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Journal of Cleaner Production 25 (2012) 60e67

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Journal of Cleaner Production

journal homepage: www.elsevier .com/locate/ jc lepro

Implementation of best available techniques in cement manufacturing:a life-cycle assessment study

César Valderrama a,*, Ricard Granados b, José Luis Cortina a,c, Carles M. Gasol d, Manel Guillem e,Alejandro Josa f,g

aDepartment of Chemical Engineering, Universitat Politècnica de Catalunya-Barcelona Tech (UPC), Carrer Colom 1, 08222 Terrassa, Barcelona, SpainbAUMA Consultants in Energy and Environment S.L., Barcelona, SpaincWater Technology Center CETaqua, Barcelona, Spaind Inèdit Innovació SL, UAB Parc de Recerca, Cabrils, Barcelona, SpaineCementos Molins Industrial S.A., Sant Vicenç dels Horts, SpainfDepartment of Geotechnical Engineering and Geosciences, School of Civil Engineering, Universitat Politècnica de Catalunya-Barcelona Tech (UPC), Barcelona, Spaing Institute of Sustainability, Universitat Politècnica de Catalunya-Barcelona Tech (UPC), Barcelona, Spain

a r t i c l e i n f o

Article history:Received 5 September 2011Received in revised form28 October 2011Accepted 17 November 2011Available online 13 December 2011

Keywords:BATClinkerEnvironmental impactLCAGlobal warming potentialDamage assessment

* Corresponding author. Tel.: þ34 93 4011818; fax:E-mail address: cesar.alberto.valderrama@upc.edu

0959-6526/$ e see front matter � 2011 Elsevier Ltd.doi:10.1016/j.jclepro.2011.11.055

a b s t r a c t

A cement manufacturing company located in Catalonia (Spain) has upgraded its cement productionplant. The new cement production line (L6) has replaced the former lines (L3, L4 and L5) which havebeen operating for 30 years. The new line production L6 has been designed and constructed taking intoaccount the best available techniques (BAT) for the cement industry. The significant improvementsachieved with the new plant are related to the energy efficiency of the new kiln systemwhich representsless amount of fossil fuel and to less emission to the atmosphere per kg of clinker produced. Life-cycleassessment (LCA) methodology has been used for the quantification and evaluation of the environmentalimpacts of the new production line (L6) considering the designed goals proposed and those achieved atfirst trimester of 2011 compared to the former production lines. To reduce uncertainty this manuscriptpresents a cradle-to-gate life-cycle assessment of both scenarios. Analysis using SimaPro 7.2 softwareshows that new production line (L6) provides a significant reduction of the environmental impact forglobal warming (5%), acidification (15%), eutrophication (17%) and cumulative exergy demand (13%). Thedamage assessment also confirmed that new production line (L6) reported a significant reduction impactfor the human health (11%), ecosystem quality (11%) and resources (14%) damage compared to the formerlines.

� 2011 Elsevier Ltd. All rights reserved.

1. Introduction

The production of cement involves the consumption of largequantities of raw materials and energy (heat and electricity). Themanufacturing process is very complex, involving a high number ofmaterials (with varying material properties), pyroprocessing tech-niques (van Oss and Padovani, 2002, 2003), and fuel sources(e.g., coal, petroleum, coke, natural gas, fuel oil, biomass, ordifferent types of wastes) (van Oss and Padovani, 2002, 2003;Huntzinger and Eatmon, 2009). The main emissions of cementindustries are atmospheric emissions from the kiln system. Thesederive from the physic-chemical reactions involving the raw

þ34 93 401 58 14.(C. Valderrama).

