A review of Industry 4.0 potential to accelerate the transition to a Circular Economy

MÁSTER UNIVERSITARIO EN INGENIERÍA INDUSTRIAL TRABAJO FIN DE MÁSTER A REVIEW OF INDUSTRY 4.0 POTENTIAL TO ACCELERATE THE TRANSITION TO A CIRCULAR ECONOMY Estudiante Irache Cabello Iñigo Director/Directora Minguez Gabiña Rikardo Departamento Expresión Gráfica y Proyectos de Ingeniería Curso académico 2019/2020 Bilbao, 31, Agosto, 2020 A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 2 ABSTRACT The actual model of consumption is challenging the planet capabilities to withstand the pressure generated from excess resource consumption. The continuous growth of population and the increment of the middle class threats planet’s sustainability. The model of Circular Economy based on the optimization of resources trough the maximization of use and the reduction of waste, appears as the new key to solve the problem. However, the transition to this new system comprises a certain degree of complexity. At same time, industry is confronting its fourth revolution also known as Industry 4.0, which intends to digitalize the whole industry through the use of technologies like the Internet of Things or Additive Manufacturing with the aim of optimizing the industrial systems. Along this work both terms of Circular Economy and Industry 4.0 are presented and analyzed in order to generate an adequate context for providing an insight of how these emergent industrial technologies can accelerate the transition to this new model of economy. This work has the intention of serving as foundation for future research around a topic that offers a great potential and still remains underdeveloped. Key words: Sustainability, Circular Economy, Industry 4.0, Internet of Things, Additive Manufacturing, Transition. RESUMEN El modelo actual de consumo desafía las capacidades del planeta para soportar la presión generada por el excesivo consumo de recursos. El crecimiento continuo de la población y el incremento de la clase media en el mundo amenaza la sostenibilidad. El modelo de Economía Circular basado en la optimización de los recursos a través de la maximización de su uso y la reducción de residuos, aparece como la clave para solventar el problema. Sin embargo la transición hacia este nuevo sistema comprende cierto grado de complejidad. Al mismo tiempo la industria enfronta su cuarta revolución, también conocida como Industria 4.0, que propone digitalizar el total de la industria a través de tecnologías como el Internet de las cosas o la impresión 3D con el objeto de optimizar los sistemas industriales. En este trabajo se presentan ambos conceptos de Economía Circular e Industria 4.0 con el objeto de generar un contexto adecuado sobre el cual analizar cómo estas emergentes tecnologías industriales pueden ayudar a acelerar la transición hacia el nuevo modelo de economía. Con la intención de que este A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 3 trabajo sirva como una buena base sobre la cual desarrollar futuras investigaciones alrededor de un tema que posee gran potencial y aun no se encuentra suficientemente desarrollado. Palabras clave: Sostenibilidad, Economía Circular, Industria 4.0, Internet de las cosas, Impresión 3D, Transición. LABURPENA Egungo kontsumo-ereduak erronka egiten die planetak baliabideen gehiegizko kontsumoak eragindako presioa jasateko dituen gaitasunei. Biztanleriaren etengabeko hazkundeak eta munduko klase ertainaren hazkundeak jasangarritasuna mehatxatzen du. Ekonomia zirkularraren eredua baliabideen optimizazioan oinarritzen da, erabilera maximizatuz eta hondakinak murriztuz, eta arazoa konpontzeko gakoa da. Hala ere, sistema berri horretaranzko trantsizioak konplexutasun maila bat hartzen du. Aldi berean, industriak aurre egiten dio bere laugarren iraultzari, Industria 4.0 izenaz ere ezagutzen dena, industriaren guztizkoa digitalizatzea proposatzen duena, Gauzen Internet edo 3D inprimaketa bezalako teknologien bidez, industria-sistemak optimizatzeko asmoz. Lan honetan, Ekonomia Zirkularra eta Industria 4.0 kontzeptuak aurkezten dira, testuinguru egoki bat sortzeko helburuarekin. Testuinguru horretan, industria-teknologia berri horiek ekonomia-eredu berrirako trantsizioa bizkortzen nola lagun dezaketen aztertzen da. Lan hau potentzial handia duen eta oraindik behar bezala garatuta ez dagoen gai baten inguruko etorkizuneko ikerketak garatzeko oinarri ona izan dadin. Hitz-gakoak: Iraunkortasun, Economia Zircular, Industria 4.0, Interneten gauzak, 3D inprimatzaile, trantsizio A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 4 Table of Contents ABSTRACT ............................................................................................................................... 2 RESUMEN ................................................................................................................................. 2 LABURPENA ............................................................................................................................ 3 List of figures ............................................................................................................................. 7 List of tables ............................................................................................................................... 7 Abbreviations ............................................................................................................................. 8 Introduction ................................................................................................................................ 9 Context ..................................................................................................................................... 11 Natural resource consumption .............................................................................................. 11 Sustainability and Circular Economy ................................................................................... 12 Industry 4.0 as a sustainable tool ......................................................................................... 14 Goals and scope ........................................................................................................................ 15 Benefits of the project .............................................................................................................. 17 Circular economy ..................................................................................................................... 