Analyzing the Environmental Benefits of Industrial Symbiosis

RESEARCH AND ANALYSIS Analyzing the Environmental Beneﬁts of Industrial Symbiosis Life Cycle Assessment Applied to a Finnish Forest Industry Complex

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

Keywords: Summary environmental impact Finland Studies of industrial symbiosis (IS) focus on the physical flows industrial ecology of materials and energy in local industrial systems. In an ideal industrial ecosystem IS, waste material and energy are shared or exchanged among life cycle assessment the actors of the system, thereby reducing the consumption pulp and paper industry of virgin material and energy inputs, and likewise the generation of waste and emissions. In this study, the environmental Supporting information is available impacts of an industrial ecosystem centered around a pulp on the JIE Web site and paper mill and operating as an IS are analyzed using life cycle assessment (LCA). The system is compared with two hypothetical reference systems in which the actors would operate in isolation. Moreover, the system is analyzed further in order to identify possibilities for additional links between the actors. The results show that of the total life cycle impacts of the system, upstream processes made the greatest overall contribution to the results. Comparison with stand-alone production shows that in the case studied, the industrial symbiosis results in modest improvements, 5% to 20% in most impact categories, in the overall environmental impacts of the system. Most of the benefits occur upstream through heat and electricity production for the local town. All in all it is recommended that when the environmental impacts of industrial symbiosis are assessed, the impacts occurring upstream should Address correspondence to: also be studied, not only the impacts within the ecosystem. Laura Sokka VTT Technical Research Centre of Finland P.O. Box 1000 FI-02044 VTT, Finland laura.sokka@helsinki.fi

c 2010 by Yale University DOI: 10.1111/j.1530-9290.2010.00276.x

Volume 15, Number 1 www.wileyonlinelibrary.com/journal/jie Journal of Industrial Ecology 137 RESEARCH AND ANALYSIS

pacts. They called for further research to develop Introduction comprehensive methods for the quantification of Industrial symbiosis (IS) studies examine the the environmental and economic benefits of in- flows of materials and energy in local industrial dustrial symbioses. systems using a systems approach (Chertow 2000; Singh and colleagues (2007) studied an agro- Wolf 2007; Zhao et al. 2008).1 The approach an- chemical complex consisting of 13 chemical and alyzes economic systems through their material petrochemical industries in the state of Missis- and energy flows (Hart et al. 2005). The key idea sippi, USA. They conducted a so-called “entry to of the concept is that in an IS, waste material exit” life cycle assessment (LCA) study of the sys- and energy is shared or exchanged among the tem, thus considering only materials used inside actors of the system and the consumption of vir- the complex. Raw material production and waste gin material, energy inputs, and the generation of treatment were not taken into account. The en- waste and emissions are thereby reduced (Korho- vironmental impacts of the system were analyzed nen and Snakin¨ 2003; Ulgiati et al. 2007). Lit- using life cycle impact assessment (LCIA). The erature on identified industrial symbioses, indus- researchers concluded that LCA is an extremely trial ecosystems (IES), and eco-industrial parks useful tool for analyzing and comparing differ- has burgeoned during the past 10 to 15 years (cf. ent designs of industrial ecosystems and recom- Sterr and Ott 2004). While numerous descriptive mended conducting a comprehensive LCA be- analyses have been conducted on the concept, fore starting a new eco-industrial park in order there are relatively few quantitative assessments to assess the potential advantages and disadvan- of the environmental benefits of industrial sym- tages of the system and to thereby select the best bioses (for a discussion and review, see Sokka design option from the perspective of sustainable et al. 2008 and 2009). development. Most of the assessments of the environmen- Only a few studies have also considered the tal impacts of industrial symbioses have focused life cycle impacts of industrial symbioses. Sendra on the ecosystem itself and excluded upstream and colleagues (2007) applied material flow ana- and downstream impacts. For instance, the eco- lysis (MFA) methodology to an industrial area in nomic and environmental costs and advantages Spain. In the study, MFA-based indicators, with of symbiosis partners were assessed in Guayama, additional water and energy indicators, were used a symbiosis network in Puerto Rico (Chertow to evaluate how the area could be transformed and Lombardi 2005). According to the study, into an eco-industrial park. The study thus had the symbiosis resulted in a substantial decrease in a life cycle view but did not include an impact some emissions, such as SO2, and in water extrac- assessment. More recently, Eckelman and Cher- tion, but simultaneously there was an increase in tow (2009) studied industrial waste production the emissions of CO2. The researchers concluded in Pennsylvania. They combined waste data from that the participating organizations derived con- the area with life cycle inventory (LCI) data and siderable economic and environmental benefits thereby calculated the present and potential en- from the symbiosis but that those benefits were vironmental benefits of utilizing this waste. It was unevenly distributed among the participants. found that in all cases except for the energy use In another example, Van Berkel and col- of waste oil and substitution of virgin steel with leagues (2009) quantitatively assessed 14 indus- scrap steel, the reuse of the waste streams studied trial symbioses in Kawasaki, Japan. They found results in positive environmental impacts com- that the by-product exchanges of the symbioses pared with the use of the substituted material. altogether diverted 565,000 tons of waste from Uihlein and Schebek (2009) compared the waste management annually. In addition, it was environmental impacts of a ligno-cellulosic feed- estimated that the documented resource ex- stock biorefinery to the production of fossil al- changes compensated for 513,000 tons of raw ternatives using LCA. The system was not con- material use annually. However, the researchers sidered a form of industrial symbiosis, but in pointed out that there are trade-offs between ma- practice its operation is similar. Since the ligno- terial flow benefits and other environmental im- cellulosic feedstock biorefinery has not yet been

