A Systems Perspectiveof Waste and Energy

Strengths and Weaknesses of the ORWARE Model

Ola Eriksson

Licentiate thesis

Royal Institute of TechnologyDepartment of Chemical Engineering and Technology

Section of Industrial Ecology

Stockholm, November 2000

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Title:A Systems Perspective of Waste and Energy- Strengths and Weaknesses of the ORWARE Model

Author:Ola Eriksson

Registration:ISSN 1402-7615TRITA-KET-IM 2000:16

Published by:Royal Institute of TechnologyDepartment of Chemical Engineering and TechnologySection of Industrial EcologySE - 100 44 STOCKHOLM, SWEDENPhone: (+46) 8 790 87 93 (distribution) (+46) 8 790 93 31 (author)Fax: (+46) 8 790 50 34E-mail: ola.eriksson@ket.kth.se

Printed by:KTH/Högskoletryckeriet, Stockholm, Sweden, 2000.

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AbstractWaste management of today in Sweden is a complex phenomenon that demands for ascientific and systematic approach. The complexity is a result of a wide variety of actors,technologies, and impact on the environment, health, and the economy. Waste managementalso has a high relevance with respect to energy. There are direct connections as e.g. energyrecovery from waste, but also indirect as the systems complexity and the environmental andeconomical impacts.

Helpful tools in the planning of waste management are different types of models of whichORWARE is one. Based on principles from Life Cycle Analysis (LCA) and complemented witha simple Cost Benefit Analysis (CBA) ORWARE can provide some help in findingenvironmentally sound solutions for waste management systems. The model does not answerall questions raised by practitioners but can still be used for advisory purposes. The modeldoes not include sociological or political aspects but it covers the area of physical flows withimpacts on environment, society and economy. Other impacts have to be considered withother methods.

The experiences from using ORWARE in Swedish municipalities during more than a halfdecade clearly shows the advantages and disadvantages of the tool. The model is very flexiblewhen it comes to the possibility of site-specific adjustments of input data and processfunctions. With help of the model the complexity of the studied system can be illustrated bye.g. a map of the number of connections between different types of information. In this wayORWARE supports dialogue between different stakeholders and collects knowledge in a uniqueway. On the other hand, modelling such an extensive and complex system often leads toerrors that takes time to find and correct. The model can not be considered as user friendlyand does not cover all aspects wanted by the society. There are also educational problems withdifferent time frames and space boundaries in the analysis that make the results hard tointerpret.

As there are many similarities between waste management and energy management,experiences from systems analysis of waste management can be used for planning of moresustainable solutions in the energy management. That is why it is interesting to develop themethodology used in ORWARE and adapt it to a partly new area like e.g. energy management.One example of improving the methodology is to extend the number of impact categories.Another example is to put the functions delivered in focus. ORWARE focuses at the wastemanagement system, and thus "treating waste from a certain area" is one fundamentalfunctional unit. Translated to energy that would mean to build a model of the energy supplysystem. But to optimise the whole system that delivers a function ought to be a more efficientway to head for sustainability than to study the supply system and the applications separately.That would mean to put the end user functions provided by some kind of energytransformation in focus instead.

In systems analysis it is also important to consider the alternatives to different options oftechnologies or system designs. In order to understand and assess the influence from e.g.waste management and energy on the environment and the socio-technical system calledsociety, a systems perspective is thus very important. The systems perspective should work atall decision levels and with a life cycle perspective on the function.

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Summary in SwedishDagens svenska avfallshantering är en komplex företeelse som kräver ett vetenskapligt ochsystematiskt angreppssätt. Komplexiteten bottnar i en rik flora av aktörer och tekniklösningarinom avfallsområdet. Avfallshanteringen påverkar såväl miljö och hälsa som ekonomi.Avfallshantering är också starkt knuten till energi. Den uppenbara kopplingen sker genomenergiutvinning från avfall men påverkan på miljö och ekonomi förenar också de bägge.

I planeringsarbetet med avfallshantering kan olika typer av verktyg i form av modelleranvändas, där ORWARE utgör en av dessa modeller. ORWARE baseras på principer frånlivscykelanalys (LCA) och är kompletterad med en enkel kostnads/nytto-analys. Genom attanvända modellen kan en del av de problem lösas som uppstår när avfallshanteringssystemmed goda miljöprestanda skall utformas. Modellen svarar inte på alla frågor som aktörer villha svar på, men kan ändå utgöra ett beslutsstöd. Modellen inbegriper inte sociala eller politiskaparametrar utan fokuserar på fysiska materialflöden med påverkan på miljö, samhälle ochekonomi. Annan påverkan från avfallshantering får lösas separat med andra metoder.

Efter att ha använt ORWARE under mer än ett halvt decennium visar erfarenheterna tydligt påmodellens för- och nackdelar. Modellen är väldigt flexibel vad gäller platsspecifikaanpassningar. Med hjälp av modellen kan ett systems komplexitet belysas genom att t.ex. ge enbild av hur olika typer av information beror av varandra. På detta vis är ORWARE ett stöd idiskussionen mellan olika aktörer och ett instrument för att på ett unikt sätt sammanställa,bearbeta och presentera kunskap. Å andra sidan leder modelleringen av ett så omfattande ochkomplext system ofta till olika typer av felaktigheter som tar tid att upptäcka och åtgärda.Modellen är inte heller användarvänlig och täcker inte in alla aspekter som samhället ställerkrav på. Pedagogiska problem föreligger också genom olika tids- och rumsgränser i modellensom gör resultaten svåra att tolka.

Då avfallshantering och energihantering uppvisar många likheter kan erfarenheter frånsystemanalys av avfall användas för planering av mer hållbara lösningar i energihanteringen.Därför är det intressant att utveckla metodiken som används i ORWARE och anpassa den tillbitvis nya områden som t.ex. energihantering. Ett exempel på hur metodiken kan förbättras äratt utöka antalet påverkanskategorier. Ett annat exempel är att sätta systemets funktioner ifokus. ORWARE har avfallshanteringssystemet, och därmed ”behandla avfall från ett visstområde”, som en grundläggande funktionell enhet. Översatt till energisystemet skulle detbetyda att en modell över energiförsörjningen skulle byggas. Men att optimera hela systemetfram till nyttiggjord funktion borde vara ett effektivare sätt att arbeta för hållbarhet än attstudera tillförsel och användning separat. Det betyder att fokus istället skulle läggas på denfunktion som uppfylls genom någon form av energiomvandling.

I en systemanalys är det också viktigt att betrakta alternativen till olika tekniklösningar ellersystemutformningar. För att kunna förstå och uppskatta påverkan från till exempelavfallshantering och energi på miljön och det socio-tekniska system vi kallar samhälle, ärsystemperspektivet således mycket viktigt. Systemperspektivet skall verka på alla beslutsnivåeroch ha ett livscykelperspektiv på uppfylld funktion.

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AcknowledgementsSo, after almost three years of discussing, calculating, programming, simulating, writing,mailing, calling, supervising, travelling, talking, reading, learning and understanding (anddrinking some cups of coffee too) this is what has become of my efforts. Does this thesis givea correct picture of everything I have been through? Of course not! But with great helpfulguidance of kind people I have managed to write a licentiate thesis about something I knewnothing about for three years ago. This has been accomplished without knowing which werethe questions to be answered. In other words, it was about time to find the questions to themany answers from my research. This is what I call jeopardy research.

First of all I would like to thank the Swedish National Energy Administration(Energimyndigheten, STEM), Stockholms renhållningsnämnd (former known as Skafab) andBirka Energi (former known as Stockholm Energi) for funding my work.

Former and present members of the ORWARE group were and are of great importance,without them this thesis would not have been possible to write.

I am very thankful to my supervisor Björn Frostell. During these three years, which alsoencompasses my diploma thesis, he has always supported me in all activities I have beeninvolved in and taught me a lot about life in general and environmental research in particular.I also highly appreciate my ORWARE colleague at the department, Anna Björklund, for fruitfuldiscussions and making the work a lot more fun.

People involved in the research project "Energy from waste" (performed with ORWARE) andmaster students using ORWARE in their theses deserve to be mentioned. The local participantsof the research project from Stockholm, Uppsala and Älvdalen are remembered for improvingthe outcome of the project, and the students (Axel Fliedner, Getachew Assefa, FrancisOngondo, Sara Jonsson and Charlotta Skoglund) have contributed directly and indirectly tothe production of this thesis.

Colleagues and friends within the Research school of Environmental Management are alsoacknowledged. Maria Johansson helped me to refine my writing for which I am very grateful.

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List of appended papersA summary of the papers included is presented in chapter 3.

Paper IEriksson, O., Olander, J., Frostell, B., (1999) Simulations of Material Flows in a DistrictHeating System - Influence of Solar Heating and Flue Gas Condensing, In proceedings ofR'99, Volume 1 pp 304-309, 2-5 February, 1999, Geneva, Switzerland.

Paper IIEriksson, O., Frostell, B., Björklund, A., Assefa, G., Sundqvist, J. -O., Granath, J., Carlsson,M., Baky, A., Thyselius, L. (2000) ORWARE - A simulation tool for waste management,Submitted to Resources, Conservation and Recycling.

