comparative life cycle assessments of conventional

IN DEGREE PROJECT MATERIALS SCIENCE AND ENGINEERING,SECOND CYCLE, 30 CREDITS

, STOCKHOLM SWEDEN 2020

Comparative Life Cycle Assessments of Conventional Products and 3D-Printed Wood-Plastic Composite Alternatives

SANGHO KIM

KTH ROYAL INSTITUTE OF TECHNOLOGYSCHOOL OF INDUSTRIAL ENGINEERING AND MANAGEMENT

i

As additive manufacturing gains market potential as a mainstream process in various

sectors of industry, there is a growing need for addressing environmental aspects of

this technology and the materials associated with it. In this master thesis, comparative

life cycle assessments (LCAs) from cradle to grave between the conventional products

and 3D-printed alternatives made of wood-plastic composite (WPC) were conducted

based on the ISO 14044:2006 standard. Environmental impacts of each product were

quantified for 10 impact categories. The goal of the LCAs was to determine whether

the use of the 3D-printed WPC products may suggest a sustainable alternative to the

conventional ones.

This master thesis presents three case studies in which comparative LCAs were

carried out. The first two case studies are about storage compartments for trucks from

Scania, and the third one is about ceiling boards from Veidekke. The results showed

that, in all case studies, the 3D-printed WPC alternatives would have smaller

environmental impacts compared with the conventional products. The most

significant difference was observed in the first two case studies because of the light-

weighting effect. The alternatives showed 51%, 68% and 13% lower global warming

potential (GWP) than the conventional products in each case study, respectively.

However, the results of the cradle-to-gate LCAs suggested that the 3D-printed WPC

alternative might cause greater environmental impact than the conventional products

regarding some impact categories.

Therefore, in the LCA context, the 3D-printed WPC alternatives would be much

more beneficial to the environment compared with the conventional products, but the

environmental benefits might be insignificant from the manufacturer’s perspective.

Keywords: Life cycle assessment, Wood-plastic composite, Additive manufacturing,

3D printing, Environmental impact, Global warming

ii

Eftersom additive tillverkningsteknik ökar marknadspotentialen som en vanlig

process inom olika industrisektorer, finns det ett växande behov av att ta itu med

miljöaspekterna av denna teknik och de material som är associerade med den. I detta

examensarbete avhandling genomfördes jämförande livscykelanalys (LCA) från vagga

till grav mellan de konventionella produkterna och 3D-printade alternativ av

träplastkomposit (WPC) baserat på ISO 14044: 2006-standarden. Miljöpåverkan av

varje produkt kvantifierades för 10 miljöeffekter. Målet med LCA var att avgöra om

användningen av de 3D-printade WPC-produkterna kan vara ett hållbart alternativ

till de konventionella.

Denna avhandling presenterar tre fallstudier där jämförande LCA utfördes. De

två första fallstudierna handlar om förvaringsutrymmen för lastbilar från Scania, och

den tredje om takskivor från Veidekke. Resultaten visade att de 3D- printade WPC-

alternativen i alla fallstudier skulle ha mindre miljöpåverkan jämfört med

konventionella produkter. Den mest signifikanta skillnaden observerades i de två

första fallstudierna på grund av den lägre vikten viktningseffekten. Alternativen

visade 51%, 68% och 13% lägre global uppvärmningspotential (GWP) än de

konventionella produkterna i respektive fallstudie. Emellertid föreslog resultaten av

vaggan-till-grind-LCA att det 3D-printade WPC-alternativet kan orsaka större

miljöpåverkan än de konventionella produkterna avseende vissa miljöeffekter.

Därför, i LCA-sammanhang, skulle de 3D-printade WPC-alternativen vara

mycket mer fördelaktiga för miljön jämfört med konventionella produkter, men

miljöfördelarna kan vara obetydliga ur tillverkarens perspektiv.

Nyckelord: Livscykelanalys, Träplastkomposit, Additive tillverkningsteknik,

Friformsframställning, Miljöpåverkan, Global uppvärmning

iii

Abstract .................................................................................................. i

Sammanfattning .................................................................................... ii

Table of contents .................................................................................. iii

Nomenclature........................................................................................ v

1 Introduction .................................................................................... 1

1.1 Motivation .................................................................................................. 1

1.2 Problem definition ..................................................................................... 1

1.3 Case studies ................................................................................................ 2

2 Literature review ............................................................................. 4

2.1 Wood-plastic composites ........................................................................... 4

2.2 AM and conventional manufacturing ........................................................ 4

2.3 WPCs integrated with AM .......................................................................... 5

3 Methods .......................................................................................... 7

4 Case studies ................................................................................... 10

iv

4.1 Case study A: storage box ......................................................................... 10

4.1.1 Goal and scope definition ............................................................. 10

4.1.2 Inventory analysis ......................................................................... 12

4.1.3 Life cycle impact assessment ........................................................ 16

4.1.4 Life cycle interpretation ................................................................ 18

4.2 Case study B: tunnel storage .................................................................... 20





4.3 Case study C: ceiling board ...................................................................... 30





5 Conclusions ................................................................................... 39

6 Future work .................................................................................. 40

7 Acknowledgements ....................................................................... 41

8 References .................................................................................... 42

Appendix A: LCI details ....................................................................... 47

Appendix B: LCIA details ..................................................................... 54

v

3D three-dimensional

AD terrestrial acidification

AM additive manufacturing

APP ammonium polyphosphate

DB database

EP freshwater eutrophication

EU European Union

FD fossil depletion

FDM fused deposition modelling

FEC freshwater ecotoxicity

FFF fused filament fabrication

FGF fused granular fabrication

FP fine particulate matter formation

FPF fused particle fabrication

GW global warming

GWP global warming potential

vi

HT human toxicity

IM injection moulding

ISO International Organization for Standardization

LCA life cycle assessment

LCCA life cycle cost analysis

LCI life cycle inventory

LCIA life cycle impact assessment

MEC marine ecotoxicity

MSW municipal solid waste

OD stratospheric ozone depletion

PLA polylactic acid

PP polypropylene

PUR polyurethane

RISE Research Institutes of Sweden

SEC specific energy consumption

STPP sodium tripolyphosphate

TEC terrestrial ecotoxicity

UCO used cooking oil

UNGA United Nations General Assembly

WPC wood-plastic composite

1

Environmental issues such as climate change and resource depletion have been global

concerns in recent decades. In September 2015 the United Nations General Assembly

(UNGA) included details on climate action and responsible consumption and

production in 17 sustainable development goals [1], and in December most countries

agreed on efforts to curb climate change through the Paris Agreement [2]. Sweden

also aims to reach zero net atmospheric greenhouse gas emissions by the year 2045,

and pursues reduction measures including carbon dioxide and energy taxes, the

European Union (EU) Emissions Trading System and the Environmental Code [3].

Accordingly, companies are committed to reducing their carbon footprint and

developing resource-efficient products [4]. However, these efforts are concentrated

on traditional manufacturing—subtractive and formative manufacturing, and

research on environmental impacts of additive manufacturing (AM) is still scarce.

AM, commonly known as three-dimensional (3D) printing, is a manufacturing

process used to build a product layer by layer using a digital model. Since its advent

in the 1980s, AM has mostly been used for rapid prototyping due to its ability to create

objects with complex geometries [5]. Recent studies have shown that there is market

potential for this technology as a manufacturing process to produce end-use parts in

various sectors of industry—such as automotive and construction [6, 7, 8, 9]. These

studies, however, often do not address environmental benefits and drawbacks that

AM has over traditional manufacturing.

2

To consider the environmental aspects, a systematic approach is necessary.