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material calcination (decarbonisation of limestone) and fuelcombustion (Nadal et al., 2009; BREF, 2010). Emissions of CO2

depend mainly on the type of production process and on the fuelused (Gäbel et al., 2004). For instance, in a typical dry process withfive stage preheater, precalciner and 100% petroleum coke as a fuel,CO2 emissions derived from the chemical reactions are around0.53 t of CO2 per t of clinker, while CO2 emissions derived from thefuel consumption are 0.31 t of clinker (BREF, 2010; Moya et al.,2010). Increased public awareness of the threats posed by globalwarming has led to greater concern over the impact of anthropo-genic carbon emissions on the global climate change. The currentlevel of carbon dioxide (CO2) in the atmosphere is approaching380 ppm (Sabine et al., 2004). Without drastic market, technolog-ical, and societal changes CO2 concentrations are projected toincrease to over 800 ppm by the end of the century (Huntzingerand Eatmon, 2009). Cement production is responsible for 5% of

C. Valderrama et al. / Journal of Cleaner Production 25 (2012) 60e67 61

global anthropogenic CO2 emissions and 7% of industrial fuels use(Worrell et al., 2000, 2001). Thus, the cement industry is animportant industrial polluter in terms of greenhouse gases (GHG),and emission reductions in this sector may lead to significantdecreases of overall GHG releases (Boesch and Hellweg, 2010).

In addition to CO2, atmospheric emissions from cement plantsinclude other pollutants such as particles, NOx, SO2, and someminor pollutants, which range from local to global environmentalimpacts. Other environmental issues associated with cementinclude the energy required for production and transportation ofraw materials, fuels, clinker and cement and the impact of mining,resource depletion and waste generation (Phair, 2006). Amongothers, process developments (optimise and develop the existingprocess) and end-of-pipe solutions (adding emission reductionsystems) are both of actions integrated in order to minimize theenvironmental impact of cement manufacturing (Gäbel et al.,2004). Recently, studies on clinker and cement production haveapplied life-cycle assessment (LCA) to analyse direct impacts fromthe production site as well as indirect impacts, e.g. from resourcesmining and electricity production (Gäbel et al., 2004; Huntzingerand Eatmon, 2009; Boesch and Hellweg, 2009, 2010). LCA isa suitable tool for assessing environmental impacts of clinkerproduction and its associated supply chains (Boesch and Hellweg,2009). The EU Directive concerning Integrated Pollution Preven-tion and Control (IPPC) (EC, 2008) highlights that manufacturingprocesses have impacts on the environment which exceed theboundaries of the specific installations being regulated. Indepen-dently of whether these impacts arise from off-site generation ofelectricity or processing of raw materials, they must be consideredwhen making the choice of the Best Available Techniques (BAT) forany specific installation (Nicholas et al., 2000). The elementarymeasures recommended by BAT are connected among others withthe improvement of the output and energy efficiency of thecement production process through replacement of the oldequipment with new one, less energy-consuming, in order tominimize CO2 and other emissions (Deja et al., 2010; Hasanbeigiet al., 2010). In that sense, the study performed by Moya et al.(2011) confirms that BAT can contribute to decreasing the energyconsumption and CO2 emissions in the European Union’s (EU27)cement industry.

The environmental impact improvement of BAT implementa-tion for the cement industry is here demonstrated by a case study ofa cement manufacturing plant located in Catalonia (Spain). LCAmethodology is used to evaluate and compare the environmental

Table 1Design characteristics of new production line (L6) compared to former lines L3eL5 of Ce

Stage L3, L4 and L5

Grinding raw material 3 Ball mills air swept (375 t h�1)Specific consumption: 24e26 kWh t�1

Cyclone tower Four cyclone preheater stages (L5)Two cyclone preheater stages (L3, L4)Height: 40 m (L3, L4); 50 m (L5)

Reduction of NOx emissions

Kiln L3/4: 4.15 m� 106 m; L5: 5.25 m� 78 mL3/L4: Fired burner, flame not adjustableL5: Greco burner, flame and intensity ad

Cooler Satellite (10 per kiln)Clinker outside temperature:175 �Cþ air temperature

Kiln filter L3: Bags filter; L4/L5: Electrostatic precip

Fuel consumption 3697 kJ kg�1

impact of the former clinker production lines (L3þ L4þ L5) whichhave been operated for more than 30 years and the new productionline (L6) which has started operations in 2010. The energy effi-ciency achieved by L6 represents an environmental improvement,from the point of view of less amount of fuel required per kg ofclinker and less emissions into the atmosphere. The study isrestricted to the production of clinker since it is the dominantdriver of the environmental impact and the main changes intro-duced in the plant are related to this process.

