Caspersen and Schmidt, 2000]


Cabinet 1 Plastic ,Polystyrene 1,1

1 Aluminium 0,1

1 Steel 0,1

Cord 1 Copper 0,02

1 Softened PVC 0,02

Glass jug 1 Glass 0,34

Handle 1 Plastic ,Polystyrene 0,02

Strap 1 Aluminium 0,01

Packaging 1 Cardboard 0,39

4.5.5.2 Use

Coffee machines perform different in the use stage due to consumer habits and product specifications. From a lifecycle check example (Wenzel, et al., 2000) values for the coffee machine usage scenario are taken. Technical values are based on measurements (Dansk-Energi).


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An ordinary domestic coffee machine is brewing one litre of coffee twice a day, 7 days a week throughout the whole lifetime.

The coffee machines heating element has a power consumption of 1150 W, and it takes 6,5 minutes to brew 1 litre of coffee, so the energy consumption is 1,150 kW*6,5/60 hours*2*365 equal to 91 kWh a year.

The hot plate, keeping the coffee warm has a power consumption of 55 W. Each brew is kept warm for 30 minutes, resulting in 0,055 kW*0,5 hours*2*365 equal to 20 kWh a year. Total energy consumption in the use stage is 91+20 = 111 kWh = 400 MJ per year, which is assumed to be the scenario 3 use stage energy consumption.

For scenario 2 there is ½ mm lime scale, which results in energy consumption of:

E=400+400*0,09*0,5 = 418 MJ/year.

For scenario 1 there is 1 mm lime scale, which results in energy consumption of:

E=400+400*0,09*1 = 436 MJ/year.

The energy consumptions are based on the use in an ordinary two-person household. To get an expression for the functional unit which is consumption for one person, these numbers are divided by two, which are seen in Table 12.

The life time of the coffee machine varies with the degree of hardness (odH) in the water. The lifetime is prolonged 3-4 times when going from 22 odH to 10 odH (Calgon). Assuming a linear relation the life times of the coffee machine for the three scenarios are calculated from the lifetime of an average domestic coffee machine of 7 years. The lifetimes are seen in Table 12.

Consumption of acetic acid in an average household for descaling of especially boilers is considered to be 2 litres a year. The two litterers are included in the use stage of the coffee machine and boiler, and the sum of these use stage consumptions make up the two litres. When softened water is used, less acetic acid is used due to less calcium. There is assumed to be a linear relation between acetic acid consumption and amount of calcium in the water.


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Table 12 - Lifetime, energy use and acetic acid use for the 3 scenarios for a 2-people household coffee machine

Scenario Lifetime (years)

Energy consumption (MJ/year per person)

Acetic acid

(L/year per person)

Scenario 1 - 20dH

7 218 1

Scenario 2 - 14dH

14 209 0,7

Scenario 3 - 8dH 21 200 0,4

4.5.5.3 Disposal

The products are assumed to be produced and disposed in the country of use stage, which is Denmark. The coffee machine contains materials with very different ways of disposal. Computer software has information of material fraction recycled and incinerated.

4.5.6 Boiler

The boiler life cycle is used to assess the impact of the water softening process and in Figure 12 the stages of the boiler life cycle taken into account are sketched. The assumptions and considerations leading to the choice of these processes are described in the following.


materials and manufactoring of boiler

Boiling water for 1 yearRecycling and

inceneration of the boiler

Figure 12 - flow chart of the considered processes in the life cycle of the boiler

4.5.6.1 Production

Boilers can be made of various materials as well as the coffee machine. The two products are actually much alike, thus the materials for the boiler is assumed to be the same as for the coffee


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machine except from the glass jug needed in a coffee machine. In Table 13 the boiler materials are listed.

Table 13 - Resource list for a domestic boiler [Wenzel, Caspersen and Schmidt, 2000]


Cabinet 1 Plastic ,Polystyrene 1,1

1 Aluminium 0,1

1 Steel 0,1

Cord 1 Copper 0,02

1 Softened PVC 0,02

Handle 1 Plastic ,Polystyrene 0,02

Strap 1 Aluminium 0,01

Packaging 1 Cardboard 0,39

4.5.6.2 Use

The use stage scenario for the boiler is assumed to be an average of the households of the writers. Technical data is taken from measurements (Dansk-Energi). A household uses the boiler for 1,5 litres of water a day every day in one year. It takes 3,5 minutes with a 2200 W boiler to boil one litre of water. Energy consumption is:

2,2 kWh*3,5/60 hour*1,5*365 days = 70 kWh = 253 MJ a year

This value is assumed to be for scenario 3.

Due to ½ mm lime scale for scenario 2 and 1 mm for scenario 1, the annual energy consumptions are 264 MJ and 276 MJ for scenario 2 and 1, respectively. Again the values are divided by two to get the average consumption for one person, which is seen in Table 14.

The life time of the boiler varies with the degree of hardness (dH) in the water. The lifetime is prolonged 3-4 times when going from 22 dH to 10 dH [Calcon.dk]. Assuming a linear relation the life times of the coffee machine for the three scenarios are calculated from the lifetime of an average domestic boiler of 7 years. The lifetimes are seen in Table 14.