138 Journal of Industrial Ecology RESEARCH AND ANALYSIS implemented in practice, the researchers assessed Materials and Methods three different variants of the concept. For all Case Study IES variants it was found that the environmental performance of the biorefinery was superior to the The chosen case study IES is situated in the corresponding fossil-based production in some town of Kouvola in southeastern Finland. The impact categories and inferior in other impact system has evolved spontaneously (meaning that categories. Nevertheless, from the overall results it was not intentionally developed as an indus- the researchers concluded that from an environ- trial symbiosis) around an integrated pulp and mental point of view, the ligno-cellulose biore- paper manufacturer, the Kymi mill of the UPM finery concept would be beneficial compared with Kymmene Corporation (figure 1). Paper produc- the existing fossil production options. tion began at the site in 1874. The current annual In another study on the symbiotic exchanges production capacity of the integrated facility is within an eco-industrial park in China, it was 840,000 tons of paper and 530,000 tons of pulp. suggested that companies tend to out-source the Some 55% of the wood used by the UPM Kymi lowest value-added and often pollution-intensive mill is hardwood (birch) and the rest softwood production of materials and intermediate com- (pine and spruce). The mill produces higher- ponents to outside the parks (Shi et al. 2010). quality papers (coated and uncoated fine papers), Therefore, the researchers concluded that in the which typically contain approximately 20% to long-run assessments of the environmental per- 25% fillers (Hart et al. 2005), such as kaolin and formance of eco-industrial parks should be ex- starches. Thus, fillers and other additives are an tended to these spill-over effects as well. important production input. In our previous study (Sokka et al. 2009), we In addition to the pulp and paper mill, the focused on the CO2 emissions and fuel consump- system includes a power plant, running on wood tion of the same IES as in this study. It was found residues and sludge from the pulp and paper mill. that upstream processes accounted for over two The power plant then sells heat and electricity thirds of the total fossil greenhouse gas (GHG) back to the pulp and paper mill. The power plant emissions of the system. Production of pigments also provides electricity and district heat to Kou- and fillers had a considerable impact on the to- vola town. There are three chemical plants in tal results, causing altogether over 35% of the the system: a chlorine dioxide plant, a calcium total fossil GHG emissions. However, in order carbonate plant, and a hydrogen peroxide plant. to give an overall picture of the environmental Besides providing chemicals for the pulp and pa- performance of the case system, it is important per mill, the chlorine dioxide and the calcium to look at other environmental impacts as well, carbonate plants receive energy and chemically since GHG emissions alone do not give a com- purified water from the pulp and paper mill. The plete picture of the environmental performance calcium carbonate plant also utilizes carbon diox- of the system. ide from the flue gases of the pulp and paper mill In this study, the environmental impacts of an as a raw material. The municipal sewage plant de- industrial symbiosis that developed around pulp livers part of its sewage sludge to the wastewater and paper production are assessed with LCA and treatment plant of the pulp and paper mill. The compared with two hypothetical reference sys- nutrient-rich sewage sludge reduces the need to tems in which the actors work on their own. add urea and phosphoric acid to the wastewater Moreover, the possibilities for additional linkages treatment process. Moreover, the pulp and paper between the system’s actors are studied in order to mill manages the waste of the power plant, cal- assess their environmental relevance. Yet, instead cium carbonate plant, and chlorine dioxide plant. of providing a full, detailed assessment of the system’s environmental impacts, the main objective Calculation Tools and Materials Used of this study is to analyze the potential relative environmental benefits achieved through an in- The analysis was conducted with LCA dustrial symbiosis and to discuss the conditions based on International Organization for Stan- under which these benefits may be achieved. dardization (ISO) standards 14040:2006 and

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

Figure 1 Processes included in the study and the ﬂows of material and energy between the case industrial ecosystem actors. The outer line represents the system boundary of the study and the inner broken line the boundary 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 = sodium hydroxide (NaOH); T = biomaterials used as fuel; U = steam, electricity, heat; V = steam; X = steam and electricity; Y = electricity; Z = waste; XX = water.

14044:2006 (ISO 2006a, 2006b). In the study, The LCI analysis was conducted as described the case study IES was treated as a “black box,” in our earlier article (Sokka et al. 2009). Pri- as one of the life cycle phases of the product mary data received directly from the compa- system. The other life cycle phases were up- nies and from their environmental permits and stream processes, divided into the production from the VAHTI database of the Finnish En- of raw materials (including transportation) and vironmental Administration (2008)2 were used production of energy and fuels (including trans- for the direct raw material and energy use and portation) used by the IES; waste management, emissions and waste production. Secondary data covering the disposal and treatment of waste ma- received from available LCA databases, mainly terials outside of the IES; and avoided impacts, the Ecoinvent database (Swiss Centre for Life which covered the inputs and outputs avoided Cycle Inventories, 2007),3 from the VAHTI through recycled waste (deducted from the to- database (Finnish Environmental Administra- tal) (see ﬁgure 1). The functional unit of the tion 2008), other companies’ environmental re- study was the total annual production of the ports, and other literature were used for the IES (tons or GWh in 2005) at the gate of production of raw materials and recycling and the symbiosis. treatment of waste. The life cycle inventory