2. Methodology

2.1. Description of the cement plant (Cementos Molins Industrial)facilities

Cementos Molins Industrial is a company that has beenworkingin calcium aluminate and Portland cement production for morethan 75 years. In recent years, investments have strengthenedefforts to improve productivity, quality and safety as well as tominimize the environmental impact. This strategy was conceptu-alized through the construction of the new production line (L6),actually a new factory that incorporates the BAT in terms of overallefficiency for clinker production (BREF, 2010). From the beginning,L6 has been a challenge due to the specific requirements ofa production line designed to be one the most technologicallyadvanced cement plant in Spain and Europe with the aim ofachieving the best results in terms of efficiency and sustainability.Further, the forced and difficult cohabitation of L6 construction andthe operation of former L3, L4 and L5, resulted in complex main-tenance and construction tasks.

The new Cementos Molins Industrial production line (L6) hasa crusher and two pre-homogenization halls for the initial treat-ment of main raw materials and one vertical mill with 3 rollers toproduce the raw mix, which is then stored in a silo (16,000 t ofcapacity) with special exit control system to assure the homoge-neity of the kiln feed. The preheating tower with 120 m of heightdisposes of five cyclone stages, an in-line precalciner, and theselective non-catalytic reduction (SNCR) unit to reduce the NOxemission. The kiln system has a low NOx multi-air burner, anefficient grate cooler, and a unique over dimensioned bag filter toseparate the dust from all the raw mix and clinker gas ducts. Toproduce cement, the plant disposes of four closed circuit ball millfacilities with different production ratios. In Table 1, the mostsignificant design improvements of the new L6 compared to the

mentos Molins Industrial.

L6

Vertical roller mill (385 t h�1)Specific consumption: 17e18 kWh t�1

Five cyclone preheater stagesand precalciner (55% of fuel)Height: 120 m

Selective non-catalytic reduction (SNCR)

4.75 m� 56 mDuoflex burner; flame and intensity adjustable

justable

Grate (97.2 m2)Clinker outside temperature: 65 �Cþ air temperature

itator Bags Filter (15,839 m2; 10 chambers)6600 bags per chamber; 6 m length� 12.7 cm diameter

2956 kJ kg�1

C. Valderrama et al. / Journal of Cleaner Production 25 (2012) 60e6762

formers lines L3eL5 are summarized. It is important to point outthat most of these differences are based on the BAT for the cementindustry defined by the European Commission. In particular,energy demand in clinker production has been significantlyreduced. BAT levels for new plants and major upgrades are2900e3300 MJ/t clinker, based on dry process kilns withmultistage-preheaters and precalciners (BREF, 2010; Schneideret al., 2011). L6 reduced the energy demand to 3035 MJ/t clinkerrepresenting 17% of energy savings. On the other hand and froma technology point of view, grinding remains the biggest source ofelectrical power consumption in cement production. The corre-sponding BAT aims to minimize the electrical energy consumptionby using grinding equipment with low energy consumption. In thiscase, the new roller mill for raw material grinding reduces around30% of the electrical energy consumption compared to the formerballs mills.

2.2. Environmental improving of new production line (L6)

The scheme of L6 design is shown in Fig. 1. The most significantefficiency improvements achieved are: the dosing optimisation ofrawmaterials (1); the increasing efficiency in grinding rawmaterial(2); the emissions reduction in the cyclone tower (3); the lastgeneration kiln system (more efficient/less emissions) (4); the lessnoisy grate cooler (more efficient/less noise/less maintained) (5)and the high capacity of the kiln filter (6).

As a consequence of the efficiency increase of L6 based on BATfor the cement industry, improvements are also achieved whichcontribute to the conservation of the natural resources, the mini-mization of the local, regional and global environmental impactsand the increase of the life quality of residents surrounding thecement facility. In Table 2, the energy consumption and emissionsfrom the formers and new line are compared considering thedesign goals proposed by the new L6 (to be reached at the end2011) and the values achieved in the first trimester of 2011;furthermore the environmental improvements are also summa-rized as savings. Finally, fuel consumption reduction representsalso economic benefits as reported by Benhelal et al. in their studyof a novel design for green and economical cement manufacturing(Benhelal et al., 2011).