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Table 14 - Lifetime, energy use and acetic acid use for the 3 scenarios for a 2-people household boiler

Scenario Lifetime (years)

Energy consumption (MJ/year per person)

Acetic acid

(L/year per person)

Scenario 1 - 20dH

7 138 1

Scenario 2 - 14dH

14 132 0,7

Scenario 3 – 8dH

21 127 0,4

4.5.6.3 Disposal

The products are assumed to be produced and disposed in the country of the use stage, which is Denmark. The coffee machine contains materials with very different ways of disposal. Computer software has information of material fraction recycled and incinerated.

4.5.7 Soap for personal hygiene

For the evaluation of the effect of the water hardness on the consumption of personal care products, the system was simpler than for other household products, as no domestic machines was considered for this part of the system. Thus, the following processes were included:

Production of soap and related products

Use in personal hygiene for 1 year

Figure 13 - Flow chart of the processes evaluated for the personal care products.

4.5.7.1 Production

Due to the complex nature of the body products’ market and the difficulty of finding an average composition for these products, only approximate values can be provided. Thus, only the amount


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of some common substances that are present, with minor variations, in most of the body cleaning products can be included in the inventory. In this regard, the most used anionic surfactants are the family of Linear Alkane Sulfates (LAS), which are sulfate derivatives of fatty acids and alcohols. Similarly, the most used nonionic surfactants are fatty alcohols. In Table 15 the relative quantities are presented:

Table 15 - Main components in personal hygiene products (Miljøstyrelsen, 2005)

Component Average composition (%)

Water 70 Anionic tensides 20 Non-ionic tensides 5 Other components 5 Total 100

.

4.5.7.2 Use

In the search for the influence of water hardness on the consumption of soaps in general, and of body hygiene products in particular, it is not easy to find experimental data. Consumer trend surveys are usually focused on economic parameters, and the actual amount of product consumed is usually not stated. These two factors make it very difficult to find accurate values for the region considered in this case study. Because of this, only average consumption values could be found for Denmark (Miljøstyrelsen, 2001) , and no information on the dependence on water hardness. In order to assess this, the same dependence as with detergents was assumed, calculating a 50% reduction in soap consumption for soft water with respect to the average level of hardness found in the Copenhagen area. When we apply this approximation to the consumption values, the results in Table 16 are obtained:

Table 16 - Soap consumption for the different scenarios

Scenario Anionic surfactants consumption kg/person-year

Nonionic surfactants consumption kg/person-year

Total consumption kg/person-year

Scenario 1 - 20dH

2,18 0,55 2,73

Scenario 2 - 14dH

1,56 0,46 2,32

Scenario 3 - 8dH 1,53 0,38 1,91


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In the data about consumption personal care products, there is no mention of the amount of plastics and other materials used for the package of the products. As with the product compositions, the lack of available data and the diversity of package materials (although mostly plastics), shapes and container volumes makes it very difficult to select an average material consumption for this element of the product. In short, no consumption of plastic or other material was considered for this part of the system.

4.5.8 Other relevant issues for the inventory

In this chapter processes which have not been included in the LCA are discussed. A reason for not including a process can be it is quantified and found insignificant or data has not been found.

4.5.8.1 Pipeline

The deliverance of drinking water happens through the distribution net of pipelines administrated by Copenhagen Energy. The softening of the water will result in an altering of the composition of the drinking water. However, the goal is to keep the water saturated with calcium carbonate so that the water will not be aggressive and start to corrode the metals of the pipelines or plumbing installations. To ensure this the pH will have to be adjusted according to Figure 13 before the softened water is distributed to the households.


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Figure 14 - Calcium carbonate and water equilibrium under the simplification that all Calcium originates from CaCO3 (Mons, et al., 2007).

4.5.8.2 Change of sludge

When looking at countries situated close to Denmark as e.g. the Netherlands and Sweden a main driver for introducing central softening of water has been to avoid corrosion of pipe materials and plumbing installations. Before introducing central softening the Netherlands and Sweden experienced a high concentration of copper and lead in the sludge preventing them for recycling sludge on agricultural land. In these two examples central softening was introduced in order to prevent corrosion of pipe materials and plumbing installations. On the contrary, a water utility in the Netherlands has experienced an increase in corrosion of the pipes and installations leading to more often occurring leakages of the distribution net.

These two opposite experiences on correlations between central softening and corrosion emphasize that the calcium carbonate and water equilibrium must be carefully studied and adjusted, so that the drinking water does not become aggressive, see Figure 14.

This assessment only investigated the experience in Sweden and the Netherlands but did not include any quantification of the change in the composition of sludge. This should be looked into in future studies.


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4.5.8.3 Energy for pumps

During the LCA it was investigated whether energy consumption in pumps was decreased due to a lower scaling effect in distribution line when introducing central softening. A calculation program was established (Winther, 2009) which could estimate the increasing need for energy for pumps distributing water when a layer of lime scale is precipitated on the inside of distribution pipes. The program takes the following parameters into account: roughness of the material of the pipes, diameter of the pipe, the flow of water, temperature of water, pressure drop.

When calculating the energy savings in the most conservative way it was found that savings in energy was 2.42 %. Since one person uses 7.15 kWh/year for pumping water to the household resulting in a energy saving of 0.17 kWh/year a person. This is insignificant comparing with the other energy consumptions in the system, e.g. the energy usage for one person brewing coffee is 61 kWh/year. Therefore, the energy savings for pumping water when introducing central softening of water is not included in this LCA.