140 Journal of Industrial Ecology RESEARCH AND ANALYSIS assessment was conducted using the KCL-ECO cations (e.g., the infrastructure required) are not LCA software (Finnish Pulp and Paper Research assessed in this study. The reference systems were Institute 2004).4 GHG emissions of the system designed to contain production systems that are have been discussed in another of our articles actually currently in use somewhere. In both of (Sokka et al. 2009) and are thus only briefly ad- the reference systems the total energy use and the dressed here. amount of products produced by the actors of the LCIA was conducted according to ISO stan- IES is the same as in the case study IES, except dards 14040:2006 and 14044:2006. Characteriza- for the power plant, which produces less heat and tion factors that are site and temporally generic electricity. However, its production is replaced by have been used in many studies for reasons of external production purchased by the town (see practicality and due to uncertainties about the below). location or time at which the emissions occur In Reference system 1, the following assump- (Krewitt et al. 2001; Pennington et al. 2004). tions were made: However, several studies have shown that within some impact categories there may be significant • The local town would use electricity pro- variation in the estimated damage between coun- duced with hydropower as before, but meet tries due to, for example, local environmental the rest of its electricity demand from reg- conditions (Krewitt et al. 2001; Seppal¨ aetal.¨ ular markets. Average Finnish production 2006). Since most of the processes in this study (Koskela and Laukka 2003) was used to took place in Finland or Russia, Finland-specific represent this electricity. Instead of buy- characterization factors were used for impacts on ing heat from the power plant, the town acidification, eutrophication, tropospheric ozone would use average heat from the Kymen- formation, and particulate matter (table 1). Tox- laakso region. The fuel profile of the district icity impacts were calculated with the ReCiPe heat production in Kymenlaakso was taken methodology (Sleeswijk et al. 2008; Goedkoop from Finnish Energy Industries (2006). The et al. 2009) and adjusted for Finland according to power plant would only produce electricity method described by Seppal¨ a¨ (2008). and heat for the pulp and paper mill, and its In normalization, the impact category indica- production would be reduced accordingly. tor results are divided by an appropriate reference It would still utilize all the wood residues value (e.g., impacts of a society’s total activities of the pulp and paper mill but purchase less in a given area over a certain time period). Since wood from markets. product life cycles can extend all over the world, • The calcium carbonate (CaCO3)plantand the global system is often chosen as a reference the chlorine dioxide (ClO2) plant, which situation (Sleeswijk et al. 2008). However, pol- presently obtain electricity and steam from icymakers are typically interested in results on the pulp and paper mill, would also use av- a smaller geographic scale because such results erage heat from Kymenlaakso and average offer a more direct link to policy aims. In this Finnish electricity. study the results were normalized with European • The calcium carbonate plant would not get reference values (Sleeswijk et al. 2008). Weight- fossil CO2 from the pulp and paper mill but 5 ing was not conducted as weighting is not usually would buy liquid CO2 instead. The CO2 recommended in comparative studies presented would be released in the air. to the public due to its subjectivity (Pennington • The pulp and paper mill was assumed not et al. 2004). to get any sewage sludge from the municipal wastewater treatment plant. Sewage Hypothetical Reference Systems sludge addition replaces urea and phosphorous acid in the wastewater treatment pro- Two hypothetical reference systems in which cess of the pulp and paper mill. Therefore, the main actors of the system work on their own extra nitrogen and phosphorus would need were designed. It should be emphasized that these to be added to the system. The amount scenarios are hypothetical and their actual impli- of nutrients needed was calculated with

Sokka et al., Analyzing the Environmental Beneﬁts of Industrial Symbiosis 141 RESEARCH AND ANALYSIS

Ta bl e 1 Impact Categories, Emissions Included in Them, and References Impact category Contributing emissions Source

Climate change Carbon dioxide (CO2), methane (CH4), Solomon et al. 2007 dinitrogen monoxide (N2O) Acidiﬁcation Nitrogen oxides (NOX), sulphur dioxide Seppal¨ a¨ et al. 2006 (SO2), ammonia (NH3) Aquatic eutrophication Nitrogen oxides (NOX), ammonia (NH3), Seppal¨ a¨ et al. 2004, 2006 total phosphorous (P), total nitrogen (N) Terrestrial eutrophication Nitrogen oxides (NOX), ammonia (NH3)Seppal¨ a¨ et al. 2004, 2006 Tropospheric ozone Methane (CH4), nitrogen oxides (NOx), Hauschild et al. 2004 formation, impacts on nonmethane volatile organic compounds human health (NMVOC) Tropospheric ozone Methane (CH4), nitrogen oxides (NOx), Hauschild et al. 2004 formation, impacts on nonmethane volatile organic compounds vegetation (NMVOC) Freshwater ecotoxicity, Arsenic (As), cadmium (Cd), chromium Sleeswijk et al. 2008; terrestrial ecotoxicity (Cr), chromium IV (Cr IV, water), cobalt Seppal¨ a¨ 2008 and human toxicity (Co, water), copper (Cu), mercury (Hg), nickel (Ni), lead (Pb), tin (Sn, water), zinc (Zn), vanadium (V), polyaromatic hydrocarbons (PAH), dioxins and furans (PCDD/-F), phenols (water), tributyltin (C12H28Sn, water) Particulate matter Nitrogen oxides (NOX), sulphur dioxide Van Zelm et al. 2008 (SO2), ammonia (NH3), particulate matter (PM10) Abiotic resource Aluminum (Al), barite, chromium (Cr), Van Oers et al. 2002 depletion 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, brown coal, natural gas, peat

