Research Article

Yen Ta Thi and Tuyet Nguyen Thi Anh*

Determination of life cycle GHG emission factorfor paper products of Vietnam

https://doi.org/10.1515/gps-2020-0061received August 03, 2020; accepted October 11, 2020

Abstract: The paper industry is an essential but energy-intensive economic sector. This study aims to propose anappropriate inventory method to first determine the GHGemission factor in the life cycle of paper products ofVietnam. The approach overcomes the limitations of theISO 14067 method by including the environmental bur-dens from the paper mill’s processes. In 2018, the amountof GHG emitted from cradle to gate when producing a tonof carton box, writing paper, and tissue products (EFCO2eq)was 1,366 kg CO2eq, 1,224 kg CO2eq, and 751 kg CO2eq,respectively. High energy intensity is identified as themain reason that causes high life cycle analysis (LCA)GHG emission factors and virgin paper-based products oftenemit higher LCA GHG amounts than recycled paper-basedproducts. To reduce the emission, the Vietnamese papermills should increase the use of recycled paper and replacefossil fuels with environmentally friendly energy resources.

Keywords: LCA GHG emission factor, pulp and paperindustry, Vietnam

1 Introduction

Pulp and paper production is the fourth most energy-inten-sive industry in theworld. In 2018, this sector occupiedabout5% of total energy consumption and 2% of total CO2 emis-sions of industrial sectors [1]. In Vietnam, pulp and paperproduction ishaving thehighest growth rate in the industry’shistory. The industry’s domestic output reached 3,674 mil-lion tons of paper in 2018, increased by 31% compared to

2017. The average consumptionper capitawas 51 kg of paperin 2018, and this trend is continuing in the coming years [2].Carton board, tissue, andwriting paper are themain producttypes of the industry, accounts for about 70% and 23% oftotal paper demand, respectively. Other product typesinclude votive paper, printing paper, and other packagingpapers. Being an energy-intensive industry, the pulp andpaper production in Vietnam received many investigationsand supports for applying cleaner production and energyefficiency solutions. However, researches related to the in-dustry’s life cycle burdens are still very limited.

Globally, life cycle analysis (LCA) studies have beenfocused on paper products to determine the allocation ofinputs/outputs from/to the paper production system to/from other systems and analyze the distribution of envir-onmental burdens of paper products. Numbers of methodssuch as ISO/TS 14067, PAS 2050, GHG Protocol, AFNOR BPX30-323, PCR Tissue, and PEF 2013 have been applied tocompare CO2 equivalent (CO2eq) emissions of printingpaper product and writing paper product, virgin pulp-based tissue product and recycled paper-based tissue pro-duct [3–5]. Some of the studies used the cut-off method todetermine material flows; therefore, the environmentalburdens from previous cycles of paper products have notbeen considered. The materials of the paper productionsystem were partly or fully recycled into another produc-tion system while undergoing a change to its inherentproperties (open-loop recycling). The GHG protocol isa strict attributional cut-off method, which means thatonly the life cycle of the product is included [6]. Each cyclecarries the environmental burdens that occur within its lifecycle (allocation = 0). This method is easy-to-use, butthe environmental burdens shared between stages in thewhole life cycle of paper products cannot be determined.PAS 2050 method does not explicitly exclude the possibi-lity to apply the end-of-life recycling approach in one lifecycle and the cut-off approach in a subsequent life cycle[7]. Therefore, the practice results in double counting therecycling credits. In other words, combining the cut-offapproach and the end-of-life recycling method suggestedby the PAS 2050 leads to inconsistencies for differentsituations of open-loop recycling [8]. In PEF 2013, the

Yen Ta Thi: School of Environmental Science and Technology, HanoiUniversity of Science and Technology, Hanoi, Vietnam; Faculty ofEnvironment, Hanoi University of Natural Resources and Environment,Hanoi, Vietnam

* Corresponding author: Tuyet Nguyen Thi Anh, School ofEnvironmental Science and Technology, Hanoi University of Science andTechnology,Hanoi, Vietnam, e-mail: tuyet.nguyenthianh@hust.edu.vn

