Laura Sokka Suvi Lehtoranta Ari Nissinen and Matti Melanen · 2018. 2. 12. · Laura Sokka, Suvi Lehtoranta, Ari Nissinen, and Matti Melanen Keywords: environmental impact Finland

R E S E A R C H A N D A N A LYS I S

Analyzing the EnvironmentalBenefits of IndustrialSymbiosisLife Cycle Assessment Applied to a FinnishForest Industry Complex

Laura Sokka, Suvi Lehtoranta, Ari Nissinen, and Matti Melanen

Keywords:

environmental impactFinlandindustrial ecologyindustrial ecosystemlife cycle assessmentpulp and paper industry

Supporting information is availableon the JIE Web site

Address correspondence to:Laura SokkaVTT Technical Research Centre of

FinlandP.O. Box 1000FI-02044 VTT, [email protected]

c© 2010 by Yale UniversityDOI: 10.1111/j.1530-9290.2010.00276.x

Volume 15, Number 1

Summary

Studies of industrial symbiosis (IS) focus on the physical flowsof materials and energy in local industrial systems. In an idealIS, waste material and energy are shared or exchanged amongthe actors of the system, thereby reducing the consumptionof virgin material and energy inputs, and likewise the genera-tion of waste and emissions. In this study, the environmentalimpacts of an industrial ecosystem centered around a pulpand paper mill and operating as an IS are analyzed using lifecycle assessment (LCA). The system is compared with twohypothetical reference systems in which the actors would op-erate in isolation. Moreover, the system is analyzed further inorder to identify possibilities for additional links between theactors. The results show that of the total life cycle impactsof the system, upstream processes made the greatest overallcontribution to the results. Comparison with stand-alone pro-duction shows that in the case studied, the industrial symbiosisresults in modest improvements, 5% to 20% in most impactcategories, in the overall environmental impacts of the sys-tem. Most of the benefits occur upstream through heat andelectricity production for the local town. All in all it is rec-ommended that when the environmental impacts of industrialsymbiosis are assessed, the impacts occurring upstream shouldalso be studied, not only the impacts within the ecosystem.

www.wileyonlinelibrary.com/journal/jie Journal of Industrial Ecology 137


Introduction

Industrial symbiosis (IS) studies examine theflows of materials and energy in local industrialsystems using a systems approach (Chertow 2000;Wolf 2007; Zhao et al. 2008).1 The approach an-alyzes economic systems through their materialand energy flows (Hart et al. 2005). The key ideaof the concept is that in an IS, waste materialand energy is shared or exchanged among theactors of the system and the consumption of vir-gin material, energy inputs, and the generation ofwaste and emissions are thereby reduced (Korho-nen and Snäkin 2003; Ulgiati et al. 2007). Lit-erature on identified industrial symbioses, indus-trial ecosystems (IES), and eco-industrial parkshas burgeoned during the past 10 to 15 years (cf.Sterr and Ott 2004). While numerous descriptiveanalyses have been conducted on the concept,there are relatively few quantitative assessmentsof the environmental benefits of industrial sym-bioses (for a discussion and review, see Sokkaet al. 2008 and 2009).

Most of the assessments of the environmen-tal impacts of industrial symbioses have focusedon the ecosystem itself and excluded upstreamand downstream impacts. For instance, the eco-nomic and environmental costs and advantagesof symbiosis partners were assessed in Guayama,a symbiosis network in Puerto Rico (Chertowand Lombardi 2005). According to the study,the symbiosis resulted in a substantial decrease insome emissions, such as SO2, and in water extrac-tion, but simultaneously there was an increase inthe emissions of CO2. The researchers concludedthat the participating organizations derived con-siderable economic and environmental benefitsfrom the symbiosis but that those benefits wereunevenly distributed among the participants.

In another example, Van Berkel and col-leagues (2009) quantitatively assessed 14 indus-trial symbioses in Kawasaki, Japan. They foundthat the by-product exchanges of the symbiosesaltogether diverted 565,000 tons of waste fromwaste management annually. In addition, it wasestimated that the documented resource ex-changes compensated for 513,000 tons of rawmaterial use annually. However, the researcherspointed out that there are trade-offs between ma-terial flow benefits and other environmental im-

pacts. They called for further research to developcomprehensive methods for the quantification ofthe environmental and economic benefits of in-dustrial symbioses.

Singh and colleagues (2007) studied an agro-chemical complex consisting of 13 chemical andpetrochemical industries in the state of Missis-sippi, USA. They conducted a so-called “entry toexit” life cycle assessment (LCA) study of the sys-tem, thus considering only materials used insidethe complex. Raw material production and wastetreatment were not taken into account. The en-vironmental impacts of the system were analyzedusing life cycle impact assessment (LCIA). Theresearchers concluded that LCA is an extremelyuseful tool for analyzing and comparing differ-ent designs of industrial ecosystems and recom-mended conducting a comprehensive LCA be-fore starting a new eco-industrial park in orderto assess the potential advantages and disadvan-tages of the system and to thereby select the bestdesign option from the perspective of sustainabledevelopment.