Therefore, the purpose of this master thesis is to investigate the potential

environmental impacts of AM through comparative life cycle assessments (LCAs) of

the conventional products and the 3D-printed alternatives. LCA is an analytical

technique for assessing environmental impacts associated with the phases of a

product’s life [10]. It provides a quantitative evaluation on the environmental impacts

that would occur during the life cycle of the product so that users can identify which

phase causes which environmental impacts and make decisions based on that.

This master thesis presents three case studies which are part of a project called

Wouldwood coordinated by Research Institutes of Sweden (RISE) and funded by

Vinnova together with various partners. The project is an integrated platform to

develop wood-based materials and apply them to large-scale AM. It also covers digital

design, production equipment and recycling strategies. [11]

In each case study, a comparative LCA was conducted for the existing

conventional product and the 3D-printed alternative made of wood-based materials.

Due to the different nature of the products, each case study is discussed in the separate

sections. The first two case studies are about storage compartments for trucks from

Scania, a Swedish vehicle manufacturer [12]. Both compare the original injection-

moulded products made of mineral-filled plastics with the 3D-printed alternatives

made of wood-based composites. The third one is about ceiling boards from Veidekke,

a Norwegian construction company [13]. It compares a commercial gypsum

plasterboard with the 3D-printed alternative made of wood-based composites.

Although fused filament fabrication (FFF)—more commonly known as the

trademarked term, fused deposition modelling (FDM)—is the most common

technology of material extrusion, fused particle fabrication (FPF)—also known as

fused granular fabrication (FGF)—is used as the AM process for all the case studies.

This process is a newer type of FDM that uses pellets directly instead of converting

them into filaments, and has the possibility to utilize more recycled materials [14].

The pellets for AM are from Stora Enso, a Finnish wood-based material manufacturer

[15]. Other types of AM such as photopolymerization and powder bed fusion are not

discussed in this report (see Table 1.)

3

Table 1 Common AM technologies

Type Technologies

Material extrusion Fused filament fabrication (FFF)

Fused particle fabrication (FPF)

Photopolymerization Stereolithography (SLA)

Powder bed fusion Selective laser sintering (SLS)

4

Wood is one of the oldest structural materials. Due to its long history associated with

traditional manufacturing industries, the image of wood-based materials has been

obsolete in an engineering sense. In contrast to this misperception of them as low-

tech, new wood-based materials are being continuously developed and introduced to

the high-tech engineering field and construction market. For example, wood-based

composites such as laminated veneer lumber have acted as a solution to overcome

structural limitations of today's plantation wood caused by its small diameter, and

increase the reliability of final products by minimizing local deformation through the

random distribution of defects. They also allow utilization of recycled materials as

new resource supplies. [16]

Recently, the trend is to directly combine wood and synthetic materials. Among

this type of materials, wood-plastic composites (WPCs) emerged as a solution for

sustainable development because there are more and more demands for

biodegradability for both automotive and architectural applications [17, 18]. WPCs

have already gained substantial ground in the market by offering the light-weighting

potential in automotive industries and the flexibility in designing buildings [19, 20].

As the use of AM increases around the world, research is being actively conducted to

compare this technology with traditional manufacturing. While there are numerous

opportunities for AM to make significant changes in the way products are

manufactured in various industries, it is still facing several challenges to its

implementation.

5

Most 3D printers can only produce objects that are smaller than the printer

enclosure. It means there is a limit on the size of objects that can be manufactured at

a time, which necessitates segmented production and additional assembly. Besides,

AM is slower in mass production than conventional manufacturing processes such as

injection moulding (IM). Longer production time leads to higher cost, and relatively

expensive 3D printing equipment and the materials also contribute to rising

production cost although they will be cheaper and cheaper as the related technologies

advance. [6]

Experts do not believe AM will replace existing manufacturing processes: it will

not revolutionize manufacturing industry to shut down traditional factories. Instead,

it is recommended to utilize its unique features as a complement to conventional

manufacturing. For example, conventional manufacturing processes are still

dominant in manufacturing industries with high production volume. However, even

for these industries AM can be more useful than conventional manufacturing when

the complexity of a product’s geometry or the customization of a product are the main

concern. Its strength is best shown in manufacturing industries with low production

volume such as rapid prototyping and component manufacturing. Manufacturers can

modify or redesign a part with no penalty thanks to its process flexibility, which

facilitates rapid tooling and on-demand manufacturing. AM can also be more eco-

friendly than conventional manufacturing as it leaves little waste. [6, 21]

Thanks to their superior aesthetics, WPCs for AM have market recognition [22]. The

following included only research on materials for AM using material extrusion

processes because these materials and the materials used for other AM technologies

are different in nature.

When it comes to material, polylactic acid (PLA) filled with wood fibre is the most

common in the market. While the plastic part is mostly fixed with PLA, various types

of wood are used as wood materials [23].

With respect to the optimal wood content, there is a big difference from study to

study although commercial products typically have 30%. Tao et el. published a paper

on the development of wood flour-filled PLA composite filament for FDM. The

researchers observed that the composite filament with 5wt% wood content had

enhanced deformation resistance compared with pure PLA filament, displaying

different microstructure on the material’s fracture surface [24]. Kariz et al.

investigated the effect of wood content in FDM filament on the properties by varying

6

wood content in wood-PLA composite filaments from 0wt% to 50wt%. The results

showed that tensile strength increased at 10% wood content but decreased with

higher levels of wood content [25]. Liu et al. investigated the effect of wood content

and types of wood filler in PLA-based WPC on the properties such as tensile strength

and thermal stability. The results showed that the optimal wood content was 15% and

the superior combination was lignin-PLA under the same wood content [26].

Montalvo Navarrete et al. tested thermal and mechanical behaviour of polypropylene

and PLA filled with different percentages of wood flour. They concluded that the

samples with 20% wood content were suitable for AM and those with 30% wood

content were relatively brittle [27]. Martikka et al. published a paper on the

mechanical properties of 3D-printed WPCs. The results indicated that the tensile

strength and impact resistance of WPC parts are about 50% of those of pure PLA parts

when the infill percentage is the same, however, it was implied that these WPC parts

could be strong enough for low-stress applications [28].

In addition to the material composition, infill percentage has a significant impact

on the properties of 3D-printed products. The infill is the amount of material that fills

up the internal structure of the 3D-printed products. Alvarez et al. investigated the

influence of infill percentage on the mechanical properties and effective printing time

of 3D-printed parts. The results showed that the tensile strength and impact

resistance improve as the infill percentage increases, and the parts have their

maximum tensile strength and impact resistance with 100% infill. It was also

observed that the tensile strength does not improve efficiently as the infill percentage

gets close to 100%. In reference to the effective printing time, it is longer with 50-98%

infill than with 100% infill. Therefore, the researchers indicated that 50-98% infill is

not recommended from the manufacturing perspective. However, actual products

manufactured with AM often do not have 100% either. [28, 29]

7

This master thesis applied the LCA methodology based on the ISO 14044:2006

standard by the International Organization for Standardization (ISO) [30]. LCA is an

analytical technique for assessing environmental impacts associated with the phases

of a product’s life—pre-manufacturing (resource extraction and materials processing),

manufacturing, distribution, use and disposal (end-of-life). According to the ISO

standard, an LCA consists of the following four steps (see also Figure 1):

• Goal and scope definition

• Life cycle inventory analysis (LCI)

• Life cycle impact assessment (LCIA)

• Life cycle interpretation

Figure 1 General steps of an LCA

In the first step, the goal and scope of the LCA are defined. The definition shall

be consistent with the intended application and the reasons for carrying out the study.

