Disruptive technology as an enabler of the circular economy:

What potential does 3D printing hold?

3D printing has been widely identified as an emerging disruptive technology. In this

study we investigate how this technology could enable the circular economy by

disrupting the existing materials value chain. Specifically we ask whether this novel

technology could be used to locally manufacture new goods from local sources of

recycled plastic waste, thereby offering benefits for the efficiency and effectiveness

of materials cycling. We use the London metropolitan area as our empirical setting

for analyzing the system conditions already present – in the form of local material

flows, technology and actors – and for assessing 3D printing's viability as an enabler

of a circular economy at local level. Subsequent analysis of stakeholder perceptions

identifies economic, technological, social, organizational and regulatory barriers to

mainstream implementation, and their likelihood to be overcome. We conclude with

implications for practice and policy.

1 3D printing as an enabler of the circular economy

The circular economy is conceptualized as an economic model for closed-loop production and

consumption systems, where waste is designated a valuable resource, and economic growth

and resource use are decoupled. The concept of a circular economy has its roots in ecological

economics and industrial ecology scholarshipi, and has been recently articulated as a set of

principles for economic development and business model design involving product

maintenance, reuse, remanufacture, and recycling and the broad cycling of material flows ii.

3D printingiii is widely believed to be one of the key disruptive technologies that is

transforming businessiv. While the scale of this transformation, as well as its speed, is subject to

a vigorous debatev, there is a growing consensus that the technology is adding new capabilities

and changing the underlying economics in many manufacturing sectorsvi. These shifts are

important to understand in order to identify new leverage points for transitioning to a circular

economy. The circular economy has been termed the ‘killer app’ for 3D printingvii, a disruptive

technology with benefits at the product level of radical material efficiency through design and

fabricationviii. At the systems level, the potential to ‘upcycle’ waste plastics into new printed

objects by integrating recycling processes has been recognized ix, as well the potential to reduce

transport emissions and packaging through effective use of local production platformsx. We

build on this notion by investigating the materials value chain for 3D printing, in order to

identify potential points of leverage for creating more efficient and effective material flows

within a circular economy.

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3

Leveraging the economics of 3D printing

When studying 3D printing as a production system, one can compare traditional economies of

scale resulting from ‘production lines carefully built for volume and speed’xi, to the economies

of scope tapped by 3D printing’s ‘software-defined supply chain’xii where a greater variety of

products can be built per unit of capitalxiii . By reducing the minimum efficient scale of

production, 3D printing effectively lowers barriers to market entry and enables the radical

localization of manufacturing to demand locationsxiv. This means 3D printing ‘allows scaling

capacity more closely to the needs of the market’xv.

The relationship between circular economy aims and the economics of 3D printing as a

system of production is only beginning to be articulated in the literature xvi. We build on the

conceptual work of Kreiger, Mulder, Glover, and Pearce who conduct a hypothetical Life Cycle

Analysis (LCA) of distributed recycling of HDPE for 3D printingxvii. They find that a distributed

model for producing 3D printing filament from waste uses less energy than conventional

methods. Savings in embodied energy and greenhouse gas emissions come largely from the

reduction of transportation costs inherent in transporting waste plastic to central recycling

facilitiesxviii. Beyond these contributions, at present there is a lack of research into the

implications of disrupting value chains from a circular economy perspective. More specifically,

there is a lack of attention paid to how the relative distribution of production and consumption

relate to the opportunity set for creating circular material flows.

As 3D printing enables the economic production of small batches, or even single

customized units, it is logically possible to restructure the manufacturing footprint into

distributed 3D printing facilities that could feed off local materials. We posit that closing the

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loop at a local level of scale by matching local waste sources with demand from 3D printing may

offer benefits in terms of the efficiency and effectiveness of materials cycling. Efficiency gains

may be made by decreasing cost and carbon emissions associated with transporting plastic

waste to centralized recycling facilities and foreign markets. Waste may also be more effectively

recycled when processed in small volumes from single sources for local markets, avoiding

information loss and mixing that can come with aggregation of highly distributed waste

sourcesxix, leading to improved material quality and cost savings related to waste sorting.

Envisioning a local material flow loop

The key aim of this paper is to identify the current opportunities and barriers of using waste

feedstock for 3D printing at a local scale. As part of this, we analyze the system conditions

already present, in the form of local material flows, technology and actors. Figure 1 illustrates

the various material flows at the national and international level in combination with our

proposed local material flow. We envision that 3D printing of products from local materials will

be combined with a digital information system which integrates available feedstock, digital

product designs and consumer demand to form an online market place. This virtual market

place links global product designers with local consumers, material suppliers and production

platforms. However, this study focuses on the actual material flows as indicated with the green

arrows in Figure 1.

*** Figure 1 about here ***

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During the review of the materials market we identified materials that presently enter

waste streams that can be feedstock for 3D printing. We examined in particular metals,

biomass and plastics. Metals were ruled out on basis of the high investment cost for existing

metal 3D printing technologies, limiting their distribution, as well as on the basis of high metal

recycling rates already in place due to the economic value of the material. Biomass offers

potential in the form of biodegradable polymers, which is already used to produce 3D printing

filament such as offered by the company Biomexx, however, the existing proprietary technology

limits the distribution of the material. Plastics have been the first materials applied in 3D

printing; recent developments have resulted in affordable 3D printers adding to the widespread

availability of this technology. Therefore, we focus on plastics as feedstock material.