Green Processing and Synthesis 2020; 9: 586–594

Open Access. © 2020 Yen Ta Thi and Tuyet Nguyen Thi Anh, published by De Gruyter. This work is licensed under the Creative CommonsAttribution 4.0 International License.

environmental burdens of virgin production and wastecan be shared. The method introduces several additionalparameters such as credit for energy recovery, qualitydegradation between secondary and primary fibers, andthe national energy recovery rate for raw materials. How-ever, the estimation is time-consuming in many cases, andthe appropriate data conditions are highly required. ISO14067 method identifies the distribution of effects betweenthe paper product life cycle through credit and debit.Credit is given when the material is recycled after useand debit means that one must pay the burden of theinitial virgin production. ISO 14067 requires defining theallocation factor carefully [9]. However, this method doesnot consider the environmental burdens from paper mill’sprocesses (including pulp processing, paper machine, andconverting operations).

This study proposes an appropriate LCA for analyzingopen-loop recycling for paper products of Vietnam basedon the ISO 14067 method and the environmental burdensfrom transportation activities and paper mill’s processes areincluded in the inventory. Then, GHG emission in the lifecycles of a ton of products (hereinafter referred to as anLCA GHG emission factor) of three paper products (namelywriting paper, tissue paper, and carton box) is determined.Primary data in 2018 were collected through surveys at thepulp and/or paper mills. Secondary data were taken frompeer-reviewed publications, standard guidelines, and tech-nical documents.

2 Methods and data

2.1 Methods

The research method diagram and system boundary fordetermining LCA GHG emission factor of writing paper,tissue paper, and carton box are presented in Figures 1and 2, respectively.

Virgin pulp and used paper are inputted into thepaper production processes as materials. Materials aretransported from the pulp mills and/or recycled villagesto the paper mills. Both virgin pulp and used paper areeither domestic and/or imported sources. In the virginpulp processing process, under a certain temperatureand pressure, cellulose is extracted from the wood bychemicals. In the paper production process, hydrauliccrushing, paper machining, paper pressing, and paperdrying are four main stages, except for the extra stageof carton box machining which is only for the carton

box. Electricity from the national grid and heat producedfrom coal-fired boilers are energy sources for the produc-tion processes, diesel is an energy source for transporta-tion. In pulp and paper mills, the black liquor is used asbiomass-derived energy. In this analysis, the GHG emis-sion of woods is considered as neutral because trees growby absorbing CO2 through photosynthesis.

LCA GHG emissions are principally calculated as thefollowing:

( )

× ( )

= ( )

Data from the process e.g. Virgin pulp, chemicalsData for conversion e.g. Emission factors

GHG emissions incl. Direct and indirect emissions

(1)

where direct emissions occur during the use of materials or fuels

(e.g. Combustion of fossil fuel) and indirect emissions occur

during the production of materials or fuels (e.g. Production of

a virgin pulp)The following formulas are developed based on ISO

14067 guidelines and considered the environmental bur-dens of the paper mill’s processes and domestic trans-portation:

= ( − ) + + −

+ +

E r E r E E a r Ea r E T

1 ⁎ ⁎ ⁎ ⁎⁎ ⁎ ,

w 1w VW 1W RW PW 2W VW

1W VW TR–W(2)

= ( − ) + + −

+ +

E r E r E E a r Ea r E T

1 ⁎ ⁎ ⁎ ⁎⁎ ⁎ ,

TT 1 VT 1T RT PT 2T VT

1T VT TR–T(3)

= + + +E E E E T60%⁎ 40%⁎ ,CB C K CBM TR–CB (4)

where

= + +E r E E T⁎ ,C 1C RC PC TR–C (5)