This step shall describe the product system to be studied, the functional unit and the

system boundary. The functional unit is a quantified description that represents the

performance requirements fulfilled by the studied product system. It provides a

8

reference associated with the inputs and outputs. The system boundary is a boundary

that determines which unit processes of the product’s life cycle to be included in the

LCA. If an LCA covers from resource extraction to disposal phase, it is called cradle-

to-grave (see Figure 2). If it only covers until manufacturing phase before the product

is transported to the consumer, it is called cradle-to-gate. All general decisions shall

be made including geography, time horizon, allocation method, LCIA method and

types of impact categories to be included in the LCA. Assumptions and limitations

shall also be stated in this step.

Figure 2 General phases of life cycle

Next, an LCI consists of the data collection on the inputs and outputs of materials

and energy related to the product studied and the calculation process for quantifying

them. Data shall be collected for every raw material, process and activity in the

product’s life cycle that has impacts on the environment. The collected data shall be

reliable to simulate a valid model for each phase in the product’s life cycle.

Then in an LCIA, the collected data shall be processed and the actual results of

the LCA shall be given. The emissions of the product shall be divided into different

environmental impact categories that are selected during goal and scope definition.

The final step is life cycle interpretation. The significant issues shall be identified

and discussed based on the results of the LCI and LCIA. This step includes conclusions

and recommendations. Sensitivity analysis may also be conducted for further

investigation of the effect of certain materials and processes on the environmental

impact categories.

9

The LCI and LCIA have been conducted with the software SimaPro 9.1.0.11, one

of the leading LCA tools to model a life cycle of a product or system and analyse the

environmental impacts. With its resourceful database, it is possible to simulate almost

all materials and processes, and build a life cycle with them. [31]

10

The main goal of this case study is to perform a comparative LCA between two interior

parts for trucks from Scania. One is the conventional injection-moulded storage box

made of mineral-filled polypropylene (PP), and the other is the 3D-printed alternative

made of wood fibre and PP with a small addition of a flame retardant (see Figure 3).

The objective is to determine, with a quantitative analysis, if the use of the 3D-printed

WPC product may suggest a sustainable alternative to the conventional storage box.

Figure 3 3D modeling of the compared products in the case study A

The functional unit for the storage boxes is simply a single unit product with a

volume of 4.04 L, each having a different material composition. The difference in

11

mass between them was considered irrelevant because both the products achieve the

same task. Since it was intended is to compare the products based on the functional

unit, the production volume was excluded from consideration.

The system boundary for the LCAs of this study is cradle-to-grave: pre-

manufacturing, manufacturing, distribution, use and end-of-life phases. The process

trees for the injection-moulded storage box and the 3D-printed WPC alternative are

presented in Figure 4 and Figure 5, respectively. The system boundary and the

assumptions and limitations used in data collection are presented in Table 2.

Figure 4 Process tree of the injection-moulded storage box

Figure 5 Process tree of the 3D-printed WPC storage box

The geography for the manufacturing, distribution, use and end-of-life phases

was set to Sweden, and the time horizon 2020. Ecoinvent 3 was used for the LCI

database [32]. Allocation at the point of substitution—which is also called Ecoinvent

default—was chosen as the allocation method [33]. The chosen LCIA method is

ReCiPe 2016 Midpoint (Hierarchist) which is considered to be the default model [34].

The impact categories included in the LCAs are: global warming, stratospheric ozone

depletion, fine particulate matter formation, terrestrial acidification, freshwater

eutrophication, human toxicity, fossil depletion and three types of ecotoxicity—

terrestrial ecotoxicity, freshwater ecotoxicity and marine ecotoxicity.

12

Table 2 System boundary and assumptions/limitations for the case study A

Life cycle stages

System boundary Assumptions and

limitations

Pre-manufacturing

- Resource extraction

- Materials processing

- Transport from the suppliers to the processing site

- Geography data are unavailable for some raw materials

Manufacturing - Product manufacturing

- Transport from the processing site to the manufacturing site

- SEC for FPF is the same as SEC for FDM

- Energy consumption and emissions for the manufacturing facilities are excluded

Distribution - Transport from the manufacturing site to the distribution site

- Distribution to the individual consumers is excluded

Use - Consumer use 40,570 km per year [35]

- Consumer use for 6.2 years [36]

- Both products have the same use phase

End-of-life - Incineration

- Recycling

- Wasted PP during IM is recycled

Inventory analysis was performed in accordance with the framework provided by the

ISO. Data collected are: the list of the raw materials, transport modes and distance for

each item, production data of manufacturing processes, fuel consumption during the

use phase, and disposal processed. The project Wouldwood is based in Sweden, so the

energy and production data were used according to the average value of the European

market. The field data were primarily collected, and if they were unavailable

experimental data from the literature were adopted.

All the databases used in the LCAs for the injection-moulded storage box and the

3D-printed WPC alternative are presented in Table 3 and Table 4, respectively. Data

collection and processing methods are described separately for each stage of the LCAs.

The shortcuts attached to the end of each item show geographical reference. For

example, SE represents Sweden and means the corresponding item contains average

data for Sweden. GLO and RER represent global and Europe, respectively.

13

Table 3 Life cycle inventory database used for the injection-moulded storage box

Life cycle stages

Items LCI DB (Ecoinvent 3)

Pre-

manufacturing

Polypropylene, SE Polypropylene, granulate, GLO

Mineral, SE Kaolin, GLO

Grinding, SE Electricity, medium voltage, SE

Compounding, SE Electricity, medium voltage, SE

Water, lake, SE

Road Transport, lorry, EURO5, RER

Manufacturing Injection moulding, SE Injection moulding, RER


Distribution Road Transport, lorry, EURO5, RER

Use Road Transport, lorry, EURO6, RER

End-of-life Incineration, SE Incineration of MSW, SE

Recycling of PP, SE Recycling of PP, GLO


Table 4 Life cycle inventory database used for the 3D-printed WPC storage box

Life cycle stages


Pre-

manufacturing

Polypropylene, SE Polypropylene, granulate, RER

Woold wool, SE Wood wool, RER

Flame retardant, SE Sodium tripolyphosphate, GLO


Water, lake, SE


Water Transport, sea, natural gas, GLO

Manufacturing Fused particle fabrication, SE Electricity, low voltage, SE

Transport, lorry, EURO5, RER




14

The pre-manufacture phase includes extraction, acquisition, processing, and

transportation of raw materials. Masses of the raw materials were calculated based on

the volume and material composition of the products. Raw material productivity—the

ratio of production quantity against the amount of raw material used—is assumed to

be 100% for the sake of simplicity. When the transportation data for the raw materials

were not available, average transportation modes and distance in the European

market were adopted.

The conventional storage box is made of mineral-filled PP. Therefore, the pre-

manufacturing process begins with the extraction and acquisition of granulated PP

and raw minerals. The material data obtained from the manufacturer only specified

the filler as mineral, so kaolin—a mineral filler known to increase impact strength and

heat resistance—was chosen as the filler material in the simulation. The process is

followed by the grinding of kaolin [37]. It ends with the compounding of PP and kaolin,

obtaining PP (20% kaolin).

Pellets for the WPC storage box are made of wood fibre, PP, and a small addition of a

flame retardant. Therefore, the pre-manufacturing process begins with the extraction

and acquisition of them. According to the material data obtained from the

manufacturer, the flame retardant was supposed to be ammonium polyphosphate

(APP), however, sodium tripolyphosphate (STPP)—which is also used as a flame

retardant—was chosen as the flame retardant in the simulation because APP was not

available in the LCI DB [38]. It is assumed that the flame retardant is prepared as

powder form. The process ends with the compounding of wood fibre, PP, and the

flame retardant, obtaining flame retarded wood-plastic pellets (40% PP, 10% STPP).

The manufacturing phase normally includes assembly and inspection as well as

manufacturing process. However, since the assembly of a storage box to a truck is a

relatively simple process and it is assumed that there is no failure in manufacturing,

only the manufacturing process was considered in the simulation. Energy

consumption and emissions for the manufacturing facilities were excluded.