4.6 Results of impact assessment

The results are in the following presented separated in the three major impact categories; environmental impacts, toxicity impacts and resource consumption.

4.6.1 Environmental impacts

From Figure 15 it is seen that the category making up the highest environmental impact is global warming (GWP) reaching a level from 16 to 17 person equivalent targeted (mPET) for the three scenarios (scenario 1 is 16,1 mPET; scenario 3 is 16,8 mPET). Global warming is followed by acidification ranging from 8,8 (scenario 1) to 7,9 (scenario 3) mPET.

Figure 15 also shows that there is a linear relation between the hardness of the water and the environmental impact within the three scenarios in this study.

In Figure 16 it is seen that washing of clothes is the main contributor to the environmental impact, followed by coffee brewing. Figure 16 also shows that the impact sources observed are contributing to different impact categories.


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Figure 15 - Environmental impacts of the three scenarios

Figure 16 - Contribution of each impact source on the environmental impacts for scenario 3

02468

1012141618

mPET

Environmental impacts

Scenario 1

Scenario 2

Scenario 3

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Acid GWP Nutrient Ozone strat Smog, low Nox

Softening

Boiler

Soap

Manual dish

Dish washer

Coffee Machine

Cloth washing


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4.6.2 Toxicity impacts

The toxicity impacts are shown in Figure 17. The human toxicity impact through soil makes up 120-148 mPET, which is the highest impact in this study comparing both the environmental and toxicity impacts. It is followed by acute eco-toxicity through water that also has a high impact, constituting around 100 mPET.

There is a rather even distribution of impacts sources on the given toxicity categories except for chronic soil toxicity that is dominated by the consumption of soap as seen in Figure 18. The impact is very low though and therefore not significant compared to other impact categories.

Figure 17 - Toxicity impacts of the three scenarios

0

20

40

60

80

100

120

140

160

Soil chronic Water acute

Water chronic

Human air Human soil Human water

mPET

Toxicity impacts

Scenario 1

Scenario 2

Scenario 3


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Figure 18 – Contribution of each impact source on the toxicity impacts of scenario 3

4.6.3 Resource consumption

In Figure 19 a selection of the most relevant resource consumptions of the product system are shown. Only the resources with a high consumption are shown, since the rest of resources considered in the EDIP method have much smaller values. Nickel is the raw material with highest impact after normalization and weighting. Lead and chrome consumption also have relatively high impacts.

The breakdown of the resource consumption to resources in Figure 20 reveals that the washing of clothes again is a major contributor to the consumptions of raw materials, especially lead and zinc.

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Soil chronic

Water acute

Water chronic

Human air

Human soil

Human water

Softening

Boiler

Soap

Manual dish

Dish washer

Coffee

Cloth Washing


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Figure 19 - Resource consumption of the three scenarios

Figure 20 - Contribution of each impact source on the resource consumption for scenario 3

In Figure 21 the difference from the scenarios with softened water (scenario 2 and 3) compared to the reference scenario is plotted, showing the net savings of the scenario 1 and 2. The net savings shows that the environmental impacts have the lowest benefits, since they in general are below 2

0

5

10

15

20

25

Cr Cu Pb Lignite Ni Zn Fe Mo

mPR

Resource consumption

Scenario 1

Scenario 2

Scenario 3

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Cr Cu Pb Lignite Ni Zn Fe Mo

Softening

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Soap

Manual dish

Dish washer

Coffee

Cloth Washing


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mPET. The highest benefits are seen for the toxicity. The resource consumption benefits lie in between with the nickel consumption being the highest.

Note, in Figure 21, the environmental and toxicity impact categories carry the unit mPET and for resource consumption the unit is mPR.


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Figure 21 - Net savings for scenario 2 and 3

Acid

GWP

Nutrient

Ozone strat

Smog, high Nox

Net impact savings for scenario 2 and 3Environmental impacts

Soil chronic

Water acute

Water chronic

Human air

Human soil

Human water

Toxicity impacts

-5 0 5 10 15 20 25 30

CrCuFePb

LigniteMo

NiZn

mPET/mPR


Scenario 3 savings Scenario 2 savings


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4.7 Discussion of the results

4.7.1 Environmental impact

Global warming is the most significant environmental impact in this product system. The reason for this is the high electricity consumption in two parts of the life cycle assessment; the softening at the waterworks and the effects in the households. Acidification is also a significant environmental impact also due to electricity consumption.

The source for the production of electricity is given by the GaBi software and may vary over the years. But the overall scenario is that coal and oil is dominating the fuels being used for producing the electricity in Denmark resulting in acidification and global warming.

It is seen that there is a linear relation between the degree of hardness of the water and the environmental impacts shows within the three scenarios in this study meaning that a more extensive softening leads to a decrease of environmental impacts. Even softening of water from 20 odH (scenario 1) to 14 odH (scenario 2) results in an environmental improvement, and softening from 20 odH to 8 odH (scenario 3) results in an even better improvement when considering the environment.