Fig. 1. Diagram of new production line (L6) and the most significant improvements in itsgeneration kiln system, 5) grate cooler and 6) kiln filter.

2.3. Life-cycle assessment

LCA has been proved to be a potential tool to evaluate theimprovement of industrial processes, used to avoid sub-optimisa-tion in the development of more environmental adapted cementand concrete products and manufacturing processes (Gäbel et al.,2004; Josa et al., 2004; Marceau et al., 2006; Navia et al., 2006).Furthermore, LCA is a suitable tool for assessing environmentalimpacts of clinker production and its associated supply chains(Boesch and Hellweg, 2009, 2010). The mains parts of LCA arediscussed in the next section.

2.3.1. Goal and scope, functional unit and system boundariesThe goal of the present study was to assess and compare the

environmental performance of the former and new lines for clinkerproduction in Cementos Molins Industrial plant. The LCA of themain scenarios was performed from a ‘cradle-to-gate’ perspectiveand comprises all environmentally relevant processes fromresource mining to the finished clinker product (ISO 14044, 2006).The model focuses on clinker production in the cement kiln andexcludes the blending and grinding of clinker and additionalmineral components to produce cement. The functional unit ofanalysis in this study is the production of 1 kg of clinker. In Fig. 2,the overall scope of this study comprising the most importantprocessing stages involved in clinker production and considered inthe LCA study is shown.

2.3.2. Data qualityThis study is based on the process data supplied by Cementos

Molins Industrial for clinker production. Data of formers lines(L3, L4 and L5) was based on historical plant records from years2007 to 2009; on the other hand data from L6 is mainly based onthe nominal consumption expected by design and emissions datafrom the equipment suppliers. Production data was obtained sincethe star-up of operation (last trimester of 2010). The LCA softwareSimaPro 7.2 (PRé Consultants, 2008) was used to evaluate theenvironmental impacts of inventory aspects and to create productassemblies and life cycles for three scenarios. Inventory data forraw material acquisition (mining of limestone, sand, iron ore andclay), along with electricity production and heat generation by fuel

design: 1) dosing of raw materials, 2) grinding raw material, 3) cyclone tower, 4) last

Table 2Energy consumption and emissions of new production line (L6) compared to former lines L3eL5.

L3þ L4þ L5 New L6(design data)

Expected savings(design data)

New L6(first trimester 2011)

Achieved savings(first trimester 2011)

Electricity kWh/t clinker 76 68 10% 69 8.4%

Fuel kJ/kg clinker 3697 2956 20%, 87 t pet coke/day 3153 14.7%, 64 t pet coke/dayCO2 t/t clinker 0.52 decarbonisation 0.52 7%, 246 t CO2/day 0.52 4%, 137 t CO2/day

0.33 pet coke 0.31 0.32NOx mg/Nm3 585 (1200a) 293 (500a) 50% 465 (500a) 20.5%SO2 mg/Nm3 113 (600a) 71 (400a) 36% 52 (400a) 54%Emission dust mg/Nm3 L3: 1e5; L4: 15e25;

L5: 5e15 (50a)5.5 (30a) 50% 1.6 (30a) 84.7%

Water m3/any Grinding raw material: 11,200 5000 25%, 50,000e70,000 5000 25%, 50,000e70,000Kiln filter: 35,000 0 0Grinding cement: 40,000 10,000 10,000Overall facility: 250,000 190,000 190,000

Noise (processþ aliento facility)

dBA 62 (maxim allowed 65 dayand 55 night)

Apr. 55 10%, 5/7 dBA 57 7.5%, 4.5 dBA

a Maximum allowed for the Local Environment Authority (more restricted for new line 6).

