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Resources, Conservation and Recycling 81 (2013) 105– 114

Contents lists available at ScienceDirect

Resources, Conservation and Recycling

journa l h om epa ge: www.elsev ier .com/ locate / resconrec

nvironmental and economic aspects of production and utilization ofDF as alternative fuel in cement plants: A case study of Metroancouver Waste Management

ahareh Reza ∗, Atousa Soltani, Rajeev Ruparathna, Rehan Sadiq, Kasun Hewagechool of Engineering, University of British Columbia, 1137 Alumni Avenue, Kelowna, BC V1V 1V7, Canada

r t i c l e i n f o

rticle history:eceived 3 June 2013eceived in revised form 10 October 2013ccepted 13 October 2013

eywords:efuse derived fuel (RDF)unicipal solid waste (MSW)

ife cycle assessment (LCA)ost benefit analysis (CBA)ement manufacturing

a b s t r a c t

Municipal solid waste (MSW) disposal and management is one of the most significant challenges facedby urban communities around the world. Municipal solid waste management (MSWM) over the yearshas utilized many sophisticated technologies and smart strategies. Municipalities worldwide have pur-sued numerous initiatives to reduce the environmental burden of the MSW treatment strategies. Oneof the most beneficial MSWM strategies is the thermal treatment or energy recovery to obtain cleanerrenewable energy from waste. Among many waste-to-energy strategies, refuse-derived fuel (RDF) is a solidrecovered fuel that can be used as a substitute for conventional fossil fuel. The scope of this study is toinvestigate the feasibility of RDF production with MSW generated in Metro Vancouver, for co-processingin two cement kilns in the region. This study investigates environmental impacts and benefits and eco-nomic costs and profits of RDF production. In addition, RDF utilization as an alternative fuel in cement

kilns has been assessed. Cement manufacturing has been selected as one of the most environmentallychallenged industries and as a potential destination for RDF to replace a portion of conventional fossilfuels with less energy-intensive fuel. A comprehensive environmental assessment is conducted usinga life cycle assessment (LCA) approach. In addition, cost–benefit analysis (CBA) has been carried out tostudy the economic factors. This research confirmed that RDF production and use in cement kilns can beenvironmentally and economically viable solution for Metro Vancouver.

. Introduction

Waste is an unavoidable by-product of human activities. Cur-ently, solid waste management is one of the most critical andhallenging environmental problems in urban settings (Dong andee, 2009). Among different types of solid waste, municipal solidaste (MSW) is one of the principal challenges faced by urban

ommunities around the world. Annually, more than 34 millionons MSW (1031 kg per capita) is generated by households, busi-esses, institutions, and industry sources in Canada (Statisticsanada, 2012). Under the Environmental Management Act ofritish Columbia (BC), MSW is defined as the refuse that origi-ates from residential, commercial, institutional, demolition, landlearing, or light construction sources (MOB-BC, 2012). MSW essen-ially includes all garbage, except industrial, hazardous, or heavy

onstruction waste.

Despite increasing investments in reduce, reuse, and recyclingRRR) management plans and energy recovery, there is still a large

∗ Corresponding author. Tel.: +1 250 807 9013; fax: +1 250 807 9850.E-mail addresses: bahareh.reza@ubc.ca, bh.reza@yahoo.com (B. Reza).

921-3449/$ – see front matter © 2013 Elsevier B.V. All rights reserved.ttp://dx.doi.org/10.1016/j.resconrec.2013.10.009

© 2013 Elsevier B.V. All rights reserved.

amount of residual material requiring treatment. As an example inBC only about 35% of the generated waste are diverted for RRR man-agement plans (Statistics Canada, 2012). A significant amount ofMSW continues to be disposed of in landfills, mostly due to its lowercost and the availability of land. However, if more waste is land-filled, many valuable resources are wasted (IEA Bioenergy, 2003).In addition, the biodegradable components of MSW (e.g., paper andfood wastes) decompose in the landfilling process and release asignificant amount of methane, which is a greenhouse gas (GHG)with adverse effects on the environment 21 times greater than car-bon dioxide (Environment Canada, 2013; USEPA, 2013; EuropeanUnion, 2013). Furthermore, landfilling may cause other significantenvironmental impacts such as leachate causing groundwater pol-lution, and unpleasant odors.

Municipal solid waste management (MSWM) over the yearshas encouraged the use of many sophisticated technologies andrecommended adoption of smart strategies. Nevertheless, MSWMis still facing many challenges as a result of shrinking space for

landfills, stringent environmental regulations, and increasing dis-posal costs. Growing population, increasing amounts of MSW anddisposal costs, besides strict federal and provincial regulations forMSW disposal have led municipalities to develop and apply more

1 ation and Recycling 81 (2013) 105– 114

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Table 1Scenarios for RDF production.

Scenarios Description

Scenario 1 Metro Vancouver achieves MSW diversion targets in 2015and adequate amounts of MSW are available for producing80,000 tons of RDF

Scenario 2 Metro Vancouver achieves MSW diversion targets in 2015and 100,000 tons of MSW are available for producing RDF

Scenario 3 Metro Vancouver achieves MSW diversion targets in 2020and adequate amounts of MSW are available for producing80,000 tons of RDF

Scenario 4 Metro Vancouver achieves MSW diversion targets in 2020and 100,000 tons of MSW are available for producing RDF

Table 2RDF yield (%) by weight from MSW for years 2015 and 2020.

Waste category Year

2015 2020

Paper 26% 5.7%Plastic 19.1% 24.2%Leather 2.3% 3.0%Wood 1% 1.3%Textiles 2.9% 3.7%Rubber 0.2% 0.2%Finesa 1.3% 1.8%

RDF yield from MSW 52.8% 39.9%Calorific value (kJ/kg) 15.84 × 103 19.40 × 103

06 B. Reza et al. / Resources, Conserv

dvanced and effective waste management strategies. Above andeyond, the short- and long-term impacts of each MSW treatmentption and effects of related activities (e.g., collection, transfer,aste-to-energy, etc.) on public health and safety, and the envi-

onment must be estimated.One of the most favorable MSWM strategies is thermal treat-

ent or energy recovery to obtain cleaner renewable energy forndustries. Among many waste-to-fuel strategies, refuse-deriveduel (RDF) is a solid recovered fuel that can be used as a substitute foronventional fossil fuel (Genon and Brizio, 2008). RDF is an alterna-ive fuel produced from energy-rich MSW materials diverted fromandfills. RDF can be used as a substitute energy source in differentndustries.