Only a few studies have also considered thelife cycle impacts of industrial symbioses. Sendraand colleagues (2007) applied material flow ana-lysis (MFA) methodology to an industrial area inSpain. In the study, MFA-based indicators, withadditional water and energy indicators, were usedto evaluate how the area could be transformedinto an eco-industrial park. The study thus hada life cycle view but did not include an impactassessment. More recently, Eckelman and Cher-tow (2009) studied industrial waste productionin Pennsylvania. They combined waste data fromthe area with life cycle inventory (LCI) data andthereby calculated the present and potential en-vironmental benefits of utilizing this waste. It wasfound that in all cases except for the energy useof waste oil and substitution of virgin steel withscrap steel, the reuse of the waste streams studiedresults in positive environmental impacts com-pared with the use of the substituted material.

Uihlein and Schebek (2009) compared theenvironmental impacts of a ligno-cellulosic feed-stock biorefinery to the production of fossil al-ternatives using LCA. The system was not con-sidered a form of industrial symbiosis, but inpractice its operation is similar. Since the ligno-cellulosic feedstock biorefinery has not yet been

138 Journal of Industrial Ecology


implemented in practice, the researchers assessedthree different variants of the concept. For allvariants it was found that the environmental per-formance of the biorefinery was superior to thecorresponding fossil-based production in someimpact categories and inferior in other impactcategories. Nevertheless, from the overall resultsthe researchers concluded that from an environ-mental point of view, the ligno-cellulose biore-finery concept would be beneficial compared withthe existing fossil production options.

In another study on the symbiotic exchangeswithin an eco-industrial park in China, it wassuggested that companies tend to out-source thelowest value-added and often pollution-intensiveproduction of materials and intermediate com-ponents to outside the parks (Shi et al. 2010).Therefore, the researchers concluded that in thelong-run assessments of the environmental per-formance of eco-industrial parks should be ex-tended to these spill-over effects as well.

In our previous study (Sokka et al. 2009), wefocused on the CO2 emissions and fuel consump-tion of the same IES as in this study. It was foundthat upstream processes accounted for over twothirds of the total fossil greenhouse gas (GHG)emissions of the system. Production of pigmentsand fillers had a considerable impact on the to-tal results, causing altogether over 35% of thetotal fossil GHG emissions. However, in orderto give an overall picture of the environmentalperformance of the case system, it is importantto look at other environmental impacts as well,since GHG emissions alone do not give a com-plete picture of the environmental performanceof the system.

In this study, the environmental impacts of anindustrial symbiosis that developed around pulpand paper production are assessed with LCA andcompared with two hypothetical reference sys-tems in which the actors work on their own.Moreover, the possibilities for additional linkagesbetween the system’s actors are studied in order toassess their environmental relevance. Yet, insteadof providing a full, detailed assessment of the sys-tem’s environmental impacts, the main objectiveof this study is to analyze the potential relativeenvironmental benefits achieved through an in-dustrial symbiosis and to discuss the conditionsunder which these benefits may be achieved.

Materials and Methods

Case Study IES

The chosen case study IES is situated in thetown of Kouvola in southeastern Finland. Thesystem has evolved spontaneously (meaning thatit was not intentionally developed as an indus-trial symbiosis) around an integrated pulp andpaper manufacturer, the Kymi mill of the UPMKymmene Corporation (figure 1). Paper produc-tion began at the site in 1874. The current annualproduction capacity of the integrated facility is840,000 tons of paper and 530,000 tons of pulp.Some 55% of the wood used by the UPM Kymimill is hardwood (birch) and the rest softwood(pine and spruce). The mill produces higher-quality papers (coated and uncoated fine papers),which typically contain approximately 20% to25% fillers (Hart et al. 2005), such as kaolin andstarches. Thus, fillers and other additives are animportant production input.

In addition to the pulp and paper mill, thesystem includes a power plant, running on woodresidues and sludge from the pulp and paper mill.The power plant then sells heat and electricityback to the pulp and paper mill. The power plantalso provides electricity and district heat to Kou-vola town. There are three chemical plants inthe system: a chlorine dioxide plant, a calciumcarbonate plant, and a hydrogen peroxide plant.Besides providing chemicals for the pulp and pa-per mill, the chlorine dioxide and the calciumcarbonate plants receive energy and chemicallypurified water from the pulp and paper mill. Thecalcium carbonate plant also utilizes carbon diox-ide from the flue gases of the pulp and paper millas a raw material. The municipal sewage plant de-livers part of its sewage sludge to the wastewatertreatment plant of the pulp and paper mill. Thenutrient-rich sewage sludge reduces the need toadd urea and phosphoric acid to the wastewatertreatment process. Moreover, the pulp and papermill manages the waste of the power plant, cal-cium carbonate plant, and chlorine dioxide plant.

Calculation Tools and Materials Used

The analysis was conducted with LCAbased on International Organization for Stan-dardization (ISO) standards 14040:2006 and

Sokka et al., Analyzing the Environmental Benefits of Industrial Symbiosis 139


Figure 1 Processes included in the study and the flows of material and energy between the case industrialecosystem actors. The outer line represents the system boundary of the study and the inner broken line theboundary of the ecosystem. The functional unit of the system is one year of production at the gate in 2005.A = district heat and electricity; B = sewage sludge; C = wastewater ; D = sewage sludge; E = wastewater ;F = ash; G = hydrogen peroxide (H2O2); H = miscellaneous inert waste; I = wastewater ; J = water;K = calcium carbonate (CaCO3); L = miscellaneous waste; M = carbon dioxide (CO2); N = chlorine (Cl2)wastewater ; P = chlorine dioxide (ClO2); Q = water; R = sodium hydroxide (NaOH); S = sodiumhydroxide (NaOH); T = biomaterials used as fuel; U = steam, electricity, heat; V = steam; X = steam andelectricity; Y = electricity; Z = waste; XX = water.