From a circular economy perspective, plastics are of particular interest to be used as

locally recycled material: plastics recycling rates are still low, and the low value density of the

material causes higher transportation costs compared with other materials. Considering the

potential for distributed materials supply, plastics are highly distributed already, producing

steady waste flows, since they can be found in many fast-moving consumer goods.

Plastics as a packaging material have come under increasing scrutiny for pollution to the

land and sea, in particular, the five garbage gyres that have formed in the oceans are a major

concern. More than 40 years after the launch of the well-known recycling symbol, globally only

14% of plastic packaging is collected for recycling. When additional value losses in sorting and

reprocessing are factored in, only 5% of material value is retained for a subsequent use. Plastics

that do get recycled are mostly recycled into lower-value applications that are not again

recyclable after usexxi. The 'New Plastics Economy' report by the Ellen MacArthur found that

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32% of plastic packaging escapes collection systems, generating significant economic costs by

reducing the productivity of vital natural systems such as the ocean and clogging urban

infrastructure: ‘The cost of such after-use externalities for plastic packaging, plus the cost

associated with greenhouse gas emissions from its production, is conservatively estimated at

US$40 billion annually — exceeding the plastic packaging industry’s profit pool.’xxii Policy

initiatives to stem use of plastic bags and packaging are underway in many countries, including

laws that introduced a mandatory charge for plastic carrier bags, a mandatory return scheme of

plastic bottles, and others.

Our analysis of local capabilities for utilizing recycled plastics for 3D printing should be

framed in the context of current work on plastics in the circular economy, where opportunities

and challenges at the macro-economic level for creating closed loop flows of material value are

well known. We provide a complementary analysis of the specific opportunities and challenges

for 3D printing using circular material flows at a local level. In circular economy initiatives,

business models and technologies commonly employed for their disruptive impact are

servitization, materials tracking and tracing technologies, as well as materials sorting and

reprocessing technologyxxiii. Adding to this, we offer a way to harness 3D printing for circular

economy aims by matching production with local waste streams.

We discuss the opportunities and barriers by combining insights from three different

perspectives, namely by: reviewing existing literature on the current state of the art to turn

waste plastics into feedstock for 3D printing; an empirical case study focusing on London to

obtain an initial quantification of the potential benefits of using locally recycled plastics as 3D

print feedstock; and a stakeholder analysis to uncover barriers to mainstream implementation

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of using local waste infrastructure for 3D printing markets. These three perspectives are

discussed in the subsequent three sections which are followed by the conclusions.

2 3D printing with recycled plastics: A primer

The term ‘3D printing’ or additive manufacturing (AM) covers a wide range of technologies with

varying functionalities, applications and product qualities (the Appendix provides an overview).

We focus mainly on material extrusion processes, also known as fused deposition modelling

(FDM), which uses thermoplastic filament on a spool to produce objects, layer by layer. With

prices below US$1,000, 3D printers based on this technology are the cheapest in the broad

range of 3D printers available, contributing to the wide distribution of these printers. This

technology has been selected since it is the most distributed AM technology due to its lower

capital cost compared with other AM technologies, and thus offers opportunities to recycle

materials which are widely available on a local scale. Due to current technology limitations, the

quality of the mechanical properties of the 3D printed objects is low so these products are

mainly used for prototyping, scale modelling or decorative purposes. The final 3D products can

be post-processed in order to get a better aesthetic quality. Post printing, the ways to improve

the final product appearance are sanding, polishing and paintingxxiv. Most 3D printers use

filament with a diameter of either 1.75mm or 2.85mm. A constant density of the material is

required to support a steady extrusion rate and high quality printsxxv. The current price

difference between recycled plastic material (which ranges between US$45 to US$425 per ton,

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depending on quality and typexxvi) and 3D print filament (which is around US$45 per kg) can

make plastic recycling cost-effective.

The idea of recycling materials for 3D printing is not new. Producing feedstock from waste

plastic lowers the costs and reduces the environmental impact of rapid prototyping xxvii. Besides,

recycling waste in-house can decrease the greenhouse gas emissions associated with the

collection, transport and transfer of recyclable wastexxviii. There are several projects which

studied the use of recycled plastics for 3D printing and some waste plastic extruders are

commercially availablexxix, and several companies sell recycled filament alreadyxxx.

Recycling plastic waste for 3D printing has been applied both in the developing world and

in rural area contextsxxxi. Some organizations such as the Ethical Filament Foundation work

together with local waste pickers, industry and entrepreneurs to create more value for the local

community by producing 3D printer filament out of recycled waste.

To create filament from plastic household waste, a waste plastic item has first to be

cleaned before it is cut in smaller pieces which are further ground into small flakes.

Subsequently, the flakes are heated and a screw will move the material through a heated barrel

where it is compressed, melted, mixed and forced through a die to give the filament its shape.

We consider two prominent material options in our study, PET and HDPE, due to their

availability in the waste stream and proven printing capabilities. Both plastics are mainly used

for packagingxxxii, so we limit the scope of our study further to household plastic packaging.

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Option #1: Recycled PET as feedstock for 3D printing

PET bottles collected for recycling are sent to a PET recycling company where they are ground

into flakes. The yield of this process is in the range of 40% – 75%, depending on the amount of

contamination in the waste stream. Part of this contamination is caused by the product itself

such as glue, labels and caps of the bottles and potential residual liquid. Another part is caused

by impurities due to mixing with other waste materials like metal cans and paper.