An industry that is particularly well-suited to the employmentf alternative fuels is the cement industry (Mokrzycki et al., 2003).ement manufacturing and other industrial sectors are facing sev-ral environmental challenges such as high energy consumptionnd GHG emissions. Globally 5–7% of human generated CO2 emis-ions are contributed by the cement manufacturing (Karagiannidis,012; Ali et al., 2011). A significant reduction of this environmentalurden can be achieved by replacing conventional fossil fuel with

ess carbon and resource-intensive alternative fuel (Cullinen et al.,011). Experiences of European nations suggest that the use of RDF

n cement manufacturing offers environmental benefits in terms ofHG reduction (UNEP, 2005).

Several researches have conducted to study the use of wasteerived fuels in different heating conditions (Piao et al., 2000; Velist al., 2012; Guo et al., 2001; Ferrer et al., 2005). Chlorine contents one of the key concerns with waste derived fuels, since it mayause corrosion in the system due to vaporization and condensa-ion of alkali chlorides (Velis et al., 2012; Guo et al., 2001). Ferrert al. (2005) stated that alkali aluminosilicates content in the co-ring fuel is capable of capturing the alkali chloride. Balampanist al. (2010) studied the residues from solid recovered fuels (SRF)n East London. They found that applying modern separation meth-ds to remove the waste components which are rich in metals andhlorine will result in reduction of hazardous residues. Waglandt al. (2011) compared the performance of SRF and RDF. They con-luded that theuse coal and SRF fuel mixture in fluidized bed reactoreleases less emissions compared to coal and RDF mixture.

The use of MSW to produce RDF and its usage as an alterna-ive fuel in cement kilns are still a relatively new concept in Northmerica. A detailed literature review and discussion with Cana-ian cement manufactures revealed that RDF has not been used asn alternative fuel in cement manufacturing in Canada. RDF’s envi-onmental impacts and financial benefits are debatable dependentn a number of factors such as MSW composition, recovery percent-ge, RDF production line, heating value, etc. Furthermore, there areany significant financial unknowns of RDF production and utiliza-

ion. As RDF’s composition and properties vary significantly fromne place to another, environmental impacts and economic consid-rations associated with RDF production and application can alsoe diverse.

This study investigated both economic feasibility of produc-ion and utilization of RDF (for cement kilns) and environmental

mpacts in the context of Metro Vancouver’s integrated solid wasteesource management plan (ISWMP).1

1 Metro Vancouver is the inter-municipal administrative body responsible forlanning and management of recycling and solid waste services for the Greaterancouver Regional District in the lower mainland of BC. Being the authority respon-ible for MSW generated in the lower mainland area, Metro Vancouver is committedo fulfilling its ambitious goals of achieving MSW reduction and diversion targetseported in ISWMP (Metro Vancouver 2010).

a Assumption: Fines will not be separated by the separation processes.

2. Method

This paper aims to evaluate and quantify potential environmen-tal impacts and economic consequences (costs and benefits) forboth cement plants and Metro Vancouver, in terms of RDF produc-tion and utilization. A step-by-step method used for this study isdescribed below.

2.1. RDF yield percentage and properties

The first step of this study aims to identify specific characteris-tics, i.e. recovery percentages and calorific value of RDF, based onMetro Vancouver MSW source. Considering the changes in MSWdisposal and management plans of Metro Vancouver, four scenar-ios were developed to assess RDF production feasibility with theconsultation of Metro Vancouver and Cement Industry (Table 1).

Metro Vancouver solid waste composition study conducted byTRI Environmental Consulting Inc. (2012) was used to collect nec-essary data. Considering Metro Vancouver strategic Plan, wastecompositions were projected for the years 2015 and 2020 (MetroVancouver 2011). These projected waste compositions were usedfor calculating RDF recovery percentages (useful part of raw MSWthat can be used for RDF) (Table 2). The total RDF yield from MSWfor the years 2015 and 2020 were calculated using the mass balanceas summarized in Table 3.

Numbers of methods were observed in literature, which can the-oretically calculate the net calorific of RDF. The theoretical methodsinclude Dulong formula (Eq. (1)) and Institute of Gas Technology(IGT) formula (Eq. (2)) (Nithikul, 2007; Chan et al., 1997; Buckley &Domalski, 1988). Studies conducted by the above authors showedthat higher heating value (HHV) of RDF predicted by dulong formulaand IGT formula was close to the experimental value. Hence, both

formulas were used for calculating the HHV of RDF for 2015 and2020 scenarios. The net calorific value which is identified as the

B. Reza et al. / Resources, Conservation and Recycling 81 (2013) 105– 114 107

Table 3Mass balance for RDF production.

Mass balance 2015 2020

Input MSW flow 100% 100%Output Main output RDF 52.8% 39.9%

For recovery Metals 6.8% 8.6%Glass

Disposal via environmentally responsible methods Electronic waste 16.4% 20.8%Building materialHousehold hazardous

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aggregation of impact indicators for different mass and energyinflows/outflows (that were estimated in the LCI phase) and a fur-ther aggregation of different indicators to obtain a single-value ofenvironmental performance (Consonni et al., 2005). In this study,

2 Created by PE INTERNATIONAL GaBi Databases are the largest internally consis-tent LCA databases on the market and contain over 4500 LCI profiles. GaBi supportsLCA according to ISO 14040/14044 and includes extensive, high-quality databases

Landfilling

ower heating value (LHV) was calculated from Eq. (3) (Nithikul,007):

HV MJ/kg = 0.336 C + 1.419 H + 0.94 S – 0.145 O (1)

HV MJ/kg = 0.3417 C + 1.3221 H + 0.1232 S

– 0.1198(O + N) – 0.0153 A (2)

HV (MJ/kg) = HHV (MJ/kg) – 0.0244 (W + 9H) (3)

(carbon), H (hydrogen), O (oxygen), S (sulfur), N (nitrogen), Hhydrogen), W (water) and A (ash) represent content percentage ineight.