19 Definition and working principles ........................................................................................ 19 Environmental, social and economic impacts ...................................................................... 22 Circular Economy enabling factors ...................................................................................... 25 Innovative business models .............................................................................................. 25 Eco-design ........................................................................................................................ 27 Extending the lifetime of products through reuse and repair ........................................... 29 Waste prevention programs .............................................................................................. 30 Products in the Circular Economy ....................................................................................... 31 Policies and barriers ............................................................................................................. 34 European policies for Circular Economy ......................................................................... 34 Perceived barriers and current performance of Circular Economy .................................. 36 A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 5 Measuring circularity ........................................................................................................... 38 Micro-level circularity evaluation .................................................................................... 38 Macro-level circularity evaluation ................................................................................... 39 Industry 4.0 ............................................................................................................................... 42 Introduction .......................................................................................................................... 42 Vision and features of Industry 4.0 ...................................................................................... 44 Key Industry 4.0 technologies .............................................................................................. 46 Industrial Internet of Things and Cyber-Physical Systems .................................................. 47 Internet of Things ............................................................................................................. 47 Cyber-Physical Systems ................................................................................................... 49 Cloud computing .................................................................................................................. 52 Cloud manufacturing ........................................................................................................ 54 Fog and Edge computing .................................................................................................. 54 Big Data analytics ................................................................................................................ 55 Simulation ............................................................................................................................ 58 Digital Twin ..................................................................................................................... 58 Augmented Reality ........................................................................................................... 60 Additive Manufacturing ....................................................................................................... 63 Perceived challenges for Industry 4.0 implementation ........................................................ 67 The challenges for SMEs ................................................................................................. 68 Cybersecurity ................................................................................................................... 68 Energy efficiency ............................................................................................................. 69 Connecting Circular Economy and Industry 4.0 ...................................................................... 72 Conceptual framework of the Digital Circular Economy .................................................... 73 Opportunities of 4IR technologies to promote Circular Economy .................................. 73 Circular Economy and Intelligent assets interaction as opportunity creators .................. 75 Impact of Industry 4.0 value drivers for sustainable and circular manufacturing ............ 77 A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 6 In which CE area has Industry 4.0 technologies more potential? .................................... 79 Case studies .......................................................................................................................... 82 Resource efficiency in the textile industry ........................................................................... 83 CircularID initiative ......................................................................................................... 84 How does CircularID works? .......................................................................................... 84 Modeclix ........................................................................................................................... 88 Sustainable manufacturing ............................................................................................... 89 Waste generation in construction and buildings .................................................................. 91 Concrete 3D Printing ........................................................................................................ 93 How concrete 3D printing can reduce CO2 emissions? ................................................... 94 Case studies ...................................................................................................................... 95 BIM and Augmented reality for waste reduction ............................................................. 97 BIM and AR application for improving construction performance ................................. 