Paper IIIFliedner, A., Eriksson, O., Sundqvist, J. -O., Frostell, B. (1999) Anaerobic treatment ofMunicipal Biodegradable Waste. Submitted to Waste Management and Research.

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Table of contents

ABSTRACT.....................................................................................................................................III

SUMMARY IN SWEDISH..........................................................................................................IV

ACKNOWLEDGEMENTS ...........................................................................................................V

LIST OF APPENDED PAPERS ................................................................................................VI

TABLE OF CONTENTS ........................................................................................................... VII

1 INTRODUCTION................................................................................................................... 1

1.1 BACKGROUND.....................................................................................................................11.2 AIMS OF THE THESIS...........................................................................................................4

2 METHODS AND CONCEP TS ........................................................................................... 5

2.1 WHAT IS ENVIRONMENTAL SYSTEMS ANALYSIS?..........................................................52.2 TOOLS FOR ENVIRONMENTAL SYSTEMS ANALYSIS........................................................62.3 MODELS FOR SYSTEMS ANALYSIS OF WASTE MANAGEMENT ......................................8

3 SUMMARY OF INCLUDED PAPERS ..........................................................................13

3.1 PAPER I ..............................................................................................................................133.2 PAPER II.............................................................................................................................133.3 PAPER III............................................................................................................................163.4 COMMENTS ON THE PAPERS............................................................................................17

4 DISCUSSION.........................................................................................................................19

4.1 WASTE MANAGEMENT AND THE IMPORTANCE OF A SYSTEMS PERSPECTIVE ..........194.2 ORWARE OF TODAY - STRENGTHS AND WEAKNESSES.............................................204.3 RELIABILITY OF ORWARE............................................................................................244.4 ORWARE OF TOMORROW - NO TIME TO WASTE........................................................254.5 FUTURE RESEARCH ..........................................................................................................29

5 REFERENCES ......................................................................................................................31

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1 Introduction

In this chapter some statistics about energy from waste in Sweden are presented andalso legislation on national and European level. Predictions about the energypotential from waste in Sweden are displayed together with the aims of this thesis.

1.1 Background

In 1999 the total amount of household waste in Sweden was 3 794 000 tonnes (RVF, 2000).The distribution of this amount between different fractions and treatments is displayed inTable 1.

Table 1 Amounts and treatments of household waste in Sweden 1999 (RVF, 2000).

Waste type/treatment Amount (ktonnes) Part of tot. (%)Hazardous waste 20 0.5Incineration 1 440 38.0Biological treatment 320 8.4

Landfill 920 24.3Material recycling* 1 034 28.8

*) Metal scrap 100 2.6Waste paper 437 11.5

Packaging 497 13.0

Hazardous waste is normally not discussed as having a potential for energy recovery fromwaste. Energy can be recovered from waste by¤ heat and power generation from incineration,¤ biogas production from anaerobic treatment in digesters,¤ landfill gas extraction, or indirectly by¤ recycling of products and material and thus saving energy.

It is worth mentioning that, as the recycling of materials not is eternal; sooner or later multi-recycled combustible materials will end in the incinerators. Therefore the annual figures coulddiffer from figures for a longer period of time.

The most common method in Sweden for energy recovery from waste is incineration. In 1999an amount of 1 440 ktonnes household waste together with 700 ktonnes of industrial wastewas incinerated giving 6.4 TWh, mostly as district heating (see Figure 1). District heating fromwaste covers 10 % of the total need in Sweden. Incineration takes place in 22 plantscorresponding to a total fuel power of 740 MW.

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Quantities of incinerated wasteand recovery of energy in Sweden 1980-1997

0.91.1

1.5 1.7 1.7 1.8 1.9 1.81.4

2.3

3.4

4.4 4.3

55.2 5.1

6.4

2.1

0

1

2

3

4

5

6

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1980 1983 1986 1991 1994 1995 1996 1997 1999Waste (Mtonnes) Energy (TWh)

Figure 1 Quantities of incinerated waste and recovery of energy in Sweden 1980-1997 (RVF,1998)

Since 1980 (cf. Figure 1), the quantity of waste incinerated for energy purposes has more thandoubled in Sweden. At the same time, the energy production has more than quadrupled. Thisis partly because the waste used for incineration has become higher in energy content, butabove all it is due to more efficient energy recovery.

Another way of utilising energy in waste is to combust methane gas generated in landfills andanaerobic digesters. In 1999, biocells at landfills generated 435 GWh from combustion ofmethane of which 405 GWh for heating purposes and 30 GWh for electricity generation(RVF, 2000). All new landfills are constructed to collect landfill gas. A more efficient methodfor generating methane from biodegradable organic waste is treatment in anaerobic digesters.Anaerobic digestion has been used for over 60 years in Sweden to stabilise sludge frommunicipal sewage treatment. In recent years, digesters specifically aimed at treatment of solidorganic waste have been built in several Swedish cities, such as Uppsala, Borlänge, Kalmar andLinköping. The biogas is mostly used as a fuel for busses and cars.

Recycling often reduces the use of energy and is thus a method for indirect energy recoveryfrom waste. The Swedish Environmental protection Agency's studies regarding material flowsin society show that increased recycling can yield great profits, mainly by reducing energy use.Reclamation of metals, for example, saves not only natural resources, but also energy.(Naturvårdsverket)

The national borders do not limit emissions and thus waste management. Political decisionsconcerning the circumstances in Sweden are more and more taken within the EU. In wastemanagement, the EU waste directives are incorporated into Swedish legislation. A few legalrestrictions in Sweden and EU are displayed in Table 2.

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Table 2 Important steps in existing and coming waste treatment legislation at the Swedish andEuropean level (RVF, 2000).

Year Type of legislation measure1999 The new environmental law (Miljöbalken) is in force.

EG directive regarding landfilling.2000 Tax on waste to landfill with 250 SEK/ton.2001 Evaluation of producers’ responsibility will be presented.

Regulation about producers’ responsibility for electronic waste will be introduced.2002 Combustible waste must be sorted. Ban on landfilling of sorted combustible waste.2003 EG directive about electronic waste (preliminary).2004 Planned evaluation of the consequences of the landfill tax.

2005 Ban on landfilling of organic waste.Compared to the level of 1994 the total amount of landfilled waste must be cut by half.

2008 Sweden: All landfills should fulfil the standard requirements restricted in the EG directive.

How may waste contribute to the energy supply in the future? In Sweden, the expectationsvary widely. Some expect the waste amount to decrease and recycling to increase to such anextent that waste incinerators will become short of waste fuel. Another opinion is thatSwedish incinerators are very well designed and operated, and have a high environmentalstandard. Therefore, Sweden could import waste from abroad for energy recovery purposesand by doing so also decrease landfilling.

In a study made by a project group with members from the Swedish National EnergyAdministration (Energimyndigheten), the Swedish District Heating Association(Fjärrvärmeföreningen), the Swedish Power Association (Kraftverksföreningen) and theSwedish Environmental protection Agency (Naturvårdsverket), some calculations for a futureSwedish sustainable energy system were made (Naturvårdsverket, 1999). Today, the energyproduction from waste is 6.4 TWh/year (cf. Figure 1). The future theoretical potential ofenergy from waste is assumed to be 21 TWh/year. A low estimate gives a potential of 7TWh/year and a high estimate 13 TWh/year. In the report estimates of the future energypotential from waste are conservative. That is because the transport sector will needsignificant amounts of biogas in the future. The uncertainties depend on an expected increasein generation and import of industrial waste, especially building and demolition waste. Table 3summarises the estimates from the study.

Table 3 An estimate of the energy potentials from waste in Sweden 2050 (Naturvårdsverket, 1999).

Energy source [TWh] Low level High levelIndustrial waste 3 6

Unsorted household waste, central incineration 2 3Household waste, local biogas production 0 1Landfill gas 1 1

Incineration of sludge 1 2Total 7 13

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1.2 Aims of the thesis

Earlier theses published within the ORWARE project (Mingarini, 1996; Björklund, 1998;Sonesson, 1998; Dalemo, 1999; Björklund, 2000) have focused on the hypothesis that there isa need for a holistic approach to waste management, supported by environmental systemsanalysis and computer modelling. In different projects the Ph. D. students have built andevaluated submodels of different processes and the hypothesis has been tested. This thesis willfocus on systems analysis of waste and energy. The four main objectives - formulated asquestions- of this thesis are:

1. What is environmental systems analysis in general and the computer modelORWARE in particular?

Environmental systems analysis is described in chapter 2 and the computer model is brieflydescribed in chapter 3.2. A more detailed model description can be found in Paper 2.

2. Why is the systems perspective important in the planning of waste management?This part can be found in the first part of the discussion, chapter 4.

3. Which are the strengths and the weaknesses with the current ORWARE approach?As a second part of the discussion, the advantages and disadvantages with the existingORWARE as a method for analysing impacts of waste management on the environment, theenergy turnover and the economy, is discussed.

4. How can the experiences of ORWARE be developed to an approach tosustainability assessment of technology chains?

Some ideas of how to develop the model to meet new demands, predominantly in the energyfield, are explained at the end of the discussion part.

The research, and thus the content of this thesis, is aimed to be useful for practitioners.Important target groups are persons in waste managing companies, authorities and otherresearchers within the field. The readers are assumed to have a background in natural scienceand/or technology with interests in waste, energy, environment and systems thinking.