RDF yield percentage and calorific value for years 2015 and 2020ave been summarized in Table 2.

.2. Environmental assessment using LCA

In general, production and utilization of RDF is associated with diverse combination of potential environmental benefits andmpacts. On one hand, RDF production impacts the environmenthrough energy and material consumption (Chen et al., 2007), onhe other hand replacing fossil fuel by RDF in industrial plants leadso energy recovery and emission reduction (Chen et al., 2007). Atandardized LCA framework suggested by the International Stan-ards Organization (ISO 14040, 2006) has been applied in thistudy. To assess the environmental impacts/benefits of a recoveryystem such as RDF, it is necessary to compare this practice basedn a life cycle perspective with two schemes: (1) not using RDF asn alternative fuel and (2) other alternatives for the managementf MSW such as landfilling. The LCA framework to investigate RDFroduction and utilization is presented in the following sections.

.2.1. Goal and scope definitionThe main goal of LCA in this study was estimating the potential

nvironmental benefits and impacts of RDF production (from Metroancouver MSW sources), and co-incineration in two regionalement plants, have been investigated. Then the result has beenompared with the environmental impacts of not using RDF (usingonventional fossil fuel) to estimate the ultimate energy and emis-ion savings in the cement industry as a result of production andse of RDF. In addition, energy and emission savings from metalecovery and landfill reduction has been considered.

The LCA “system boundary” starts with the collection of wasterom transit stations and continues to mechanical treatment in theDF facility. The waste later passes through a trommel screen unitnd divides the fine particles from bulky objects. In following step,

errous metals (i.e., iron, steel, etc.) are separated by a magneticeparator and sent to the secondary market for sale. At this stage,he separated MSW can travel through a shredder to become a fineowder of combustible materials. The product is later dried and

Household hygiene 24 .0% 30.7%Bulky objectsCompostable organics

sent to the cement kilns as RDF. The same procedure is developedin GaBi LCA software2 for analysis of the related emissions, materi-als, and energy. LCA boundary for RDF production and use has beenshown in Fig. 1. The LCA “functional unit” of this analysis is pro-duction and utilization of one ton (1 ton) of RDF, which combustedin cement work replacing 647 kg hard coal for scenarios 1 and 2(2015) and 792 kg of hard coal for scenarios 2 and 3 (2020).

2.2.2. Life cycle inventory (LCI)The RDF production (mechanical treatment) consists of different

stages that presented in Appendix. These steps consume a cer-tain amount of energy and produce emissions, which can impactthe environment through ozone depletion, global warming, landuse, human health, etc. Energy consumption per ton of MSW treat-ment has been estimated based on the designed production lines(trommel screen, magnetic separator, and shredder), to be about48.5 kWh per ton of MSW treatment.3

In cement production, RDF is partially combined with con-ventional fossil fuels to obtain the energy requirement. Theco-processing of RDF in cement kilns is the most important lifecycle stage of the RDF process. Environmental benefits due to RDFcombustion in cement kilns include energy recovery, and avoidingfossil fuel consumption. On the other hand, environmental impactsdue to emissions released from RDF combustion in cement kilnsmust be determined and compared to the substituted fossil fuel. Ingeneral, environmental impacts associated with RDF combustion incement kilns are more significant than RDF mechanical treatment(e.g., CO2 emission from the RDF mechanical treatment is ∼0.18% ofthe emission from RDF combustion). Environmental impacts asso-ciated with RDF co-incineration in cement kilns are affected bycomposition and chemical content of the RDF yield product. Allassociated emission impacts due to RDF combustion have been esti-mated using GaBi LCA software and its data inventory, and are basedon percentages of different materials in the RDF final product froma MSW source (Table 2) and its chemical content. The chemicalcontent of RDF is compared with fossil fuel in Table 4.

2.2.3. Life cycle impact assessment (LCIA)LCIA is typically the most critical step of a LCA. LCIA requires

(http://www.gabi-software.com/america/databases/).3 In this study, after consulting with some experts in the field of designing MSW

treatment plants, a RDF production line was designed and customized, and thetotal electricity requirement was estimated considering all required machinery andrequired RDF production capacity.

108 B. Reza et al. / Resources, Conservation and Recycling 81 (2013) 105– 114

Mechanical Treatment

Raw MS W

48.5 kWh

1 tonne

Energy RDF528 kg

Inert

Metals

240 kg

68 kg50 kg Metal recovery

plants

18 kg

Landfill

Cement Kiln

Emission

Emission

Landfill

Fig. 1. LCA boundary for RDF production and use (mass balance shows per ton MSW treatment based on year 2015 MSW diversion target).

Table 4Composition of RDF and traditional fuels in cement work.

Parameter Unit RDF Fossil fuels

Europe Metro Vancouver Coal Coke

EURITSa standard Genon and Brizio (2008) Calculated valuesb Genon and Brizio (2008),Porteous (1981)

2015 2020

Calorific Value GJ/t 15.00 20.00 17.80 21.60 23–33 33.00C % – 53.00 42.20 47.30 61.00 86.00H % – 7.00 5.80 6.80 4.50 3.60Cl % 0.50 0.28–0.70 0.70 0.70 – 0.01S % 0.40 0.10–0.20 0.28 0.30 1.00 5.00N % 0.70 0.52 0.62 0.93 1.30 2.00Hg ppm 2.00 0.10–0.40 – – 0.02–4.40 0.02–0.10Ti ppm 2.00 0.02–0.5 0.16 0.62 1.00 0.04–3.00Sb ppm 10.00 9.00–14.70 – – 1.00 0.20As ppm 10.00 0.90–8.80 – – 0.5–10.0 0.46Cd ppm 10.00 0.18–2.60 – – 0.05–10 0.10–0.30Cu, ppm 200 45–266 220 265 0.5–20 –Sn ppm 200 4–500 – – 10 –Mn ppm 200 28–210 0.692 0.781 5–300 –Co ppm 200 0.60–4.0 – – 0.5–20.0 –V ppm 200 0.30–7.00 – – 1.00 0.04–3.00Cr ppm 200 11.3–140 0.0333 0.0164 0.5–60 2–104Pb ppm 200 25–157 128 155 1–300 2.4–100Ni ppm 200 0.85–21 14 20 0.5–100 200–300Zn ppm 500 225–340 344 281 1–1000 6.8Ash % 5.00 5.00 9.00 9.50 10–11 –

ithikul, 2007)A software.