The only category in the environmental impacts which does not show an improvement is ozone depletion as illustrated in Figure 15. This is because the difference in degree of hardness primarily affects the electricity consumption which does not have an impact on the ozone depletion. In fact there is a reverse impact compared to the other impact categories. The reverse impact is due to R114 and R12, which are ozone depleting gasses emitted during the production of the higher amount of NaOH used in the reactor to soften the water.

4.7.2 Toxicity

The toxicity caused by the product system is in general reduced when the water is softened proportional with the degree of hardness of the water, see Figure 17. This is because of the less use of soaps and cleaning agents. To some extent this is also because of the reduced consumption of electricity which entails a less amount of toxic emissions when producing less electricity.

Chronic soil toxicity is an eco-toxicity category which is almost exclusively caused by the consumption of soap. This means that the consumption of electricity is not having an impact on this toxicity category. This does not seem very important though since the impact of this toxicity category is very low and therefore not significant compared to other impact categories. This is also the case for human toxicity through air and the reason for this seems to be the control of toxic emissions to air by filter technology in power plants.


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The acute toxicity through water and the human toxicity through soil are relatively high. This is because of the production of electricity.

Washing of clothes is causing the highest toxicity impact which is due to the higher electricity consumption from the use phase of the washing machine.

As concluded with the environmental impacts there is an overall positive effect looking at toxicity when softening water from 20 odH to 14 odH and an even more positive effect when softening to 8 odH.

4.7.3 Resources

The raw materials being the most consumed resources in this study are nickel, lead and chromium. Nickel is the most problematic having the highest consumption, see Figure 19. This is due to the fact that the steel in especially the washing machine and the dishwasher - but also the boiler and the coffee machine – contains nickel and chromium.

It is though seen that there is a major difference in the consumption of nickel and chromium between the boiler and the coffee machine. This is due to the fact that different types of steel are identified as production material for these two household machines.

The relatively high consumption of lead is coming from the production of detergents used in the washing machine. So is the consumption of zinc but this is not that important because of the low resource consumption of zinc.

4.7.4 Working environment

An assessment of the working environment focuses on the “conditions and factors that affect, or could affect, the health and safety of employees or other workers (including temporary workers and contractors), visitors, or any other person in the work place” (Jørgensen, 2009).

This report does not contain a full working environment assessment with normalization and weighting according to reference values for working environment in Denmark, but will instead show where in the system there are conditions or factors that might affect the health and safety.

The working environment analysis is shown in table 17. It is divided in to two main parts – one is scenario 1 where no softening takes place, and the other is scenario 2 and 3 where central softening is introduced to the system.


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Table 17 - Working environment analysis presenting health and safety risks for scenarios with and without central softening.

Scenario Health & Safety area Risk Without softening (scenario 1) Higher consumption of

chemicals in households due to removal of lime scale on surfaces

Contact between chemicals and skin or through airways, e.g. acetic acids, might have corrosive effect

Higher consumption of detergents and soap

Contact between chemicals and skin or airways might lead to allergies

With central softening (scenario 2 and 3)

Building stage of softening reactor: Heavy lifting or controlling heavy machines

Accidents or injuries when doing heavy lifting or controlling heavy machines

Building stage of softening reactor: Breathing of dust and chemicals

Airway problems from breathing dust and chemicals

Use stage of softening reactor: Handling chemicals

Corrosion if contact between NaOH and skin

Use stage of softening reactor: Automatic water intake and addition of NaOH and sand

Noise leading to hearing damages

The table shows that there are more possibilities for affecting health and safety for employees working at the water utility when introducing central softening.

In the households the central softening of water will lead to a decrease in use of chemicals for removing lime scale. Therefore, in the households central softening has a positive effect on working environment.

However, the risk of damaging health or safety seems relatively small for central softening of drinking water and the assessment has not been further investigated.

4.7.5 Uncertainty- and sensitivity analysis

4.7.5.1 Uncertainty analysis

4.7.5.1.1 The model of the product system

In this LCA it has been necessary to make some assumptions and estimations. This is not surprisingly because almost any LCA is to some extent based on assumptions and estimations, and some uncertainty in the results cannot be avoided. Uncertainties occur in the goal and scope phase, where processes are identified, included or excluded; in the inventory, where the inputs and outputs of the processes are quantified; and in the impact assessment, where different factors are applied to characterize and normalize the results.


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Scoping the project implies making some assumptions about systems liable to be affected. In this study, these assumptions are reflected in the way the system is described and in the elements included in the inventory.

The system boundaries in this study are including some processes and excluding others. The LCC performed before this LCA concluded that the environmental impact of building the pellet reactor for softening was extremely low and not significant in comparison with other factors like the use of the reactor and the use of household machines and therefore this was not included in the LCA. This might result in a very small error in the final calculation but it is not changing the result.

The study does not include transport of drinking water in the LCA. The reason for this is, that the energy used for transporting the water is assumed to be the same regardless of whether it is softened or not. This is not necessarily true because the lime in the distribution pipes when transporting hard water might be an obstacle to the effectiveness of the transport and then lead to more use of transport energy consumption. This might make a small error in the results.

4.7.5.1.2 Values for environmental impacts of the concerned processes

In the inventory the hardness of the water lies within a range of 17 to 23 odH. This study has used an average of 20 odH, which was chosen as the hardness of the drinking water for scenario 1. The use of an average measure instead of the exact interval might result in a little miscalculation.