14044:2006 (ISO 2006a, 2006b). In the study,the case study IES was treated as a “black box,”as one of the life cycle phases of the productsystem. The other life cycle phases were up-stream processes, divided into the productionof raw materials (including transportation) andproduction of energy and fuels (including trans-portation) used by the IES; waste management,covering the disposal and treatment of waste ma-terials outside of the IES; and avoided impacts,which covered the inputs and outputs avoidedthrough recycled waste (deducted from the to-tal) (see figure 1). The functional unit of thestudy was the total annual production of theIES (tons or GWh in 2005) at the gate ofthe symbiosis.

The LCI analysis was conducted as describedin our earlier article (Sokka et al. 2009). Pri-mary data received directly from the compa-nies and from their environmental permits andfrom the VAHTI database of the Finnish En-vironmental Administration (2008)2 were usedfor the direct raw material and energy use andemissions and waste production. Secondary datareceived from available LCA databases, mainlythe Ecoinvent database (Swiss Centre for LifeCycle Inventories, 2007),3 from the VAHTIdatabase (Finnish Environmental Administra-tion 2008), other companies’ environmental re-ports, and other literature were used for theproduction of raw materials and recycling andtreatment of waste. The life cycle inventory



assessment was conducted using the KCL-ECOLCA software (Finnish Pulp and Paper ResearchInstitute 2004).4 GHG emissions of the systemhave been discussed in another of our articles(Sokka et al. 2009) and are thus only briefly ad-dressed here.

LCIA was conducted according to ISO stan-dards 14040:2006 and 14044:2006. Characteriza-tion factors that are site and temporally generichave been used in many studies for reasons ofpracticality and due to uncertainties about thelocation or time at which the emissions occur(Krewitt et al. 2001; Pennington et al. 2004).However, several studies have shown that withinsome impact categories there may be significantvariation in the estimated damage between coun-tries due to, for example, local environmentalconditions (Krewitt et al. 2001; Seppälä et al.2006). Since most of the processes in this studytook place in Finland or Russia, Finland-specificcharacterization factors were used for impacts onacidification, eutrophication, tropospheric ozoneformation, and particulate matter (table 1). Tox-icity impacts were calculated with the ReCiPemethodology (Sleeswijk et al. 2008; Goedkoopet al. 2009) and adjusted for Finland according tomethod described by Seppälä (2008).

In normalization, the impact category indica-tor results are divided by an appropriate referencevalue (e.g., impacts of a society’s total activitiesin a given area over a certain time period). Sinceproduct life cycles can extend all over the world,the global system is often chosen as a referencesituation (Sleeswijk et al. 2008). However, pol-icymakers are typically interested in results ona smaller geographic scale because such resultsoffer a more direct link to policy aims. In thisstudy the results were normalized with Europeanreference values (Sleeswijk et al. 2008). Weight-ing was not conducted as weighting is not usuallyrecommended in comparative studies presentedto the public due to its subjectivity (Penningtonet al. 2004).

Hypothetical Reference Systems

Two hypothetical reference systems in whichthe main actors of the system work on their ownwere designed. It should be emphasized that thesescenarios are hypothetical and their actual impli-

cations (e.g., the infrastructure required) are notassessed in this study. The reference systems weredesigned to contain production systems that areactually currently in use somewhere. In both ofthe reference systems the total energy use and theamount of products produced by the actors of theIES is the same as in the case study IES, exceptfor the power plant, which produces less heat andelectricity. However, its production is replaced byexternal production purchased by the town (seebelow).

In Reference system 1, the following assump-tions were made:

• The local town would use electricity pro-duced with hydropower as before, but meetthe rest of its electricity demand from reg-ular markets. Average Finnish production(Koskela and Laukka 2003) was used torepresent this electricity. Instead of buy-ing heat from the power plant, the townwould use average heat from the Kymen-laakso region. The fuel profile of the districtheat production in Kymenlaakso was takenfrom Finnish Energy Industries (2006). Thepower plant would only produce electricityand heat for the pulp and paper mill, and itsproduction would be reduced accordingly.It would still utilize all the wood residuesof the pulp and paper mill but purchase lesswood from markets.

• The calcium carbonate (CaCO3) plant andthe chlorine dioxide (ClO2) plant, whichpresently obtain electricity and steam fromthe pulp and paper mill, would also use av-erage heat from Kymenlaakso and averageFinnish electricity.

• The calcium carbonate plant would not getfossil CO2 from the pulp and paper mill butwould buy liquid CO2 instead.5 The CO2would be released in the air.

• The pulp and paper mill was assumed notto get any sewage sludge from the munic-ipal wastewater treatment plant. Sewagesludge addition replaces urea and phospho-rous acid in the wastewater treatment pro-cess of the pulp and paper mill. Therefore,extra nitrogen and phosphorus would needto be added to the system. The amountof nutrients needed was calculated with



Table 1 Impact Categories, Emissions Included in Them, and References

Impact category Contributing emissions Source

Climate change Carbon dioxide (CO2), methane (CH4),dinitrogen monoxide (N2O)

Solomon et al. 2007

Acidification Nitrogen oxides (NOX), sulphur dioxide(SO2), ammonia (NH3)

Seppälä et al. 2006

Aquatic eutrophication Nitrogen oxides (NOX), ammonia (NH3),total phosphorous (P), total nitrogen (N)