97 BIM for buildings’ End-of-Life scenarios ........................................................................ 99 Recycling and recovery in the Electronics and ICT sector ................................................ 100 Apple’s Daisy robot ....................................................................................................... 102 Digital Twin and Cloud Computing for WEEE chain management .............................. 104 Conclusions ............................................................................................................................ 107 Circular Economy implications and feasibility .................................................................. 107 Industry 4.0 opportunities .................................................................................................. 108 Industry 4.0 for Circular Economy implementation .......................................................... 109 Works Cited ............................................................................................................................ 111 Appendix 1 ............................................................................................................................. 119 Appendix 2 ............................................................................................................................. 121 A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 7 List of figures Figure 1: Current planet boundaries [4] ................................................................................... 12 Figure 2: United Nations sustainable development goals ........................................................ 13 Figure 3: Outline of the circular economy. .............................................................................. 20 Figure 4: EU emissions reductions with Circular Economy [14]. ........................................... 23 Figure 5: Multiple loops Life Cycle design strategies [21] ...................................................... 28 Figure 6: Overview of existing and planned circular economy strategies in Europe [26] ....... 35 Figure 7: Circular economy monitoring framework [32]. ........................................................ 39 Figure 8: The four industrial revolutions. ................................................................................ 43 Figure 9: IoT architecture layer [38] . ...................................................................................... 49 Figure 10: Augmented Reality applications [33] ..................................................................... 62 Figure 11: Digitalization in the transition to a CE [60]. ........................................................... 75 Figure 12: CircularID connected product components [66] ..................................................... 86 Figure 13: Modeclix printed links and panels [67]. ................................................................. 88 Figure 14: Modeclix chocolate mint dress [68] ....................................................................... 89 Figure 15: Drivers for change to circular economy in urban buildings [69]. ........................... 91 Figure 16: Wujiang 3D Printing Three-storey Villa [73]. ........................................................ 95 Figure 17: Construction process BE MORE 3D [74] .............................................................. 96 Figure 18: AR4C application used in construction site [75]. ................................................... 98 Figure 19: Phones’ elements periodic table [77] .................................................................... 100 Figure 20: Components and materials disassembly robot Daisy recovers [81] ..................... 103 Figure 21: WEEE digital twin-enabled cyber-physical system [82]. ..................................... 105 List of tables Table 1: Key mechanisms shaping the role of products in circular and linear economies ...... 33 Table 2: CPS applications in industry ...................................................................................... 51 Table 3: Characteristics of CC platforms. ................................................................................ 52 Table 4: Characteristics of the different AM processes. .......................................................... 66 Table 5: Interaction matrix of CE and Intelligent assets value drivers [61] ............................ 77 Table 6: CircularID Protocol value creation among stakeholders [66]. ................................... 87 A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 8 Abbreviations “AM”-Additive Manufacturing “AR”-Augmented Reality “BDA”-BigData Analytics “CO2”-Carbon dioxide “CAD”- Computer-Aided Design “CE”-Circular economy “DT”-Digital Twin “EEA”-European Environment Agency “Eol”-End of life “EU”-European Union “GDP”-Gross domestic product “GHG”- Greenhouse gas “IT”-Information technology “IoT”-Internet of things “PLM”- Product lifecycle management. “SDG”-Sustainable development goals “SME”- Small and medium sized enterprises “PLC”- Programmable Logic Controller “RFID”- Radio-frequency identification “4IR”-Fourth Industrial Revolution A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 9 Introduction Humanity has been facing challenges of all kind during its development through the years, in the last decades the concern about the planet capability of providing enough resources and stand human disruption has emerged as the main barrier for pursuing development. The evolution of modern society has been accompanied with an increase in the consumption of resources along with an increment in environmental damage. There are many convincing facts that suggest that this model of production-consumption is becoming obsolete with regards of meeting the sustainable challenges that human society faces. What served in the past is no longer capable of creating opportunities for the future. The traditional linear economy, where the resources are taken for granted and the waste is hide behind the carpet needs to come to an end. Decupling economic growth from resource consumption is a must for achieving sustainable goals. Here is when the concept of Circular Economy arises as an opportunity for change to a more sustainable paradigm, a system that is based on the optimization of the potential of resources by generating value through maximizing the use, minimizing the waste and desmaterilazing when possible. The reasons for implementing