The energy consumption for the softening process is assumed to be the same for scenario 1, 2 and 3 and not affected by the amount of sodium hydroxide and sand. This might not be the precise truth but the LCC performed before this study shows that it is close to.

It is assumed that each household has one of each product: a dishwasher, a washing machine, a boiler and a coffee machine. This is of course not true but it is necessary here to make an assumption because such data simply do not exist.

Because of difficulties in finding data it is assumed that a dish washer and a washing machine is equivalent in the materials and manufacturing stage due to nearly same size and construction. It is also assumed that the coffee machine and the boiler are equivalent in the materials and manufacturing stage except from the fact that only the coffee machine contains glass.

The lifetime of the household products – and the extended lifetime because of lesser scale production – has been found on the internet by Google research. Much of the information is coming from the manufacturers of the products and it might be questioned if such data are fully reliable.

It has been assumed in the study that one person washes ones a week. This is of course not certain but on the other hand not unrealistic.


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The household products are assumed to be produced and disposed in Denmark. The latter is to be presumed as they are used in Denmark but the former is an assumption that very well might not be true and therefore probably is giving a minor error.

Transport of NaOH and sand to the waterworks for the softening process is included in the LCA. An average distance of 200 km by lorry is assumed. Also the transport of lime scale to the agricultural land is included and an average distance of 150 km by lorry is assumed. This is of course not known for certain as this is a hypothetical situation but it seems likely.

It is assumed that all waste from the softening process is reused (agricultural land or lakes for increasing the pH). This might not be true but it is a possible situation and it seems acceptable to use this scenario in the LCA.

4.7.5.1.3 The impact assessment

In section 4.6 the results from the impact assessment has been shown. There are many uncertainties in this study as already mentioned. But the main uncertainty seems to be connected to the data used for the production of electricity because this issue is so important for the whole product system and the results of the LCA performed.

It is seen from the impact assessment that the energy produced to make the electricity available for both the use of the reactor and the use of the household machines is of crucial importance in this study when describing the LCA results.

The uncertainty connected to the use of electricity is of course the production of the electricity. The data used to define the sources of energy production is incorporated in the GaBi software, but the energy production situation in Denmark is very complex and it is almost impossible to say exactly where - and from which sources – the energy is coming from.

The amounts and percentages of emissions enhancing environmental impacts like global warming, acidification and toxicity is a direct consequence of the energy producing source.

And this is constantly changing in relation to the ability in Denmark to produce energy from existing energy generating installations – versus the need to import energy from other countries where the production sources are different or at least differently mixed.

The conclusion is that the mix of energy sources behind the GaBi data for the environmental impact of electricity use can be somehow uncertain.

To illustrate that there are other references to the energy mix in Denmark an EU statistic has been shown in Table 18.


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Table 18 - Sources for production of energy in Denmark in 2006 in % of total production (Kohlenwirtschaft, 2006)

Hard coal Oil Natural Gas

Wind energy, Hydropower and other sources

53.9 3.5 20.6 22

Characterization, normalization and weighting in this study are based on data from the GaBi software. These data are not 2009-data and of course this is probably giving some uncertainty.

Equivalency factors used for characterization in the impact assessment reflect the current knowledge of the cause-effect relationship between emission and actual impacts in the environment. As the normalization references are based on statistics, they are considered as relatively certain in this respect. So is the weighting. The exception is the toxicity references, which are still difficult to quantify and are being debated in international LCA fora (Hedal, et al., 2009.).

Further uncertainties are added in the long-term perspective, since the future is inherently uncertain. It is much more difficult to foresee the consequences in a longer term than in a short term. A sensitivity analysis, examining some of the most important assumption, helps determining the robustness of results.

4.7.5.2 Sensitivity analysis

The observations of key figures for environmental impacts, resource consumption and toxicity are described in Table 19.

Table 19 - Key figures for the sensitivity analysis for environmental impacts, toxicity and resource consumption

Category Main environmental impact category

Main process contributing

Main sub process contributing

Environmental impacts

Global warming (has the highest effect)

Clothes washing and coffee brewer

Power consumption

Acidification (second highest)


Power consumption

Toxicity Human toxicity soil (has the highest impact)


Power consumption

Water acute ecotoxicity Clothes washing and coffee brewer

Power consumption


Ni (has the highest resource consumption)

Clothes washing and dishwashing

Steel

Pb (second highest and unexptected since is not a known resource of the system)

Clothes washing Detergents


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The main sub process contributing to both environmental impacts and toxicity is found to be power consumption, see Table 19. As described in Uncertainty analysis data collection for power consumption was always aimed at not overestimating the energy use. Therefore a medium to low value was always chosen. This contributes to the table above showing that power consumption is an obvious parameter for checking the sensitivity of the results regarding environmental and toxicity impacts.

The energy consumption is changed by adding 20 % to the energy consumption for both clothes wash and coffee brewing to see how it influences the result of environmental impacts and toxicity. The sensitivity analysis is comparing changes in scenario 1 and 3.