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Table 5Impact categories, Indicators and classified data categories.

Impact categories and indicators Data categories of the inventory

Resource consumption (kJ) Cumulative energy demand from fossilenergy resources (oil, gas, coal)

Global warming (kg CO2-eq) CO2 fossil, CH4, N2OSummer smog (kg C2H4-eq) NOx , div. volatile organic compoundsAcidification (kg SO2-eq) SO2, NOx , NH3, HCl, HFNutrification (kg PO4

3+-eq) NH3, NOx

Human toxicity (kg As-eq) Represented by indicator “carcinogenic

a European Union for responsible incineration and treatment of special waste (Nb These values have been calculated based on RDF composition and using GaBi LC

tandard LCIA procedure (classification, characterization, normal-zation and grouping) has been followed to aggregate the LCI resultso different impact indicators, based on ISO standard 14042: Lifeycle Impact Assessment. A list of impact categories and indicatorshat have been used in this study are presented in Table 5.

.3. Economic assessment

This section aims to investigate the economic feasibility of RDFtilization as an alternative fuel for two cement companies in Metroancouver. Generally, economic feasibility can be studied usingustainability assessment tools such as cost–benefit analysis (CBA)nd Life Cycle Costing (LCC) (Begum et al., 2006). In this study, the

et benefit is expressed as the subtraction of the total costs fromotal benefits:

B = TB–TC (4)

risk potential” (As, Cd, Cr-VI, Ni,benzo(a)pyrene, dioxin/duran)

Other toxic emission (kg) Represented by single data categories (Hg,Pb)

ation and Recycling 81 (2013) 105– 114 109

wa

T

T

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2

fttu

b

d

2

d

b

1

0

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Total(CED)

GWP NCPOC P AP NP CRP Hg

RDF

Equal Coal

B. Reza et al. / Resources, Conserv

here NB represents the net benefits, TB (Eq. (5)) the total benefits,nd TC (Eq. (6)) the total costs.

B = PFF + RR + SL + Em (5)

C = PC + OC + ACC + TR (6)

here PFF represents the price of fossil fuels and the quantityeplaced by RDF, RR is the revenue from selling the recovered mate-ials, SL represents the savings by avoiding landfilling, and Em is themployment impact. In addition, PC represents the plant construc-ion cost, OC is the operation costs (including the costs of processingDF), ACC is the additional cement production cost, and TR repre-ents the transportation cost. The life cycle considered costs andenefits are presented in followings.

.3.1. Life cycle costsIn general, the cost per unit weight of MSW is lower than that of

ossil fuels; however, the cost of a heat unit of MSW can be higherhan that of coal (Genon and Brizio, 2008). In this section, some ofhe most considerable costs associated with RDF production andtilization in Metro Vancouver is summarized (Table 6):

a. Operational costs: Costs related to the operation of a businessare considered as operational costs and included as the variablecosts of maintenance, labor, and electricity.

. Plant construction and land cost: To have a valid estimate of con-struction cost of the proposed RDF facility, related costs of similarfacilities in Canada such as Dongara Pellet Factory for RDF inOntario (Gombu, 2008; Swainson, 2006) were studied. Then theconstruction costs were scaled for Metro Vancouver region.

c. Additional costs for cement production: Cement manufacturing’sadditional costs include building extra storage, implementingsafety measures, purchasing or updating technical equipment,modifying kilns and upgrading fuel feed system, which will beconsidered for every 20 years.

. Transportation costs: The transportation costs between trans-fer stations, facilities, and landfills are the same for all wastemanagement options in Metro Vancouver; therefore, only trans-portation cost for RDF delivery to cement kilns is considered inthis study. The delivery costs are estimated based on the pro-posed area for the RDF facility in region.

.3.2. Associated benefitsThe benefits associated with RDF production and utilization are

escribed below (Table 7):

a. Fuel saving: The fuel saving (the amount of coal saved by substi-tuting RDF) value was calculated based on amount of fossil fuelsburned to create 1 kg of clinker,4 the recovery percentage, andthe calorific value of 1 kg of RDF. Energy output from combustionper ton of RDF was considered as 15.84 GJ for scenarios 1 and 2(2015), 19.40 GJ for scenarios 3 and 4 (2020), and per ton of coalis around 24.5 GJ.

. Reduction of landfilling expenses: Landfill is the most costly wastemanagement and disposal option, as the odor, emissions, and soilerosion controlling require constant monitoring, and its environ-mental impacts are the highest. The maximum landfill saved isequal to the amount of RDF produced (to account for the landfill

after RDF production as well). Reduction of landfilling expenseswas calculated by considering the current tipping fee of landfill-ing and future changes in the landfilling expenses (33 CAD per

4 The thermal energy requirement for clinker production in Canada is 3.6 GJ per ton of clinker (Approved by the Cement Association of Canada, BC).