Seppälä et al. 2004, 2006

Terrestrial eutrophication Nitrogen oxides (NOX), ammonia (NH3) Seppälä et al. 2004, 2006Tropospheric ozone

formation, impacts onhuman health

Methane (CH4), nitrogen oxides (NOx),nonmethane volatile organic compounds(NMVOC)

Hauschild et al. 2004

Tropospheric ozoneformation, impacts onvegetation

Methane (CH4), nitrogen oxides (NOx),nonmethane volatile organic compounds(NMVOC)

Hauschild et al. 2004

Freshwater ecotoxicity,terrestrial ecotoxicityand human toxicity

Arsenic (As), cadmium (Cd), chromium(Cr), chromium IV (Cr IV, water), cobalt(Co, water), copper (Cu), mercury (Hg),nickel (Ni), lead (Pb), tin (Sn, water), zinc(Zn), vanadium (V), polyaromatichydrocarbons (PAH), dioxins and furans(PCDD/-F), phenols (water), tributyltin(C12H28Sn, water)

Sleeswijk et al. 2008;Seppälä 2008

Particulate matter Nitrogen oxides (NOX), sulphur dioxide(SO2), ammonia (NH3), particulate matter(PM10)

Van Zelm et al. 2008

Abiotic resourcedepletion

Aluminum (Al), barite, chromium (Cr),cobalt (Co), copper (Cu), fluorspar, iron(Fe), lead (Pb), manganese (Mn),molybdenum (Mo), nickel (Ni),phosphorus (P), rhenium (Re), silver (Ag),sodium sulfate, sulfur (S), talc, tin (Sn),vermiculite, zinc (Zn), oil, coal, browncoal, natural gas, peat

Van Oers et al. 2002

information from Valtonen’s thesis (2005).The sewage sludge would be composted in-stead. Sewage sludge was intended to re-place peat in soil amendment at a ratio of1:1, and negative emissions would be cal-culated for this use. Inputs and outputs ofthe composting process were taken from areport by Myllymaa and colleagues (2008).

Since there are many different ways to produceheat, a second reference system was designed inorder to reflect the sensitivity of the results tothe selected fuel. Thus, in Reference system 2, ev-erything else remains the same as in Referencesystem 1 except that the town would use heatthat was assumed to be produced with peat in-

stead of using average heat from Kymenlaakso.Peat was chosen for the comparison because it is adomestic fuel and the third most used fuel in heatproduction in Kymenlaakso (Finnish Energy In-dustries 2006). Data on heat produced with peatwere taken from the Myllymaa and colleagues re-port (2008). The harvesting of the peat was alsotaken into account.

Potential Improvements to the CaseStudy IES (Reference System 3)

A further scenario, Reference system 3, wasconstructed in order to analyze the waste andemission flows of the case study IES in or-der to identify additional possibilities for links



between the actors or for links to new actors. Thepotential environmental benefits of these con-nections were assessed in relation to the presentsituation. These possible new features of the sym-biosis included utilization of hydrogen gas fromthe chlorine dioxide plant in a new hydrogenplant in the IS, use of fly ash from the power plantin forest fertilization, and treatment of municipalwastewaters from the municipality of Kouvola atthe pulp and paper mill. In addition, the poten-tial to use the waste heat from the pulp and papermill in greenhouses was assessed. Assumptionsconcerning the aforementioned are presented inmore detail below. However, it should be empha-sized that the options studied here are hypotheti-cal and do not imply that they would actually beconsidered for implementation.

The chlorine dioxide plant produces approxi-mately 28 kilograms (kg) of hydrogen per ton ofchlorine dioxide produced. This hydrogen couldin principle be utilized in energy production. Thesame company has built a hydrogen-utilizing en-ergy unit in its chlor-alkali plant in southeast Fin-land. If such a hydrogen plant were built withinthe case study IES, it could potentially replace22,000 GJ of natural gas.6

Approximately 13,700 tons of fly ash from thepower plant was deposited in landfill in 2005.This fly ash could be utilized as a forest fertil-izer. Wood ash has been found to be beneficialparticularly on peat lands because the ash in-cludes phosphorus and potassium in appropriateproportions. There is no nitrogen in the ash, butnitrogen is not usually required on peat lands be-cause peat itself contains enough plant-availablenitrogen (Rinne 2007). The popularity of for-est fertilization has been increasing in Finlandduring the 2000s, and the National Forest Pro-gramme 2015 includes a target of increasing theamount of fertilized forests from the current ap-proximately 25,000 hectares (ha) to 80,000 ha in2015 (Ministry of Agriculture and Forestry 2008;Finnish Forest Research Institute 2004). Thus,there arguably exists an increasing demand forforest fertilizers. According to Korpilahti (2003),500 kg/ha of commercial fertilizer provides 45kg phosphorus per hectare. In order to gain thesame amount of phosphorus from ash, 3,000 to7,000 kg of ash is required. In this study it was as-sumed that 5 tons of fly ash from the power plant

would replace 500 kg of mineral fertilizer. Data onphosphorus fertilizer production were taken fromthe U.S. Life Cycle Inventory database (NationalRenewable Energy Laboratory 2008). Altogether,approximately 2,500 to 3,000 hectares could befertilized with the currently landfilled ashes of thecase study IES. Energy use and emissions gener-ated in the process of spreading the ash were nottaken into account.