The main sub process for resource consumption is found to be steel and detergents. First the steel is changed by adding 10 % to the weight of the steel used for the washing machine. The weight then is changed from 47,45 kg to 52,2 kg. Secondly, the detergents for washing clothes is changed from 11,6 to 12,76 kg for scenario 1 and 8,2 kg to 9,02 kg for scenario 3 which is equivalent to a 10 % increase.

The increase of the key figures and the corresponding increase in the impact category and resource consumption are found in Figure 22 and Figure 23.

Figure 22 shows that if the energy consumption of washing machine and coffee brewing is increased by 20 %, due to the fact that the data collected are in the lower scale of the actual consumption, then the effect of central softening is slightly higher comparing scenario 1 with scenario 3. There is a small increase in the positive effect of softening (“Scn 3 sensitivity” minus “Scn 3 sensitivity” is a little higher than “Scn 1” minus “Scn3”) and implies that the data collected has provided results that do not overestimate the environmental benefits. However, the increase is small and almost non-existing which also shows that changing the key figure power consumption (washing machine and coffee machine) does not change the results noteworthy.

Additionally, the data collection has been focusing on not overestimating the data e.g. by choosing a medium or low value for energy consumption, the sensitivity analysis proves that the conclusions of the report are confident and not overestimating the effect of softening.


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Figure 22 - Sensitivity analysis for environmental and toxicity impacts changing the key figures for power consumption for clothes washing and coffee brewing

When it comes to resources the sensitivity analysis is focusing on use of detergents and steel and how they affect lead and nickel consumption, respectively.

It is found that the positive effect of softening (“Scn 1 sensitivity” minus “Scn 3 sensitivity” is a little higher than “Scn 1” minus “Scn3” for nickel and the same for lead) is slightly increased for nickel and the same for lead if the use of detergents and steel is increased by 10 percent, see Figure 23.

Figure 23 - Sensitivity analysis for resource consumption changing the key figures for steel and detergents

0

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0,04

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0,08

0,1

0,12

0,14

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0,18

Acidification Global warming

Ecotoxicity water acute

Human toxicity soil

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T Scn 1

Scn 3

Scn 1 sensitivity

Scn 3 sensitivity

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Scn 3 sensitivity


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As with the environmental and toxicity impacts this stresses that the conclusion of the LCA is confident due to always collecting data which are not overestimating the actual consumption of energy, detergents or steel.

4.7.6 A critical viewpoint of the LCA

Keeping Bras-Klapwijk’s theory in mind, it is always an advantage to identify areas in a LCA which could be met with criticism by different stakeholders. A limitation in many LCA’s and also in this specific LCA is that many normative and implicit assumptions are made. This can to some extent lead to an interpretation which is neither completely objective nor repeatable (Bras-Klapwijk, 1998).

Two critical viewpoints of this LCA are found to be:

- Will the consumers adjust their dosage of soap, detergents (both for washing and dishwashing) and chemicals according to the degree of hardness of the water after introducing central softening of drinking water?

- This report builds on the assumption that the households will adjust to the lower dosage needed of soap, detergents and chemicals when receiving soft water. There is a possibility that this adjustment might happen gradually and maybe not to the intended level of dosage.

- Will the consumers take advantage of the extended life time of household

machines (washing machine, dishwasher, coffee machine and boiler) which occur when introducing central softening?

- This report is built on the assumption that the consumers will use the household machines until it stops to function. The report does not reflect whether the consumer patterns encourage the consumer to buy e.g. a new washing machine before it breaks down because the consumer is economically capable of buying a new machine. To include this in the report would demand an analysis of the consumer patterns in Copenhagen.

The two critical viewpoints are not studied further here, but could be an aspect of further work. The viewpoints however, are not found to be based in key figures in the LCA and therefore have not been a part of the sensitivity analysis.


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5 Conclusion

The aim of the project has been to evaluate whether it is environmentally beneficial to introduce central softening of drinking water in Copenhagen.

The central softening of drinking water has shown to pose both negative and positive effects to the water system. The negative effects are caused by use of chemicals, sand and energy. On the other hand the positive effects of softening drinking water are now known to be:

- reduced used of energy when washing, dishwashing, coffee brewing and boiling water - Longer life time of household machines - reduced use of cleaning agents for removing lime scale - less use of soap and shampoo - less energy consumption when distributing the water

The quantitative assessment of the water system shows that there is an overall positive effect of introducing central softening in Copenhagen when softening water from 20 odH (scenario 1) to 14 odH (scenario 2) and an even more pronounced positive effect of softening water from 20 odH to 8 odH (scenario 3). In the evaluated categories the lifecycle assessment shows that the introduction of central softening in Copenhagen will lead to:

- Decrease of the environmental impacts categorized as acidification, global warming, nutrient enrichment and photochemical oxidant formation. Only the impact category ozone depletion performs a slightly increase when water is softened.

- Decrease of the resource consumption. The key resources where found to be nickel, lead and chromium.

- Notable reduction in the toxicity impacts. Because the impacts are relatively high for toxicity, central softening of drinking water can really make a difference on the toxicity impacts. This is also reflected in the quantitative difference between the scenarios; human toxicity through soil is about 28 mPET higher for scenario 1 than for scenario 3.