Fig. 2. Comparative LCIA of RDF and coal for 2015 scenarios (impact values werenormalized).

ton waste was used for 2015 scenarios and 60 CAD per ton wasteis proposed5 for scenarios of 2020).

c. Recovered material: Material recovery is a source of income forwaste-to-energy (WTE) plants (Stantec, 2011). The revenue fromthe sale of recovered material depends on the percentage ofrecovery, grade of recovered product, cost per ton to recover, andmarket demand. The benefits associated with metal recovery inan RDF plant were calculated based on the recovery efficiencyand recovery percentages for MSW in 2015 and 2020.

d. Employment impact: The proposed RDF facility will need about20–35 (depending on the scenario) skilled workers. The design,construction, and maintenance of a new facility will createapproximately 200 high-level fulltime jobs. The landfill will loseapproximately a quarter of this amount (i.e. there is still threequarters of created jobs) as the workers in the transfer and col-lection line will not be affected. The generation of new jobs alsocontributes indirectly to the economy through purchases, hous-ing, etc.

3. Results and discussion

3.1. Environmental assessment result

Results of the LCA are summarized in Tables 8 and 9. The func-tional unit of the LCA calculation is one ton of RDF delivering heatto produce ∼4.4 tons (∼5.4 tons for year 2020 scenario) of clinkerif processed in a cement plants, by replacing ∼647 kg (∼792 kg foryear 2020 scenario) of hard coal. In order to obtain impact indica-tors the inventory results are aggregated to the impact categoriesindicated in Table 5. For example, to get the sum in “global warm-ing potential (GWP)”, the value of CO2 is added to the value ofCH4, which is multiplied by 21 (the impact equivalency of methanerelated to the effectiveness of CO2) and added to the value of N2O,which is multiplied by 320. Life cycle impact assessment resultsare compared to processing and use of replaced primary fuels(hard coal) as it was shown in Figs. 2 and 3. In addition, mitigatedimpacts due to RDF utilization as an alternative fuel in cement workhave been estimated per ton of clinker production (last column ofTables 8 and 9).

LCIA results for years 2015 and 2020 scenarios indicate thatproduction and utilization of RDF is beneficial according to thecumulated energy demand (CED) indicator, which is approximately

5 The estimation is suggested by Metro Vancouver professional engineer.

110 B. Reza et al. / Resources, Conservation and Recycling 81 (2013) 105– 114

Table 6Total annual costs (CAD).

Scenarios MSW inflow (tons) RDF quantity (tons) Operation costa Construction costb Land costc Additional costs Transportation costd

1 167,000 80,000 ∼3,700,000 ∼40,000,000 8,400,000 4,400,000 800,0002 100,000 47,520 ∼2,200,000 ∼24,000,000 6,000,000 4,320,000 475,2003 221,000 80,000 ∼4,900,000 ∼53,000,000 10,800,000 6,400,000 800,0004 100,000 35,910 ∼2,200,000 ∼24,000,000 6,000,000 6,200,000 359,100

a Operation cost per ton of MSW = 22 CAD.b The envisioned RDF plant is estimated to be around 9 acres for scenario 3, 7 acres for scenario 1, and 5 acres for scenarios 2 and 4.c The average land price in Burnaby and Richmond multiplied by the plant size.d Transport cost per ton RDF = 10 CAD.

Table 7Total annual benefits (CAD).

Scenarios MSW inflow (tons) RDF quantity (tons) Fossil fuel saving* Landfill saving Metal recovery benefit**

1 167,000 80,000 7,616,000 2,640,000 2,670,0002 100,000 47,520 ∼4,524,000 1,570,000 1,600,0003 221,000 80,000 8,848,000 4,800,000 4,420,0004 100,000 35,910 ∼3,972,000 2,155,000 2,000,000

*Coal saving for 1 ton RDF is:1. 15.84/24.5 = 0.68 for scenario 1 and 2.2. 19.40/24.5 = 0.79 for scenario 3 and 4.

Price per ton of coal is estimated as 140 CAD for year 2012.(Coal saved per ton RDF) × (total RDF production per year) × (price of coal).*12 al).

4ccpfpbipcaaw(

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Fn

*Metal recovery (1) * Metal price (2):. (4% for scenarios 1 and 2, and 5% for scenarios 3 and 4) × (MSW inflow).. (Revenue of WTE facility in Burnaby from metal sale)/(amount of recovered met

.7 GJ (per ton of clinker) less resource demanding than equivalentonventional fuel (hard coal). The use of RDF as a secondary fuel inement manufacturing allows a reduction of ∼3.8 tons of CO2-eqer ton of RDF utilization as compared to using conventional fossiluel (hard coal), and 863 kg CO2-eq reduction per ton of clinkerroduction, based on year 2015 MSW composition. In additionased on year 2020 projected MSW, GHG emissions reduction can

mprove significantly, to the amount of ∼4.8 tons CO2-eq decreaseer ton of RDF utilization, and 888 kg CO2-eq saving per ton ofement production. Furthermore, production and utilization of RDFs an alternative fuel in cement manufacturing is advantageousccording to the summer smog potential (Kg C2H4-eq) indicator,hich is 3.7–4.1 times less harmful than conventional fossil fuel

hard coal).From LCIA results (Tables 8 and 9), it can be concluded that

DF combustion releases slightly more SO2, NH3, HCl, and HF,

0.0

0.2

0.4

0.6

0.8

1.0

1.2

Total(CED)

GWP NCPOC P AP NP CRP Hg

RDF

Equal coal

ig. 3. Comparative LCIA of RDF and coal for 2020 scenario (impact values wereormalized).

(without any filtration6) as compared to hard coal. However, thetotal acidification (kg SO2-eq) and nutrification potential (kg PO4

3+-eq) indicators indicate declines, 1.89–3.37 times, as a result ofsignificant decrease of NOx formation from RDF co-incineration.Furthermore, the toxic load of heavy metals such as mercury,arsenic, polychlorinated dibenzodioxines and furanes is less detri-mental than hard coal. As a result, the ultimate carcinogenic riskpotential (kg As-eq) is ∼3.4–4 times less prejudicial for 2015 and2020 MSW diversion target.

By processing and converting each ton of MSW to RDF, less than40% of that portion of MSW needs to be disposed of in landfill (seeTable 3). As a result, MSW treatment to produce RDF can bringmore than a 60% landfill reduction. Approximately 28500 tons ofMSW can occupy 1 ha of land (Zhang et al., 2010). Therefore, byapplying RDF technology and treatment to 100,000 tons of MSWannually, ∼3.5 ha land can be saved from landfilling each year. Inaddition, global and local air pollution, as well as soil and waterleachate pollution due to landfilling, can be decreased significantly.Avoided environmental impacts due to landfill reduction, use ofRDF in cement manufacturing, and metals recovery have been com-pared in Table 10 (functional unit for all analysis is 1 ton of RDFproduction and use).