15

The conventional storage box is manufactured through IM at Backa, Swden. It is

assumed that there is no failure in manufacturing, so material loss only occurs during

machine start-up, cleaning, and maintenance. The production yield—the ratio of the

manufactured quantity against the amount of material used—for IM is assumed to be

90% [39]. It is assumed that the wasted material at this phase is recycled [40]. Energy

consumption and emissions during IM was set according to the LCI DB. The weight

of the manufactured item is 4.20 kg.

The WPC storage box is manufactured through AM at Södertälje, Sweden. It is

assumed that there is no failure in manufacturing, so material loss is only contributed

by the support material, which is a technically inevitable waste. The production yield

for AM is assumed to be 84.4% [41]. Since there has not been any research on energy

consumption and emissions data for FPF, data for FDM from the literature were

adopted [41, 42]. FPF does not involve filament manufacturing process, so one of the

lowest energy consumption data for FDM was chosen. The infill percentage was set to

50%. It must be noted that the weight of the manufactured item is 2.07 kg, which is

less than half of the injection-moulded one.

Distribution to individual consumers was excluded in the simulation because the

consumers are expected to come and get the vehicles at the distribution site in

Södertälje, Sweden themselves.

The conventional storage box is transported from the manufacturing facility in Backa,

Sweden to the distribution centre in Södertälje, Sweden by using roads.

The WPC storage box is manufactured in the same place as the distribution centre in

Södertälje, Sweden. Therefore, the product does not need to be transported.

The use phase calculated the amount of fuel consumed by a truck due to the weight of

each storage box assembled with the truck during the useful life of the vehicle. In

Sweden, average mileage of heavy trucks is 40,570 km per year [35], and medium and

heavy commercial vehicles are on average 6.2 years old [36].

16

All storage boxes were considered disposed when the vehicles on which they were

assembled reach the end of their useful life. It was assumed that the discarded

products are classified as municipal solid waste and incinerated in Södertälje, Sweden.

The classification and characterization process were carried out in accordance with

the ISO 14040s standard. For the impact assessment, ReCiPe Midpoint (Hierachist)

was applied to calculate the environmental impacts, and the following 10 impact

categories were included in the LCA: global warming (GW), stratospheric ozone

depletion (OD), fine particulate matter formation (FP), terrestrial acidification (AD),

freshwater eutrophication (EP), human toxicity (HT), fossil depletion (FD) and three

types of ecotoxicity—terrestrial ecotoxicity (TEC), freshwater ecotoxicity (FEC) and

marine ecotoxicity (MEC).

The results of the cradle-to-grave comparative LCA between the injection-moulded

storage box and the 3D-printed WPC alternative with 50% infill are presented in

Figure 6. The results showed that the environmental impacts caused by the alternative

are about half of those caused by the conventional product. This difference is mostly

contributed by the weight effect in the use phase.

Figure 6 Characterization results of the case study A (cradle-to-grave)

0

10

20

30

40

50

60

70

80

90

100

GW OD FP AD EP HT FD TEC FEC MEC

IM Storage Box 3D Storage Box

17

Since the use phase is dominant in the full LCA, it was expected to be meaningful to

observe the results of a comparative LCA without the use phase as well. Therefore, a

cradle-to-gate comparative LCA was additionally performed. The results are shown in

Figure 7. The results indicated that the 3D-printed WPC alternative may not always

be good for the environment from the manufacturer’s perspective. Ozone depletion,

human toxicity and three types of ecotoxicity appeared to be unfavourable to the

alternative. These are contributed mostly by FPF and the flame retardant.

Figure 7 Characterization results of the case study A (cradle-to-gate)

According to the experimental data provided by the manufacturer, mechanical

properties of the material for the 3D-printed WPC alternative are competitive when

compared with those of the material for the conventional product (see Table 5).

However, there is no guarantee that mechanical properties of the actual product are

suitable for the usage because those of the 3D-printed products are highly dependent

on the infill percentage. That is, there is a possibility that 50% infill will not offer

enough mechanical properties that are needed for the usage. Therefore, it was

expected to be meaningful to set up a hypothetical scenario where the manufacturer

prints the WPC product with a higher infill percentage than 50% and observe the

results. For a dramatic comparison, it was assumed that the hypothetical product is

manufactured with 100% infill. The results of the cradle-to-grave comparative LCA

between the injection-moulded storage box and the 3D-printed WPC alternative with

100% infill are shown in Figure 8. It must be noted that the weight of the alternative

0

10

20

30

40

50

60

70

80

90

100



18

increased to 4.15 kg.

Table 5 Mechanical properties of the materials used in the case study A

Mechanical properties

PP (20% mineral) WPC (40% PP, 10% APP)

Tensile strength 38.50 MPa 28.22 MPa

Young’s modulus 2.40 GPa 4.31 GPa

Elongation 11.58% strain 1.92% strain

Figure 8 Characterization results of the case study A (100% infill)

The results displayed that the environmental impacts caused by the 3D-printed

alternative with 100% infill are slightly higher than those caused by the conventional

product for all categories except fossil depletion (FD).

For the 3D-printed WPC storage box, process contribution—a percentage of the

contribution made by the impact values of each phase on those of whole life cycle in

the given impact categories—was investigated. The results are shown in Figure 9. The

use phase is dominant as observed in 4.1.3.1. There is no contribution made by the

impact of the distribution phase because distribution to individual consumers is

excluded.

Sensitivity analysis was performed to determine the sensitivity of certain

0

10

20

30

40

50

60

70

80

90

100



19

materials and processes to the impact value of the investigated impact category. The

results are presented in Table 6. The base product is the 3D-printed WPC storage box.

In the first scenario, petrochemical PP—one of the raw materials—is replaced by PP

made of used cooking oil (UCO)—a renewable resource [43]. In the second scenario,

end-of-life treatment is changed: recycling plastic materials from the used product,

instead of incinerating everything. The unit for global warming potential (GWP) is kg

CO2 eq.

Figure 9 Process contribution of the 3D-printed WPC storage box

Table 6 Sensitivity analysis for the 3D-printed WPC storage box

Scenario Case Total GWP Deviation

(A-B) Sensitivity

(A-B)/A Base (A) Alt. (B) Base (A) Alt. (B)

Raw material

Petrochemical PP

UCO-PP 76.5 75.2 1.3 1.7%

End-of-life Incineration Recycling PP 76.5 74.4 2.1 2.7%

5.0

5.4

7.6

4.8

16.6

10.3

7.9

5.3

9.0

10.7

7.7

10.9

5.1

3.9

7.5

3.1

59.1

50.9

96.1

90.9

68.0

71.3

84.3

88.1

88.4

89.9

26.9

33.0

19.4

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

MEC

FEC

TEC

FD

HT

EP

AD

FP

OD

GW

Pre-manufacturing Manufacturing Distribution Use End-of-life

20

The main goal of this case study is to perform a comparative LCA between two interior

parts for trucks from Scania. One is the conventional injection-moulded tunnel

storage made of mineral-filled polyurethane (PUR), and the other is the 3D-printed

alternative made of wood fibre and PUR with a small addition of a flame retardant

(see Figure 10). The objective is to determine, with a quantitative analysis, if the use

of the 3D-printed WPC product may suggest a sustainable alternative to the

conventional tunnel storage.

Figure 10 3D modeling of the compared products in the case study B

The functional unit for the tunnel storages is simply a single unit product with a

volume of 2.63 L, each having a different material composition. The difference in

mass between them was considered irrelevant because both the products achieve the

same task. Since it was intended is to compare the products based on the functional

unit, the production volume was excluded from consideration.



trees for the injection-moulded tunnel storage and the 3D-printed WPC alternative

are presented in Figure 11 and Figure 12, respectively. The system boundary and the

assumptions and limitations used in data collection are presented in Table 7.