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2 Methods and concepts

The term Environmental Systems Analysis is described in this part. Tools forenvironmental systems analysis in general and waste management in particular aresurveyed.

2.1 What is environmental systems analysis?

One of the first applications of systems analysis was military. In order to provide the troopswith enough food, ammunition, fuel etc. and at the same time consider actions like taking careof the wounded and fight the enemy, a systems approach had to be used. A clear definition ofthe military systems analysis is hard to produce but a guess would be that an overall aim withthe systems analysis was to bring "the right man on the right place at the right time with theright equipment". Today, systems analysis is used in a number of areas. The world of softwareprogramming is perhaps one of the most widely used, but also for city planning and designingof factories, systems analysis is helpful.

It is not entirely easy to define systems analysis in general terms, but an attempt could be touse definitions from a thesaurus (Malmström et al, 1994). Here, a "system" is defined as:

“Methodical or naturally ordered connected entirety”

The meaning of "analysis" is described as

“Deep investigation of the connections between different parts in a phenomenon”

Combining these two definitions, a somewhat complicated description of systems analysis is

“Deep investigation of the connections between different parts in a methodical ornaturally ordered connected entirety”

Another way of describing systems analysis can be found in the literature. Systems analysis isdiscussed in detail in “Handbook of systems analysis (Miser & Quade, 1995). In the book noclear definition of the term is given, but a rather extensive discussion on what it contains. Itstates that

“…a systems analysis commonly focuses on a problem arising from interactionsamong elements in society, enterprises and the environment; considers variousresponses to this problem; and supplies evidence about the consequences-good, bad,and indifferent-of these responses” (Miser & Quade, 1995).

Whether the broad explanation or the more precise by Miser and Quade is used, it isunderstood that systems analysis is a method to understand complex connections betweendifferent entities by working systematically.

As the meaning of systems analysis now is described, an explanation of the more narrow termenvironmental systems analysis is to be found. Adding the word “environment” to thecomplicated definition from the thesaurus above gives following explanation ofenvironmental systems analysis:

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“Deep investigation of the connections between different parts in a methodical ornaturally ordered connected entirety and their impact on the environment"

The term “environmental systems analysis” has been used at the Division of IndustrialEcology, Department of Chemical Engineering, Royal Institute of Technology (KTH) since1996 as a common name for the analytical and assessment work gradually being built up since1993. The term “environmental” is used to emphasise the purpose of the systems analysis,environmental improvements. We define environmental systems analysis as:

“…models and methods for integrated quantification and presentation of material andenergy flows in different sub-systems of nature and society and the evaluation of thefuture sustainability of different alternatives of action”.

In our definition of environmental systems analysis at KTH (which also is the definition to beused in this thesis), several common analytical approaches fit in, such as

¤ Environmental Impact Assessments (EIA; Petts, 1999),¤ Life Cycle Assessments (LCA; ISO 1997),¤ Material Flow/Flux Analysis/Assessments/Accountings (MFA; Baccini & Brunner, 1991;

Burström, 1998),¤ Substance Flow Analysis (SFA; van der Voet et al, 1995; Udo de Haes et al, 1997),¤ Ecological Footprints (EF; Wackernagel & Rees, 1996),¤ Ecological Economy (Costanza et al, 1993) and to some extent¤ Environmental Economics (Turner et al, 1994).

Different scopes (and therefore different system boundaries) are being used in the above-mentioned analyses. Some include social, economical and ecological issues, while others arestrictly used for one aspect of sustainability only. The methods are developed individually fordifferent purposes, which explains the difference. Each method shows strengths andweaknesses and by combining and adapting two or three of them it is possible to "do morewith less".

The ORWARE approach, which will be described further on, combines LCA, MFA, SFA andto some extent environmental economics to a tool for environmental systems analysis ofwaste management. All strengths and weaknesses with ORWARE, as described in chapter 4.2,are inherited from these existing methods.

2.2 Tools for environmental systems analysis

With the aim to place ORWARE on the map of environmental systems analysis, some examplesof environmental systems analysis tools will be given. The tools will only be shortly discussed.For more information on the subject, reference is made to Moberg (1999).

The comparison includes four different tools, namely Life Cycle Assessment (LCA), Cost-Benefit Analysis (CBA), Exergy Analysis (EA) and Risk Assessment (RA). These tools arethen compared with ORWARE. The selection of these methods can be considered subjectivebut also based on tools from which ORWARE originates (LCA and CBA) and tools that Ibelieve could add a substantial value to the type of analysis performed with ORWARE. Thecomparison made here is not so detailed and some of the originally compared categories havebeen left out. For more information about the compared categories, see Moberg (1999).

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Table 4 Comparison of different tools for environmental systems analysis (LCA = Life CycleAssessment; CBA = Cost/Benefit Analysis; EA = Exergy Analysis; RA = Risk Assessment).

LCA CBA EA RA ORWARE

PURPOSE communicationdecisionsupport

learning

decisionsupport

decisionsupport

learning

decisionsupport

communicationdecisionsupport

learning

OBJECT productsfunctions projects

strategies

productsprojectseconomies

chemicalsubstance

wastemanagement

PERSPECTIVE lifetimeprospective

retrospective

prospective prospective

retrospective

prospectivelifetimeprospective

retrospective

SYSTEMBOUNDARIES

core-extensionfunctiontime

economicgeographical geographical

populationarea

core-extensionfunctiontime

REFERENCE yes yes (zero) yes tolerablelevel

yes

UNIT emissions

extractionimpacts

monetary Joule of exergy probability emissions

MJ primarymonetaryimpacts

EFFECTSenvironmental

economicalenvironmental

social

environmentalhumanhealth

peace ofmind

economyenvironment

energy

QUANTITATIVE/QUALITATIVE

quantitative quantitative quantitative quantitativequalitative

quantitative

STANDARD yes roughguidelines

no within EU no

FREQUENCY high high low medium Low

Note to Table 4:Overall purpose of the tool?Describes the main reason for the development of the tool.Which object is being analysed?In which perspective may the analysis be used?The tool may be used for monitoring/accounting as well as keeping record of progress(retrospective). The tool may be used to predict future situations (prospective). The tool may alsocover the whole time frame wherein a product or project has an impact (lifetime).Which are the system boundaries?Which are the temporal, spatial and functional boundaries?Is there a need for a reference object?Does the result stand on its own or is a comparison with a reference object necessary?What is the unit of the result?Gives a hint about how the results are presented.What kinds of effects are considered?Are environmental, economical and /or social effects included?Is the method quantitative or qualitative?Is the method standardised/harmonised?Where and how frequently is it being used?

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As can be seen in Table 4 the similarities between ORWARE and LCA are quite obvious. Acombination of column 1 (LCA) and 2 (CBA) reflects ORWARE very well. From this one couldsay that ORWARE is an LCA for the function of waste management extended by a simplifiedcost-benefit analysis.

Exergy analysis as well as risk analysis is hard to interpret in this context. Exergy is anotherway of communicating energy balances where the quality of energy plays an important role. Inan LCA of an energy system (not just electricity) it could be wise to include exergy analysis. Asthe emissions are valued with respect to different potential environmental impacts the energyalso could be valued with respect to potential applications. That means that it does not haveto be a conflict between exergy analysis and e.g. ORWARE.

Risk analysis is more of estimating the probability and the consequences of accidents and doesnot fit in with the other methods with respect to using almost the same input data. But theresult of a risk analysis can be valuable in the interpretation of the results from the othermethods. Impact on human health is probably the uniting factor between risk analysis and theother methods.

2.3 Models for systems analysis of waste management

ORWARE is a tool for environmental systems analysis of waste management. It is a computer-based model for calculation of substance flows, environmental impacts, and costs of wastemanagement. It was first developed for systems analysis of organic waste management, hencethe acronym ORWARE (ORganic WAste REsearch), but now covers inorganic fractions inmunicipal waste as well. ORWARE consists of a number of separate submodels, which may becombined to design a waste management system for e.g. a city, a municipality or a company.Each submodel describes a process in a real waste management system, e.g. waste collection,waste transport, or a waste treatment facility (e.g. incineration).

But ORWARE is not the only computer model for systems analysis of waste management. Aliterature survey on different environmental waste models has been done in order to compareORWARE with similar models. The models were chosen because of not being compared toORWARE before and for their significant similarities with ORWARE.