A study has been conducted on the possibilityof treating the wastewaters from the municipal-ity of Kouvola at the UPM Kymi pulp and pa-per mill’s wastewater treatment plant (Valtonen2005). In that study, the resulting potential sav-ings in nutrients and other chemicals were cal-culated. The sewage sludge from the municipalwastewater treatment plant is already being de-livered to the Kymi mill. According to Valtonen(2005), if the wastewater from both plants weretreated together, no phosphorus would need tobe added to the system and the use of urea couldbe reduced to 300 tons/year from the present 500tons/year. Moreover, the ferrous sulfate (FeSO4),poly-aluminum chloride, and other resources thatare used in phosphorus removal at the munici-pal wastewater treatment plant would no longerbe needed. The combined treatment would re-duce the total nitrogen emissions of both plantsby almost 50% and the phosphorus emissions byapproximately 10% (Valtonen 2005). It was con-cluded in the study that despite the investmentcosts this combined treatment would need, theoption would be cheaper for the town in the longrun.

The total heat load from the case studyIES that is annually released to the surfacewaters is approximately 2,500 GWh. It wasassumed that some of this waste heat couldbe utilized in greenhouses, and emissions sav-ings were thus calculated. In 2005, approxi-mately 4.5% (based on production area) of thetotal Finnish greenhouse production was lo-cated in the Kymenlaakso region (Ministry ofAgriculture and Forestry 2006). Of this, thegreenhouses located in municipalities close toKouvola accounted for approximately 40%. Thetotal energy use of greenhouses was approxi-mately 2,000 MWh in Finland in 2004 (Hiltunenet al. 2005). If the waste heat from the Kymi pulpand paper mill could cover the total energy needs



of the greenhouses close to Kouvola, they woulduse approximately 35 MWh of its waste heat. Themost common energy source in the Finnish green-houses at the beginning of the 2000s was heavyfuel oil (Hiltunen et al. 2005), so the waste heatwas taken to replace heat produced with heavyfuel oil. Data on heavy fuel oil energy were takenfrom the Ecoinvent database.

Results

Impacts of the Case Study IES

When looking at the normalized environmen-tal impacts, acidification had the highest values,7

3.27 E-04, followed by terrestrial eutrophication,tropospheric ozone formation (human health im-pacts), climate change, impacts on particulatematter formation, and aquatic eutrophication.For terrestrial eutrophication, the normalized val-ues were approximately 40% smaller than acidi-fication impacts. The normalized impacts of cli-mate change, particulate matter formation, andaquatic eutrophication were 60% to 80% smallerthan acidification impacts. Most of the acidifica-tion, terrestrial eutrophication, and troposphericozone formation originated from the emissionsof nitrogen oxides. Most of the NOX emissionswere generated by the pulp and paper mill, thepower plant, production and transportation ofhardwood, and transportation of kaolin and cal-cite. According to the normalized values, the im-pacts were 1.21E-6 to 8.05E-6 for the toxicity im-pact categories and 1.95E-6 for abiotic resourcedepletion. Thus, the normalized values for toxic-ity and abiotic resource depletion were very smallcompared with the other impact categories andwere omitted from the figures presented below.

When studying the contribution of differentlife cycle stages (raw material extraction andprocessing, energy and fuel extraction and pro-duction, production within the IES, waste man-agement processes, and impacts avoided throughrecovered materials) one can see that the raw ma-terial extraction and processing made the largestsingle contribution to the results in most impactcategories (figure 2). Fuel production and energygeneration contributed approximately 19% to theclimate change impacts. Its contribution to theother impact categories ranged between 3% and

15%. The shares of waste management and im-pacts avoided through waste recovery were verysmall, less than 1.5% in all impact categories. Ascould be expected, given the large size of the pulpand paper mill, over 60% of all impacts except forterrestrial ecotoxicity impacts were caused by themill and the upstream processes related to it. Ofthe total impacts of the pulp and paper mill, up-stream processes caused 70% to 80% of the totalimpacts in most impact categories. Of the partic-ulate matter impacts, the share of upstream pro-cesses was 60% and that of the toxicity impactswas over 90%.

Impacts of the Reference Systems

The comparison of the case study IES to Ref-erence systems 1 and 2 indicates that the envi-ronmental impacts of the reference systems arehigher in most impact categories (figure 3 andtable 2; please also see tables S-1 and S-2 in thesupporting information on the Journal’s Web sitefor the detailed inventory results). The resultsshow that in Reference system 1, impacts on cli-mate change would increase by 12% and those onacidification and particulate matter by approxi-mately 5%. Reference system 2 would result inlarger changes in all the impact categories, par-ticularly in acidification, which would grow by al-most 40%. The other impacts, except for aquaticeutrophication, would increase by 10% to 20%.

The assumed increases in the recycling of by-products generated by the case study IES (Ref-erence system 3) would result in an almost 30%decrease in the aquatic eutrophication impacts(see figure 3). The other impacts would decreaseby less than 10%.