information from Valtonen’s thesis (2005). stead of using average heat from Kymenlaakso. The sewage sludge would be composted in- Peat was chosen for the comparison because it is a stead. Sewage sludge was intended to re- domestic fuel and the third most used fuel in heat place peat in soil amendment at a ratio of production in Kymenlaakso (Finnish Energy In- 1:1, and negative emissions would be cal- dustries 2006). Data on heat produced with peat culated for this use. Inputs and outputs of were taken from the Myllymaa and colleagues re- the composting process were taken from a port (2008). The harvesting of the peat was also report by Myllymaa and colleagues (2008). taken into account.

Since there are many different ways to produce Potential Improvements to the Case heat, a second reference system was designed in Study IES (Reference System 3) order to reﬂect the sensitivity of the results to the selected fuel. Thus, in Reference system 2,ev- A further scenario, Reference system 3,was erything else remains the same as in Reference constructed in order to analyze the waste and system 1 except that the town would use heat emission ﬂows of the case study IES in or- that was assumed to be produced with peat in- der to identify additional possibilities for links

142 Journal of Industrial Ecology RESEARCH AND ANALYSIS between the actors or for links to new actors. The would replace 500 kg of mineral fertilizer. Data on potential environmental benefits of these con- phosphorus fertilizer production were taken from nections were assessed in relation to the present the U.S. Life Cycle Inventory database (National situation. These possible new features of the sym- Renewable Energy Laboratory 2008). Altogether, biosis included utilization of hydrogen gas from approximately 2,500 to 3,000 hectares could be the chlorine dioxide plant in a new hydrogen fertilized with the currently landfilled ashes of the plant in the IS, use of fly ash from the power plant case study IES. Energy use and emissions gener- in forest fertilization, and treatment of municipal ated in the process of spreading the ash were not wastewaters from the municipality of Kouvola at taken into account. the pulp and paper mill. In addition, the poten- A study has been conducted on the possibility tial to use the waste heat from the pulp and paper of treating the wastewaters from the municipal- mill in greenhouses was assessed. Assumptions ity of Kouvola at the UPM Kymi pulp and pa- concerning the aforementioned are presented in per mill’s wastewater treatment plant (Valtonen more detail below. However, it should be empha- 2005). In that study, the resulting potential sav- sized that the options studied here are hypotheti- ings in nutrients and other chemicals were cal- cal and do not imply that they would actually be culated. The sewage sludge from the municipal considered for implementation. wastewater treatment plant is already being de- The chlorine dioxide plant produces approxi- livered to the Kymi mill. According to Valtonen mately 28 kilograms (kg) of hydrogen per ton of (2005), if the wastewater from both plants were chlorine dioxide produced. This hydrogen could treated together, no phosphorus would need to in principle be utilized in energy production. The be added to the system and the use of urea could same company has built a hydrogen-utilizing en- be reduced to 300 tons/year from the present 500 ergy unit in its chlor-alkali plant in southeast Fin- tons/year. Moreover, the ferrous sulfate (FeSO4), land. If such a hydrogen plant were built within poly-aluminum chloride, and other resources that the case study IES, it could potentially replace are used in phosphorus removal at the munici- 22,000 GJ of natural gas.6 pal wastewater treatment plant would no longer Approximately 13,700 tons of fly ash from the be needed. The combined treatment would re- power plant was deposited in landfill in 2005. duce the total nitrogen emissions of both plants This fly ash could be utilized as a forest fertil- by almost 50% and the phosphorus emissions by izer. Wood ash has been found to be beneficial approximately 10% (Valtonen 2005). It was con- particularly on peat lands because the ash included in the study that despite the investment cludes phosphorus and potassium in appropriate costs this combined treatment would need, the proportions. There is no nitrogen in the ash, but option would be cheaper for the town in the long nitrogen is not usually required on peat lands be- run. cause peat itself contains enough plant-available The total heat load from the case study nitrogen (Rinne 2007). The popularity of for- IES that is annually released to the surface est fertilization has been increasing in Finland waters is approximately 2,500 GWh. It was during the 2000s, and the National Forest Pro- assumed that some of this waste heat could gramme 2015 includes a target of increasing the be utilized in greenhouses, and emissions sav- amount of fertilized forests from the current ap- ings were thus calculated. In 2005, approxi- proximately 25,000 hectares (ha) to 80,000 ha in mately 4.5% (based on production area) of the 2015 (Ministry of Agriculture and Forestry 2008; total Finnish greenhouse production was lo- Finnish Forest Research Institute 2004). Thus, cated in the Kymenlaakso region (Ministry of there arguably exists an increasing demand for Agriculture and Forestry 2006). Of this, the forest fertilizers. According to Korpilahti (2003), greenhouses located in municipalities close to 500 kg/ha of commercial fertilizer provides 45 Kouvola accounted for approximately 40%. The kg phosphorus per hectare. In order to gain the total energy use of greenhouses was approxi- same amount of phosphorus from ash, 3,000 to mately 2,000 MWh in Finland in 2004 (Hiltunen 7,000 kg of ash is required. In this study it was as- et al. 2005). If the waste heat from the Kymi pulp sumed that 5 tons of fly ash from the power plant and paper mill could cover the total energy needs