= ( − ) + + −

+ +

E r E r E E a r Ea r E T

1 ⁎ ⁎ ⁎ ⁎⁎ ⁎ ,

K 1K VK 1K RK PK 2K VK

1K VK TR–K(6)

where EW, ET, EC, EK, ECB are LCA GHG emission factor ofwriting paper, tissue paper, corrugated paper, kraft-linerpaper, and carton box, respectively; r1W, r1T, r1C, r1K are pro-portion of recycled material inputs for producing writingpaper, tissue, corrugated paper, and kraft-liner paper,respectively; r2W, r2T, r2C, r2K are proportion of materialrecovery after use ofwriting paper, tissue, corrugated paper,and kraft-liner paper, respectively; EVT, EVW are GHG emis-sion factors of virgin pulpused toproduce tissue andwritingpaper, respectively; ERT, ERW are GHG emission factors ofusedpaperused toproduce tissueandwritingpaper, respec-tively; EPT, EPW are GHG emissions from the production pro-cess of a ton of tissue andwriting papers respectively; EVK istheGHGemission factor of virginpulpused toproducekraft-liner paper; ERC, ERK are GHG emission factors of used paper

Determination of life cycle GHG emission factor for paper products of Vietnam 587

used to produce corrugated and kraft-liner, respectively;EPC, EPK, ECBM are GHG emissions from the production pro-cess of a ton of corrugated paper, kraft-liner paper, andcarton box machining, respectively; TTR–W, TTR–T, TTR–C,TTR–K, TTR–CB are GHG emissions from domestic transportsin a life cycle of a ton of writing paper, tissue paper, corru-gated paper, kraft-liner paper, and carton box, respectively.The GHG emission from materials’ transport is estimatedbased on the distance between paper mills. It is the sum ofthe emission from virgin pulp transport (from pulp mills topaper mills) and the emission of paper and/or used papertransport (between papermills, from paper recycling villageto paper mills).

It isnoted that thepapermills recoverfibers fromwaste-water. The average recovery ratio of corrugated paper andotherpapers is 3%and5%, respectively. These amounts aresubtracted from the domestic recycled pulp flows.

For open-loop recycling analysis, allocation factordetermination is very important, it will help LCA results are

not subjective by implementers. Allocation factor, a, canbe determined based on the mean number of uses andmean fiber age [10,11]. However, the calculation processis relatively complicated and requires comprehensivedata. This study uses a simple, but standardized one: anallocation factor is identified based on the recovering ratioand the number of times the fiber is recycled [12].

( ) = ( − )/a z u u1 , (7)

where a is the allocation factor; z is the recovering ratio ofused paper (z = 45% [13]); and u is the number of recy-cling times in Vietnam (u = 5 times [13]).

2.2 Data

There are three types of paper mills in Vietnam include (I)pulp and paper; (II) paper products (writing paper, tissue,

Figure 1: Method diagram and system boundary.

588 Yen Ta Thi and Tuyet Nguyen Thi Anh

kraft, corrugatepaper); and (III) cartonboxandotherpacka-ging papers. The papermills are divided into three scales: (i)large scale (capacity > 1,00,000 tons of product/year); (ii)medium scale (capacity of 1,000–10,000 tons of product/year); and (iii) small scale (capacity <300 tons of product/year), accounts for about 4%, 50%, and 46% of the totalnumber of paper mills, respectively [14].

Domestic used paper is classified at source and coll-ectedby retail collectors, transported to collectionagents inthe papercraft villages, and then transported to the pulpand paper mills. Greenhouse gas emissions from deliveryto consumers and collection from small collectors are notincluded in this study. Most paper mills are located in cen-tral areas of the North and the South (Figure 2), and thetransportation of materials and paper products is relativelyindependent between the regions.

In the North, there is a full range of paper mills and abalanced ratio of paper products, while in the South, thenumber of tissue production mills accounts for only 7% oftotal tissuemills inVietnam. Therefore, this study surveyedand collected primary data at paper mills in the North.

Primary data include the materials (pulp and usedpaper), energy (electricity, coal, and diesel), and chemicalsare operational data. For each data item of each paper milltype, the input data are the average value of the primary

data collected. Detail information regarding the inventoryof the foreground system of paper production is presentedin Table 1. Generally, the filler is used to increase productqualityand reduceproductioncosts. Papermills inVietnamoften mix filler about 8–10% in the paper production pro-cess. Transport of pulpand/orpaper frompulpmills (type I)to other paper mills (types II and III) using 2.5 tons-truck(full load) averagely consumes 0.1 L of diesel per kilo-meter [15].