According to the comparative LCIA results presented in Table 10,despite the smaller recovery fraction (∼39.9%) of the 2020 MSWdiversion target, the total avoided environmental impact due toproduction and use of RDF is better than that of the 2015 MSWdiversion target. Comparative LCA results confirm that landfillreduction leads to improved GHG emission reduction in compar-ison to the two other strategies. This is because GHG emission

(specifically Methane) is one of the most intensive environmentalimpacts of MSW disposal in landfill. RDF co-incineration in cementkilns causes more significant energy saving as compared to other

6 Preheated tower in cement kilns can work as filtration system due to highinteraction of raw meal (limestone) and exhaust gas. The effect of this filtrationon emission reduction is complicated and hasn’t considered in this study.

B. Reza et al. / Resources, Conservation and Recycling 81 (2013) 105– 114 111

Table 8Comparative LCIA for production and combustion of RDF (2015 scenarios).

Environmental impact categories Functional unit (per ton RDF) Substituted fuel (647 kg hard coala) Avoided impactsb (per ton clinker)

Fossil resourceRaw oil kg 0.1 26.8 6.1Natural gas kg 1.4 6.5 1.2Hard coal kg 0.1 686.5 156.0Brown coal kg 0.2 63.2 14.3Total (CED) GJ 0.1 20.8 4.7

Global warmingCO2 (fossil) kg 1020.1 4619.5 818.1CH4 kg 1.6 8.7 1.6N2O g 18.4 11.9 −1.5GWP ton CO2-eq 1.1 4.8 0.9

Summer smogCH4 kg 1.6 8.7 1.6NMVOC g 49.6 71.5 5.0NOx kg 1.1 8.5 1.7NCPOCP kg C2H4-eq 0.2 0.9 0.2

AcidificationSO2 g 1240.9 1175.5 −14.9NOx kg 1.1 8.5 1.7NH3 g 28.9 1.1 −6.3HCl g 36.5 24.1 −2.8HF g 8.0 2.9 −1.2AP kg SO2-eq 2.1 7.1 1.1

NutrificationNOx kg 1.1 8.5 1.7NH3 g 28.9 1.1 −6.3NP kg PO4

3+-eq 0.2 1.1 0.2

Human toxicity: carcinogenic risk potentialAs mg 1.4 3.5 0.5Cd mg 0.6 1.7 0.3Cr mg 0.2 0.6 0.1Ni mg 24.1 478.4 103.3BaP mg 0.7 0.3 −0.1PCDD/PCDF mcg 0.1 0.2 0.02CRP mg As-eq 20.5 68.7 11.0

Human toxicity: single data categoriesHg mg 7.4 356.2 79.3Pb mg 6.0 2.0 −0.9

Note: 1 ton RDF = ∼1.89 ton processed MSW.CED, cumulated energy demand; GWP, global warming potential; NMVOC, non-methane volatile organic compounds; NCPOCP, NOx-corrected photooxidantial creationpotential; AP, acidification potential; NP, nutrification potential; CRP, carcinogenic risk potential; BaP., benzo(a)pyren; PCDD/F, polychlorinated dibenzodioxines and –furanes (summed as toxic equivalents).

m Eu than c

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a Emission related to burning coal in cement manufacturing has been adopted frob Negative numbers indicate adverse impacts (RDF releases more emission to air

trategies, as a result of replacing fossil fuel with RDF. While, metalecovery leads to a more significant reduction in summer smog,cidification, nutrification, and carcinogenic risk potential.

As it was discussed in introduction section, RDF chlorine contents one of the major environmental concerns which can causes cor-osion in the system due to vaporization and condensation of alkalihlorides. Therefore, it is important to consider the concentrationf chlorine, and some other substance (e.g. sulphur, nitrogen) inDF (Table 4). As it was show in Table 4, nitrogen and sulphur have

lower value in RDF than in fossil fuels, which will be beneficials the formation of nitrogen and sulphur oxides will also decrease.owever, according to Table 4 the concentration of chlorine in RDF

s higher as opposed to fossil fuels and the production line may needo act on limiting the chloride in the produced clinker. As a result,xtra considerations must be made to increase the heat consump-ion and temperature of kiln by ∼10% to limit the chloride formationn the produced clinker and to restrict the presence of chlorinated

icro-pollutants. It is necessary to mention that, because of highlkalinity atmosphere of clinkers, sulphur and chlorine present inDF will not produce critical amounts of gaseous pollutants (Genonnd Brizio, 2008).

ropean Commission Report (Gendebien et al., 2003)oal).

3.2. Economic assessment results

The results of economic assessment will illustrate whetherRDF production for cement companies in Metro Vancouver isfeasible, given the current waste stream in Vancouver, expectedwaste diversion in years 2015 and 2020, RDF capacity demandedby the cement manufacturers, and existing waste managementalternatives. RDF is proposed for Metro Vancouver to reduce theamount of landfilling, the most costly (environmentally and eco-nomically) MSWM in the region.

The economic assessment was carried out based on the follow-ing assumptions:

- Life expectancy for a plant is considered to be 35 years (Jackson,2009; Austin, 2011).

- Life expectancy of storage and other additional investments incement manufactures is assumed to be 20 years (Hutjens, 2012).

- All calculations are for one accounting year.

Four distinct scenarios are considered for economic assess-ment; these scenarios represent the results based on different

112 B. Reza et al. / Resources, Conservation and Recycling 81 (2013) 105– 114

Table 9Comparative LCIA for production and combustion of RDF (2020 scenarios).