The sources of aquatic eutrophication, partic-ulate matter formation, acidification, and terres-trial eutrophication were studied in more detail(figure 4). The largest contributors to these im-pacts except for aquatic eutrophication, in boththe case study IES and the reference systems,throughout the whole life cycle of the productionsystem were the pulp and paper mill, the powerplant, the production of potato starch, opticalbrighteners, and sodium hydroxide, transporta-tion of kaolin and quicklime, and productionof hardwood. The pulp and paper mill and thepower plant are represented as the source of direct



Figure 2 Normalized values according to different life cycle phases in the case study industrial ecosystem.Energy and fuel production includes extraction of fuels. Normalized values for freshwater ecotoxicity,terrestrial ecotoxicity, human toxicity, and abiotic resource depletion were so small that they were omittedfrom the figure. The contributions of the life cycle phases waste management processes and impacts avoidedare so small that they are not visible in the figure except for the small contribution of impacts avoided inparticulate matter formation. Symbiosis stands for inputs to and outputs from the symbiosis.

emissions of the case study IES, while the otherprocesses are represented as upstream processes.The largest contributors to the aquatic eutrophi-cation impacts in the case study IS and Referencesystems 1 and 2, were the municipal wastewa-ter treatment plant (Akanoja sewage plant infigure 4a) and sodium hydroxide production.There are no emissions from the municipalwastewater treatment plant in Reference system3 since in Reference system 3 municipal wastew-aters are treated at the pulp and paper mill. Ap-proximately 35% of the reduction in aquatic eu-trophication impacts is caused by the combinedtreatment of wastewaters at the pulp and papermill (direct emissions of the IES), while the restof the reduction is caused by the replacement ofadded phosphorus and nitrogen at the pulp andpaper mill with sewage sludge and the utiliza-tion of wood ash in forest fertilization (upstreamprocesses).

The role of optical brighteners in particularwas perhaps surprisingly high considering that theamount used was fairly small: 1,550 tons (100%purity). The production of optical brightenersis very energy intensive compared with that ofsome other bleaching chemicals such as H2O2,but on the other hand, the amount of chemicalsneeded is much lower (Scheringer et al. 1999).One can see that the role of transportation ofkaolin, quicklime, and hardwood was fairly largeas well; altogether they accounted for 9% to 15%of the total impacts.

The difference in environmental impacts be-tween Reference systems 1 and 2 and the casestudy IES is mainly attributable to the differencesin energy production. In the reference systems,emissions from the power plant, which especiallyaffect impacts related to NOX emissions, de-crease (see table 2). At the same time, emissionsfrom the average production of district heating



Figure 3 Environmental impacts of the reference systems in relation to those of the case study industrialecosystem (IES) (the environmental impacts of the IES get the value 1). Normalized values for freshwaterecotoxicity, terrestrial ecotoxicity, human toxicity, and abiotic resource depletion were so small that theywere omitted from the figure.

and electricity increase. This impacts the CO2emissions in particular. Moreover, in Referencesystem 2, in which more peat is used, CO2, NOX,and SO2 emissions from energy production in-

crease. Thus, it can be concluded that in Refer-ence systems 1 and 2 the contribution of upstreamprocesses to the total impacts is higher than inthe case study IES. This is mainly because in

Table 2 Absolute and Relative Differences in the Main Emissions and Consumption of Fuels Between theCase Study Industrial Ecosystem and Reference Systems 1, 2, and 3

Difference Difference Differencefrom from from

Case study reference Difference reference Difference reference DifferenceIES system 1 (%) system 2 (%) system 3 (%)

CO2 6.20E+08 7.59E+07 12% 1.27E+08 21% −1.47E+07 −2%CH4 1.30E+06 1.17E+05 9% −6.77E+04 −5% −8.22E+04 −6%N2O 4.99E+04 3.42E+03 7% 1.29E+03 3% −4.84E+01 0%NOX 3.02E+06 −2.94E+04 −1% 4.25E+05 14% −1.24E+04 0%SO2 1.31E+06 1.88E+05 14% 9.71E+05 74% −3.18E+04 −2%PM10 5.41E+05 1.95E+04 4% −1.03E+04 −2% −9.89E+02 0%NMVOC 4.32E+05 5.74E+03 1% −5.61E+03 −1% −5.85E+03 −1%NH3 1.06E+05 −2.80E+02 0% −1.68E+03 −2% −6.74E+02 −1%Nwater 4.83E+05 8.12E+02 0% 3.53E+03 1% −9.09E+04 −19%Pwater 5.40E+04 4.21E+02 1% 9.82E+02 2% −3.27E+04 −61%Oil 5.38E+07 4.90E+05 1% 5.06E+05 1% −4.24E+07 −79%Hard coal 4.79E+07 1.36E+07 28% 3.45E+06 7% −1.69E+04 0%Natural gas 9.94E+07 1.95E+06 2% −5.88E+06 −6% −7.22E+06 −7%



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the reference systems the power plant does notsupply the local town with heat and electricity.Therefore, the town needs to purchase electric-ity and heat from other sources, which leads tohigher upstream emissions. Carbon dioxide emis-sions also grow because the pulp and paper millno longer delivers part of its CO2 to the calciumcarbonate plant. The significance of the otherprocesses is minor.

The reduction in aquatic emissions andthereby aquatic eutrophication impacts in Refer-ence system 3 is due to the treatment of municipalwastewater at the case study IES and replace-ment of phosphorus fertilizer through utilizationof wood ash in forests. Large reductions in thesystem’s environmental impacts could potentiallybe achieved if more of the waste heat from thepulp and paper mill could be utilized. However,at present such heat is not being used anywhereon a large scale. In the analysis it was assumedthat a small proportion of it could be utilized inthe heating of greenhouses.

Sensitivity Analysis

The main uncertainties of this study relateto the data on upstream processes. The amountof raw materials, fuels, and energy used wasreceived directly from the actors of the casestudy IES and is fairly accurate, but the dataon the production of these materials and fu-els are mainly generic, originating from differ-ent databases, and do not necessarily representthe actual production processes. Therefore, thedata sources of those upstream processes con-tributing most to the results were varied in thesensitivity analysis. Four different scenarios wereconstructed:

• In Scenario 1, external electricity pur-chased by the pulp and paper mill wasassumed to represent the electricity pro-file of the Finnish forest industries in2007 (Finnish Forest Industries Federation2009).