Looking at the quantitative impacts of the product system, the toxicity impacts are obvious where the largest decrease of impacts is found by introducing softening of water. This LCA does not announce toxicity as the most severe, but this LCA rather understands the high impacts of toxicity as an opportunity of influence. Because there are such high impacts on toxicity, central softening of drinking water can really make a difference on the toxicity impacts.

The study has involved many different ways of collecting data and some assumptions. Focus in this assessment has been not to overestimate data which also is in accordance with the results of the uncertainty and sensitivity analysis. Consequently the conclusions made above seem to be reliable.


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6 References

Andreasen, Peter and Anneke, Stubsgard. 2002. Reduktion af miljøbelastningen fra tøjvask - Effekten af blødgøring af brugsvand før vask. Copenhagen : DHI - Institut for Vand og Miljø, 2002. Bolius. Bolius. [Online] http://www.bolius.dk/viden-om/koekken/artikel/koeb-af-vaskemaskine/. Bras-Klapwijk, Remke. 1998. Adjusting Life Cycle Assessment Methodology for Use in Public Policy Discourse. 1998. p. Note 26. Calgon. Calgon. [Online] http://www.calgon.dk/waterhardness-map.php?town=Herning%3BBl%C3%B8dt. Dansk-Energi. Dansk Energi - Gode elvaner. [Online] [Cited: 23 11 2009.] www.danskenergi.dk (forbrugeren/spar_el.aspx). Energi, Københavns. 2009. Københavns Energi. Kort over indvindingsområder. [Online] 2009. http://www.ke.dk/portal/page/portal/Privat/Vand/Saadan_producerer_vi_vand?page=204 Energistyrelsen. 2009. Energistyrelsen. [Online] 2009. http://www.ens.dk/DA-DK/POLITIK/DANSK-KLIMA-OG-ENERGI-POLITIK/Sider/dansk-klima-og-energipolitik.aspx. EPA, Danish. 2007. Status for LCA i Danmark 2003 - Introduktion til det danske LCA metode og konsensusprojekt. 2007. Geus. 2009. Drikkevandets hårdhed. [Online] 2009. http://www.geus.dk/geuspage-dk.htm?http://www.geus.dk/program-areas/water/denmark/data_and_maps/haardhedskort-dk.htm. Hauschild, Michael and Wenzel, H. 1997. Environmental assessment of products. s.l. : Kluwer acedemic Publishers, 1997. Hauschild, Michael. 2009. Lecture information. 2009. Hedal, K. and Schmidt, A. 2009. FORCE Tecnologies. Kgs. Lyngby, 18 11 2009.


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Hofman, Jan, et al. 2007. Twenty years of experience with centralised softening in The Netherlands: Water quality, environmental benefits, and costs. 2007. Haapala, Karl, Brown, Kari and Sutherland, John. 2008. A life cycle environmental and economic comparison of clothes washing product-service system. Michigan : MTU - Sustainable Futures insitut , 2008. ISO-14040. 2006. Environmental management - Life cyle assessment -principles and framework. Geneve : International Organisation for Standardisation (ISO), 2006. Jerlang, j., et al. 2001. Livscyklusvurderinger - en kommenteret udgave af ISO 14040 til 14043. København : Dansk Standard, 2001. Jørgensen, Michael Søgaard. 26th October 2009. Working environment – in life cycle perspective and in LCA. 26th October 2009. Kohlenwirtschaft, Statistik der. 2006. Energie/Jährliche statestik 2006. 2006. Miljøstyrelsen. 2001. Environmental and Health Assessment of Substances in Household Detergents and Cosmetic Detergent Products. [Online] Danish Enviromental Ministry, 2001. [Cited: 26 11 2009.] http://www2.mst.dk/udgiv/publications/2001/87-7944-596-9/html/kap02_eng.htm. —. 2005. Survey of chemical substamces in dandruff shampoo. [Online] Danish Environmen Ministry, 2005. [Cited: 26 11 2009.] http://www2.mst.dk/Udgiv/publications/2005/87-7614-648-0/html/helepubl_eng.htm#sum_eng. Mons, Margreet, et al. 2007. Softening, conditioning and the optimal composition of drinking water. s.l. : Ny-linh, 2007. Nielsen, K. D. 2009. Research of cradle to cradle principles - FORCE Technology. 2009. Niras. 2009. Søndersø vandværk, Central blødgøring af vand. Århus : Niras, 2009. Rosedi. 2009. Rosedi. [Online] Rosedi, 2009. [Cited: 21 11 2009.] http://rosedi.com/wp-content/uploads/2009/05/lifecycle1.jpg. Statestik, Danmarks. 2009. [Online] Danmarks Statestik, 2009. http://www.dst.dk/.


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Teknologisk, institut. 2004. Elbesparelser ved kalk- og fouling og friktionsnedsættende materialer - Fase 1. s.l. : Teknologisk Institut, 2004. Vombverket. 2009. Vombverket. [Online] 2009. http://www.sydvatten.se/page.php?sid=22. Wenzel, Caspersen and Schmidt. 2000. Product Life Cycle Check, A guide, Translation - Note 9 course 42372 compendium. 2000. Winther, Niels. 2009. Teknologisk institut. Århus, 2009. WRAP. 2009. Waste & Resources Action Programme. [Online] 2009. www.wrap.org.uk. Wupti. 2009. Wupti. [Online] 2009. www.Wupti.dk.