PET can be recycled in various ways using mechanical or chemical recyclingxxxiii.

Mechanical recycling by grinding down PET bottles results in amorphous PET. Using this

amorphous PET to produce filament directly would yield a low quality feedstock which in turn

can result in the crystallization of the material in the nozzle of the 3D printer, creating

blockages during printing, and sub-optimal mechanical properties in the extruded filament.

Chemical recycling processes offer methods to produce premium PET material from PET

waste, allowing for full recycling into primary products. To achieve this, the recycled PET is

depolymerized and purified before it is reused as raw material for the production of PET

products. One such chemical process to depolymerize PET is glycolysisxxxiv.

Recycled filament can consist of up to 90% recycled material, yet delivering the same

quality and properties for the filament based on different batches of PET bottles remains the

biggest issue. Controlling the quality, contamination level and color variation of the input

material is important.

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A half-liter single-serve PET water bottle weighs about 10 g: based on a density of 1,380

kg/m3 for PET and assuming no material losses, such a bottle can be recycled into about 3.0 or

1.1 meter of filament with a diameter of 1.75 mm or 2.85 mm, respectively.

Option #2: Recycled HPDE as feedstock for 3D printing

A second plastic that is very prevalent in the household waste is high-density polyethylene, or

HDPE. It is commonly found in milk jugs and detergent bottles. Baechler et al. studied the

recycling of HDPE bottles into 3D printing filament and found that the energy required to

produce a meter of filament was roughly 60Wh, whereby heating accounted for roughly two

thirds and the motor energy use accounted for the other thirdxxxv. The energy required for the

shredding process was found to be negligible.

Three issues were found in their experiments. First, the filament production required

some physical assistance to draw the filament from the extruder. Devices to automatically draw

the filament failed, mainly due to the second issue related to an inconsistent rate of extrusion

which is related to the third limitation, namely the heterogeneous waste feedstock. So, using

homogenous waste feedstock or large batch mixing after shredding will decrease these issues.

Extrusion was also affected by the size and type of shredded plastic. For example, thin, light

pieces from milk jugs did not extrude well because there were not easily drawn into the heating

section of the extruder.

Still, some products have been successfully 3D printed from the recycled HDPE filament in

the above experiments; however the quality did not match the quality of products printed from

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commercially available virgin ABS (a standard 3D printing material) on the same machine. The

reasons for this difference can be attributed to: the thermal properties of HDPE which makes

the material harder to work with, printing settings which have been optimized for ABS, as well

as the variation in diameter of the filament which make it hard to print at a constant rate. To

date, commercially available HDPE filament from recycled materials is still hard to find.

In summary, the technologies for turning waste plastic into feedstock for 3D printing are

available today, albeit on a small and experimental scale. The case for moving these from small-

scale to mainstream applications depends on the underlying economics; we thus proceed to

assess and quantify the potential benefits of turning locally available waste plastics into new

products in a real-world context.

3 Analyzing plastic waste streams: The case of London

In our empirical study we focus on London, yet our findings will equally apply to any major

metropolitan area that is likely to yield sufficient quantities of waste streams and operates a

waste collection and recycling infrastructure. Beyond these basic features, London is interesting

from a research point of view as it is part of the Circular Cities Network xxxvi, has a road map to a

circular economy in 2036 which includes plastics as a focus areaxxxvii and is one of the top cities

based on the number of 3D printing facilities in the worldxxxviii.

We use material flow analysis (MFA), a method derived from industrial ecology, which can

be adopted to quantify stock and flow variations. It is a ‘systematic assessment of the flows and

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stocks of materials within a system defined in space and time’ xxxix. The key steps involve the

system definition, process chain analysis and evaluation. In this study, the primary objective is

to identify the throughput of plastic waste streams, within the spatial boundary of the

metropolitan area of London for waste stream generation, the UK for waste stream distribution

and processing, and the time span of one calendar year. As most of the plastic wastes are

resulting from the consumption of fast-moving consumer goods, variation in net stock within

the analyzed system is negligible. Consequently, the analysis was driven solely by the generated

waste flows.

To understand the economics of the plastic recycling value chain and 3D printing filament

production, we conducted focal case studies with several key players, including a material

recovery facility (Shanks East London), a PET bottles recycling company (EcoTech London Ltdxl),

and ObjectForm Ltdxli which recycles plastic waste materials to produce 3D printing filament.

These three cases were particularly helpful in mapping the process, charting the flows in terms

of volume and quality, and most crucially, determining the economic foundations these

businesses are based on.

Plastic waste streams: Volumes and destinations

Plastics are a common means of packaging consumer goods; Figure 2 shows the prevalence of

plastics in the waste stream. The use of PET and HDPE for bottles is particularly pronounced and

leads to the high-volume waste streams needed for these to act as 3D printing feedstock.

Plastic bottles and pots, tubs and trays (PTTs) represent 73% of the waste. PET (e.g. bottles) and

HDPE (e.g. milk jugs and shampoo flasks) are the major plastics in the household waste stream, 13

representing 49% and 19% of the total plastic packaging waste, respectively. Both materials are

also widely recycled already, although UK recycling rates are still relatively low, with 57% for

plastic bottles and 30% for PTTsxlii.