C. Valderrama et al. / Journal of Cleaner Production 25 (2012) 60e67 63

type for the various processing steps were obtained from theSimaPro libraries and databases. The supply chain of resources andauxiliary materials data were taken from the ecoinvent database(v2.2) (Kellenberg et al., 2007).

2.3.3. Impact assessmentLCA impacts considered in this study were climate change (IPCC,

100 years) (IPCC, 2001); acidification, eutrophication, abioticdepletion, ozone layer depletion, fresh water aquatic ecotoxicityand photochemical oxidation (CML 2000), which are mid-pointapproach (Guinèe et al., 2001); and the Cumulative ExergyDemand in order to evaluate the global energy requirement(Boesch et al., 2007). Cumulative Exergy Demand (CExD) is similarto the more common Cumulative Energy Demand (CED) indicator.In contrast to CED, CExD takes into account the quality of energeticresources. Furthermore, CExD has the advantage of including alsonon-energetic resources such as minerals and metals (Boesch andHellweg, 2010). Finally, damage oriented impact assessmentmethodology was also considered by means of the Ecoindicator 99method (hierarchic perspective) (Rivela et al., 2004; Navia et al.,2006), since this approach provides not only characterization butalso damage assessment for safeguard fields such as human health.

Fig. 2. System boundaries of the cradle-to-gate for clinker pro

3. Results and discussion

The inventory data of 1 kg of clinker processing in threescenarios are summarized in Table 3. It is important to point outthat remarkable differences are related to less consumption ofelectricity and pet coke per kg of clinker produced, due to theenergy efficiency improvement achieved in new production line(L6). The emissions to air from the clinker production systemlargely depend on the design of the system and the nature andcomposition of raw materials and fuels (Gäbel, 2001). In this case,emissions are reduced due to efficient and improved design of kilnsystem as well as for the higher efficiency of the modern indirectlyfired burner and the SNCR unit (in the case of NOx emissions) andthe less amount of fossil fuel per kg of clinker (in the case of SO2emissions). The values reported as first trimester 2011 are thoseobtained from October 2010 to March 2011 since the new lineproduction (L6) was started up.

3.1. Global warming mid-point impact

The focus of this section is that global warming potential can bereduced by considering BAT in clinker manufacturing. The

duction plant of Cementos Molins Industrial in this study.

Table 3Selected parameters of inventory data for 1 kg of clinker production for three scenarios.

Units Input or emission

L3, L4 and L5 New L6(design data)

New L6(first trimester 2011)

Raw materials (Kellenberg et al., 2007)Limestone, milled, loose, at plant/CH U kg/kg clinker 1.181Clay, at mine/CH U kg/kg clinker 0.346Sand, at mine/CH U kg/kg clinker 0.069Iron ore from mine ETH U kg/kg clinker 0.013Water, unspecified natural origin/m3 m3/kg clinker 5.56� 10�4 1.39� 10�4

Energy (Spielmann et al., 2007)Electricity, medium voltage, at grid/CH U kWh/kg clinker 7.57� 10�2 6.81� 10�2 6.94� 10�2

Petroleum coke, at refinery/RER U kg/kg clinker 1.06� 10�1 8.50� 10�2 9.06� 10�2

Hard coal, at regional storage/WEU U kg/kg clinker 5.61� 10�9

Diesel, at regional storage/RER U kg/kg clinker 9.12� 10�7

Heavy fuel oil, at regional storage/CH U kg/kg clinker 1.61� 10�9

Transport (Dones et al., 2007)Transport, barge/RER U (Pet coke) t km 1.008 0.806Transport, lorry 20e28 t, fleet average/CH U (Limestone) t km 1.7E� 10�2

Transport, lorry 20e28 t, fleet average/CH U (Clay) t km 3.5� 10�4

Transport, lorry 20e28 t, fleet average/CH U (Sandstone) t km 1.4� 10�4

Transport, lorry 20e28 t, fleet average/CH U (Iron Ore) t km 1.3� 10�4

EmissionsCO2 kg/kg clinker 0.856 0.796 0.822NOx kg/kg clinker 1.55� 10�3 7.75� 10�4 1.23� 10�3

SO2 kg/kg clinker 5.06� 10�4 3.22� 10�4 2.32� 10�4

Particulates kg/kg clinker 3.00� 10�5 1.50� 10�5 4.59� 10�6

CH: Switzerland; U: Unit process; ETH: Ethiopia; RER: Europe; WEU: Western Europe.