EUGENEA French model for regional planning of solid waste management.MARKALA model developed by several countries for energy purposes. Extended to include material flows likewaste.MWSA Swedish model developed from the model MIMES/Waste to cover the national level.ETHA Swiss model for comparison of different incineration alternatives. The model has no name but isdeveloped at ETH in Zürich.FMSA Swedish model developed during the last two years using ORWARE as a pattern for some parts ofthe model. The model has no name but is developed by the Swedish research group FMS(Forskningsgruppen för Miljöstrategiska Studier; Environmental Strategies Research Group)

Abbreviations and additional information to Table 5 (adapted from Björklund, 1998):

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Decision areasArea about which information is provided by the model: waste generation prediction (WG), facilitysite selection (FS), facility capacity expansion (FC), facility operation (FO), vehicle routing (VR),manpower assignment (MA), over-all system operation (not including waste collection) (OS), systemscheduling (SS), waste flow (WF), environmental performance (EP), technology selection (TS)Model typeKey model features: static, dynamic, simulation, optimisation, multi criteria optimisation (MCO),scenario comparisons, input-output analysis (IO), multiple criteria analysis (MCA), geographicinformation system (GIS)ObjectiveParameters in goal function in optimisation models, or other aim with the modelEnvironmental aspectsEnvironmental aspects covered by the model.CostsFinancial and/or environmental costs covered by the model.LCIData on the life cycle inventory available from the model.Impact assessmentImpact categories covered by the model.OptimisationOptimisation parameters covered by the model.Waste typesCharacterisation of waste types handled by the model.Waste descriptorsHow the waste is described in the model.Waste management processesDifferent types of waste management processes included in the core system of the model.Other processesUpstream, downstream and complementary processes covered by the model.Functional unitsFunctional units covered by the model.

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Table 5 Comparison of different waste models.

EUGENE MARKAL MWS ETH FMSAuthors Berger et al (1998) Gielen, D. J (1998) Ljunggren, M. (1997) Hellweg et al (1998) Finnveden et al (2000)

Decision areas FS, FC, OS, TS WG, FC, OS, SS, EP,TS

OS, SS, WF, EP, TS WG, EP, TS OS, SS, WF, EP, TS

Model type Dynamic, optimisation,scenario comparisons

Dynamic Static, simulation,scenario comparisons

Dynamic, scenariocomparisons, IO

Static, simulation,scenario comparisons

Objective Decision support systemfor regional decisionmakers

Calculates least costsystem configurationSelection ofimprovement options

Minimise the totalannualised cost for thenational wastemanagement system.

Dynamic calculation ofwaste inventory data asa first step of life cycleassessment

Evaluate environmentalimpacts and total energyturnover for differenttreatment options andwaste fractions.

Environmental aspects None Emissions (NOz, SOx,CO2), resource use,land use, waste volume

Emissions (CO2, NOx,SOx, CH4, CO, HC, Hg,Pb, Cd, Zn)

Emissions (CO, VOC,dioxins and furans),resources and energy

Air, water and soilemissions, energyturnover, use ofresources

Costs Yes Yes Yes. No No

LCI No Yes No Yes Yes

Impact assessment No No No Yes Yes

Optimisation Total discounted netsystem costTotal cumulativelandfilling

Costs CostsEmissions

No No

Waste types Regional solid waste Municipal solid waste Household waste, non-specific industrial waste,construction anddemolition waste

Inert and combustiblewastes

Municipal solid waste

Waste descriptors Waste fractions1 Waste fractions2 Waste fractions3 andsubstances

Waste fractions4, inert orcombustible, elementsand compounds

Waste fractions5,elements andcompounds

1 Paper, cardboard, containers, HDPE, LDPE, PET, sewage sludge, sawdust and even more2 30 categories e.g. Paper and board, kitchen waste, garden waste, glass, metals, plastics, textiles, wood products

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Waste managementprocesses

Collection, transports,material recyclingcomposting,incineration, landfilling

Different recyclingoptions and thermaltreatment options,landfilling

Source separation,collection, transports,central separation,transfer stations,anaerobic digestion,composting,incineration, landfilling

Collection, transportsincineration, landfillingof slag and incinerationresidues

Collection, transports,material recycling,anaerobic digestion,composting,incineration, landfilling

Other processes Markets for energy andrecyclable materials.

None. None. Production of processadditives, infrastructure,transportation

Heat production,electricity production,production of differentadditives, production ofrecycled materials fromvirgin raw materials,production of fertilisers,production ofimpregnated wood,production of biogasand fossil vehicle fuel

Functional units Treatment of waste fromcertain area.

Treatment of waste fromcertain area.

Treatment of waste fromcertain area.District heating.

1 kg waste Treatment of theamount of the includedwaste fractions collectedin Sweden during oneyear

3 Paper, glass, cardboard, metal, plastics, wood, combustible fraction, non-combustible fraction, compostable fraction4 Paper, glass, metals, ceramics, PVC and even more5 Food waste, newspaper, mixed cardboard, corrugated cardboard, PE, PP, PS, PVC and PET.

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The comparison is based on the principles presented by Björklund (1998) where four differentcomputer models were compared with each other from a number of perspectives (Table 3, p.18 in Björklund, 1998). As other models have arisen on the arena since 1998 and ORWARE hasbeen updated and extended, an updated version of the survey was necessary.

A continuous modernisation of ORWARE has been made since 1998. The functional units inORWARE have today been extended to also include recycled material (cardboard and HDPEfrom packaging) and transports by bus and/or car. Some new processes in the wastemanagement system and the complementary system have also been added, see paper 2. In anongoing project, ORWARE is being complemented with emissions and primary energyconsumption for the construction phase in those cases the discrepancies between the wasteprocesses and the complementary processes regarding these impacts are considerably large.

Taking into consideration the survey made by Björklund and the survey made here someconclusions can be drawn. The number of models is still increasing. Sweden is a small countrywhere two models, MIMES/Waste (from which the MWS model is based upon) andORWARE, are constructed. Despite that, a third model from Sweden has arrived on the arena.How come? Are Swedes more concerned about the environment and more skilled in wastemanagement and modelling than others? The models already existing ought to be “goodenough” as many people have worked them out for many years, constantly refining them. Theanswer is perhaps that the apprehension about how to assess the problem and the variety ofaims with the assessment gave birth to still another model. Following the curve of invention(growth-stagnation-regression) it seems that the modelling approaches are still in the growthphase.

In the survey of Björklund the model of US-EPA, the British model by White andMIMES/Waste can be considered to be “ORWARE -alike”. In this survey the two outstandingmodels are MWS and FMS as they are most “ORWARE -alike”. The other models lack e.g.economy or cover less fractions of waste. The MWS model is a development ofMIMES/Waste from a regional model to a national one. ORWARE can also be developed andadjusted in that way by using statistical data. If environmental impact assessment would beincluded in MIMES/Waste and the MWS models they could be of interest to be comparedmore in detail with ORWARE, e.g. in a case study. Then also the FMS model could beevaluated against the others.

It is worth mentioning that large parts of the world like South America, Asia and Africa arenot represented here. Asia is perhaps the most important of these as the population growthrate is very high and the society development is very rapid. Developing ORWARE to Asianconditions is probably harder than to Swedish, but also probably more challenging.

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3 Summary of included papers

This chapter presents a summary of each appended paper. The summaries arefollowed by a part about the personal experiences from the studies and theconsequences for the following research.

3.1 Paper I

Simulations of Material Flows in a District Heating System -Influence of Solar Heating and Flue Gas Condensing

A study of material flows of carbon, sulphur, nitrogen and phosphorous for different kinds offuels was conducted for the district heating system of the southern part of the city ofStockholm. Different scenarios were set up for the year of 2000. The reference scenariodescribes a system according to the present plans at Stockholm Energi (today Birka Energi),the main supplier of district heating for Stockholm. From this reference, some technicalsolutions were introduced; large scale solar heating and flue gas condensing.

3.1.1 Aim of the study

The aim of the study was to describe how different material- and energy flows would decreaseduring operation time with the introduction of solar heating or flue gas condensing or acombination of the two in a district heating system in Stockholm. The system studied iscomparatively large and complex; therefore emphasis was put more on trends in changedmaterial flows than on exactness.

3.1.2 System boundaries

The geographical area was the southern system of district heating in Stockholm correspondingto a need for about 3000 GWh of heat. The time frame was one year although the calculationswere made month by month. The functional units were district heating and electricity.

3.1.3 Results

The combination of flue gas condensing, solar heating and long-term heat storage maydecrease the flows of the studied materials with 15 - 20 %. To accomplish such a decrease, atotal solar panel area of 540 000 m2 would be required. A solar plant of this size will have aheat production of 204 GWh, which corresponds to about 7 % of the delivered heat from theSouthern net. To store enough with heated water for the winter period, twelve long-term heatstorage tanks with a total volume of approx. 1.2 Million m3 would be needed. A long-termstorage for heated water gives a large decrease of material flows since it reduces originalproduction in the winter when the emissions reaches a maximum.

3.2 Paper II

ORWARE 2000 - a calculation tool for waste management

ORWARE is a tool for environmental systems analysis of waste management. It is a computer-based model for calculation of substance flows, environmental impacts, and costs of wastemanagement. It was first developed for systems analysis of organic waste management, hencethe acronym ORWARE (ORganic WAste Research), but now covers inorganic fractions inmunicipal waste as well.

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ORWARE consists of a number of separate submodels, which may be combined to design awaste management system. Each submodel describes a process in a real waste managementsystem, e.g. waste collection, waste transport, or a waste treatment facility (e.g. incineration).

3.2.1 Methods and general description of the model

All submodels in ORWARE calculate the turnover of materials, energy and financial resourcesin the process. Processes within the waste management system are e.g. waste collection,anaerobic digestion or landfill disposal. Materials turnover is characterised by the supply ofwaste materials and process chemicals, and by the output of products, secondary wastes, andemissions to air, water and soil. Energy turnover is the use of different energy carriers such aselectricity, coal, oil or heat, and recovery of e.g. heat, electricity, hydrogen, or biogas. Thefinancial turnover is defined as costs and revenues of individual processes.