Plastics from municipal solid waste are usually collected from curbside recycling bins or

drop-off sites. The collected waste is sent to a material recovery facility, where the materials

are sorted by plastic type, baled, and sent to a reclaiming facility. At the facility, any trash or

dirt is sorted out, plastics are then further sorted based on color and plastic type, and often,

near infrared light is used to sort plastics. Next, the sorted plastics are cleaned and turned into

flakes. The flakes could be sold directly or turned into pellets before being sold to a plastic

product manufacturer. The recycled plastics could be used in a wide variety of products, from

clothing to packaging materials. In the case of packaging materials, the plastic is used in a final

product (e.g. food packaging), before it is being sold to the end-user/customer. After using the

product, the plastic waste will be collected again.

*** Figure 2 about here ***

In our analysis we turn our attention to two immediate and measurable benefits of using

waste plastic for local distributed manufacture using 3D printing: the reduction in landfill, and

the reduction in road transportation.

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The potential for reducing landfill and road transportation

To analyze the potential for reductions in landfill and road transportation we focus on PET

because of its proven printing capabilities of the material. Since PET is mainly found in

household packaging, only the Local Authority Collected Waste (LACW) has been analyzed. Of

the total of roughly 4 million metric tons of London’s LACW, about 10% is plasticsxliii. Data on the

composition of London’s plastic waste are lacking, therefore overall data from the UK are used,

as reported by RECycling Of Used Plastics Limited (RECOUP), a registered charity and not-for-

profit member based organizationxliv.

Based on 55% of PET currently landfilled and assuming a maximum yield of 75% in turning

PET waste into PET flakesxlv, 80,000 tons of PET could potentially be recovered for 3D printing.

Relative to the 889,000 tons of London’s annual landfill in the year 2013/2014 xlvi, the potential

landfill reduction is 9% by diverting PET to 3D printing alone. With a landfill cost of US$152 per

ton (including tax), the total cost savings could amount to US$12.2m. This value is expected to

increase due to tax raises in the coming years in the UK.

To calculate the potential reduction in road haulage, we use the waste data collected by

the Local Authorities in London. The database WasteDataFlowxlvii contains information about

the amount and types of waste, locations of material recovery facilities (MRFs) and recycling

plants, and the amount of waste sent to the recycling plants. For detailed assumptions and

calculations we refer to our technical studyxlviii. Due to data limitations on plastic type, the total

plastic waste sent for recycling has been analyzed, which has been found to be 60,854 tons over

2014. Of this amount, 87% is sent to known locations, which are all within the UK, see Figure 3.

Part of the plastic waste is sent to transfer stations or multiple MRFs, before the recyclable

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material is sent to the recycling plants. Each MRF has a number of recycling plants to which the

waste is sent; however, the exact flows to these locations related to these multistage waste

streams are unknown. Therefore we analyzed the minimum, average and maximum road

distances involved. Based on data from 2014, on average 24% of the total plastic waste is sent

to locations within London, assuming a distance of 70 km within (Greater) London itself. This

suggests a potential to recycle the plastic waste more locally, provided that the local demand

for recycled plastics increases.

*** Figure 3 about here ***

To determine the CO2 emissions caused by the plastic waste transportation, data from a

study by WRAP are usedxlix. Based on the estimated average transportation distances for the

plastic waste arising in London’s LACW, the CO2 emissions have been estimated to be 1,100

tons on an annual basis, which is equivalent to the annual CO2 emissions of roughly 120

households in Londonl. Based on average distances, the CO2 emissions can be reduced by 66%,

if recycling occurs within London only. This reduction potential is a conservative estimate as it is

based on mileage only; the overall CO2 reduction will be larger due to the avoided emissions

embedded in the supply chain of virgin materials and the potential reduction in the amount of

trucks required.

The reduced mileage will also lead to cost reductions due to avoided fuel costs and driver

salaries and due to other factors which are harder to quantify, such as increased flexibility in

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the use of the assets (e.g. trucks and waste recycling plants) and potential reduction in

maintenance. If recycling occurs in London only, fuel savings would amount to 255 kl

corresponding to cost savings of US$404k, based on average distances, a fuel economy of 35

liters per 100 kmli and US$1.63 for a liter diesellii.

While the potential benefits are clear, the barriers to implementation are not. In the third

stage of our research we therefore confronted the economic, technological, regulatory, social,

and organizational barriers to implementation.

4 Potential barriers to implementation

The technology for distributed 3D printing from recycled plastics has been developed and

demonstrated at small scale. The material flow analysis of London has demonstrated that the

quantity and quality of waste plastic streams is sufficient to sustain the local manufacture of 3D

printed goods from recycled plastic. The resulting question therefore is: what are the barriers to

mainstream implementation? In the third phase of our research we hence broadened the pool

of stakeholders that we worked with: in addition to firms currently active in the plastics waste

value chain (waste collectors, plastic recyclers, filament producers, and local 3D printing

operators), we also included researchers from engineering engaged in 3D printing research (to

cover the technology side of 3D printing), from design (to cover the product development

aspects), and from business schools (to cover the business model/economic aspects of 3D

printing). In total 24 stakeholders were included in this part of the analysis. The aim of bringing

these firms and scholars together was to provide a comprehensive representation of all actors

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within, and interacting with, the materials value chain. While we were able to provide a

comprehensive coverage of the entire value chain, our findings of course are limited by the

selection of stakeholders. As the pool of firms working 3D printing, and recycled materials as

feedstock for 3D printing grows, a comprehensive survey of these firms would greatly

complement our initial study.