21








Figure 11 Process tree of the injection-moulded tunnel storage

Figure 12 Process tree of the 3D-printed WPC tunnel storage

22

Table 7 System boundary and assumptions/limitations for the case study B

Life cycle stages


limitations

Pre-manufacturing










- Distribution to the individual consumers is excluded

Use - Consumer use 40,570 km per year [35]

- Consumer use for 6.2 years [36]

- Both products have the same use phase


- Recycling

- Wasted PUR during IM is recycled








All the databases used in the LCAs for the injection-moulded tunnel storage and

the 3D-printed WPC alternative are presented in Table 8 and Table 9, respectively.

Data collection and processing methods are described separately for each stage of the

LCAs.




23

Table 8 Life cycle inventory database used for the injection-moulded tunnel storage

Life cycle stages


Pre-

manufacturing

Polyurethane, SE Polyurethane, rigid foam, GLO

Barium sulfate, SE Barite, GLO

Grinding, SE Electricity, medium voltage, SE


Water, lake, SE


Manufacturing Injection moulding, SE Injection moulding, RER





Recycling of PP, SE Recycling of PP, GLO


Table 9 Life cycle inventory database used for the 3D-printed WPC tunnel storage

Life cycle stages


Pre-

manufacturing





Water, lake, SE








24








The conventional tunnel storage is made of mineral-filled PUR. Therefore, the pre-

manufacturing process begins with the extraction and acquisition of PUR and barite.

The process is followed by the grinding of barite [37]. It ends with the compounding

of PUR and barium sulfate, obtaining PUR (40% barium sulfate).

Pellets for the WPC tunnel storage are made of wood fibre, PP, and a small addition

of a flame retardant. Therefore, the pre-manufacturing process begins with the

extraction and acquisition of them. According to the material data obtained from the







The manufacturing phase normally includes assembly and inspection as well as

manufacturing process. However, since the assembly of a tunnel storage to a truck is

a relatively simple process and it is assumed that there is no failure in manufacturing,

only the manufacturing process was considered in the simulation. Energy

consumption and emissions for the manufacturing facilities were excluded.

The conventional tunnel storage is manufactured through IM at Monza, Italy. It is

assumed that there is no failure in manufacturing, so material loss only occurs during

machine start-up, cleaning, and maintenance. The production yield—the ratio of the

manufactured quantity against the amount of material used—for IM is assumed to be

25

90% [39]. It is assumed that the wasted material at this phase is recycled [40]. Energy

consumption and emissions during IM was set according to the LCI DB. The weight

of the manufactured item is 4.10 kg.

The WPC tunnel storage is manufactured through AM at Södertälje, Sweden. It is








less than half of the injection-moulded one.

Distribution to individual consumers was excluded in the simulation because it is

assumed that the consumers would come to get the vehicles themselves.

The conventional tunnel storage is transported from the manufacturing facility in

Monza, Italy to the distribution centre in Södertälje, Sweden by using roads and ocean.

The WPC tunnel storage is manufactured in the same place as the distribution centre

in Södertälje, Sweden. Therefore, the product does not need to be transported.

The use phase calculated the amount of fuel consumed by a truck due to the weight of

each tunnel storage assembled with the truck during the useful life of the vehicle. In

Sweden, average mileage of heavy trucks is 40,570 km per year [35], and medium and

heavy commercial vehicles are on average 6.2 years old [36].

All tunnel storages were considered disposed when the vehicles on which they were

assembled reach the end of their useful life. It was assumed that the discarded

products are classified as municipal solid waste and incinerated in Södertälje, Sweden.

26









The results of the cradle-to-grave comparative LCA between the injection-moulded

tunnel storage and the 3D-printed WPC alternative with 50% infill are presented in

Figure 13. The results showed that the environmental impacts caused by the

alternative are about 30% of those caused by the conventional product. This difference

is mostly contributed by the weight effect in the use phase.

Figure 13 Characterization results of the case study B (cradle-to-grave)

Since the use phase is dominant in the full LCA, it was expected to be meaningful to

observe the results of a comparative LCA without the use phase as well. Therefore, a

cradle-to-gate comparative LCA was additionally performed. The results are shown in

Figure 14. Due to PUR—a material that causes much more environmental impacts

0

10

20

30

40

50

60

70

80

90

100


IM Tunnel Storage 3D Tunnel Storage

27

compared with PP—and the long transportation between Italy and Sweden, the results

without the use phase were still favourable to the 3D-printed WPC alternative

although it showed higher impacts on ozone depletion, human toxicity and three types

of ecotoxicity because of FPF and the flame retardant.

Figure 14 Characterization results of the case study B (cradle-to-gate)

According to the experimental data provided by the manufacturer, mechanical

properties of the material for the 3D-printed WPC alternative are competitive when

compared with those of the material for the conventional product (see Table 10).

However, there is no guarantee that mechanical properties of the actual product are

suitable for the usage because those of the 3D-printed products are highly dependent

on the infill percentage. That is, there is a possibility that 50% infill will not offer

enough mechanical properties that are needed for the usage. Therefore, it was

expected to be meaningful to set up a hypothetical scenario where the manufacturer

prints the WPC product with a higher infill percentage than 50% and observe the

results. For a dramatic comparison, it was assumed that the hypothetical product is

manufactured with 100% infill. The results of the cradle-to-grave comparative LCA

between injection-moulded tunnel storage and the 3D-printed WPC alternative with

100% infill are shown in Figure 15. It must be noted that the weight of the alternative

increased to 2.70 kg.

0

10

20

30

40

50

60

70

80

90

100



28

Table 10 Mechanical properties of the materials used in the case study B


PUR (40% BaSO4) WPC (40% PP, 10% APP)




Figure 15 Characterization results of case study B (100% infill)

Due to PUR and the long transportation between Italy and Sweden, the results

were still favourable to the 3D-printed WPC alternative even with 100% infill. The

environmental impacts caused by the alternative are about 65% of those caused by

the conventional product. This shows how important it is to shorten transportation

distance between the supplier, manufacturer, and consumer.

For the 3D-printed WPC tunnel storage, process contribution—a percentage of the


the given impact categories—was investigated. The results are shown in Figure 16.

The use phase is dominant as observed in 4.2.3.1. There is no contribution made by

the impact of the distribution phase because distribution to individual consumers is

excluded.


0

10

20

30

40

50

60

70

80

90

100



29


results are presented in Table 11. The base product is the 3D-printed WPC tunnel

storage. In the first scenario, petrochemical PP—one of the raw materials—is replaced

by PP made of used cooking oil (UCO)—a renewable resource [43]. In the second

scenario, end-of-life treatment is changed: recycling plastic materials from the used

product, instead of incinerating everything. The unit for global warming potential

(GWP) is kg CO2 eq.

Figure 16 Process contribution of the 3D-printed WPC tunnel storage

Table 11 Sensitivity analysis for the 3D-printed WPC tunnel storage


(A-B) Sensitivity


Raw material

Petrochemical PP

UCO-PP 49.9 49.0 0.8 1.7%


5.0

5.4

7.5

4.8

16.5

10.2

7.9

5.3

9.0

10.6

7.7

10.8

5.1

3.9

7.5

3.1

59.2

51.0

96.1

91.0

68.1

71.3

84.4

88.1

88.4

89.9

26.9

33.0

19.4

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

MEC

FEC

TEC

FD

HT

EP

AD

FP

OD

GW


30

The main goal of this case study is to perform a comparative LCA between two ceiling

boards from Veidekke. One is the conventional gypsum plasterboard, and the other is

the 3D-printed alternative made of wood fibre and polypropylene (PP) with a small

addition of a flame retardant (see Figure 17). The objective is to determine, with a

quantitative analysis, if the use of the 3D-printed WPC product may suggest a

sustainable alternative to the conventional gypsum plasterboard.