Secondary data include emission factors of importedvirgin pulp and used paper, which is inputted to producepaper products, and energy sources were referred fromscientific publications and prestigious reports. In recentyears, the industry imports from abroad about 50% and55% of pulp and used paper, respectively. The biggest pulpsuppliers are North America (accounting for 40.5%), LatinAmerica (33%), and Europe (13.3%). The biggest used papersuppliers are the USA (accounting for 47%), Japan (29%),and Europe (17%) [2]. This study uses the average emissionfactors: 508 kgCO2eq/ton of kraft and 513 kgCO2eq/ton of che-mical–mechanical [16]. The emission factors of carton boxand writing paper imported from Europe, Japan, and US are964 kgCO2eq [17], 810 kgCO2eq [18], 1,040 kgCO2eq [19] (cartonbox) and 800 kgCO2eq [20], 830 kgCO2eq [18], 1,152 kgCO2eq

[21] (writing paper), respectively. Then, emission factors of

Figure 2: Types and locations of pulp and paper mills in Vietnam.

Determination of life cycle GHG emission factor for paper products of Vietnam 589

the paper products are calculated according to the con-tribution rate of imported raw materials from the abovecountries, resulted in 954 kgCO2eq/ton of carton box and987 kgCO2eq/ton of writing paper. It is noted that the useand end-of-life phases of the papers were excluded fromthe above values. The emission factor of the Vietnamesegrid in 2018 is 0.854 kgCO2/kW h [22]. The GHG emissionfactors of coal use for boilers and diesel use for transporta-tion are referred to as IPCC 2006 guidelines [15].

3 Results and discussion

3.1 Open-loop recycling and allocation

The systemboundaries andmaterial flows forwriting paper,tissue, and carton box are determined based on the open-loop recycling approach, as seen in Figure 3a and b. Virgin

pulp and used paper were used as material inputs in papermills of the three paper products. Used paper isrecycled and allocated to paper products in subsequentlife cycles. Carton box paper has a higher demand forused paper than writing paper and tissue. The usedpapers that are disposed and/or allocated to otherpaper mill types (such as votive paper, printing paper,and other packaging paper) are not considered in thescope of the boundary.

3.2 LCA GHG emission factor of the paperproducts

The LCA GHG emission factor of each paper product iscalculated by Eq. 2–4. Table 2 presents a summary of thecalculations.

As the results, LCA GHG emission factor (EFCO2eq) ofwriting paper, tissue paper, and carton box is 1,224 kgCO2eq,751 kgCO2eq, and 1,366 kgCO2eq, respectively. The LCA GHGemission factor of carton box product is higher than otherproducts because its production process hasmore stages andconsumes more energy.

The LCA system boundary of pulp and papers nor-mally includes four primary life-cycle stages: pulp pro-cessing, paper production (includes converting papers tofinal paper products), transportation (transport-in-use),and end-of-life (landfill and incineration). In this study,the LCA system boundaries include the first three stages.To ensure comparability between this study and the casesover the world in the same systematic boundaries, the end-of-life stage of the paper products were excluded from thescope because of high uncertainty in the paper-use phasesand disposal methods after use. Comparing over the cases,LCA GHG emissions of Vietnamese pulp and papers belongto the medium-high emission group and strongly relate tothe energymix. The industry consumes coal and chemicalsintensively [2]. In addition, technologies of recovery energyfromblack liquor are ineffective [13]. Energymix in thepulpand paper industry variesmarkedly between the countries.In Vietnam, coal and electricity are the two main energysources, just a small amount of renewable energy is usedfrom the black liquor recovery process in Bai Bang and AnHoapulp andpapermills (type I). This situation is similar totheChinesepulpandpaper industry thatused64.1%of coal[23],whileEuropeusedonly 3%of coal [24]and theUSused8.7% of coal [25]. In European countries, USA, and Brazil,renewables such as hydropower and biomass play a majorrole in the energymix, the systemof recoveringenergy fromblack liquor is modernized. The emission factor of Chinese