We convened a meeting of all stakeholders where participants were first asked to fill in a

structured survey on the barriers to using local materials for 3D printing. The barriers could be

related to five predefined categories: (1) technological, (2) economic, (3)

social/cultural/behavioral, (4) organizational and (5) regulatory. For each identified barrier the

stakeholders were asked to rate the severity of the barrier and the likelihood to overcome

them within predefined time periods. At the end, the participants were asked to indicate which

three barriers they considered to be the most important ones. In a second step, stakeholders

were grouped into three subgroups and asked to focus on the perceived most important

barriers and devise potential solutions to these. Finally, the findings of the workshop were

recorded, transcribed and circulated to all stakeholders for comments, to ensure their views

have been accurately reflected.

As shown in Figure 4, the majority of the barriers spanning across all the dimensions,

which are perceived as of medium to high severity, but likely to overcome within the short- or

medium-term. Equally, several severe barriers are believed to remain in the foreseeable future.

While only few barriers exist in this category, these are of particular interest since they might

prevent the whole concept of locally recycling of plastics for 3DP from becoming reality. The

barriers mentioned in this context include important economic barriers that relate to the

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current economic and power structure within the plastics value chain. Specifically, the price of

virgin vs. recycled materials/production was mentioned, as well as the market power of existing

players. Furthermore, the contamination and safety issues in terms of regulation, as well as the

poor recycling rates amongst consumers were seen as inhibitors. Lastly, an open question was

raised whether 3D printing will ever become competitive enough to compete against the

established plastic value chains, unless customization or improved functionality would raise

profit margins.

*** Figure 4 about here ***

Regarding the technological barriers, first and foremost the functional quality of 3D-

printed products, their high cost, and in turn, limited consumer demand for such recycled

products were mentioned. The group reached consensus that this represented the greatest

barrier of all, yet also acknowledged the fast pace of innovation in printing technology. Further,

the general lack of materials which are suitable to be recycled in order to be used in 3D printing

and the availability of local materials were seen as a major barrier. A number of respondents

identified top barriers to be the cost of small-scale sorting/recycling equipment and the

inherent lower efficiency of these processes at this scale. Besides, the availability or absence of

machines suitable for small-scale recycling is regarded as an important barrier. Also the lack of

a quality-assured material supply was mentioned. Lastly, local skills and the awareness about

3D printing capabilities and limitations were seen as main barriers for more distributed 3D

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printer assisted manufacturing. Although the latter could be perceived as a social/educational

barrier, it is also related to the current state of the technology which requires a high level of

skills.

The top economic barriers are related to the current consumer demand for 3D printed

products and the cost of 3D printed vs. traditional manufactured products. Besides, the price

difference of virgin and recycled materials, especially related to plastics with current low oil

prices, is considered to be a high barrier. The cost of recycled material is also related to the

economy of scale required to recycle materials. Recycling processes become more efficient at a

larger scale, which favors centralized recycling facilities. Moreover, the current market

demands a certain volume of recycled materials, which is another driver for large-scale

recycling processes. Since a recycled plastic is a commodity, it competes with international

prices and, in the case of the UK, a strong pound favors imports of recycled material. Another

barrier is related to the PRN/PERN (Packaging Recovery Notes/Packaging Export Recovery

Notes) regulations, which stimulates exports of recycled material. Finally, the start-up cost for

equipment is regarded as a top economic barrier; especially as the 3D printing industry is in its

early stages and is constantly being improved (i.e. investment in today's technology could be

rendered obsolete, fairly quickly).

The most important social barriers are associated with the lack of the acceptance/need to

use recycled over virgin materials. This links to the poor recycling rates amongst consumers,

who should become more aware of the value of the materials inside their waste. Lack of

education about this topic is seen as a main barrier. As with most behavior related issues, it is

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hard to say when this will change, which is also reflected by the stakeholders, indicating the

time period to overcome these barriers mostly as unknown or never.

Organizational barriers which are classified as important are related to the lack of open

data and hardware for knowledge and skill sharing in- and outside companies. However,

existing 3D printing firms have the desire to have proprietary materials on which they can make

revenues, so for some materials this open data sharing might not be a viable option. The lack of

specific information about local materials is mentioned as another main barrier, which adds to

the difficulty to coordinate the proper use of small-scale sources of waste. The lack of

distributed, circular business models and players in the value chain to organize local materials

recycling is regarded as another important obstacle. This relates to the absence of coordination

across the business value chain to reduce risk and increase stability in supply and quality of

materials.

Legislation and regulations regarding the use of materials (e.g. REACH) are considered

important barriers to use locally sourced materials. As an example, small companies need to

invest a larger share of their available resources to comply to (inter)national regulations

compared to large companies, which could pose a hurdle for local market entry. Besides, health

and safety regulations and thorough tests of materials and 3D printed products and processes

are needed. Furthermore, the government could develop regulations to further incentivize the

use of recycled materials.

In summary, Figure 5 groups all barriers by common theme, showing both how often they

were mentioned as well as how often they were rated as the top barrier. Since some barriers

could be associated with more themes, some are counted multiple times. From the figure it can 21

be observed that current technology limitations and the lack of standardization are mentioned

most often as a barrier to using more locally sourced materials for 3D printing. Besides, the

limited availability and efficiency of small-scale recycling technologies is another often stated

barrier. Furthermore, the category ‘other’ comprises other perceived obstacles stemming from

Intellectual Property regulations on proprietary materials which limit knowledge sharing, the

need for innovative materials, and the lack of monitoring data and collaboration in the material

recycling supply chain.