Figure 17 3D modeling of the compared products in the case study C

The functional unit for the ceiling boards is simply a single unit product with a

volume of 13.5 L (12.5 mm × 900 mm × 1200 mm), each having a different material

composition. The difference in mass between them was considered irrelevant because

both the products achieve the same task. Since it was intended is to compare the

products based on the functional unit, the production volume was excluded from

consideration.



trees for the gypsum plasterboard and the 3D-printed WPC alternative are presented

in Figure 18 and Figure 19, respectively. The system boundary and the assumptions

and limitations used in data collection are presented in Table 12.



31








Figure 18 Process tree of the gypsum plasterboard

Figure 19 Process tree of the 3D-printed WPC ceiling board

32

Table 12 System boundary and assumptions/limitations for the case study C

Life cycle stages


limitations

Pre-manufacturing










- Consumer location is assumed to be Stockholm, Sweden









All the databases used in the LCAs for the gypsum plasterboard and the 3D-

printed WPC alternative are presented in Table 13 and Table 14, respectively. Data

collection and processing methods are described separately for each stage of the LCAs.




33

Table 13 Life cycle inventory database used for the gypsum plasterboard

Life cycle stages


Pre-

manufacturing

Gypsum plasterboard Gypsum plasterboard, GLO

Road Transport, lorry, EURO5, GLO

Manufacturing Paint, SE Alkyd paint, GLO





Table 14 Life cycle inventory database used for the 3D-printed ceiling board

Life cycle stages


Pre-

manufacturing





Water, lake, SE














34


Since gypsum plasterboard exists in the LCI DB as a complete product, pre-

manufacturing data for gypsum plasterboard were not manually entered.

Pellets for the WPC ceiling board are made of wood fibre, PP, and a small addition of

a flame retardant. Therefore, the pre-manufacturing process begins with the

extraction and acquisition of them. According to the material data obtained from the







The manufacturing phase normally includes inspection as well as manufacturing

process. However, since it is assumed that there is no failure in manufacturing, only

the manufacturing process was considered in the simulation. Energy consumption

and emissions for the manufacturing facilities were excluded.

Since gypsum plasterboard exists in the LCI DB as a complete product, manufacturing

data for gypsum plasterboard were not manually entered. The weight of the

manufactured item is 15.53 kg.

The WPC ceiling board is manufactured through AM at Södertälje, Sweden. It is








much lighter than the conventional gypsum plasterboard.

35

Distribution phase for the ceiling boards include installing, which is human labour,

and it was assumed that human labour creates no impact on the environment, thus

excluded in the simulation. Consumer location for distribution was assumed to be

Stockholm, Sweden.

The gypsum plasterboard is transported from the manufacturing facility in Södertälje,

Sweden to the construction site in Stockholm, Sweden by using roads. It is then

painted by human. Since it is also human labour, only the amount of paint was

considered in the simulation. The weight of the paint required is 0.072 kg for each

gypsum plasterboard. It was calculated considering the theoretical spreading rate of

a commercial paint and the area of surface of the gypsum plasterboard.

The WPC ceiling board is transported from the manufacturing facility in Södertälje,

Sweden to the construction site in Stockholm, Sweden by using roads. Painting is not

necessary for the 3D-printed WPC alternative.

Ceiling boards are stationary once installed and there is neither energy consumed nor

emissions released while in use, therefore there was no data input for the use phase.

It was assumed that the discarded ceiling boards are classified as municipal solid

waste and incinerated in Södertälje, Sweden.









36

The results of the cradle-to-grave comparative LCA between the gypsum plasterboard

and the 3D-printed WPC alternative with 30% infill are presented in Figure 20. The

results were mostly favourable to the alternative, but the impacts caused by the

alternative on terrestrial acidification (AD), freshwater eutrophication (EP), fossil

depletion (FD) and terrestrial ecotoxicity (TEC) were higher than those caused by the

gypsum plasterboard. AD, EP, and FD are mostly contributed by the flame retardant,

and TEC by FPF.

Figure 20 Characterization results of the case study C (cradle-to-grave)

According to the experimental data provided the manufacturer, mechanical

properties of the material for the 3D-printed WPC alternative are superior to those of

the material for the conventional product (see Table 15). However, there is no

guarantee that mechanical properties of the actual product are suitable for the usage

because those of the 3D-printed products are highly dependent on the infill

percentage. That is, there is a possibility that 30% infill will not offer enough

mechanical properties that are needed for the usage. Therefore, it was expected to be

meaningful to set up a hypothetical scenario where the manufacturer prints the WPC

product with a higher infill percentage than 30% and observe the results. It was

assumed that the hypothetical product is manufactured with 50% infill. The results of

the cradle-to-grave comparative LCA between the gypsum plasterboard and the 3D-

printed WPC alternative with 50% infill are shown in Figure 21. Except human

toxicity (HT), freshwater ecotoxicity (FEC), and marine ecotoxicity (MEC), the results

0

10

20

30

40

50

60

70

80

90

100


Gypsum Ceiling Board 3D Ceiling Board

37

were unfavourable to the alternative.

Table 15 Mechanical properties of the materials used in the case study C


Gypsum bonded particleboard

WPC (40% PP, 10% APP)




Figure 21 Characterization results of the case study C (50% infill)

For the 3D-printed WPC tunnel storage, process contribution—a percentage of the


the given impact categories—was investigated. The results are shown in Figure 22.

Each phase contributes to the impact values evenly. There is no contribution made by

the impact of the use phase because there is neither energy consumed nor emissions

released while the ceiling board is in use.



results are presented in Table 16. The base product is the 3D-printed WPC tunnel

storage. In the first scenario, petrochemical PP—one of the raw materials—is replaced

0

10

20

30

40

50

60

70

80

90

100


Gypsum Ceiling Board 3D Ceiling Board

38

by PP made of used cooking oil (UCO)—a renewable resource [42]. In the second

scenario, end-of-life treatment is changed: recycling plastic materials from the used

product, instead of incinerating everything. The unit for global warming potential

(GWP) is kg CO2 eq.

Figure 22 Process contribution of the 3D-printed WPC ceiling board

Table 16 Sensitivity analysis for 3D-printed WPC ceiling board


(A-B) Sensitivity


Raw material

Petrochemical PP

UCO-PP 15.0 12.5 2.5 16.5%


12.2

11.1

27.4

83.2

15.0

57.7

65.5

66.0

13.7

52.4

22.0

21.7

70.2

15.8

24.2

37.8

32.7

32.7

64.7

30.9

65.8

67.2

60.8

4.5

21.5

16.6

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

MEC

FEC

TEC

FD

HT

EP

AD

FP

OD

GW


39

The results of the cradle-to-grave LCAs showed that, in all case studies, the 3D-

printed WPC alternatives would have smaller environmental impacts compared with

the conventional products regarding most impact categories although the extent to

which environmental impacts can be reduced by replacing the conventional products

with the alternatives varied from case study to case study. The most significant

difference was observed in the case study A and B because of the light-weighting effect.

In terms of global warming potential (GWP), the alternative in the case study A scored

51% lower impact than the conventional storage box, the alternative in the case study

B had 68% lower impact than the conventional tunnel storage, and the 3D-printed

WPC ceiling board in the case study C had 13% lower GWP than the conventional

gypsum plasterboard. However, the results of the cradle-to-gate LCAs suggested that

the 3D-printed WPC alternative might cause greater environmental impacts than the

conventional products regarding some impact categories because where the light-

weighting effect is insignificant.

Therefore, in the LCA context, the 3D-printed WPC alternatives would be much

more beneficial to the environment compared with the conventional products, but the

environmental benefits might be insignificant from the manufacturer’s perspective.