Environmental impact categories Functional unit (per ton RDF) Substituted fuel (792 kg hard coala) Avoided impactb (per ton clinker)

Fossil resourceRaw oil kg 0.1 32.8 6.1Natural gas kg 1.7 7.9 1.2Hard coal kg 0.1 841.0 155.7Brown coal kg 0.2 77.5 14.3Total (CED) GJ 0.1 25.5 4.7

Global warmingCO2 (fossil) kg 1010.5 5659.2 860.9CH4 kg 2.0 10.7 1.6N2O g 23.2 14.5 −1.6GWP ton CO2-eq 1.1 5.9 0.9

Summer smogCH4 kg 2.0 10.7 1.6NMVOC g 64.1 87.6 4.3NOx kg 1.5 10.4 1.6NCPOCP kg C2H4-eq 0.3 1.1 0.2

AcidificationSO2 kg 3.3 1.4 −0.4NOx kg 1.5 10.4 1.6NH3 g 35.6 1.4 −6.3HCl g 89.6 29.5 −11.1HF g 18.6 3.5 −2.8AP kg SO2-eq 4.6 8.7 0.8

NutrificationNOx kg 1.5 10.4 1.6NH3 g 35.6 1.4 −6.3NP kg PO4

3+-eq 0.2 1.4 0.2

Human toxicity: carcinogenic risk potentialAs mg 1.8 4.3 0.5Cd mg 1.0 2.1 0.2Cr mg 0.7 0.7 0.0Ni mg 80.0 586.1 93.7BaP mg 0.3 0.4 0.02PCDD/PCDF mcg 0.2 0.3 0.02CRP mg As-eq 21.2 84.2 11.7

Human toxicity: single data categoriesHg mg 16.6 436.3 77.7Pb mg 45.7 2.4 −8.0

Note: 1 ton RDF = ∼2.5 ton processed MSW.CED, cumulated energy demand; GWP, global warming potential; NMVOC, non-methane volatile organic compounds; NCPOCP, NOx-corrected photooxidantial creationpotential; AP, acidification potential; NP, nutrification potential; CRP, carcinogenic risk potential; BaP., benzo(a)pyren; PCDD/F, polychlorinated Dibenzodioxines and –f

om Eu than c

aynstcT

from Metro Vancouver, expert judgments, and construction and

TA

uranes (summed as toxic equivalents).a Emission related to burning coal in cement manufacturing has been adopted frb Negative numbers indicate adverse impacts (RDF releases more emission to air

ssumptions on the volumes of MSW inflow and RDF outflow inears 2015 and 2020. Costs and benefits associated with each sce-ario are calculated and summed up separately. In Table 11, theummation of all costs is presented as Total costs, and the addi-

ion of all benefits is called Total benefits. Net benefit, the totalost reduced from the total benefits, is also presented in Table 11.otal cost and total benefit were divided by the quantity of RDF in

able 10voided environmental impacts per ton of RDF production and use.

Impact categories and indicators Year 2015

Co-incineration Metalrecovery

Landfillreduction

Ti

Resource consumption (GJ) 20.8 0.7 0.0

Global warming (ton CO2-eq) 3.8 3.6 6.7

Summer smog (kg C2H4-eq) 0.7 23.9 0.0

Acidification (kg SO2-eq) 5.0 473.3 0.4

Nutrification, terrestrial(kg PO4

3+-eq)0.9 14.5 0.1

Human toxicity (mg As-eq) 48.2 1855.8 1.6 1Other toxic emission (mg Hg) 348.8 106.2 0.3

ropean Commission Report (Gendebien et al., 2003).oal).

order to compare scenarios’ costs and benefits based on unit of RDFproduced.

Costs and benefits have been calculated based on actual data

operation costs of analogous waste treatment plants in Canada. Theresults of economic analysis and CBA indicate that a financial profitcan be predicted through fossil fuel savings, reduction of landfilling

Year 2020

otal avoidedmpact

Co-incineration Metalrecovery

Landfillreduction

Total avoidedimpact

21.5 25.4 1.1 0.0 26.514.0 4.8 5.7 8.8 19.324.6 0.8 37.9 0.0 38.7

478.7 4.2 750.3 0.5 755.015.4 1.1 23.0 0.1 24.1

905.6 63.0 2941.5 2.1 3006.6455.3 419.7 168.4 0.4 588.5

B. Reza et al. / Resources, Conservation a

Table 11Results of economic assessment.

Year/scenariosa Year 2015 Year 2020

Scenario 1 Scenario 2 Scenario 3 Scenario 4

Costs (CAD)Operation cost 3,700,000 2,200,000 4,900,000 2,200,000Plant costb 1,383,000 857,000 1,823,000 857,000Additional cost 220,000 216,000 320,000 310,000Transportation 800,000 475,000 800,000 359,000Total cost 6,103,000 3,748,000 7,843,000 3,726,000Total cost per ton RDF 76.3 78.9 98.0 103.8

Benefits (CAD)Fuel saving 7,616,000 4,524,000 8,848,000 3,972,000Landfill reduction 2,640,000 1,570,000 4,800,000 2,155,000Recovery material 2,670,000 1,600,000 4,420,000 2,000,000Total benefit 12,926,000 7,694,000 18,068,000 8,127,000Total benefit per ton RDF 161.6 161.9 225.8 226.3Net benefit 6,823,000 3,946,000 10,225,000 4,401,000Net benefit per ton RDF 85.3 83.0 127.8 122.6

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a All costs and benefits are based on one financial year to make the analysis moreonsistent with the general financial assessment approach.

b Total construction and land costs/35 years.

ost, recovered material sale, and employment effect. The positiveet benefits show that the envisioned benefits are greater than theredicted construction and operation of RDF plant costs, additionalechnical costs, and annual transportation expenses. Some of theseosts and benefits are specific to the Metro Vancouver; some othersre specific to cement industries. Both stakeholders may proceed toounds of negotiation in order to decide on their shares from costsnd benefits.