Table 1: Input data for three paper production types

Writing paper (I) Tissue paper (II)

Materials Value Unit Materials Value Unit

Domestic pulp 433.93 kg Domestic pulp 303.33 kgImport pulp 415 kg Import pulp 511.67 kgDomestic usedpaper

88 kg Import usedpaper

96 kg

Import usedpaper

83 kg Domestic usedpaper

140.33 kg

Chemicals 15 kg Chemicals 6 kgFiller 132 kg Filler 148 kgCoal 350 kg Coal 220 kgElectricity 320 kW h Electricity 280 kW h

Carton box (III)

Corrugated paper (a) Kraft paper (b)

Domesticused paper

611 kg Domestic pulp 73.40 kg

Import usedpaper

509 kg Import pulp 128 kg

Cassava 30 kg Domestic usedpaper

385 kg

Chemicals 3 kg Import usedpaper

436 kg

Filler 138 kg Filler 144 kgCoal 340 kg Chemicals 13 kgElectricity 310 kW h Coal 350 kgProcessing of cartonbox (c)

Electricity 325 kW h

Electricity 95 kW h All the inventory data refer to thefunctional unit of the study: a ton ofpaper product

Cassava 80 kgNaOH 5 kg

590 Yen Ta Thi and Tuyet Nguyen Thi Anh

writing papers belonged to high emission group with over1,500 kgCO2eq [16],while thevalues in theUSandBrazilwere1,152 and 1,050 kgCO2eq, respectively [26,27]. The emissionfactor of tissue paper in Europe was 692 kgCO2eq [28]. Theemission factors of the cartonbox in Europe and theUSwere964 and 1,040 kg CO2eq [17,19].

Figure 4 shows the LCA GHG emissions associatedwith the input materials and processes. The emissionsfrom transportation take the smallest fraction, accountedfor 0.69% to 1.06%. It is noted that the burdenof importingmaterials (transportation) is not considered in this scope.The emissions from materials (pulp and used paper)

Figure 3: (a) System boundary and material flow for LCA of writing paper and tissue and (b) system boundary and material flow for LCA ofcarton box.

Determination of life cycle GHG emission factor for paper products of Vietnam 591

accounted for about 12.74% to 23.66% of total emissions.The biggest burdens come from the paper production pro-cess (crushing, machining, pressing, etc.), accounted for75.65% to 86.31% of total emissions. This distribution issimilar to other countries in the world [23,29].

Figures located in the bottom left corners of Figure 4to unveil the percentage of GHG emissions contributedfrom different inputs in the life cycle of Vietnamese paperproducts. As seen, the emission from electricity useaccounted for 23.12% to 32.97% of total GHG emissions,which is similar to the other countries [16,29]. The emis-sion from coal use accounted for 45.02% to 52.47% oftotal GHG emissions, higher than the other countries nor-mally accounted for 20% to 25% of total GHG emissions[30]. Some countries use gas and other energy instead ofcoal, such as European countries: 43.9% biomass, 26.3%gas, 24% electricity, and 3.0% coal [24]; the US: 43%

biomass, 38.5% gas, 9.2% electricity, and 8.7% coal[25]. The emissions from chemicals use in Vietnam werelow and responsible for only 0.87% to 5.53% of total GHGemissions.

At 2015-Paris Agreement, Vietnam has set a goal to2030 that “…by domestic resources, 8% of the total GHGemissions will be reduced in comparison with normaldevelopmental trajectory and the target can rise up to25% when receiving international support by means ofbilateral, multilateral cooperation and performing newmechanisms.” To reach the goal, all economic sectors,in general, and the pulp and paper industry needs tofind out the solutions to diminish the sector’s energyintensity and GHG emission factor as well.