*** Figure 5 about here ***

5 Conclusions and implications for policy and practice

We have posed the question whether 3D printing could act as an enabler of the circular

economy; more specifically we have asked how this novel technology could disrupt existing

material value chains, and enable a cost-efficient distributed production of new goods from

recycled materials. In doing so, we contribute a further aspect to the debate on the circular

economy by highlighting the link between circular economy aims, and redistributive production

and consumption models enabled by 3D printing.

Our findings confirm that 3D printing indeed has strong potential to act as an enabler of

the circular economy, for three reasons: firstly, 3D printing has the intrinsic potential to alter

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the economics of the existing manufacturing value chain, thus at least in principle can enable

local small-scale production that is economically viable. Secondly, all technologies needed to

collect and process waste plastics to turn them into 3D printing feedstock are already available.

Thirdly, we have also shown that the waste streams could provide plastic feedstock in sufficient

quality and quantity.

Despite the obvious potential, however, we have also uncovered significant barriers to

turning this vision into reality: first and foremost, it is the present quality of the 3D printed

product (whether made from virgin or waste material) that is the greatest hindrance. The value

proposition – so far – is still too unfavorable to make 3D printed products from waste plastic

economically viable. Thus, the most important driver for turning the vision into reality will be

further technological innovation that improves the speed, cost and quality of the 3D printed

product. As key patents related to 3D printing have recently expired, it is reasonable to assume

that printing technologies will keep innovating at a fast pace.

Another perennial barrier is the low economic appeal of keeping plastics in the system, as

has also been identified by other studiesliii. The regulator has a responsibility here, although it is

clearly an economic question. Increasing the value generated by the newly made product from

recycled plastics is the key driver that will foster the adoption of 3D printing in the context of

the circular economy. A further barrier is the dependence on the oil price, as determinant for

the price of both virgin and waste plastic. The recycling and processing of waste plastic is only

viable beyond certain oil price levels as it consistently commands prices below virgin plastic.

Again, the regulator can intervene by supporting circular economy ventures through incentives,

possibly linked to demonstrated reductions in landfill and CO2 emissions. Also, improved

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regulation related to the collection and mandated reuse of resources, like plastics, will help

both create even more accessible material streams and educate the public so that these

products become accepted merchandise of equal value to new products.

More generally, this study contributes an empirical perspective on how a disruptive

technology, in this case 3D printing, could alter the economies of established markets and value

chains that traditionally have not been conducive to supporting a circular economy liv. We

empirically verify the link between circular economy aims and redistributive production and

consumption models enabled by 3D printing. This provides novel and complementary insights

to the recent macro-economic studies of a new plastics economy that would enable the

transition to a circular economylv. In analyzing the viability of distributed materials supply for

local 3D printing markets, we offer a critical first step in considering local material and

economic system conditions, and the emergent potential they may have in enabling the circular

economy.

For companies in both the developed and developing world, 3D printing from local waste

will increasingly represent a feasible business opportunity. To support business and policy

initiatives in this area, there is a need to critically assess the presence of appropriate material,

technological, and economic conditions. Our framework for systemic enquiry is designed to be

used as a starting point for both business and policy leaders interested in assessing the viability

of local waste infrastructure for 3D printing in their own market context. Such concrete

assessments are necessary to provide empirical foundation for businesses and policymakers

leading the transition to a circular economy. For policymakers, developing local material re-use

24

and remanufacture offers the potential to redistribute, and reshore, manufacturing activity,

enhancing both employment and economic value creation at local level.

*********

In summary, 3D printing offers the clear potential to develop a local material recycling

and manufacturing loop that offers benefits in terms of reductions in landfill and emissions, as

well local employment and value creation. Continued innovation in 3D printing technology will

help improve the business case. Regulators can further the cause by enforcing recycling and

reuse rates, and by developing recycling capabilities at local scale. How quickly such a vision

could become reality, however, will ultimately be determined by society's tolerance for a

system that currently sees 86% of plastics waste flow turn into landfill, waste-based energy and

pollution.

25

Appendix – Process & material matrix of 3D printing technologieslvi

*** Table 1 here ***

26

Notes

27

i Ghisellini, P., et al. 2016. A review on circular economy: the expected transition to a balanced interplay of environmental and economic systems, Journal of Cleaner Production, Vol. 114, pp. 11–32

ii Ellen MacArthur Foundation, 2012. Towards the Circular Economy Vol. 1: an economic and business rationale for an accelerated transition. Available: http://www.ellenmacarthurfoundation.org/business/reports (accessed May 27 2017).

iii 3D printing is part of a family of additive manufacturing technologies, defined by the process of building up an object layer upon layer, directed by a computerized model (see ASTM standard F2792−12a). We use the term ‘3D printing’ to refer to a class of additive manufacturing techniques; the appendix gives an overview of common technologies and materials.

iv McKinsey Global Institute, 2013. Disruptive technologies: Advances that will transform life, business and the global economy. http://www.mckinsey.com/business-functions/digital-mckinsey/our-insights/disruptive-technologies

v See Richard D'Aveni, 2015. ‘The 3-D revolution.’ Harvard business review 93(5): 40-48 and Richard D’Aveni, 2013. ‘3-D printing will change the world.’ Harvard Business Review, 91(3): 34-35, Matthias Holweg , 2015. ‘The limits of 3-D printing’, Harvard Business Review, June 23, https://hbr.org/2015/06/the-limits-of-3d-printing and Jan Holmström, Matthias Holweg, Siavash H. Khajavi, and Jouni Partanen. 2016. ‘The direct digital manufacturing (r) evolution: definition of a research agenda.’ Operations Management Research, 1-10.