• In Scenario 2, the transportation distanceof kaolin was changed. On the basis of in-formation about the producers it was origi-nally assumed that one third of the kaolinoriginated in the United States and two

thirds in the United Kingdom. Transporta-tion mode was assumed to be a roll-on shipby sea and fully loaded Euro3 truck on land.For the sensitivity assessment, we assumedthat all the kaolin was imported from theUnited Kingdom. Transportation mode wasassumed to be the same.

• In Scenario 3, the data source of opticalbrighteners was changed. Instead of usingthe Ecoinvent Database version 2.01 (SwissCentre for Life Cycle Inventories 2007),data from the article by Scheringer and col-leagues (1999) was used.

• In Scenario 4, it was assumed that the pulpand paper mill used maize starch instead ofpotato starch. Data on maize starch weretaken from the Ecoinvent database version2.01 (Swiss Centre for Life Cycle Invento-ries 2007).

The impact of these factors was less than15% on most of the main emissions (table S-3in the supporting information on the Web) andless than 10% on the main impact categories(figure 5) for all scenarios. The greatest changeswere caused by Scenario 3, which resulted inan 8% decrease in the acidification impacts anda 5% decrease in the terrestrial eutrophicationimpacts.

Discussion

In this study, normalized LCA results werepresented and no weighting was applied to theimpact categories. Normalized values can bejudged to rank the impacts in their order of im-portance provided that all environmental effectsare considered equally important; for example,the significance of total current levels of globalwarming and toxicity effects would be assumed tobe equal (Pennington et al. 2004). However, onemust be aware that different valuation studies in-dicate that not all the environmental impacts aregenerally considered equal in importance (e.g.,Seppälä 2003), so special care must be takenwhen comparing normalized values across impactcategories.

The study showed that the impacts occurringoutside the IES may be high. We did not findother evidence for this from the literature, but



Figure 5 Sensitivity of the main impacts to the different scenarios.

similar results have been reported for differentkinds of systems. For example, the environmentalimpacts of the Second Sydney Airport proposalwere assessed by extending environmental impactassessment with input-output analysis to cover ef-fects occurring off-site (Lenzen et al. 2003). Theresults showed that indirect impacts were consid-erable for all the factors studied. Matthews andcolleagues (2008) presented the same conclusionfor carbon footprints. Thus, one implication ofour study is that when developing or initiatingan industrial symbiosis, the analysis should be ex-tended to off-site impacts as well, as these may bedecidedly high in relation to impacts within thesymbiosis. Singh and colleagues (2007) con-cluded in their study that LCA is an extremelyuseful tool for analyzing and comparing differentdesigns of industrial symbioses. Similarly, LCAcan be applied when looking at industrial sym-bioses already in operation.

The results indicate that in the present casethe environmental impacts are smaller from thesystem operating as an industrial symbiosis thanfrom stand-alone production. The difference wasthe greatest in acidification, climate change im-pacts, and impacts on particulate matter forma-tion. Reduction in the environmental impacts

was primarily caused by energy production forKouvola town. However, as it was also foundin the study that the upstream processes madea considerable contribution to the overall results,it may be concluded that the greatest reductionsin the overall environmental performance of thesystem can be achieved by minimizing the totalraw material use of the system. However, here itwas assumed that the pulp and paper mill getsmost of its electricity and heat from wood-basedfuels also in the stand-alone situation. Assum-ing that it would either buy wood from outsidethe system or use fossil fuels instead would haveincreased its environmental impacts throughout.

It can be argued that a central environ-mental driver for IES is the increased materialefficiency through recycling and the resultingavoidance and reduction of upstream effects ofresource extraction and primary production. Thevalue of LCA lies in the possibility to locatethose flows whose reduction provides the great-est overall environmental benefits. For example,it can be used to locate areas of improvementor to assess the environmental benefits of addi-tional symbiotic links. As Reference system 3 ofour study showed, the greatest additional envi-ronmental benefits could be achieved through



combined treatment of wastewaters of the mu-nicipal wastewater treatment plant and the pulpand paper mill, replacement of nutrients with themunicipal sewage sludge, and utilization of woodash for forest fertilization.8 Approximately 35%of these benefits were achieved with respect tothe direct emissions of the case study IES andthe rest in the upstream processes. The contribu-tion of the other processes was minor. It should,however, be pointed out that additional reduc-tions in the overall environmental performanceof the system could be achieved through moreefficient technology and changes in the fuel mixused.

Significant reductions in the system’s envi-ronmental impacts could potentially be attainedif more of the waste heat from the pulp and papermill could be utilized. Fish farms have also beennoted as potential users of waste heat (Lowe andEvans 1995). However, in Finland their total en-ergy use is fairly low (Silvenius and Grönroos2004). In the future, more potential could per-haps be found in the drying of wood pellets.The drying process is usually the most energy-demanding phase of pellet production (Anders-son et al. 2006; Sokka et al. 2009). This option,however, was not studied further as only optionsthat were actually in use somewhere were cho-sen for the reference systems. Moreover, untilrecently, the production of wood pellets has beenfairly small in Finland, totalling 192,000 tons (3.2TJ) in 2005, of which over two thirds were ex-ported (Statistics Finland 2006). However, policytargets have been set to increase the use of renew-able fuels, and the Finnish long-term climate andenergy strategy aims to increase the use of pel-lets in industry and housing by 2020 (Council ofState 2008).