A number of submodels may be combined to a complete waste management system in anycity or municipality (or other system boundary). Such a conceptual ORWARE model of acomplete waste management system is shown in Figure 2.

Landfilling

Wastesource 1

Wastesource 2

Wastesource 3

Wastesource 4

Wastesource n

Transport Transport Transport Transport Transport

Materialsrecovery

Thermalgasification Incineration

Anaerobicdigestion Composting

Sewagetreatment

Transport Transport Transport Transport Transport Transport

Biogasusage

Organic fertiliserusage

Materials

Energy

Costs

Products

Revenues

Emissions

Energy

Figure 2 A conceptual model of a complete waste management system comprising a number ofprocesses described by different submodels.

At the top of the conceptual model in Figure 2 there are different waste sources, followed bydifferent transport and treatment processes. The solid line in Figure 3 encloses the wastemanagement core system, where wastes are treated and different products are formed.

3.2.2 Life Cycle Assessment in ORWARE

The material flow analysis carried out in ORWARE generates data on emissions from thesystem, which is aggregated into different environmental impact categories. This makes itpossible to compare the influence of different waste management system alternatives on e.g.the greenhouse effect, acidification, eutrophication and other impact categories.

The system boundaries are of three different types; time, space and function. In an analysis ofa certain system, the temporal system boundaries vary between different studies (depends on

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scope) and also between different submodels. Most of the process data used are annualaverages but for the landfill model and the arable land long-term effects are also included.

There is a geographical boundary delimiting the waste management system as shown in Figure2, whereas emissions and resource depletion are included regardless of where they occur. Thesystem boundaries in ORWARE are chosen with an LCA perspective, thus including inprinciple all processes that are connected to the life cycle of a product (in this case a wastemanagement system). Our coverage of life cycle impacts covers raw material extraction,refinery, production and use. Construction, demolition and final disposal of capital equipmentare not included regarding energy consumption and emissions but are included for economy.

Another aspect of the LCA perspective in ORWARE is the use of functional units. In the ISOstandard (ISO, 1997) a functional unit is defined as “the quantified performance of aproduct”. It is thus a measure of the function a product (or a system) is able to fulfil, and isimportant to define clearly in comparisons of different systems. The main function of a wastemanagement system is to treat a certain amount of waste from the defined area. Today, manywaste management systems provide energy supply in addition to waste treatment. In othercases, they provide fertiliser, or in most recent years recycled products or materials. In orderto achieve a just comparison between different waste management alternatives, functions notpresent in a certain system have to be compensated for, as mentioned in e.g. (Finnveden,1998). The compensation of functional units in ORWARE is achieved by expanding the systemboundaries to include different so-called compensatory processes (cf. Figure 3).

Compensatory systems also have up-stream and down-stream processes. Therefore, eachtreatment alternative in ORWARE has its own unique design of core system as well as differentcompensatory systems. This has been illustrated in Figure 3.

Wastemanagement

systemCompensatory

system

Upstream systems

Downstream systems

Functionalunits

Material andenergy flows

Material andenergy flows

Figure 3 Conceptual model of the total system in ORWARE (cf. Eriksson & Frostell, 2000).

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The total system comprises:¤ the waste management system with different submodels i.e. the core system of the waste

management system¤ key flows of material and energy connected to up-stream and down-stream systems¤ the compensatory system with core system as well as up- and downstream systems.

Either the waste management system or the compensatory system (cf. Figure 3) provides thefunctional units.

The different submodels are (cf. Figure 2):

¤ Waste sources and waste fractions, which act as input of material to be treated.¤ Transports that takes waste or material from the sources to and between the treatment

facilities. Transport vehicles are predominantly different kinds of trucks.¤ Incineration.¤ Thermal Gasification is a submodel not primarily developed for ORWARE purposes.¤ Landfilling is one of the more complicated models, since the fate of different compounds

differs a lot, and the environmental effects depend very much on the time span includedin the analysis The model separates surveyable time (within 100 years) from long-term(>1000 years) emissions.

¤ Material Recycling, or material recovery, covers containers made of polyethylene (PE)and cardboard and is based on data from Swedish facilities.

¤ Anaerobic Digestion.¤ Composting can be performed in three ways: large-scale reactor, large-scale windrow or

private garden composting.¤ Sewage Treatment.¤ Gas Utilisation is a downstream process for usage of the methane gas (biogas) and/or the

synthesis gas.¤ Organic fertiliser usage is a downstream process that includes spreading of residues and

arable land. It calculates the emissions from the soil compared with the use of mineralfertiliser.

¤ The Compensatory System consists of upstream and compensatory systems to the wastemanagement system.

3.3 Paper III

Anaerobic treatment of Municipal Biodegradable Waste

The aim of the study was to assess the feasibility of using biocells for anaerobic treatment ofthe organic fractions in municipal solid waste. A submodel of a biocell was constructed inORWARE and a case study performed where organic waste treatment in biocells, an anaerobicdigester and in a landfill was simulated. The organic waste was divided into a high quality partcollected from e.g. restaurants and trade and a medium/low quality part from households.The parameters considered were energy turnover, treatment costs, global warming potential,eutrophication and the fate of heavy metals.

The study showed that with available information and assumptions made, the biocell could bean alternative to the use of an anaerobic digester. The important difference to the digesteralternative is the significantly lower treatment and investment costs. However, ifenvironmental aspects are very important, the anaerobic digester is the preferable solution.The results from data and information inventory indicated that further research concerning

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the application of organic waste processed in a biocell and used as fertiliser has to beimplemented to increase the knowledge and development of this procedure. Furtherknowledge with respect to the control of biocells and the total amount of biogas that can berecovered is also essential.

A subgoal in this study was to test a new ORWARE application. Instead of evaluating acomplete waste management system, the system boundaries were set around the treatment ofthe waste. Compensation for loss of electricity, nutrients to soil etc. were accounted for, buttreatment options and waste fractions were fewer and parts of the waste management system,like waste transports, were cut out. Therefore an important result of the study was thatORWARE is feasible even on a lower system level for assessing the selection of differenttechnologies.

3.4 Comments on the papers

3.4.1 Paper I

I made this study as my Master thesis together with Johanna Olander (Olander et. al, 1997).The study can be categorised as a pioneer study as it was the first material flow analysis to bemade as a diploma thesis on this system level at the department of Industrial Ecology. Anearlier study of nitrogen flows in the municipality of Varberg (Burström, 1996) was performedbut now four substances were considered simultaneously, and the degree of detail was higher.It was also the first time that both a computer program and a case study was performed at thesame time.

The M. Sc. project was my first contact with systems analysis, something I missed from myundergraduate studies. With this analytical method, I got a much more expanded picture ofenergy conversion and environmental impact problems. To include also economy in theanalysis was desired by Stockholm Energi, but there was not sufficient time to examine thecosts for the different scenarios. The relation between environmental importance and timeconsumption for the inventory, especially for transports, was evident and something wepointed out as an important factor to see to in the work planning of a material flow analysis.

The connection to the work with ORWARE is evident. A large part of the district heatingemanated from the incineration of household waste. As flue gas condensing depends onmoisture content and the amount of wet fuel (e.g. waste) combusted, and solar heating doesnot fit with the temperature levels of the district heating, an increase of the incineration couldbe of interest. This idea is supported by the assumption that 25 % of the carbon in the wasteis fossil carbon. Thus, I realised that a more detailed analytical approach to energy from wastewould be of general interest. This was how I came to start as a Ph. D. student and switchedfrom energy technology, via energy and systems analysis to energy from waste and systemsanalysis.

3.4.2 Paper II

While the Ph. D. students of ORWARE previously were focused on development of submodelsand testing the models in case studies, I have been working with the model on a more run-and-go basis. When I started in 1998, there was a lack of detailed documentation of thedifferent submodels, as well as documentation of how to run the model. The present ORWAREgroup decided to produce a comprehensive documentation. This has later been done and thecurrent ORWARE model is described in terms of conceptual models and brief descriptions ofthe different submodels in paper 2 which is an update of (Dalemo et al, 1997).

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In each case study there is always a need to connect the submodels used with each other andto adjust the models to the local conditions. Except for some minor developments, likeintroducing a brand new structure for the compensatory system and improving thepresentation of results by "new" types of diagrams and standardised LCI data sheets, my workhas been focused on facilitating the simulation process from data inventory and modeladjustments to digestible results. Starting with a model of Uppsala models for the wastemanagement systems in Stockholm and Älvdalen (Sundqvist et. al, 2000a-2000d) have beenbuilt. To create a new system-model from scratch is often made by cutting out submodel bysubmodel from an existing ORWARE model. In this way a model of the future organic wastetreatment system in Jönköping was built (Eriksson & Svanblom, 2000). I have also beeninvolved in the model construction of the municipality of Värmdö, which has been examinedin two diploma theses (Jonsson, 2000 and Skoglund, 2000).