Comparison of the outcomes reveals that when more RDF is pro-uced, the net benefit increases; but, costs and net benefits pernit of RDF decrease. If more MSW is re-used to produce energy,hen more benefits are gained through the process; therefore, ben-fits are higher in year 2020 as compared to 2015. As a result, theverall net benefits per ton of RDF production and use have pre-icted to be higher in year 2020 as compared to 2015. Results alsohow that the most considerable cost and benefit in this projectf producing and utilizing RDF were operation cost and fuel sav-ng, respectively. These estimations consider the major costs andenefits that can affect the feasibility of RDF production and use inetro Vancouver. In addition, the costs and benefits are calculated

ased on current prices (e.g., land and fossil fuels prices), which canncrease in future.

The most important result to emerge from the economic analysiss the positive net benefits, which means that total benefits areigher than total costs in all four scenarios. Savings on the expensesf fossil fuels used in cement manufacturing alone can cover allther considered costs in this study. Consequently, producing RDFn Metro Vancouver is “feasible” for the municipalities, industry,nd society, with the costs and benefits considered in this study.7

. Conclusions

Present study was designed to investigate the feasibility of pro-ucing RDF from Metro Vancouver MSW sources, and evaluating itstilization as an alternative fuel for cement manufacturing. Accord-

ng to the hypothesis/question posed in this study, it is possible to

onclude that the RDF production and use in cement kilns insteadf coal offer environmental benefits in terms of lowering green-ouse gases emission, acidification, summer smog, nutrification,

7 Since some costs and benefits apply to only one of the involved parties (i.e. theunicipality or the cement manufacturer), other costs and benefits should be shared

y the parties through negotiations.

nd Recycling 81 (2013) 105– 114 113

and carcinogenic risk potential, and landfill costs. RDF productionand use can also result in positive financial net benefit for themunicipalities, consumers, and society. Furthermore, the results ofthe scenario analysis (considering four RDF production scenarios)show that despite a smaller recovery fraction (∼39.9%) accordingto the year 2020 diversion target, production and use of RDF incement kilns is more advantageous when compared to the year2015 diversion target.

The findings of this research provide key information aboutlong term economic and environmental aspects of MSW treat-ment that can be used as a basis for long-term MSW plan in MetroVancouver. The current study is based on projected RDF compo-sitions according to the Metro Vancouver’s Zero Waste Strategyand Metro Vancouver 2011 Solid Waste Composition Monitoringstudy. Indeed, a dedicated study on future MSW disposal plan inMetro Vancouver will provide more reliable data for the study. Inaddition, in this study, theoretical calorific value of RDF was cal-culated. Further experimental investigations are recommended toestimate calorific value using standard testing methods (e.g. ASTM-D5468-02 (2007) Standard Test Method for Gross Calorific and AshValue of Waste Materials). Further research is recommended forthe inclusion of intangible costs and benefits (e.g. environmentalimpacts and benefits) in monetary values using advanced environ-mental accounting techniques such as the Emergy Synthesis (Odum,1996) technique.

Acknowledgements

Authors would like to acknowledge Metro Vancouver SolidWaste Department for sharing valuable information related tothe MSW. The financial support from Mitacs-Accelerate is alsoacknowledged.

Appendix.

A.1. Refuse-derived fuel (RDF)

The combustible fraction (e.g., paper and plastics) recoveredfrom mixed MSW has been given the name “refuse-derived fuel”(RDF). RDF makes use of waste materials to produce an eco-friendlysource of fuel that can be utilized for production of cement. RDFis the high calorific value fraction of MSW obtained through con-ventional separation systems and is comparatively a higher-qualityfuel than mixed MSW (UNEP, 2005). RDF can be employed in indus-trial plants (such as cement kilns) in order to recover useful energy.Based on ASTM standards E856-83 (2006), RDF can be classified intofollowing seven categories:

1. RDF-1: Wastes used in discarded form.2. RDF-2 (Coarse RDF): Wastes processed to coarse particle size

with or without ferrous metal separation such that 95% byweight passes through a 6 in. square mesh screen.

3. RDF-3 (Fluff RDF): Wastes processed to separate glass, metal,and inorganic materials, and shredded such that 95% by weightpasses through a 2 in. square mesh screen.

4. RDF-4 (Powder RDF): Combustible wastes processed into pow-der form such that 95% by weight passes through a 10 meshscreen (0.035 in. square).

5. RDF-5 (Densified RDF): Combustible wastes compressed into theform of pellets, slugs, cubettes, or briquettes

6. RDF-6 (Slurry RDF): Combustible wastes processed into liquidfuels.

7. RDF-7 (Syngas RDF): Combustible wastes processed into gaseousfuels.

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14 B. Reza et al. / Resources, Conserv

In general, RDF can be utilized and converted into a source ofnergy through various options (Gendebien et al., 2003):

Integrated thermal conversion, Co-combustion in coal fired boilers, Co-processing8 in cement kilns, and Co-gasification with coal or biomass.

All of the above alternatives may be viable destinations basedn regional needs. In this study, the third option is investigated asn alternative fuel for cement manufacturing in Metro Vancouver.

Cement manufacturing requires high temperature conditions,hich are suitable for the thermal destruction of residuals, withoutroducing adverse environmental effects (Environment Agency,001). RDF could be utilized as a substitute fuel in pre-existing

ndustrial plants with notable energy consumption capacities, suchs cement plants (Genon and Brizio, 2008). Due to the heteroge-eous nature and relatively high moisture content of MSW, cementlants do not burn unsorted MSW as it can affect the quality ofement products and may cause environmental damage. Cementilns require a homogeneous RDF composition that is uniform inhape and size (preferably RDF-3 or RDF-4) as well as in calorificalue (Mariani, 2012).

In the production of RDF, MSW can undergo several processesncluding (Gendebien et al., 2003):

Separation at source. Sorting or mechanical separation. Size reduction (shredding, chipping, and milling). Screening. Blending. Drying and pelletizing (not necessarily required for cementindustry).

Packaging. Storage.

The first four steps can be categorized as the front-end sub-ystem, while the remaining four steps can be referred to as theack-end subsystem. The combination of these units for each RDFacility is different and should be decided based on the waste streamnd needs of end-point users. The sorting, screening, and separationtages extract three major divisions of the mixed MSW (Gendebient al., 2003).

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