The main uncertainties in this study related tothe data on upstream production processes. Theamount of raw materials, fuels, and energy usedwas received directly from the actors of the casestudy IES and was fairly reliable, but the data onupstream processes were mainly generic, originat-ing from different databases, and do not necessar-ily reflect the actual production processes. Thus,in the sensitivity analysis, data sources of thoseupstream processes with the greatest impact onthe results were studied. In addition, the trans-portation distance of kaolin was varied. The dif-

ferent scenarios resulted in fairly small changes,less than 10% in all impact categories comparedwith the case study IES.

One major uncertainty concerning the com-parison with stand-alone production is that it isnot clear how the stand-alone situation shouldbe defined. A symbiotic mode of operation is verytypical for the Finnish forest industry. We tried tofind the most realistic scenario of how the actorswould operate in a stand-alone scenario choos-ing a situation that does actually occur elsewhere.However, the choice is subjective and is open toquestion. We assumed that even in a stand-alonesituation the energy production of the pulp andpaper mill would be based on utilizing its ownwood residues and black liquor, as is generallythe case in the Finnish forest industry (FinnishForest Research Institute 2006). The situationwould have been different if we had assumed thatwood was not used as an energy source at thepulp and paper mill. However, this assumptionwas made because it is a common practice in theforest industry in Finland and abroad.

The study method used was a traditional LCA,which necessarily results in upstream and down-stream cut-offs. In recent years, so-called hybridmethods, where product-based LCA is combinedwith input-output accounting, have increasinglybeen used (for a review of the hybrid methods,see Suh and Huppes 2005). Because we studiedthe applicability of LCA for analyzing the envi-ronmental impacts of an industrial symbiosis andcompared the impacts of the industrial symbiosisto separately operating systems and assessed theupstream processes in relation to processes occur-ring within the symbiosis, applying a full-scalehybrid LCA was not considered necessary.

Concluding Remarks

In the case studied, comparison with thestand-alone production showed that the symbio-sis resulted in net improvements in the total en-vironmental impacts of the system, the differencebeing between 5% to 20% in most impact cate-gories. The difference was the greatest in acidifi-cation, climate change impacts, and impacts onparticulate matter formation. Reduction in theenvironmental impacts was primarily caused byenergy production for Kouvola town.



Symbiotic exchanges reduce the need to pur-chase raw material and energy from outside thesymbiosis. Efficient energy production and uti-lization are critical factors contributing to theoverall environmental performance of symbiosis-like production systems. In the case study IES,upstream processes made a considerable contri-bution to the overall results. Thus, it may be con-cluded that major reductions in the total environ-mental impacts of the system can be achieved byaffecting the extraction and production of rawmaterials and external energy. All in all it isrecommended that when assessing the environ-mental performance of an industrial symbiosis oran eco-industrial park, the impacts occurring up-stream should be studied and not merely the sit-uation within the symbiosis. LCA seems a veryuseful, albeit labor-intensive, tool for this kindof assessment. It can also help in detecting thoseflows whose utilization could provide the greatestenvironmental benefits.

Acknowledgements

Support from the Academy of Finland to the“Industrial Symbiosis System Boundaries (ISSB)”project (code 117837) is gratefully acknowl-edged. The authors would also like to thank IsmoTaskinen, Juha Kouki, Erkki Vierros, and JaniKatajala for providing information for this studyand Tuomas Mattila for his comments on themanuscript. Finally, the invaluable commentsmade by the anonymous reviewers are gratefullyacknowledged.

Notes

1. In this article the term industrial symbiosis refers tothe collection of exchanges and processes that occurwithin a system called an industrial ecosystem.

2. The VAHTI database is an emissions control andmonitoring database of the Finnish EnvironmentalAdministration.

3. Ecoinvent: www.ecoinvent.ch4. www.vtt.fi/research/technology/sustainability

assessment.jsp?lang=en5. In reality, it would probably be difficult to obtain

enough liquid CO2 available to replace the CO2received in flue gas (Taskinen 2008).

6. The heating value of hydrogen is assumed to be120 megajoules per kilogram (U.S. Department ofEnergy 2006).

7. In Finland, natural systems are particularly vulner-able to acidification due to the low buffer capacityof the soil. Therefore, the importance of acidifica-tion impacts tends to become high in studies usingFinnish-specific characterization factors.

8. The possible impacts that such a cheap phospho-rus source would have on the domestic phosphorusmarkets were not assessed in this study. On theother hand, phosphorus is a limited resource, andwith the increase of food and biofuel production,serious concerns have been raised on its long-termavailability (Lewis 2008).

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About the Authors

Laura Sokka is a researcher and Ph.D. stu-dent, Suvi Lehtoranta is a researcher, Ari Nissi-nen is a senior researcher, and Matti Melanen isa research professor at the Finnish EnvironmentInstitute, Helsinki.

Supporting Information

Additional supporting information may be found in the online version of this article:

Supporting Information S1. This supporting information contains tables showing the inventoryresults for the symbiosis case and reference systems and the sensitivity of the main emissions tothe different scenarios.

Please note: Wiley-Blackwell is not responsible for the content or functionality of any supportinginformation supplied by the authors. Any queries (other than missing material) should bedirected to the corresponding author for the article.


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