C. Valderrama et al. / Journal of Cleaner Production 25 (2012) 60e6764

dominant factors that determine CO2 emissions in clinkerproduction are energy efficiency, the fuel mix used to provide therequired heat, and in less significant importance the amount ofcarbonated materials used in clinker production (Boesch andHellweg, 2010). The relevant gas emissions related to the green-house effect in the life-cycle inventory (LCI) analysed are carbondioxide (CO2) which represents more than 99% of total globalwarming impact for three scenarios of this study; while otherclimatically relevant gases, such as nitrous oxide (N2O) or methane(CH4), are emitted in very small quantities in clinker production(Josa et al., 2007). The environmental impact profile for threescenarios of clinker production is summarized in Table 4. In the caseof global warming potential, new production line (L6) reporteda significant change of CO2 emissions compared to the former lines,reaching a total reduction of 5% in GHG during the first trimester of2011. Considering the clinker production capacity of new line(4100 t clinker per day) and considering the global warningpotential (GWP) reduction estimated by the IPCC method, it ispossible to determine a daily GWP reduction of 200 t of CO2-eq wasachieved and additionally, if the design goal is achieved at end of2011 the reduction can be around of 331 t of CO2-eq per day. Theresult obtained for L6 (938 g CO2-eq/kg of clinker) is similar tothose reported by Boesch and Hellweg (2010) for preheater and

Table 4Characterization of three scenarios by the IPCC and CML 2000 methods (per kg clinker).

Category Unit

Global warming potential (IPCC) g CO2-eqa

Acidification (CML 2000) g SO2-eqEutrophication (CML 2000) mg PO4-eqAbiotic depletion (CML 2000) g Sb-eqOzone layer depletion (CML 2000) kg CFC-11-eqFresh water aquatic ecotoxicity (CML 2000) kg 1.4-DB-eqPhotochemical oxidation (CML 2000) kg C2H4

a Includes minor contributions from CH4, N2O or HF.

precalciner kiln systemwith fuel substitution; however it should betaken into account that in this study, the scenarios proposed do notconsider the use of alternative fuels which usually leads to signif-icant (and additional) GHG reductions (Boesch and Hellweg, 2010).

3.2. Acidification, eutrophication and other mid-point impacts

The main emissions of SO2 and NOx during the production ofcement occur during the high-energy combustion (high tempera-tures) of fossil fuels used to produce clinker and those used bymechanical equipment and vehicular transport, but can also come,to a lesser extent, from raw materials used in the production ofclinker and the fraction of SO2 not chemically combined isemitted into the atmosphere. These emissions caused by theproduction of clinker have regional effects, such as acidification andeutrophication.

Acidifying substances cause a wide range of impacts on soil,groundwater, surface water, organisms, ecosystems and materials(buildings). The acidification potential is expressed in g of SO2-eqper kg of clinker. In this study, 2.55 and 2.16 were the values ob-tained for former lines and new L6 during the first trimester of 2011,respectively and represent around 15% of reduction of this category.These values can be compared to those obtained by Josa et al. (2007)

L3, L4 and L5 New L6(design data)(% reduction)

New L6(first trimester 2011)(% reduction)

987 906 (8.2) 938 (5.0)2.55 1.85 (27) 2.16 (15)372 243 (35) 310 (17)3.34 2.71 (19) 2.88 (14)6.4� 10�8 5.2� 10�8 (19) 5.5� 10�8 (14)10.5� 10�3 9.1� 10�3 (13) 9.5� 10�3 (10)1.0� 10�4 8.9� 10�5 (13) 9.3� 10�5 (10)

C. Valderrama et al. / Journal of Cleaner Production 25 (2012) 60e67 65

whichwere ranged between 1.2 and 3.4 g of SO2-eq per kg of clinkerfor different cement (Portland I) inventories in the European Union(EU). The improvement in the acidification impact is clearly due tothe NOx and SO2 emissions reduction in new line (L6) representingmore than 99% of the total acidification impact (Josa et al., 2007).These savings are related to the SNCR unit in the case of NOx and tothe reduction of fossil fuel consumption per kg of clinker (SO2).