To achieve long-term and sustainable energy-savingeffects for the paper industry, paper mills need to reducethe use of fossil energy in the pulp processing and paper

Table 2: LCA GHG emission factor of Vietnamese paper products (kg/ton of product)

Paper r1 r2 Virgin material Recycled material Paper production Debit Credit Transport Total

Writing 0.1673 0.0968 EVW = 326.31 ERW = 57.12 EPW = 926.34 19.65 −11.37 8.51 1,224.41Tissue 0.2248 0.144 EVT = 106.45 ERT = 44.89 EPT = 648.38 8.62 −5.52 7.15 751.25Carton box 0.9212 0.1591 60% EVC + 40%

EVK = 30.4260% ERC + 40% ERK= 310.17

60% EPC + 40% EPK +ECBM = 1055.60

8.79 −0.7 14.50 1,366.34

Figure 4: GHG emissions from different inputs in the life cycle of paper products. (a) Carton box, (b) writing paper, (c) tissue paper.

592 Yen Ta Thi and Tuyet Nguyen Thi Anh

production processes and increase the use of renewableenergy. The effectiveness of these solutions has beenshown in some literature [16,23]. Besides, the paper millsshould improve production machinery systems such asinstalling inverters to reduce energy consumption andincrease the durability of machinery, improving the con-vection systems to increase the boiler’s efficiency. More-over, the energy recovery systems should be modernized.All the type I paper mills in Northern Vietnam currentlyhave a black liquor-based energy recovery system in thepulp processing but the efficiency of the system is nothigh enough.

Assessing the possibility of reducing emissions whenreplacing virgin materials with recycled materials, thestudy has progressed to LCA for two paper product typesin the same paper mill: one made from virgin materialsand the other made from recycled materials (Figure 5). Asseen, the GHG emissions of virgin paper-based productsare often higher than that of recycled paper-based pro-ducts. This suggests that trying to increase the percen-tage of used paper for the production process wouldreduce the burden on the environment. Indeed, the num-bers of studies have shown similar results [16]. As thecase with Spain’s tissue production, LCA GHG emissionof recycled paper-based products was about 30% lowerthan that of virgin pulp-based products [29].

Global recycling rates of materials in the pulp andpaper industry is now over 70%, namely: USA (70%),EU (73%), Japan (81.3%), Asia (51.5%), the average ofthe world (59%), and Vietnam (45%) [13]. To reduceGHG emissions as well as production costs for the Viet-namese paper mills, it is necessary to increase the do-mestic-used paper rate in the material flows. The cost-effectiveness of the paper collection and classification

system in the country needs to be improved. The aware-ness of handling recycling products is not commensurateand needs to be enhanced.

Thepulpandpaper industry is aneconomic sectorwitha natural fit for the circular economic model. Therefore,making use of recycled paper sources and saving energyis very important. Touse recycledpapers as amainmaterialsource in the papermills, it is necessary to encouragepaperrecovery and recycling by legislating laws on recycling andsaving resources as some developed countries have done.The pulp mills need to improve machinery to save energyand improveproduction efficiencyby applying cleaner pro-duction and energy efficiency measures as well as usingrenewable energy.

4 Conclusions

This study proposes an appropriate method for analyzingthe environmental burdens in a life cycle of three paperproducts, in which the contributions of transports andpaper mill’s processes are included in the inventory. TheLCA GHG emission factor writing paper, tissue paper, andcarton box is resulted of 1,224, 751, and 1,366 kgCO2eq,respectively. This result enriches research data on theenvironmental life cycle inventory of the pulp and paperindustry in the world. High energy intensity is identified asthe main reason that causes high LCA GHG emission fac-tors. This study also shows that the GHG emissions ofvirgin paper-based products are often higher than recycledpaper-based products. The emission factors will change ifthe input – output balance and/or the production tech-nology changes.

14781364

1061

13661224

751

0

200

400

600

800

1000

1200

1400

1600

Carton box Wri�ng paper Tissue paper

kg CO2e/ton

Virgin paper Recycle paper

Figure 5: GHG emission of virgin paper-based products and recycle paper-based products.

Determination of life cycle GHG emission factor for paper products of Vietnam 593

Acknowledgments: The authors wish to thank the HanoiUniversity of Science and Technology for the academicsupports. This paper is partly financial supported by EfD-Vietnam, University of Economics Ho Chi Minh City.

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594 Yen Ta Thi and Tuyet Nguyen Thi Anh