New application areas for the systems approach in ORWARE have been discussed for a longtime. There is still more to do in the waste sector, in Sweden and also abroad, with a tool likeORWARE. The interest for using ORWARE in case studies or for educational purposes is alsoincreasing. Despite this, new applications always seem interesting and challenging. That washow I came to the vision of adapting ORWARE to deal with energy systems. Looking closer atthe existing models of energy systems I realised that energy systems analysis is a world withmany models, many stakeholders and also strong political influence. Instead of seeing that as achallenge, I changed my mind and restricted myself to correct the inconveniences with theexisting ORWARE model and to incorporate some new aspects besides the aspects of theenvironment, energy and economy. By doing so it would be possible not just to go from wasteto energy, but to a more wide range of applications. Evaluating technical solutions with asystems perspective and putting the focus on the function delivered by a technology chain(following the function from the cradle to the grave) came up as something interesting. Thisidea, displayed in paper 3 and 4, gave me information about gaps in the methodology and theneed for further development.

3.4.3 Paper III

The work was made in co-operation with a M.Sc. student and the full report can be found in(Fliedner, 1999). The existing ORWARE landfill submodel comprised submodels for mixedwaste, slag, ash and sludge and as biocells were introduced to some real landfills the researchgroup wanted to have a submodel for this as well. Other aims were to gain some more insightinto (i) the possibilities to an increased biogas production compared to ordinary landfilling, (ii)the environmental performance of biocells and (iii) the economical aspects of biocelloperation. But, as mentioned above, a sub goal also was to use ORWARE in a new way. Thiswork gave a first hint about how the model could be used to compare different technicalsolutions. In another master thesis project, more high-tech technical solutions were studied toinvestigate the potential of ORWARE as a tool for environmental technology assessment(Assefa, 2000).

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4 Discussion

The discussion is divided into five different parts. First (1) the complexity of wastemanagement is described and the importance of a systems approach is explained.After these general issues the discussion focuses (2) on the simulation modelORWARE as it is used today. The strengths and weaknesses are presented anddiscussed. In a separate part (3) the reliability of the results and the analysis isdiscussed. After that (4) follows a section with some conceptual ideas of how tocombine different systems engineering tools with new ideas of methodimprovements. Last (5) are some thoughts about future research.

4.1 Waste management and the importance of a systemsperspective

The challenge to treat different wastes in an optimal way is extremely complicated. Animportant aspect of this complexity is the large number of actors, or stakeholders, involved insociety's discussion of how the waste should be treated in the best way. A number of theseactors in Sweden are:

¤ The households who generate large amounts of mixed waste and are paying a fee for thewaste management. The households may also work as consumers of the services and theproducts generated by the waste management, e.g. district heating and recycled paper.

¤ The companies, like the households, generate different types of wastes. Household waste isheterogeneous from each source but quite homogenous for different sources. Businessand industrial waste is more homogenous from each source but varies more betweendifferent sources.

¤ The private waste companies that are included in the group above, but also are managers orentrepreneurs of different services in the waste management sector. Examples arecompanies who collect waste and run different treatment facilities.

¤ The municipality which is responsible for the waste management on behalf of the citizens.Municipal authorities in this field are offices for fresh water supply, sewage collection,waste treatment, energy supply, traffic control, environmental protection, Agenda 21 etc.

¤ The energy companies that often were owned by the municipality but have more and morebecome independent profit earning companies. Because of the importance of energysupply they are often dominating in the discussion.

¤ The agriculture that is the end user of the products generated in nutrient recycling fromorganic waste. Agriculture has a strong connection to the food industry and hence to theconsumers, predominantly the households.

¤ The material companies defined as the companies acting on a market for recycled materials.¤ The authorities with the task to monitor the fulfilment of legal requirements. Examples of

these actors are the Environmental Protection Agency (Naturvårdsverket), The LabourInspectorate (Yrkesinspektionen), the National Chemicals Inspectorate(Kemikalieinspektionen) and the Swedish Institute for Infectious Disease Control (SMI)(Smittskyddsinstitutet).

¤ The Non Governmental Organisations that often are very active in the environmental field andalso scrutinise the ongoing activities. Examples are Greenpeace, the Field Biologists, theEngineers for the Environment, and the Green Drivers to the Environment.

¤ Media that works as a forum for discussions but also scrutinise and pull opinion.

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Besides the actors, there are a large number of technical solutions to consider, shown by thefollowing examples:

¤ Collection (front loader, pack-packer, vacuum truck etc.)¤ Treatment option (product recycling, material recycling, incineration, gasification,

biological treatment, landfilling)¤ Use of products (new paper, new plastic, different fuels, nutrients to soil)

A third factor is the different impacts the waste management causes the society and theenvironment:

¤ Impact on the environment as contribution to acidification, eutrophication, globalwarming potential etc.

¤ Impact on the energy turnover as the energy in the waste can be recovered and utilised.¤ Impact on the economy for different actors.

The amount and combination of different actors, technical solutions and different kinds ofimpacts, result in waste management often being heavily discussed and criticised. Often,demands on a new- and reorientation are raised. As examples can be seen:

¤ New regulations are coming from authorities at all levels.¤ Waste is changing character and amount over time.¤ New effects on health and environment are discovered all the time.¤ Markets are de-regulated.¤ New technologies are constantly developed.

Facing this background, it is clear that the need for a systems approach is great and thatdifferent stakeholder perspectives have to be discussed and highlighted. Using a systemsapproach can be helpful in this work. Environmental systems analysis is often focused ontools for describing a complex problem and to find solutions. By using a tool that is aimed atsystematically illuminate an object from different angles, both the socio-technical problem, theenvironmental problem and the financial problem can be discussed simultaneously.

Computer models that have the ability to handle large amounts of information can be used aspractical tools to execute calculations supportive in making decisions. The rapidly improvedinformation technology creates new possibilities to collect, calculate and present information.With the help of models, different actors can be brought closer to each other as morecomplete and foreseeable information is "on the table". At the same time, the faith in thesetools should not be overestimated. There are several aspects that are not included in computermodels and therefore it is important that they are used with sense and that the conclusionsdrawn are well established.

4.2 ORWARE of today - strengths and weaknesses

The benefits of (the strengths) and the problems (the weaknesses) that normally occur, whenusing ORWARE, will be hereby be presented and explained. For the weaknesses some ideas ofhow to resolve them are also suggested. This survey is based on practical experiences fromthree years of research work with ORWARE, and reflects my own point of view.

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4.2.1 Strengths

ENABLES FLEXIBILITYOne of the strengths with ORWARE is the flexibility. The model is unique in its capacity to beadapted to local conditions. In the beginning of a case study ORWARE consists of a data set ofstatistical and empirical data, also called "default data". Together with the customer a list ofthe most important parameters is discussed. After test simulations, some data on the list mayhave to be adjusted and maybe some not on the list have to be added. This procedure takestime, but is a necessary step. It supports the gradual education of the project team and if timeand resources allow, new questions may be discovered, new scenarios constructed and newsimulations run. This however takes time and that is often seen as a disadvantage. Anotherproblem is, that the when the practitioners realise the level of details that the model provides,they tend to get in more and more detail of the system, not considering the necessity ofchanging every figure at the micro level.

ILLUSTRATES COMPLEXITYAnother strength is that ORWARE illustrates the complexity of the system. The complexity asdescribed in 4.1 (many actors with different opinions and interests, different treatmentoptions, waste sources, impacts and functional units), is best described by making a systemsanalysis. With a systems approach, it is possible to map all these actors and assess thecomplexity. The environmental impacts of the LCA, however, are very complex to determineand altogether the model may appear quite complex. The complexity is also a weakness andwill therefore be discussed further on.

SUPPORTS DIALOGUEOne positive aspect of systems analysis is that it brings different stakeholders together todiscuss theirs and other stakeholders problems from a systems perspective. More efficientsolutions are to be found when not just talking one stakeholder to another. In the ORWAREgroup, there has been an improved dialogue between the researchers themselves and betweenresearchers and waste managers. Having to speak the same language and understand eachother’s positions, have had a positive effect on the mutual understanding of the system. Thus,it is not only the results from ORWARE that are achievements but also the process of graduallyunderstanding different aspects of a very complex system. The dialogue has also resulted indemands from the customers (waste companies and waste managers) to produce legible andmore easily understandable results that can be implemented in the planning process.

COLLECTS KNOWLEDGESustainability demands expertise from various areas and disciplines. Interdisciplinary researchis not easy to work out but often desired by society. This is e.g. mentioned in the researchproposition from the Swedish government: The environmental research is another area, whichto a higher and higher degree incorporates researchers from in principle all disciplines.Garbage separation and waste recycling can only be achieved if all aspects of the process areconsidered, from sociological and economical factors that drive the interest for wasteseparation to technical solutions in order to recycle the waste. (Regeringens proposition2000/2001:3, p. 48, my translation):

In ORWARE there are scientists from different areas like mechanical and chemical engineering,as well as people with agricultural skills (agronomists) and an economist. In the currentORWARE project, a sociologist is also involved in the work. In this way, the research work ofORWARE is interdisciplinary.

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Much knowledge is also found in the actors ball court. People with long-time experience arebeing mixed with people with new and fresh ideas. In a waste company, there may not be thetime or financial resources available to work on a strategic basis as the problems of today andtomorrow have to be resolved first. Research, on the other hand, is focused on gainingknowledge for the future. It is therefore a well-weighted combination of practicians andresearchers that often ends in the most fruitful solutions.