Sokka et al., Analyzing the Environmental Benefits of Industrial Symbiosis 143 RESEARCH AND ANALYSIS of the greenhouses close to Kouvola, they would 15%. The shares of waste management and im- use approximately 35 MWh of its waste heat. The pacts avoided through waste recovery were very most common energy source in the Finnish green- small, less than 1.5% in all impact categories. As houses at the beginning of the 2000s was heavy could be expected, given the large size of the pulp fuel oil (Hiltunen et al. 2005), so the waste heat and paper mill, over 60% of all impacts except for was taken to replace heat produced with heavy terrestrial ecotoxicity impacts were caused by the fuel oil. Data on heavy fuel oil energy were taken mill and the upstream processes related to it. Of from the Ecoinvent database. the total impacts of the pulp and paper mill, upstream processes caused 70% to 80% of the total impacts in most impact categories. Of the partic- Results ulate matter impacts, the share of upstream pro- Impacts of the Case Study IES cesses was 60% and that of the toxicity impacts was over 90%. When looking at the normalized environmen- 7 tal impacts, acidification had the highest values, Impacts of the Reference Systems 3.27 E-04, followed by terrestrial eutrophication, tropospheric ozone formation (human health im- The comparison of the case study IES to Ref- pacts), climate change, impacts on particulate erence systems 1 and 2 indicates that the envi- matter formation, and aquatic eutrophication. ronmental impacts of the reference systems are For terrestrial eutrophication, the normalized val- higher in most impact categories (figure 3 and ues were approximately 40% smaller than acidi- table 2; please also see tables S-1 and S-2 in the fication impacts. The normalized impacts of cli- supporting information on the Journal’s Web site mate change, particulate matter formation, and for the detailed inventory results). The results aquatic eutrophication were 60% to 80% smaller show that in Reference system 1, impacts on cli- than acidification impacts. Most of the acidifica- mate change would increase by 12% and those on tion, terrestrial eutrophication, and tropospheric acidification and particulate matter by approxi- ozone formation originated from the emissions mately 5%. Reference system 2 would result in of nitrogen oxides. Most of the NOX emissions larger changes in all the impact categories, par- were generated by the pulp and paper mill, the ticularly in acidification, which would grow by al- power plant, production and transportation of most 40%. The other impacts, except for aquatic hardwood, and transportation of kaolin and cal- eutrophication, would increase by 10% to 20%. cite. According to the normalized values, the im- The assumed increases in the recycling of by- pacts were 1.21E-6 to 8.05E-6 for the toxicity im- products generated by the case study IES (Ref- pact categories and 1.95E-6 for abiotic resource erence system 3) would result in an almost 30% depletion. Thus, the normalized values for toxic- decrease in the aquatic eutrophication impacts ity and abiotic resource depletion were very small (see figure 3). The other impacts would decrease compared with the other impact categories and by less than 10%. were omitted from the figures presented below. The sources of aquatic eutrophication, partic- When studying the contribution of different ulate matter formation, acidification, and terres- life cycle stages (raw material extraction and trial eutrophication were studied in more detail processing, energy and fuel extraction and pro- (figure 4). The largest contributors to these im- duction, production within the IES, waste man- pacts except for aquatic eutrophication, in both agement processes, and impacts avoided through the case study IES and the reference systems, recovered materials) one can see that the raw ma- throughout the whole life cycle of the production terial extraction and processing made the largest system were the pulp and paper mill, the power single contribution to the results in most impact plant, the production of potato starch, optical categories (figure 2). Fuel production and energy brighteners, and sodium hydroxide, transporta- generation contributed approximately 19% to the tion of kaolin and quicklime, and production climate change impacts. Its contribution to the of hardwood. The pulp and paper mill and the other impact categories ranged between 3% and power plant are represented as the source of direct

144 Journal of Industrial Ecology RESEARCH AND ANALYSIS

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 omitted from the ﬁgure. The contributions of the life cycle phases waste management processes and impacts avoided are so small that they are not visible in the ﬁgure except for the small contribution of impacts avoided in particulate matter formation. Symbiosis stands for inputs to and outputs from the symbiosis.