On the other hand, eutrophication is also related to NOx emis-sion among other aspects. The consequence is related to anenrichment of nutrients in aquatic reserves and agricultural soils.There are other emissions that can be considered, such as ammonia(NH3) and total nitrogen (N-tot) but their effect in the analysedinventories is negligible in comparison with the effect of NOx.

The former lines reported 372 mg of PO4-eq per kg of clinker;value that was significant reduced for the new line L6 during thefirst trimester of 2011 to 310 mg of PO4-eq per kg of clinker.

These results clearly indicate that the new L6 representsa significant improvement from the point of view of regionalimpacts as a consequence of reduction in NOx and SO2 emissions.For instance, acidification and eutrophication parameters obtainedare lower than those reported by Chen et al. (2010) in the study ofenvironmental impact of cement production and its variationbetween different French cement plants. Furthermore, the new lineL6 design goal proposed is expected to reach significant reductionin acidification (27%) and eutrophication categories (35%) at end of2011.

In Fig. 3, the characterization of acidification and eutrophicationas well as other categories in CLM baseline method for bothscenarios in clinker production are shown. It is observed that abioticand ozone layer depletion, fresh water aquatic ecotoxicity andphotochemical oxidation categories report an improvement for thenew production line (L6) scenario (between 10 and 14%) comparedto former clinker production lines, which represent 75% of thereduction expected to the end of 2011. These improvements can berelated to the higher energyefficiency, less amount of fossil fuel per tof clinker and the emissions reduction. Other categories of CML2000are not considered since not significant variations were obtained.

3.3. Cumulative exergy demand (CExD)

In order to quantify the life-cycle exergy demand of a product,the indicator Cumulative Exergy Demand (CExD) is defined as thesum of exergy of all resources required to provide a process orproduct (Boesch et al., 2007). In this case, it is introduced to depicttotal exergy removal from nature to provide one kg of clinker.

Fig. 3. Environmental impacts determined by the CML 2000 method in clinkerproduction for three scenarios.

In this study, 8.5 and 7.4 MJ-eq per kg of clinker were the valuesobtained for the former lines and L6 during first trimester of 2011,respectively. It means, that L6 (based on BAT) achieved almost 13%reductions in resource consumption in terms of cumulative exergydemand required per one kg of clinker produced compared to theformer lines and is expected to reach around 18% reduction to theend of 2011.

3.4. Damage assessment

Fig. 4 shows the environmental fingerprint of three scenarios.The diagram allows comparing their environmental burdens. Foreach category, a characterization value was obtained and the valueof 100 was assigned to the least favourable alternative (formerlines) in the corresponding category; the characterization result foreach category is divided by the factor corresponding to the leastfavourable one, so it is easily identified how more favourable orunfavourable they are. It is shown (Fig. 4) how the fingerprint of L6is lower to this of the former lines. Significant differences are ob-tained in acidification/eutrophication, ozone layer, fossil fuels, landuse and respiratory inorganics categories, which are related to theemission reductions, the increase in energetic efficiency andreduction of fuel consumption. In Table 5 the values obtained afterthe characterization step for both scenarios are collected.

The damage assessment as the computation of all the individualcontributions of the categories was also considered. Damage tohuman health is related to the categories of carcinogens, respiratoryorganics, respiratory inorganics, climate change, radiation andozone layer and are expressed in disability adjusted life years (DALY)units; damage to ecosystem quality is associated to the categories ofecotoxicity (expressed in potentially affected fraction (PAF) units),acidification/eutrophication and land use (expressed in potentiallydisappeared fraction (PDF) units) and finally damage to resourcesare related to minerals and fossil categories, which are expressed as“surplus energy”.(Rivela et al., 2004; Navia et al., 2006); the damageassessment values are also summarized in Table 5.