40

Since energy consumption data for FPF were not available due to lack of research,

specific energy consumption (SEC) for FDM was used throughout the case studies

instead of that for FPF. This was considered reasonable because both manufacturing

methods are fundamentally the same. However, more accurate results could have

been obtained if energy consumption data for FPF were available. Therefore, it is

recommended to investigate SEC for FPF.

Another recommendation for future work is to investigate the proper infill

percentage for each product. The experimental data provided by the manufacturer

only showed the mechanical properties of the material—there was no test with a

complete product or prototype. It would have been possible to set more realistic infill

percentage if there were mechanical testing with the actual products.

Additionally, life cycle cost analysis (LCCA) would help making decisions. It is

true that the WPC 3D-printed products are more beneficial for the environment

compared with the conventional products. However, the case studies did not consider

the resources required to replace conventional manufacturing systems with 3D-

printing manufacturing system, which would incur a significant cost. Thus, a broad-

scale LCCA might suggest a different perspective.

41

First and foremost, I would like to express my gratitude towards my supervisor

Anna Hedlund Åström from the department of Machine Design at KTH for giving me

the opportunity to do my thesis within the project Wouldwood. I would like to thank

Anna and her colleagues—Björn Möller, Lars Hässler and Anton Boström for helping

me with both technical and non-technical issues on this project. I would also like to

thank Matthew Smyth from Stora Enso for providing crucial data, Oliver Schmidt

from Scania for providing constructive feedback, and Sushanth Kombathula and my

examiner Anders Eliasson from the department of Materials Science and Engineering

at KTH for giving me advice regarding my thesis work. Special thanks to Selena Torres

and BTS for encouraging me and keeping me motivated. Lastly, I would like to thank

my family and friends for their endless support.

42

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Recycling, vol. 157, p. 104750, Jun. 2020, doi: 10.1016/j.resconrec.2020.104750.

47

1. Conventional storage box (case study A)

a) Manual data input of [Grinding, SE]

Input Amount Unit Notes/Sources

Unprocessed mineral 1 kg Dummy data

Electricity, medium voltage, SE 0.02412 MJ [37]

Output Amount Unit Notes/Sources

Ground mineral 1 kg Dummy data

b) Production of 1 kg [Ground kaolin, GLO]


Kaolin, GLO 1 kg [32]

Grinding, SE 1 kg See section 1. a)


Ground kaolin, GLO 1 kg

c) Manual data input of [Compounding, SE]


Unprocessed material 1 kg Dummy data

Electricity, medium voltage, SE 1 MJ Data received from Stora Enso

Water, lake, SE 10 kg Data received from Stora Enso


48

Compounded material 1 kg Dummy data

d) Production of 1 kg [Polypropylene (20% kaolin), SE]


Polypropylene, granulate, GLO 0.8 kg [32]

Ground kaolin, GLO 0.2 kg See section 1. b)

Compounding, SE 1 kg See section 1. c)

Transport, lorry, EURO5, RER 0.322 tkm [32]


Polypropylene (20% kaolin), SE 1 kg

e) Production of 1 pc. [Storage box, injection-moulded]


Polypropylene (20% kaolin), SE 4.67 kg See section 1. d)

Injection moulding, RER 4.67 kg [32]



Storage box, injection-moulded 1 p 4.20 kg

f) Use of 1 pc. [Storage box, injection-moulded]

Processes Amount Unit Notes/Sources

Transport, lorry, EURO6, RER 1.06e3 tkm [32, 35, 36]

g) Disposal of 1 pc. [Storage box, injection-moulded]


Transport, lorry, EURO6, RER 0.0864 tkm [32, 35, 36]

Waste scenarios Amount Unit Notes/Sources

Recycling of PP, GLO 8 % [32]

Incineration of MSW, SE 92 % [32]

2. 3D-printed WPC storage box (case study A)

a) Transport of 1 kg [Wood wool, RER]


49

Wood wool, RER 1 kg Production data, [32]



Wood wool, RER 1 kg Market data

b) Transport of 1 kg [Polypropylene, granulate, RER]


Polypropylene, granulate, RER 1 kg Production data, [32]


Transport, sea, natural gas, GLO 0.206 tkm [32]


Polypropylene, granulate, RER 1 kg Market data

c) Production of 1 kg [Wood-plastic pellet, flame-retarded, SE]


Wood wool, RER 0.5 kg See section 2. a)

Polypropylene, granulate, RER 0.4 kg See section 2. b)

Sodium tripolyphosphate, GLO 0.1 kg [32]




Wood-plastic pellet,

flame-retarded, SE

1 kg

d) Manual data input of [Fused particle fabrication, SE]


Unprocessed material 1 kg Dummy data

Electricity, low voltage, SE 39.4 kg [41]


3D-printed product 1 p Dummy data

Carbon dioxide 0.2829 kg [42]

50

Methane 5.8502E-4 kg [42]

Dinitrogen monoxide 3.8662E-6 kg [42]

e) Production of 1 pc. [Storage box, 3D-printed]



flame-retarded, SE

2.46 kg See section 2. c)

Fused particle fabrication, SE 2.46 kg See section 2. d)


Storage box, 3D-printed 1 p 2.07 kg

f) Use of 1 pc. [Storage box, 3D-printed]


Transport, lorry, EURO6, RER 521 tkm [32, 35, 36]

g) Disposal of 1 pc. [Storage box, 3D-printed]





3. Conventional tunnel storage (case study B)

a) Production of 1 kg [Polyurethane (40% barite), SE]


Polyurethane, rigid foam, GLO 0.6 kg [32]

Barite, GLO 0.4 kg [32]




Polyurethane (40% barite), SE 1 kg

b) Production of 1 pc. [Tunnel storage, injection-moulded]


51

Polyurethane (40% barite), SE 4.55 kg See section 3. a)

Injection moulding, RER 4.55 kg [32]


Transport, sea, natural gas, GLO 0.0767 tkm [32]


Tunnel storage, injection-moulded 1 p 4.10 kg

c) Use of 1 pc. [Tunnel storage, injection-moulded]


Transport, lorry, EURO6, RER 1.03e3 tkm [32, 35, 36]

d) Disposal of 1 pc. [Tunnel storage, injection-moulded]




Recycling of PUR, GLO 6 % [32]


4. 3D-printed WPC tunnel storage (case study B)

a) Production of 1 pc. [Tunnel storage, 3D-printed]



flame-retarded, SE




Tunnel storage, 3D-printed 1 p 1.35 kg

b) Use of 1 pc. [Tunnel storage, 3D-printed]


Transport, lorry, EURO6, RER 340 tkm [32, 35, 36]

c) Disposal of 1 pc. [Tunnel storage, 3D-printed]


52




5. Conventional ceiling board (case study C)

a) Production of 1 pc. [Gypsum plasterboard, painted]


Gypsum plasterboard, GLO 17.64 kg [32]

Alkyd paint, white, GLO 0.072 kg [32]


Gypsum plasterboard, painted 1 p 15.6 kg

b) Distribution of 1 pc. [Gypsum plasterboard, painted]



c) Disposal of 1 pc. [Gypsum plasterboard, painted]





6. 3D-printed WPC ceiling board (case study C)

a) Production of 1 pc. [Ceiling board, 3D-printed]



flame-retarded, SE




Ceiling board, 3D-printed 1 p 4.17 kg

b) Distribution of 1 pc. [Ceiling board, 3D-printed]


53


c) Disposal of 1 pc. [Ceiling board, 3D-printed]





54

1. Characterization results

a) Case study A: storage box

Impact category

Unit IM

(cradle-to-grave)

3D 50% (cradle-

to-grave)

3D 100% (cradle-

to-grave)

IM (cradle-to-gate)

3D 50% (cradle-to-gate)