emissions of the case study IES, while the other The role of optical brighteners in particular processes are represented as upstream processes. was perhaps surprisingly high considering that the The largest contributors to the aquatic eutrophi- amount used was fairly small: 1,550 tons (100% cation impacts in the case study IS and Reference purity). The production of optical brighteners systems 1 and 2, were the municipal wastewa- is very energy intensive compared with that of ter treatment plant (Akanoja sewage plant in some other bleaching chemicals such as H2O2, ﬁgure 4a) and sodium hydroxide production. but on the other hand, the amount of chemicals There are no emissions from the municipal needed is much lower (Scheringer et al. 1999). wastewater treatment plant in Reference system One can see that the role of transportation of 3 since in Reference system 3 municipal wastew- kaolin, quicklime, and hardwood was fairly large aters are treated at the pulp and paper mill. Ap- as well; altogether they accounted for 9% to 15% proximately 35% of the reduction in aquatic eu- of the total impacts. trophication impacts is caused by the combined The difference in environmental impacts be- treatment of wastewaters at the pulp and paper tween Reference systems 1 and 2 and the case mill (direct emissions of the IES), while the rest study IES is mainly attributable to the differences of the reduction is caused by the replacement of in energy production. In the reference systems, added phosphorus and nitrogen at the pulp and emissions from the power plant, which especially paper mill with sewage sludge and the utiliza- affect impacts related to NOX emissions, de- tion of wood ash in forest fertilization (upstream crease (see table 2). At the same time, emissions processes). from the average production of district heating

Sokka et al., Analyzing the Environmental Beneﬁts of Industrial Symbiosis 145 RESEARCH AND ANALYSIS

Figure 3 Environmental impacts of the reference systems in relation to those of the case study industrial ecosystem (IES) (the environmental impacts of the IES get the value 1). Normalized values for freshwater ecotoxicity, terrestrial ecotoxicity, human toxicity, and abiotic resource depletion were so small that they were omitted from the ﬁgure. and electricity increase. This impacts the CO2 crease. Thus, it can be concluded that in Refer- emissions in particular. Moreover, in Reference ence systems 1 and 2 the contribution of upstream system 2, in which more peat is used, CO2,NOX, processes to the total impacts is higher than in and SO2 emissions from energy production in- the case study IES. This is mainly because in

Ta bl e 2 Absolute and Relative Differences in the Main Emissions and Consumption of Fuels Between the Case Study Industrial Ecosystem and Reference Systems 1, 2, and 3 Difference Difference Difference from from from Case study reference Difference reference Difference reference Difference IES 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%

146 Journal of Industrial Ecology RESEARCH AND ANALYSIS ant Comparison of the contribution of different processes in different reference scenarios and in the case study industrial ecosystem to the most import Figure 4 impact categories caused: (a) aquatic eutrophication; (b) particulate matter formation; (c) acidiﬁcation; and (d) terrestrial eutrophication.

Sokka et al., Analyzing the Environmental Beneﬁts of Industrial Symbiosis 147 RESEARCH AND ANALYSIS Continued Figure 4

148 Journal of Industrial Ecology RESEARCH AND ANALYSIS the reference systems the power plant does not thirds in the United Kingdom. Transporta- supply the local town with heat and electricity. tion mode was assumed to be a roll-on ship Therefore, the town needs to purchase electric- by sea and fully loaded Euro3 truck on land. ity and heat from other sources, which leads to For the sensitivity assessment, we assumed higher upstream emissions. Carbon dioxide emis- that all the kaolin was imported from the sions also grow because the pulp and paper mill United Kingdom. Transportation mode was no longer delivers part of its CO2 to the calcium assumed to be the same. carbonate plant. The significance of the other • In Scenario 3, the data source of optical processes is minor. brighteners was changed. Instead of using The reduction in aquatic emissions and the Ecoinvent Database version 2.01 (Swiss thereby aquatic eutrophication impacts in Refer- Centre for Life Cycle Inventories 2007), ence system 3 is due to the treatment of municipal data from the article by Scheringer and col- wastewater at the case study IES and replace- leagues (1999) was used. ment of phosphorus fertilizer through utilization • In Scenario 4, it was assumed that the pulp of wood ash in forests. Large reductions in the and paper mill used maize starch instead of system’s environmental impacts could potentially potato starch. Data on maize starch were be achieved if more of the waste heat from the taken from the Ecoinvent database version pulp and paper mill could be utilized. However, 2.01 (Swiss Centre for Life Cycle Invento- at present such heat is not being used anywhere ries 2007). on a large scale. In the analysis it was assumed The impact of these factors was less than that a small proportion of it could be utilized in 15% on most of the main emissions (table S-3 the heating of greenhouses. in the supporting information on the Web) and less than 10% on the main impact categories Sensitivity Analysis (figure 5) for all scenarios. The greatest changes The main uncertainties of this study relate were caused by Scenario 3, which resulted in to the data on upstream processes. The amount an 8% decrease in the acidification impacts and of raw materials, fuels, and energy used was a 5% decrease in the terrestrial eutrophication received directly from the actors of the case impacts. study IES and is fairly accurate, but the data on the production of these materials and fu- Discussion els are mainly generic, originating from different databases, and do not necessarily represent In this study, normalized LCA results were the actual production processes. Therefore, the presented and no weighting was applied to the data sources of those upstream processes con- impact categories. Normalized values can be tributing most to the results were varied in the judged to rank the impacts in their order of im- sensitivity analysis. Four different scenarios were portance provided that all environmental effects constructed: are considered equally important; for example, the significance of total current levels of global • In Scenario 1, external electricity pur- warming and toxicity effects would be assumed to chased by the pulp and paper mill was be equal (Pennington et al. 2004). However, one assumed to represent the electricity pro- must be aware that different valuation studies in- file of the Finnish forest industries in dicate that not all the environmental impacts are 2007 (Finnish Forest Industries Federation generally considered equal in importance (e.g., 2009). Seppal¨ a¨ 2003), so special care must be taken • In Scenario 2, the transportation distance when comparing normalized values across impact of kaolin was changed. On the basis of in- categories. formation about the producers it was origi- The study showed that the impacts occurring nally assumed that one third of the kaolin outside the IES may be high. We did not find originated in the United States and two other evidence for this from the literature, but