Building up a model like ORWARE results in an enormous amount of collected and organiseddata. The database in ORWARE is not built up on data from own measurements. Data iscollected and compiled from literature as well as reports and documents obtained fromdifferent waste management actors. Other LCA databases are also used. The collected data issomething unique and can be valuable if handled in the right way, e.g. in other LCA studiesand for regional material flow accounting.

SHOWS CONNECTIONSConnections between different types of information are hard to understand without a systemsperspective. Interesting in ORWARE, is e.g. the coupling or lack of coupling betweenenvironmental impacts and economical outcome. With a material flow analysis and a cost-benefit analysis side by side, it is possible to study the system from two perspectives, namelythe ecological and (financial) economical perspective. To finally decide between differentviewpoints, politics is necessary. As much as possible, however, political issues are excludedfrom ORWARE, except perhaps for setting up scenarios and system boundaries. The analysisshould be used as a decision support tool together with political weightings. One of the firstORWARE projects was about to evaluate waste management plans for Uppsala and Stockholm,but that was mainly due to the fact that the main task was to evaluate the reliability of themodel and not to say something about new smart system solutions. The MIMES/Waste-model (Ljunggren, 1997), on the other hand, has been used as a tool for evaluating politicaldecisions like taxes and prohibitions.

4.2.2 Weaknesses

ERRORSWhen dealing with complex items with many people involved, errors often occur. By errors isnot meant errors beyond our control like incorrect measurements etc., but errors caused bycombining a large number of data in the model is a weakness connected to ORWARE. That ismostly due to the large amount of data that has to be incorporated (with failures in typing andchecking the calculations) and also the lack of understanding about what is needed andwanted (which leads to misunderstanding and the use of wrong data). The differentstakeholders also have different customs and cultures, something that leads to problems andsometimes even to failures.

Even if the input data is satisfactory, there are other things that can fail in the calculations.This problem is sometimes discovered by the model itself and sometimes by penetrating theresults. The potential errors represent a problem, since the time needed to control such a bigsystem as ORWARE, is considerable. This must, however, be seen as a necessary evil.

Building functions into the model to monitor what is happening can solve some of theproblems with errors. Introduction of searchable databases would also make the errorhandling easier.

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SERVICE – NOT A PRODUCTPeople belonging to the waste management companies often wish to have the model installedon there own computers for every day use. At present, this is not possible if all the strengthsshould be achieved. A model easy enough to be used by a non-expert would not be as site-specific and the possibilities to lead fruitful discussions would be lost if people would use themodel and simulate scenarios on their own.

Solving sustainability problems like waste management, transportation, and energy supply etc.demands for an interdisciplinary approach as mentioned under "strengths". Butinterdisciplinary research is also a weakness when discussing the time it takes fromformulating the problem until it is solved. It takes time to (i) get the project participants tounderstand each other's objectives and way of handling and solving problems, (ii) discusscommon problems from all aspects and finally (iii) to unite and go for one solution.

The addressed problem of ORWARE as a service and not a product is not a serious problem asI can see it. But for the sake of understanding and acceptance, the model needs to exist inseveral versions. One master version as it exists today, designed for experts, one model foreducational purposes and one for illustrating the systems analysis just by visualising systemeffects without using Matlab/Simulink.

TIMEIn ORWARE there are many time perspectives. The landfill submodel is divided into surveyabletime (about one hundred years) and remaining time (cf. Paper 2). The biocell, as a part of thelandfill submodel, has a time frame of 10-20 years and a hypothetical infinite time. Asubmodel of the arable land with a nitrogen pool would work on a basis of 1-3 years and thenlong-term effects. Emissions from treatment plants, complementary energy and spreadingconditions varies from season to season. The different time frames are solvedmethodologically but are sometimes hard to explain when evaluating the results. Constructinga dynamic model would solve some of these problems but then, on the other hand, input datawould have to be more detailed. As some important factors are assumptions about the future,the analysis would be inconsistent and not useful to anyone. The time frame problem willremain for these types of systems but it is always good to minimise it.

Problems with different time perspectives must be explained and further investigated. In anongoing project "Energy from waste" - funded by the Swedish National Energy Authority -this will be done.

SPACEAn important aspect is information about where the impacts on environment, energy andeconomy are situated. Sometimes it is the clue to understand the existing situation (wasteimported and exported over municipal borders), sometimes the solutions give rise to newgeographical problems (more recycling of plastic containers reduces the emissions in thestudied municipality but the emissions increases at the recycling plant). Some space functions,like how the incineration plant interacts with the local environment such as dwelling areas androad systems, are not considered at all.

The geographical aspects could perhaps be better taken care of by a GIS (GeographicInformation System) extension, which has been tested in a project (Sivertun et al., 1998).

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INSUFFICIENTORWARE does not cover all aspects of waste management and is not meant to. Issues that arepossible to account for, like material and financial flows, are more or less included but there isstill more to deal with for a complete environmental management. When designing a wastemanagement system there are many questions to be considered. It is therefore understandablethat when many of these questions can be solely or partly answered by ORWARE, people askfor more parameters to be included. As environmental issues gradually change to sustainabilityissues, there is of course a will to broaden the ORWARE model or ORWARE approach to fitinto the discussion of sustainable waste management. As this thesis is being written, newimpact categories are investigated to be included or not. A suggestion on new tools to beincluded is discussed further on.

The strengths and weaknesses are summarised in Table 7.

Table 7 Strengths and weaknesses with the ORWARE simulation model

Strengths WeaknessesHigh degree of site specific adjustment Errors due to complexity and scopeShows the complexity of the system/problem Not a user-friendly computer program

Encourages to a dialog between actors Different time perspectivesCollects competence, information and skills Different space perspectivesMore easy to find economy/ecology connections Do not cover everything

4.3 Reliability of ORWARE

The reliability due to choice of method, modelling approach, data uncertainty etc. will not bediscussed any further here as these issues have been discussed in earlier ORWARE theses andthe issues of concern have not been dramatically changed since then. Some of the parametersof greatest importance for the result of the analysis will be discussed in this thesis. Theparameters can be divided into general assumptions and more site-specific ones. In general,there are three parameters in Swedish waste management that are of importance:

1 Everything that concerns incineration (degree of efficiency, emissions etc.).A great part of the waste studied can be incinerated and with scenarios of treating the wastewith one method or another, the incineration becomes important. Including flue gascondensing or not or using different approaches to modelling of emissions are crucial. It isvery seldom that incineration is not included in the projects carried out with ORWARE. If morestudies were done abroad, the assumptions for the landfill would tend to be crucial.

2 Choices of fuels for compensatory energy especially heat generation.This follows as a logical consequence of the importance of incineration.

3 Choice of system boundariesIncluding or excluding waste streams, treatment options or up-stream and down-streameffects are most crucial which is shown in e.g. (Björklund and Bjuggren, 1998).

The site-specific assumptions vary a lot. In particular financial costs are crucial. If themunicipality already has digestion capacity in an over-dimensioned wastewater plant, the costfor source separation and anaerobic digestion of organic waste could be several times less thanfor a municipality in a sparsely populated area with no investments made. On the energy andenvironment results the differences are often less crucial.

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Reliability is also about establishing confidence to the model and to the results. Both thecustomers (e.g. municipalities) and the researchers must be confined. The customers’confidence is achieved by

1 Regular discussions with the actors involved.2 Accurate accounts of input and output data.3 Interpretation of the results and formulation of conclusions in mutual understanding.

The researchers' faith in their own work is achieved by

1 Documentation of everything (establishing routines and responsibilities)2 Comparing the model with reality and the model with other models3 Working individually and constantly checking each other.

4.4 ORWARE of tomorrow - no time to waste

4.4.1 Aspects of energy, waste and environment

A couple of conclusions from the coupling between energy, waste and environment can bedrawn:

Waste production and energy consumption are linked to each other. They are linked in a chainalso including standard of living and environmental impact. As the standard of living raises, sodo the other factors.

Energy can be recovered from waste, and energy generation produces waste. The incinerationresults in ashes and slag, that to some extent could be used, but still landfilling has to be used.Even with a high degree of recycling, some materials can not be recycled forever and will thenhave to be incinerated which causes waste for landfilling. Does a sustainable society acceptlandfilling?

Energy generation (e.g. combustion) causes environmental impact mostly at the global level,while waste management causes direct environmental impact at a local level and indirectimpact at a national and a global level. This difference is probably one explanation to the lowunderstanding for and thus lacks of systems thinking. As a consequence, incineration has abad reputation among certain groups. People tend to see the smoke and feel the smell fromthe incineration plants instead of thinking about the alternative (that often is a quiet andpeaceful landfill on the countryside). Often the incineration plants were built several years agoand are now situated almost in the middle of the city. Energy plants are often located furtheraway from populated areas and fossil CO2 does not smell. The fact that energy is neededwhere the waste already is, is in this way both positive (short way from fuel to heat sink) andnegative (all types of waste management seem to disturb people).