GW kg CO2

eq 1.55E+02 7.65E+01 1.58E+02 1.36E+01 6.46E+00

OD kg CFC11

eq 1.01E-04 5.35E-05 1.11E-04 3.12E-06 4.86E-06

FP kg

PM2.5 eq

1.33E-01 6.80E-02 1.41E-01 1.18E-02 8.03E-03

AD kg SO2

eq 3.30E-01 1.69E-01 3.55E-01 4.03E-02 2.61E-02

EP kg P eq 1.52E-02 7.87E-03 1.71E-02 3.55E-03 2.16E-03

HT kg 1,4-DCB eq

3.60E+03 2.01E+03 4.40E+03 1.37E+02 2.52E+02

FD kg oil eq 5.64E+01 2.67E+01 5.49E+01 7.66E+00 2.40E+00

TEC kg 1,4-DCB eq

5.41E-01 2.75E-01 5.58E-01 4.36E-03 1.05E-02

FEC kg 1,4-DCB eq

3.35E+00 1.98E+00 4.53E+00 1.60E-01 3.18E-01

MEC kg 1,4-DCB eq

5.49E+00 3.15E+00 7.06E+00 2.24E-01 4.41E-01

b) Case study B: tunnel storage

55

Impact category

Unit IM

(cradle-to-grave)

3D 50% (cradle-

to-grave)

3D 100% (cradle-

to-grave)

IM (cradle-to-gate)

3D 50% (cradle-to-gate)

GW kg CO2

eq 1.58E+02 4.99E+01 9.97E+01 1.98E+01 4.20E+00

OD kg CFC11

eq 1.01E-04 3.49E-05 6.97E-05 5.27E-06 3.16E-06

FP kg

PM2.5 eq

1.41E-01 4.43E-02 8.87E-02 2.25E-02 5.22E-03

AD kg SO2

eq 3.50E-01 1.10E-01 2.21E-01 6.71E-02 1.70E-02

EP kg P eq 1.63E-02 5.13E-03 1.03E-02 5.03E-03 1.41E-03

HT kg 1,4-DCB eq

3.68E+03 1.31E+03 2.62E+03 2.94E+02 1.64E+02

FD kg oil eq 5.52E+01 1.74E+01 3.48E+01 7.51E+00 1.56E+00

TEC kg 1,4-DCB eq

5.34E-01 1.79E-01 3.59E-01 9.95E-03 6.86E-03

FEC kg 1,4-DCB eq

3.43E+00 1.29E+00 2.58E+00 3.02E-01 2.07E-01

MEC kg 1,4-DCB eq

5.59E+00 2.05E+00 4.11E+00 4.30E-01 2.87E-01

c) Case study C: ceiling board

Impact category

Unit Gypsum

plasterboard

3D ceiling board 30%

infill

3D ceiling board 50%

infill

GW kg CO2

eq 1.73E+01 1.50E+01 2.49E+01

OD kg CFC11

eq 1.28E-05 1.19E-05 1.99E-05

FP kg

PM2.5 eq

1.77E-02 1.57E-02 2.61E-02

AD kg SO2

eq 4.45E-02 5.12E-02 8.52E-02

EP kg P eq 3.23E-03 4.36E-03 7.26E-03

56

HT kg 1,4-DCB eq

2.94E+03 1.24E+03 2.06E+03

FD kg oil eq 1.98E+00 4.67E+00 7.77E+00

TEC kg 1,4-DCB eq

5.66E-03 2.08E-02 3.46E-02

FEC kg 1,4-DCB eq

4.82E+00 1.87E+00 3.12E+00

MEC kg 1,4-DCB eq

6.28E+00 2.49E+00 4.14E+00

2. Process contribution

a) 3D-printed WPC storage box (case study A)

Impact category

Unit Pre-

manu-facturing

Manu-facturing

Distri-bution

Use End-of-

life

GW kg CO2

eq 4.06E+00 2.40E+00 0.00E+00 6.87E+01 1.29E+00

OD kg CFC11

eq 8.50E-07 4.01E-06 0.00E+00 4.73E-05 1.33E-06

FP kg

PM2.5 eq

5.37E-03 2.66E-03 0.00E+00 5.99E-02 9.36E-05

AD kg SO2

eq 1.74E-02 8.67E-03 0.00E+00 1.43E-01 4.66E-04

EP kg P eq 1.30E-03 8.56E-04 0.00E+00 5.61E-03 1.01E-04

HT kg 1,4-DCB eq

9.67E+01 1.55E+02 0.00E+00 1.37E+03 3.91E+02

FD kg oil eq 2.02E+00 3.83E-01 0.00E+00 2.43E+01 1.94E-02

TEC kg 1,4-DCB eq

2.96E-03 7.58E-03 0.00E+00 2.64E-01 2.06E-04

FEC kg 1,4-DCB eq

1.08E-01 2.11E-01 0.00E+00 1.01E+00 6.53E-01

MEC kg 1,4-DCB eq

1.57E-01 2.83E-01 0.00E+00 1.86E+00 8.49E-01

b) 3D-printed WPC tunnel storage (case study B)

57

Impact category

Unit Pre-

manu-facturing

Manu-facturing

Distri-bution

Use End-of-

life

GW kg CO2

eq 2.64E+00 1.56E+00 0.00E+00 4.48E+01 8.37E-01

OD kg CFC11

eq 5.53E-07 2.61E-06 0.00E+00 3.08E-05 8.66E-07

FP kg

PM2.5 eq

3.49E-03 1.73E-03 0.00E+00 3.90E-02 6.09E-05

AD kg SO2

eq 1.13E-02 5.64E-03 0.00E+00 9.31E-02 3.03E-04

EP kg P eq 8.49E-04 5.56E-04 0.00E+00 3.66E-03 6.56E-05

HT kg 1,4-DCB eq

6.29E+01 1.01E+02 0.00E+00 8.93E+02 2.54E+02

FD kg oil eq 1.31E+00 2.49E-01 0.00E+00 1.58E+01 1.26E-02

TEC kg 1,4-DCB eq

1.93E-03 4.93E-03 0.00E+00 1.72E-01 1.34E-04

FEC kg 1,4-DCB eq

6.99E-02 1.37E-01 0.00E+00 6.57E-01 4.25E-01

MEC kg 1,4-DCB eq

1.02E-01 1.84E-01 0.00E+00 1.22E+00 5.52E-01

c) 3D-printed WPC ceiling board (case study C)

Impact category

Unit Pre-

manu-facturing

Manu-facturing

Distri-bution

Use End-of-

life

GW kg CO2

eq 7.83E+00 4.62E+00 2.51E-02 0.00E+00 2.48E+00

OD kg CFC11

eq 1.64E-06 7.73E-06 1.80E-08 0.00E+00 2.56E-06

FP kg

PM2.5 eq

1.03E-02 5.13E-03 2.19E-05 0.00E+00 1.80E-04

AD kg SO2

eq 3.35E-02 1.67E-02 6.51E-05 0.00E+00 8.97E-04

EP kg P eq 2.51E-03 1.65E-03 1.97E-06 0.00E+00 1.94E-04

58

HT kg 1,4-DCB eq

1.86E+02 2.99E+02 4.76E-01 0.00E+00 7.53E+02

FD kg oil eq 3.89E+00 7.39E-01 8.72E-03 0.00E+00 3.74E-02

TEC kg 1,4-DCB eq

5.71E-03 1.46E-02 9.72E-05 0.00E+00 3.96E-04

FEC kg 1,4-DCB eq

2.07E-01 4.06E-01 3.49E-04 0.00E+00 1.26E+00

MEC kg 1,4-DCB eq

3.03E-01 5.46E-01 6.54E-04 0.00E+00 1.64E+00

TRITA ITM-EX 2020:610

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comparative life cycle assessments of conventional

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