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Figure 5 Sensitivity of the main impacts to the different scenarios. similar results have been reported for different was primarily caused by energy production for kinds of systems. For example, the environmental Kouvola town. However, as it was also found impacts of the Second Sydney Airport proposal in the study that the upstream processes made were assessed by extending environmental impact a considerable contribution to the overall results, assessment with input-output analysis to cover ef- it may be concluded that the greatest reductions fects occurring off-site (Lenzen et al. 2003). The in the overall environmental performance of the results showed that indirect impacts were consid- system can be achieved by minimizing the total erable for all the factors studied. Matthews and raw material use of the system. However, here it colleagues (2008) presented the same conclusion was assumed that the pulp and paper mill gets for carbon footprints. Thus, one implication of most of its electricity and heat from wood-based our study is that when developing or initiating fuels also in the stand-alone situation. Assum- an industrial symbiosis, the analysis should be ex- ing that it would either buy wood from outside tended to off-site impacts as well, as these may be the system or use fossil fuels instead would have decidedly high in relation to impacts within the increased its environmental impacts throughout. symbiosis. Singh and colleagues (2007) con- It can be argued that a central environ- cluded in their study that LCA is an extremely mental driver for IES is the increased material useful tool for analyzing and comparing different efficiency through recycling and the resulting designs of industrial symbioses. Similarly, LCA avoidance and reduction of upstream effects of can be applied when looking at industrial sym- resource extraction and primary production. The bioses already in operation. value of LCA lies in the possibility to locate The results indicate that in the present case those flows whose reduction provides the great- the environmental impacts are smaller from the est overall environmental benefits. For example, system operating as an industrial symbiosis than it can be used to locate areas of improvement from stand-alone production. The difference was or to assess the environmental benefits of addi- the greatest in acidification, climate change im- tional symbiotic links. As Reference system 3 of pacts, and impacts on particulate matter forma- our study showed, the greatest additional envi- tion. Reduction in the environmental impacts ronmental benefits could be achieved through

150 Journal of Industrial Ecology RESEARCH AND ANALYSIS combined treatment of wastewaters of the mu- ferent scenarios resulted in fairly small changes, nicipal wastewater treatment plant and the pulp less than 10% in all impact categories compared and paper mill, replacement of nutrients with the with the case study IES. municipal sewage sludge, and utilization of wood One major uncertainty concerning the com- ash for forest fertilization.8 Approximately 35% parison with stand-alone production is that it is of these benefits were achieved with respect to not clear how the stand-alone situation should the direct emissions of the case study IES and be defined. A symbiotic mode of operation is very the rest in the upstream processes. The contribu- typical for the Finnish forest industry. We tried to tion of the other processes was minor. It should, find the most realistic scenario of how the actors however, be pointed out that additional reduc- would operate in a stand-alone scenario choos- tions in the overall environmental performance ing a situation that does actually occur elsewhere. of the system could be achieved through more However, the choice is subjective and is open to efficient technology and changes in the fuel mix question. We assumed that even in a stand-alone used. situation the energy production of the pulp and Significant reductions in the system’s envi- paper mill would be based on utilizing its own ronmental impacts could potentially be attained wood residues and black liquor, as is generally if more of the waste heat from the pulp and paper the case in the Finnish forest industry (Finnish mill could be utilized. Fish farms have also been Forest Research Institute 2006). The situation noted as potential users of waste heat (Lowe and would have been different if we had assumed that Evans 1995). However, in Finland their total en- wood was not used as an energy source at the ergy use is fairly low (Silvenius and Gronroos¨ pulp and paper mill. However, this assumption 2004). In the future, more potential could per- was made because it is a common practice in the haps be found in the drying of wood pellets. forest industry in Finland and abroad. The drying process is usually the most energy- The study method used was a traditional LCA, demanding phase of pellet production (Anders- which necessarily results in upstream and down- son et al. 2006; Sokka et al. 2009). This option, stream cut-offs. In recent years, so-called hybrid however, was not studied further as only options methods, where product-based LCA is combined that were actually in use somewhere were cho- with input-output accounting, have increasingly sen for the reference systems. Moreover, until been used (for a review of the hybrid methods, recently, the production of wood pellets has been see Suh and Huppes 2005). Because we studied fairly small in Finland, totalling 192,000 tons (3.2 the applicability of LCA for analyzing the envi- TJ) in 2005, of which over two thirds were ex- ronmental impacts of an industrial symbiosis and ported (Statistics Finland 2006). However, policy compared the impacts of the industrial symbiosis targets have been set to increase the use of renew- to separately operating systems and assessed the able fuels, and the Finnish long-term climate and upstream processes in relation to processes occur- energy strategy aims to increase the use of pel- ring within the symbiosis, applying a full-scale lets in industry and housing by 2020 (Council of hybrid LCA was not considered necessary. State 2008). The main uncertainties in this study related to Concluding Remarks the data on upstream production processes. The amount of raw materials, fuels, and energy used In the case studied, comparison with the was received directly from the actors of the case stand-alone production showed that the symbio- study IES and was fairly reliable, but the data on sis resulted in net improvements in the total en- upstream processes were mainly generic, originat- vironmental impacts of the system, the difference ing from different databases, and do not necessar- being between 5% to 20% in most impact cate- ily reflect the actual production processes. Thus, gories. The difference was the greatest in acidifi- in the sensitivity analysis, data sources of those cation, climate change impacts, and impacts on upstream processes with the greatest impact on particulate matter formation. Reduction in the the results were studied. In addition, the trans- environmental impacts was primarily caused by portation distance of kaolin was varied. The dif- energy production for Kouvola town.