vi Ben-Ner, A., and Siemsen, E. 2017. ‘Decentralization and Localizationof Production: The Organizational and economic consequences of Additive manufacturing (3D Printing), California Management Review, pp. 1-19.

vii Gregory Unruh, 2015. ‘The Killer App for 3D Printing? The Circular Economy’, MIT Sloan Management Review, Big Idea: Sustainability Blog, December 08, http://sloanreview.mit.edu/article/the-killer-app-for-3d-printing-the-circular-economy/

viii Susan Gladwin and Michael Floyd. 2015. ‘Towards Sustainable ‘Biofriendly’ Materials for Additive Manufacturing (Part 2 of 3)’, Autodesk Inc., November 18, https://spark.autodesk.com/blog/towards-sustainable-%E2%80%9Cbiofriendly%E2%80%9D-materials-additive-manufacturing-part-2-3

ix Unruh 2015. op. cit. and Gregory Unruh, 2016. ‘The Revolution Will Be Customized (and Recycled and Solar-Powered)’ MIT Sloan Management Review, Big Idea: Sustainability Blog, February 12: http://sloanreview.mit.edu/article/the-revolution-will-be-customized-and-recycled-and-solar-powered/?utm_source=twitter&utm_medium=social&utm_campaign=sm-direct

x Ellen MacArthur Foundation, 2016. The New Plastics Economy: Rethinking the Future of Plastics. www.ellenmacarthurfoundation.org

xi Brody and Pureswaran, V. 2013. The new software-defined supply chain. IBM Report. p. 7-8.xii Brody and Pureswaran, 2013, op cit.xiii See Mellor, S., Hao, L., & Zhang, D. 2014. ‘Additive manufacturing: A framework for implementation’. International

Journal of Production Economics, 149, p. 197, and Garrett, B. 2014. ‘3D Printing: New Economic Paradigms and Strategic Shifts’. Global Policy, 5(1), 70–75.

xiv See Cotteleer, M. J. 2014. ‘3D Opportunity for Production’. Deloitte Review (pp. 1–17), and Mellor et al. 2014. op.cit., p. 150.

xv Ben-Ner, A., and Siemsen, E, 2017. op cit.xvi See Loy, J., and Tatham, P. 2016. ‘Redesigning Production Systems’, in Subramanian, M. and M. Savalani (Eds).

Handbook of Sustainability in Additive Manufacturing, pp. 145-168, Springer, and Despeisse, M., Baumers, M., Brown, P., Charnley, F., Ford, S.J., Garmulewicz, A., Knowles, S., Minshall, T.H.W., Mortara, L., Reed-Tsochas, F.P., J. Rowley, 2016. ‘Unlocking value for a circular economy through 3D printing: a research agenda’, Technological Forecasting and Social Change., 115, pp. 75-84.

xvii Kreiger, M.A., M.L. Mulder, A.G. Glover, and J.M. Pearce. 2014. ‘Life cycle analysis of distributed recycling of post-consumer high density polyethylene for 3-D printing filament.’ Journal of Cleaner Production: 90-96.

xviii Kreiger et al. 2014, op.cit., p. 93

xix Hopewell, J., Dvorak, R., and Kosior, E., 2009. ‘Plastics recycling: challenges and opportunities’. Philosophical Transactions of the Royal Society of London, Part B: Biological Science: 364(1526), 2115–2126. doi: 10.1098/rstb.2008.0311

xx Biome Bioplastics Limited, http://biomebioplastics.com/biome3d-ready-for-us-3d-printing-market/xxi Ellen MacArthur Foundation, 2016. op.cit., p. 26xxii Ellen MacArthur Foundation, 2016. op.cit., p. 15xxiii See Terence Tse, Mark Esposito, and Khaled Soufani. 2015. ‘Why the circular economy matters’, The European Business

Review, 11 : 59-63, and Ellen MacArthur Foundation, 2016. op.cit.xxiv Wittbrodt, B., et al., 2013. ‘Life-cycle economic analysis of distributed manufacturing with open-source 3-D printers’.

Mechatronics, 23(6): p. 713-726.xxv Baechler, C., M. DeVuono, and J.M. Pearce. 2013.‘Distributed recycling of waste polymer into RepRap feedstock’. Rapid

Prototyping Journal, 19(2): p. 118-125.xxvi Environment Media Group Ltd, 2017. ‘Plastics - letsrecycle.com’, http://www.letsrecycle.com/prices/plastics/xxvii Pearce, J.M., et al. 2010. ‘3-D printing of open source appropriate technologies for self-directed sustainable

development’. Journal of Sustainable Development, 3(4): p. 17xxviii Baechler et al. (2013), op.cit.xxix Examples include the Filament Maker - Filabot (www.filabot.com), Filastruder (www.filastruder.com), Filafab

(http://d3dinnovations.com/filafab), or the open-source alternatives like the RecycleBots (http://www.appropedia.org/Recyclebot) , the MiniRecycleBot (http://reprap.org/wiki/MiniRecyclebot) and the Lyman filament extruder (https://www.thingiverse.com/thing:380987).