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7 Appendices

7.1 Appendix – List of assumptions

This appendix contains a list of all the assumptions made during the life cycle assessment. Some of the assumptions are also mentioned in the inventory, but this appendix should present an exhaustive list of the assumptions.

Water work

Transport of NaOH and sand to the waterworks for the softening process is included in the LCA. An average distance of 200 km is assumed. Also the transport of lime scale to the agricultural land is included and an average distance of 150 km is assumed. The data is shown in Table 6.

It is assumed that all waste from softening process is reused (agricultural land or lakes for increasing the pH).

It is assumed that the addition of FeCl3 and acids after the softening process in the pellet reactor are so insignificant that they are not included.

It is assumed that the energy consumption is the same for scenario 2 and 3, and thereby do not differ with the softening effect. This seems reasonable since energy is only used for pumping water in to the reactor.

Household machines (all)

Transport of the household machine to Denmark has been left out but it should be noted that by extended lifetime of the washing machine the frequency of how often a new washing machine have to be imported will decrease. This would result in a lower environmental impact for the transport.

It is assumed that for scenario 2 there is ½ mm lime scale on the heating element, and for scenario 1 there is 1 mm lime scale.

Washing machine

It has been assumed, on basis of number from (Statestik, 2009), that all people have access to a washing machine, either they own one or they use a laundry service. This has implied a general assumption that all people use a washing machine.


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The washing machine has been assumed to have an average lifetime of 11 years if 2 people share one. This has been chosen after finding lifetimes down to 6 years for a cheap washing machine and up to 16 years for an expensive washing machine (Bolius). The lifetime is a variable with the hardness of the water and by lowering the hardness of the water, the lifetime is extended, the extended lifetime in the different scenarios is shown in Table 8.

It has been assumed that one person washes once a week.

Dishwasher

It has therefore been assumed that the material composition in percentage of a dishwasher is the same as for the washing machine, with exception of the glass which is set to zero. The weight of a dishwasher is 47 kg whereas a washing machine weights 65 kg (WRAP, 2009), the materials used can be seen in Table 9.

About 59 % of all people have access to a dishwasher; it is assumed that in average 2 people share a dishwasher in Copenhagen (Statestik, 2009). The 41 % doing dishes by hand is assumed to do the dishes during a year equivalent to running the dishwasher once a week.

The life time of a dishwasher depends on the water hardness and the quality of the dishwasher, it has been found to be of an average of 10 years in Denmark.

From other LCA’s it has been shown that doing the dishes by hand has at least the same environmental impacts as using a good dishwasher when comparing toxicity impact and energy use (Hauschild, 2009). It has therefore been assumed that one person’s impact regarding energy and detergent use does not have any connection to whether it has access to a dishwasher or not.

Coffee brewer

An ordinary domestic coffee machine is assumed to brew one litre of coffee twice a day, 7 days a week throughout the whole lifetime.

Consumption of acetic acid in an average household for descaling of especially boilers is considered to be 2 litres a year. The two litterers are included in the use stage of the coffee machine and boiler, and the sum of these use stage consumptions make up the two litres. When softened water is used, less acetic acid is used due to less calcium. There is assumed to be a linear relation between acetic acid consumption and amount of calcium in the water.


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Boiler

Boilers can be made of various materials as well as the coffee machine. The two products are actually much alike, thus the materials for the boiler is assumed to be the same as for the coffee machine except from the glass jug needed in a coffee machine. In Table 13 the boiler materials are listed.

The use stage scenario for the boiler is assumed to be an average of the households of the writers. Technical data is taken from measurements (Dansk-Energi). A household uses the boiler for 1,5 litres of water a day every day in one year.

Soap for personal hygiene

Due to the complex nature of the body products’ market and the difficulty of finding an average composition for these products, only approximate values can be provided. Thus, only the amount of some common substances that are present, with minor variations, in most of the body cleaning products can be included in the inventory. In this regard, the most used anionic surfactants are the family of Linear Alkane Sulfates (LAS), which are sulfate derivatives of fatty acids and alcohols. Similarly, the most used nonionic surfactants are fatty alcohols.

In the data about consumption personal care products, there is no mention of the amount of plastics and other materials used for the package of the products. As with the product compositions, the lack of available data and the diversity of package materials (although mostly plastics), shapes and container volumes makes it very difficult to select an average material consumption for this element of the product. In short, no consumption of plastic or other material was considered for this part of the system.


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7.2 Appendix – GaBi plans

This appendix contains the GaBi plans.

The first plan is the main system and the following plans are the subsystems used in the main system, all the plans are for scenario 3. The plans are listed below and in each of the subsystems is production, usage and disposal stages included.

- Main plan - Clothes washing - Dish washer - Dishes by hand - Coffee brewing - Water boiler - Personal hygiene

Main Plan from Gabi, the reactor is the large blok in the middle. The subsystems uses the water after it have gone through the reactor and is therefore on the right side of the reactor block.

LCA of central softening of drinking water in Copenhagen

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The GaBi plan for washing clothes


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The GaBi plan for the dishwasher


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Dish washing by hand


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GaBi plan for coffee brewing


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The GaBi plan for the boiling water


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Soap

Life Cycle Assessment on Central Softening of Drinking ... · This project is carried out as a part...

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