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Symbiotic exchanges reduce the need to pur- 6. The heating value of hydrogen is assumed to be chase raw material and energy from outside the 120 megajoules per kilogram (U.S. Department of symbiosis. Efficient energy production and uti- Energy 2006). lization are critical factors contributing to the 7. In Finland, natural systems are particularly vulner- overall environmental performance of symbiosis- able to acidification due to the low buffer capacity like production systems. In the case study IES, of the soil. Therefore, the importance of acidification impacts tends to become high in studies using upstream processes made a considerable contri- Finnish-specific characterization factors. bution to the overall results. Thus, it may be con- 8. The possible impacts that such a cheap phospho- cluded that major reductions in the total environ- rus source would have on the domestic phosphorus mental impacts of the system can be achieved by markets were not assessed in this study. On the affecting the extraction and production of raw other hand, phosphorus is a limited resource, and materials and external energy. All in all it is with the increase of food and biofuel production, recommended that when assessing the environ- serious concerns have been raised on its long-term mental performance of an industrial symbiosis or availability (Lewis 2008). an eco-industrial park, the impacts occurring upstream should be studied and not merely the situation within the symbiosis. LCA seems a very References useful, albeit labor-intensive, tool for this kind Andersson, E., S. Harvey, and T. Berntsson. 2006. En- of assessment. It can also help in detecting those ergy efficient upgrading of biofuel integrated with flows whose utilization could provide the greatest a pulp mill. Energy 31(10–11): 1384–1394. environmental benefits. Chertow, M. 2000. Industrial symbiosis: Literature and taxonomy. Annual Review of Energy and the Envi- ronment 25: 313–337. Acknowledgements Chertow, M. R. and D. R. Lombardi. 2005. Quantify- ing economic and environmental benefits of co- Support from the Academy of Finland to the located firms. Environmental Science & Technology “Industrial Symbiosis System Boundaries (ISSB)” 39(17): 6535–6541. project (code 117837) is gratefully acknowl- Council of State. 2008. Long term climate and energy edged. The authors would also like to thank Ismo strategy (in Finnish). Helsinki: Council of State. Taskinen, Juha Kouki, Erkki Vierros, and Jani Eckelman, M. J. and M. R. Chertow. 2009. Quantifying Katajala for providing information for this study life cycle environmental benefits from the reuse and Tuomas Mattila for his comments on the of industrial materials in Pennsylvania. Environ- manuscript. Finally, the invaluable comments mental Science and Technology 43(7): 2550–2556. Finnish Energy Industries. 2006. District heating in made by the anonymous reviewers are gratefully Finland 2006. www.energia.fi/en/districtheating/ acknowledged. districtheating/statistics. Accessed 17 February 2009. Finnish Environmental Administration. 2008. VAHTI Notes database. Helsinki: Finnish Environmental Ad- ministration. 1. In this article the term industrial symbiosis refers to Finnish Forest Industries Federation. 2009. Forest in- the collection of exchanges and processes that occur dustry electricity purchases in 2007 by source. within a system called an industrial ecosystem. Statistics figures, energy, environment and logis- 2. The VAHTI database is an emissions control and tics. www.forestindustries.fi/tilastopalvelu/Tilasto monitoring database of the Finnish Environmental kuviot/Energy/Forms/AllItems.aspx. Accessed 17 Administration. June 2009. 3. Ecoinvent: www.ecoinvent.ch Finnish Forest Research Institute. 2004. Finnish statis- 4. www.vtt.fi/research/technology/sustainability tical yearbook of forestry. Helsinki: Finnish Forest assessment.jsp?lang=en Research Institute. 5. In reality, it would probably be difficult to obtain Finnish Forest Research Institute. 2006. Finnish statis- enough liquid CO2 available to replace the CO2 tical yearbook of forestry. Helsinki: Finnish Forest received in flue gas (Taskinen 2008). Research Institute.

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Linkoping¨ Institute of Technology, Linkoping,¨ About the Authors Sweden. Zhao, Y., J. Shang, C. Chong, and H. Wu. 2008. Sim- Laura Sokka is a researcher and Ph.D. stu- ulation and evaluation on the eco-industrial sys- dent, Suvi Lehtoranta is a researcher, Ari Nissi- tem of Changchun economic and technological nen is a senior researcher, and Matti Melanen is development zone, China. Environmental Moni- a research professor at the Finnish Environment toring and Assessment 139: 339–349. Institute, 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 inventory results for the symbiosis case and reference systems and the sensitivity of the main emissions to the different scenarios. Please note: Wiley-Blackwell is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing material) should be directed to the corresponding author for the article.

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