xxx Dutch company Refil (www.re-filament.com) is selling recycled ABS and PET filament and 3D printed products based on recycled material. They make use of an existing plastic recycling system for their materials. For the PET filament, they make use of recycled PET bottles. Another company, Fila-cycle (www.fila-cycle.co.uk), applies – among others – ABS and HIPS waste from the automotive industry to produce filament. Drinks brand Coca-Cola and musician Will.i.am collaborated to produce objects using filament made from recycled plastic bottles, using the Ekocycle 3D printer from 3D Systems Inc. (www.ekocycle.com).

xxxi Kreiger, M., et al. 2013. Distributed recycling of post-consumer plastic waste in rural areas. in MRS Proceedings. Cambridge University Press.

xxxii PlasticsEurope, 2015. 'Plastics - the facts 2014/2015. An analysis of European plastics production, demand and waste data', http://www.plasticseurope.org/documents/document/20150227150049-final_plastics_the_facts_2014_2015_260215.pdf

xxxiii Awaja, F. and D. Pavel, 2003. ‘Recycling of PET. European Polymer Journal, 2005. 41(7): p. 1453-1477, and Carta, D., G. Cao, and C. D’Angeli, Chemical recycling of poly (ethylene terephthalate)(PET) by hydrolysis and glycolysis’. Environmental Science and Pollution Research, 10(6): p. 390-394.

xxxiv During this process the PET scrap is contacted with ethylene glycol in a wide range of temperatures (453-523 K) during a time period of 0.5-8 hours, using zinc acetate as a catalyst. The main product of glycolysis is the monomer of PET, bis(hydroxyethyl)terephthalate (BHET), which can be polymerized after purification to produce PET again. For more detilal see: Carta, D., G. Cao, and C. D’Angeli, 2003. ‘Chemical recycling of poly (ethylene terephthalate)(PET) by hydrolysis and glycolysis’. Environmental Science and Pollution Research, 10(6): p. 390-394.

xxxv Baechler, C., M. DeVuono, and J.M. Pearce, 2013. Distributed recycling of waste polymer into RepRap feedstock. Rapid Prototyping Journal. 19(2): p. 118-125.

xxxvi Circular Cities Network, Ellen MacArthur Foundation, see: https://www.ellenmacarthurfoundation.org/programmes/government/circular-cities-network

xxxvii London Waste and Recycling Board, Circular Economy Report, 2015. Available from:

http://www.lwarb.gov.uk/wp-content/uploads/2016/09/LWARB-circular-economy-report_web_09.12.15.pdf

xxxviii 3D Hubs, https://www.3dhubs.com/xxxix Brunner, P. H., & Rechberger, H. 2004. Practical handbook of material flow analysis. The International Journal of Life

Cycle Assessment, 9(5), 337-338.xl Ecotech London Ltd, Ecotech London Ltd - Advanced Plastic Recycling, (http://www.ecotechcorp.co.uk/)xli ObjectForm Ltd, http://objectform.co.ukxlii Morgan, S. and K. Campbell, 2015. UK Household Plastics Collection Survey 2015. RECOUP.xliii Greater London Authority, 2011. London's Wasted Resource - The mayor's municipal waste management strategy.

Available at: https://www.london.gov.uk/sites/default/files/gla_migrate_files_destination/draft-mun-waste-strategy-jan2010.pdf.

xliv Morgan, S. and K. Campbell, 2015. op. cit. For a detailed calculation see: Garmulewicz et al., Redistributing material supply chains for 3D printing. Project report, 2016. Available from: http://www.ifm.eng.cam.ac.uk/uploads/Research/TEG/Redistributing_material_supply_chains_for_3D_printing.pdf

xlv Shen, L., E. Worrell, and M.K. Patel, 2010. Open-loop recycling: a LCA case study of PET bottle-to-fibre recycling. Resources, conservation and recycling, 55(1): p. 34-52.

xlvi Environment Statistics Service (DEFRA), 2014. Local Authority Collected Waste Management, London https://www.gov.uk/government/statistics/local-authority-collected-waste-for-england-quarterly-estimates

xlvii WasteDataFlow, WasteDataFlow Waste Management. 2015. Available from: http://www.wastedataflow.org/xlviii Garmulewicz et al., 2016, op.cit.xlix WRAP, CO2 impacts of transporting the UK’s recovered paper and plastic bottles to China 2008. Available from:

http://www.envirocentre.ie/includes/documents/CO2_Impact_of_Export_Report_v8_1Aug08.1bd19928.pdfl Centre for Sustainable Energy, The distribution of UK household CO2 emissions, 2013. Available from:

https://www.cse.org.uk/projects/view/1206li Transport and Environment, Europe’s lost decade of truck fuel economy, 2015. Available from:

https://www.transportenvironment.org/sites/te/files/publications/2015_12_trucks_lost_decade_briefing_FINAL_0.pdflii BBC, 2017. Fuel price calculator: How much do you pay?. From: http://www.bbc.co.uk/news/business-21238363liii Ellen MacArthur Foundation, 2016. op. cit.liv Tse T., Esposito M., Soufani K., 2015. op.cit.lv Ellen MacArthur Foundation, 2016. op. cit.lvi The table is based on DNV GL, 2014. Additive Manufacturing - A materials perspective, in DNV GL strategic research &

innovation position paper, and combined with data from: Wohlers Associates, 2016. Wohlers Report 2013 - Additive Manufacturing and 3D Printing State of the Industry Annual Worldwide Progress Report.