The damage analysis indicates that the new L6 during the firsttrimester of 2011 reports a significant reduction of the damage tothe human health (11%), to ecosystem quality (11%) and toresources (14%) when compared to the former lines. Furthermore,

Fig. 4. Environmental fingerprint of three scenarios. C: carcinogens; RO: respiratoryorganics; RI: respiratory inorganics; CC: climate change; R: radiation; OL: ozone layer;E: ecotoxicity; A/E: acidification/eutrophication; LU: land use; M: minerals; FF: fossilfuels.

Table 5Characterization and damage assessment/ecoindicator 99 (average value).

Category Unit L3, L4 and L5 New L6 (design data)(% reduction)

New L6 (first trimester 2011)(% reduction)

Characterization step

Carcinogens DALY$107 0.141 0.127 (10) 0.130 (8)Respiratory organics DALY$1010 3.12 2.58 (17) 2.72 (13)Respiratory inorganics DALY$107 3.40 2.42 (29) 2.90 (15)Climate change DALY$107 2.07 1.90 (8) 1.97 (5)Radiation DALY$109 1.63 1.47 (10) 1.50 (8)Ozone layer DALY$1011 6.73 5.46 (19) 5.79 (14)Ecotoxicity PAFm2 yr 0.0331 0.0298 (10) 0.0331 (7)Acidification/eutrophication PDFm2 yr 0.015 0.009 (36) 0.012 (17)Land use PDFm2 yr$103 7.15 5.84 (18) 6.19 (13)Minerals MJ surplus$103 3.28 3.06 (7) 3.11 (5)Fossil fuels MJ surplus$103 980 793 (19) 842 (14)

Damage assessmentHuman health DALY$107 5.65 4.47 (21) 5.02 (11)Ecosystem quality PDFm2 yr 102 5.54 4.54 (18) 4.94 (11)Resources MJ surplus$10 9.83 7.96 (19) 8.45 (14)

C. Valderrama et al. / Journal of Cleaner Production 25 (2012) 60e6766

the design expected to be reached at the end of 2011 can be around18e21% (Table 5) for each damage category. These results confirmthat the energy efficient in the kiln system (fossil fuel savings)represents a significant impact in the damage assessment withhigher reduction in resources category. Moreover the results alsoconfirm the environmental improvement reached by using the BATin clinker manufacturing. It is important to point out that morethan 60% reduction defined by the design goals were achievedduring the six months of operation of new L6 and the remaining40% is expected to be achieved at the end of 2011.

4. Conclusions

This study has addressed the environmental improvementsassociated with the BAT for the clinker manufacturing process.A modern cement plant was designed and constructed taking intoaccount BAT. In order to evaluate its environmental performanceconsidering the design goals and achievements reached during thefirst trimester of 2011 a comparison to the former production lineswas done by means of LCA methodology. The results indicate thatapplication of BAT for cement industry in the Cementos MolinsIndustrial case study provides significant environmental savings inclinker production. The most significant improvements are relatedto energy efficiency in kiln system, which represents less amount offossil fuel required (less emissions to the atmosphere) to produceone kg of clinker. Thus, global warming, acidification and eutro-phication impacts reported 5, 15 and 17% of reduction in newproduction line (L6) respect to the former lines. In addition, thecumulative exergy demand indicator also confirms that L6 repre-sents 13% of resources saving. The damage assessment indicatesthat L6 showed a reduction in damage to resources (14%), ecosystemquality (11%) and human health (11%)when compared to the formerlines. Further, the design goals which represent 40% in additionalsavings are expected to be reached at the end of 2011 resulting ina significant improvement compared to the former lines.

Acknowledgements

The authors gratefully acknowledge Cementos Molins Industrialand AUMA Consultants in Energy and Environment S.L. for theirhelpful cooperation and technical support. This research wasfinancially supported by the Spanish Centre for the Development ofIndustrial Technology (CDTI) through the SOSTAQUA project(CEN-20071039). The authors are also grateful for the support of

the Spanish Ministry of Education and Science (National Plan)through the project BIA2010-20789-C04-01.

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