When discussing energy recovery from waste most people probably think of district heating orelectricity generation. Or, in other parts of the world, district cooling and/or electricitygeneration. But there can be other ways of using the energy recovered from waste with ahigher environmental efficiency. A large contribution to the global warming potential comesfrom transports. Producing district heating and electricity from other, more sustainablesources does not seem to be an as big problem as the challenge to substitute petrol and dieseloil. Today hydrogen is seen as the most promising alternative to oil. Hydrogen can be

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produced from waste using either thermal gasification (where synthesis gas is formed that canbe transformed into hydrogen) or biogasification (anaerobic digestion) followed by steamreforming (a process to generate synthesis gas from biogas). Today hydrogen is mostlyproduced from natural gas but in the future more sustainable alternatives should be used.

Using the experiences from environmental systems analysis of waste management amethodology for assessment of energy management can be set up. From this it is possible tocreate a tool for decision-making with emphasis on environmental impact. Already existingmodels at different levels should be used whenever it is suitable but the systems perspectivecomes with the new ORWARE.

The conceptual idea is based on the fact that all anthropogenic activities start with extractionof natural resources and end with functions and emissions. The method of attack is, whilekeeping the functions constant, to minimise the negative impact to sustainability by designingthe system in between in different ways.

By sustainability is here meant:

¤ Environmental impact (as defined in LCA by resource use and emissions/impactcategories)

¤ Economical impact (on a welfare basis)¤ Social impact (e.g. provide the services, actors satisfaction, risks etc.)

In the following some improvements of the methodology used in ORWARE are suggested.

4.4.2 Extension of the number of impact categories

In the future, ORWARE could be developed into a concept for assessment of the sustainabilityof technological activities in society. It may combine several existing environmental systemsanalyses and systems approaches as

¤ LCA,¤ Systems engineering,¤ Cost-benefit analysis,¤ Actors (stake-holders) analysis and¤ Risk assessment

to a strong tool for decision-making in the selection of technology options.

Impacts on the environment are almost always connected to impact on human health. Withthe substance flow analysis that comes with ORWARE (up to 50 parallel flows) it should bepossible to include a simple risk (health) analysis/assessment. Perhaps an exergy analysis, as anevaluation of the energy turnover, would be fruitful. The emissions are evaluated in terms ofenvironmental impact categories and environmental economy. Energy is so far just evaluatedin terms of emissions from the energy generation but not in terms of energy quality. Finallythe social attitudes need to be included if the full meaning of sustainability should be covered.

4.4.3 Functions in focus

Functional units are defined as something useful that should be kept constant for all studiedscenarios. In the framework of a new model approach, a new way of looking at functionalunits by dividing them into three types is introduced.

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¤ Upstream functional units that describe the system input. For a waste management system atypical upstream functional unit would be a certain amount of waste treated. Anotherexample could be to consider the fate of the resources saved. When paper is recycled,forest is saved but what happens with the trees that are not being cut? Are they left todecompose or will they be used for other purposes e.g. fuel? These thoughts have beenbrought up to discussion by Göran Finnveden (Finnveden et. al, 2000), but have still notbeen considered in ORWARE. I consider the upstream functional units to those beingempowered by the systems ability to influence them.

¤ Core functional units that describe something within the system boundaries. In ORWAREsomething called constant plant capacity has been used which could follow thisdescription. For a treatment plant already built it is almost an economical systemscondition to run the plant at full capacity.

¤ Downstream functional units are the ones we know from before as something usefulprovided by the system to the outside. For waste management it is typically districtheating, electricity, recycled materials etc.

From now on the application illustrated will be as a tool for energy management but otherapplications (in general term technology chains) are also possible. ORWARE of today includesthe supply side of downstream functions and may therefore be used as a tool for minimisingthe relative impact, measured as emission/function provided. On the supply side there arenatural resources in the form of fuels (in ORWARE of today the fuel is waste) which istransformed to e.g. energy. The demand side of the downstream functional unit covers thechain from energy to a function but that is not modelled in ORWARE. This is shown in thefollowing figure:

WASTE

constant

CONVERSIONmaximised

ENERGY

constant

CONVERSIONminimised

FUNCTION

constant

CONVERSIONconstant

OTHERFUELS

variable

Figure 4 Picture of the current environmental optimisation in ORWARE.

As can be seen in Figure 4 only the supply side is modelled. A constant amount of waste isoptimised to maximise the amount of energy delivered (or rather minimising the consumptionof primary energy). The energy conversion for other fuels is constant but the amount varies atcompensation. Energy conversion to the function is left out.

By extending the system down-stream it is possible to go from electricity, heat, hydrogen etc.to end user services as light, mechanical work, cooling etc. In the future, it may be much morefruitful to express a functional unit as a function and not in terms of energy or material. Hencewe must examine the arrow from energy to function in the figure above.

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GOODENERGY

sustainable

CONVERSIONmaximised

ENERGY

minimised

CONVERSIONminimised

FUNCTION

constant

CONVERSIONmaximised

BADENERGY

variable

Figure 5 Picture of a future environmental optimisation.

In Figure 5 both supply and demand sides are included. The energy conversion to a properfunction is maximised implicating a minimising of energy available. The available energy is afunction of maximised energy conversion from environmentally sound energy resources usedat a sustainable level. This means that environmentally bad energy is minimised whencompensating. With "good energy" is meant such energy forms that are harmless or lessharmful to the environment e.g. solar, waste (could be doubted but landfilling is really bad)and "bad energy" covers energy from fossil and non-renewable fuels.

This extension of the ORWARE tool - when used for an energy system - will allow the doubleoptimisation of both supply and demand sides to be done simultaneously. Thus it may bepossible to find solutions for which the functional fulfilment can be achieved with less energythan before and thus with an increased overall efficiency. What is important is that the chainfrom resource to service is followed.

4.4.4 How can the approach be used in practise?

When analysing waste management different treatment options can be tested. That is whatORWARE does already today. If the approach is expanded to other process related activitiesone may consider bio-productive land in a specified area and try to find a combination oftechnologies that fulfil a certain need (functional unit) as well (from a sustainable point ofview) as possible.

In Sweden, the energy market is presently deregulated. Thus different energy companiescompete on an open market. For an energy company it is of interest to investigate thepossibilities to increase profits. Until recently it has been of most interest to invest inincreased production capacity and sell the product electricity. With the emerging demands formore sustainable energy systems, different options to produce the same function to acustomer, but at a lower environmental impact (and thus costs!) will be of greater and greaterimportance. The most common, and thus important, functions delivered by an energy systemare:

¤ Heating (predominantly in housing)¤ Cooling (housing, food)¤ Light¤ Mechanical work

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A further developed ORWARE model could be used to analyse how a new approach to delivera certain function would perform both with respect to economy, ecology and social values.

Another way to use an extended approach would be to start with an organisation and a certainamount of financial resources instead of a technical system or a function. Which measures shouldbe introduced in order to achieve as much ecological sustainability and social values aspossible at a certain cost? Should a condominium association make a change at the energysupply side or at the energy demand side? Is the most appropriate measure a change ofrefrigerators, new 3-glass windows, or the start-up of a car pool? What are the costs andbenefits on the social, financial and ecological side of increasing the amount of peopleworking from home? Social aspects of this issue could be the life quality and comfort.Financial aspects could be a higher market value of the apartment.

A fourth way to use an extended ORWARE could be in a broader context in the local society,e.g. to compare results from this type of technology chain assessment with regional material flowaccountings. A regional material flow accounting system is presently introduced in the City ofStockholm, as a result of the work with an integrated environmental information system (cf.Frostell et al, 1999). In such comparisons, results from the energy sector could be evaluated ina larger context of a whole local community. This would help in the discussion and theidentification of priorities on a higher political level in the local society, e.g. municipalities andcities.

4.5 Future research

Which are the needs for further development of the current ORWARE model? From thebeginning ORWARE was built for systems analysis of organic waste. Now the model covers allkinds of solid and liquid waste (sewage) with focus on household waste. An expansion tocover industrial waste would be interesting, in order to fully evaluate the energy potential fromwaste. Also metal scrap would then have to be incorporated. Doing this is just a matter oftime for building new submodels. I do not believe that enormously interesting research resultscould be achieved, but for the sake of creating a tool to be used and accepted by the society itis important.

A combination between including industrial wastes and introducing new research areas wouldbe to use ORWARE within the industry. Industrial sectors with a clear process structure and astrong influence of material flows are easy to “translate” into the world of ORWARE. InSweden the pulp and paper industry as well as the mining and steel sector seem interesting.Today the industry works with tools like LCA for their products and CER (CorporateEnvironmental Reporting) for the whole company. Hopefully ORWARE could fit in and linkthe existing tools to each other.

ORWARE is presently being further developed, now also trying to include analysis of thestakeholders, upstream activities (like the efforts made by the households) and also aqualitative analysis of the social impact. I would also like to see a development that combinesthe skills of the research group in Industrial Ecology at KTH. The research is roughly dividedinto systems analysis of buildings and construction, municipal/regional material flow analyses,environmental management in industry and risk assessment. It would be of great interest tocombine these four parts into something called "Environmental Decision Support".

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Finally, it would be of interest to compare the existing Swedish models for systems analysis ofwaste management along the same scale. That could be done by e.g. a peer review or by acommon case study.

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Paper I

Simulations of Material Flows in a District Heating System- Influence of Solar Heating and Flue Gas Condensing

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Paper II

ORWARE 2000 - a calculation tool for waste management

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Paper III

Anaerobic treatment of Municipal Biodegradable Waste