a circular approach to the production system are becoming more appealing as the linear system drawbacks are being put in evidence. The actual way of producing goods generates an estate of excessive pressure on the ecosystems out of which environmental risks arise; these risks endanger the provision of essential ecosystem services, such as water, air and soil cleaning [2]. However the implementation of a Circular Economy is still far from being fully accomplished, new strategies and innovations are required in order to achieve this new system. In this context the so called fourth industrial revolution which aims to bring the last developments of digital applications to the industrial sector, despite not being intended for that purpose appears as potential tool for accelerating the transition to CE. Through this work both topics of Circular Economy and Industry 4.0 are presented and analyzed from various perspectives, in order to provide valuable insights for the reader. The topic of CE is introduced to the reader regarding its main principles, implications and the actions required for implement it. Then Industry 4.0 is characterized from the main features that introduce, the analysis of the key technologies that includes and the challenges its present for its implementation. A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 16 In terms of the scope, in order to discuss some of the topics of the paper with a more concrete approach, a few of the analyzed issues have been particularized to certain geographical areas or economic sectors as it follows. For the description and characterization of Circular Economy, some of the considered topics have been limited to the European continent, as a global analysis would have supposed too much heterogeneity in the extracted conclusions. For the case of the description of the Industry 4.0 technologies, the focus is mainly given to their application in the manufacturing sector, as it is considered to be the more representative and an analysis of all the possible applications in more sectors would have required for a much more extended work. Also the number of Industry 4.0 technologies analyzed is restricted, and only the considered as more relevant for the paper are included. For the case studies employed in the study to represent the synergies between CE and Industry 4.0, these have been limited to certain industry sectors as it is properly explained in the corresponding chapter. With respect to the extension of the work, this has been limited to what usually is required for a Master Thesis and when some explanations were considered to be out of the scope, they have been gathered in the corresponding Annexes or referred to the existing literature. A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 17 Benefits of the project In this chapter the benefits that can be extracted from the development of this project are outlined. Since the topic of the paper is merely theoretical the benefits can be considered in two ways: The first as the work is contextualized into the development of an academic formation, is focused on which are the benefits that the elaboration of this project has reported to the author, in addition it also evaluates how the work can contribute to the researched topics and what are the valuable insights that readers can extract from the reading. The second is about the benefits that this particular topic of the implementation of Industry 4.0 technologies in Circular Economy systems can have in areas like environmental issues, economic development or societal needs among others. The second is considered to be covered along the whole project so this chapter will be centered in the discussion of the first. In terms of the benefits that the author has extracted from the elaboration of the project, it can be concluded that the main one is a significant understanding about the emergent topics of Circular Economy and Industry 4.0 and the possible synergies between the two. Also the author has gathered the required skills to elaborate a technical research paper, this includes: Adequate dissertation of valuable sources and adequate citation of the selected information sources, ability to successfully structure a scientific paper in order to efficiently transmit the core ideas of the project and the ability to draw original conclusions grounded in research. Regarding the contribution of the paper to the researched topic. As mentioned before the amount of existing research is not broad, particularly for studies considering the subject from an overarching perspective. Thus the paper serves as a great source of review of the topic as it reflects some of the most recent and relevant studies. The project also presents a particular approach to the researched area, with the introduction of original and innovative case studies that properly reflect the potential of the subject and at same time are supported with a well elaborated theoretical background. The detailed characterization of Circular Economy and Industry 4.0 serves as an introduction to the main topic and also facilitates the non-expert reader the comprehension of the core ideas of the project. The didactic way the project is approached enables the reader to acquire knowledge about the studied topics in a clear and organized manner. A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 18 A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 19 Circular economy Through this chapter the concept of circular economy is described as a whole. First a definition of the concept and its main working principles are outlined, then the impacts and implications of the accomplishment of this new system at a social, economic and environmental level are analyzed. Then the enabling factors for implementing this economic system along with a brief inside of the role of the products in the CE are outlined. Finally the policies and perceived barriers are considered as well as the existing tools for measuring the progress. Definition and working principles The concept of so called circular economy has been and still is one of the most resounding topics in the context of sustainability and sustainable development. However, outside of the academic and scientific world is not fully understood. The term appeared for the first time used in an economic model defined by [7], the development of this new economic system was based on the idea that “everything is an input to everything else” and applied the principle of the first and second law of thermodynamics [8]. From this initial idea, similar terms differently named arise, (“Cradle to cradle”, “Industrial ecology “or “Blue economy”) these concepts can be considered as an intrinsic part of circular economy or as part of a more complex vision that enrich the concept. Diverse approaches to the concept have created different definitions through the years. The authors of [9] from a resource oriented perspective, suggest that the circular economy refers to the “production and consumption of goods through closed loop material flows that internalize environmental externalities linked to virgin resource extraction and the generation of waste (including pollution) [9, p. 49].’ Another commonly used definition is the one provided by the Ellen MacArthur Foundation which characterizes the circular economy with a more wide approach to the concept: An industrial system that is restorative or regenerative by intention and design. It replaces the ‘end-of-life’ concept with restoration, shifts towards the use of renewable energy, eliminates the use of toxic chemicals, which impair reuse, and aims for the A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 20 elimination of waste through the superior design of materials, products, systems, and, within this, business models [10, p. 5]. This definition extend the vision from the resource oriented idea to a more broaden one that drive the whole system to generate a positive effect in the natural and social capital. For the interpretation of the concept, [10] establish a distinction between technical and biological cycles regarding the materials used: The technical cycle involves management of finite stocks. Technical materials are used not consumed. They are recovered and mostly restored in their cycles. The biological cycle comprise renewable materials. These biological materials are consumed and are mostly regenerated within the cycle. Figure 3: Outline of the circular economy. A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 21 Exploring more into the idea of circular economy, [10] establish three principles as the bases for taking action in the implementation of this new system as graphically shown in Figure 3: Principle 1: Preserve and enhance natural capital by controlling finite stocks and balancing renewable resource flows. Utility must be dematerialized as much as possible, virtualization and digitalization of products and services prevent resource consumption. When necessary the resources are wisely selected, they must be great-performing ones and renewables if possible. They should encourage flows of nutrients that enhance natural capital. Principle 2: Optimize resource yields by circulating products, components and materials at the highest utility at all times in both technical and biological cycles. Prioritize the product design for maintenance, remanufacturing, refurbishing and recycling, which keeps materials circulating into the technical cycles. Tighter inner loops will require less energy and material consumption to maintain the materials in the cycle. Extending the life time of the products will keep the inputs of resources to lower values and product share strategies will reduce the quantity of products manufactured. Biological cycles allow nutrients to be recovered as new resources by decomposition. Products are designed to be consumed and regenerated through their lifecycle. For biological material cascading them through other applications enhance value creation of products and materials. Principle 3: Foster system effectiveness by revealing and designing out negative externalities. Reducing the negative externalities that products generate through their cycles in their environment. The impact that the products generate in all areas of their environment (food, health, ecosystems, social activities…) should be beneficial or with low negative impacts in the social and natural capital. The above explanation gives a general overview of how a Circular Economy system should look like in the general terms, nevertheless the availability of strategies and approaches to its particular implementation will considerably differ depending on the concrete product or process. These ideas then serve as proper guidelines but each case will require for a specific analysis of the existing possibilities and the selection of proper strategies, as similar approaches will result in totally different outcomes. A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 22 Environmental, social and economic impacts Moving from a linear to a circular economy entails a great transformation for the actual system, thus the possible generated outcomes of this drastic transformation should be addressed. In this section an analysis of the impacts that the deployment of a Circular Economy can generate principally at an environmental, social and economic level are analyzed. Regarding economic and environmental issues, a recent study evaluated the impacts of the development in Europe of Circular Economy in the food, mobility and construction sectors [11]. The study predicts savings in the primary resource inputs of approximately 600 million euros in the European countries by 2030 and a reduction in greenhouse gas emissions of 48% by 2030 and 83% by 2050 compared with the levels of the year 2012, as well as the reduction of costs of externalities of 500 million euros by 2030. This study reveals, first the potential that CE practices holds to reduce the overall resource consumption and second, how the reduction in resource consumption is translated in a more environmental and economical sustainable system. In a more social context in connection with job opportunities, there are some existing studies that suggest that the deployment of circular economy will generate a change of paradigm in the labor sector in terms of the performance and the skills needed for the new job positions. A study of the impacts of CE in the United Kingdom [12], estimated that around 500 000 new jobs could be generated in the country directly related with CE practices by 2030. This study also yields how different circular economy approaches will generate different types of jobs. Labor-intensive practices like sorting or preparation of materials for reuse will mainly require low-skilled workers while recycling, remanufacturing or bio-refining will require more skilled workers. Furthermore, a report regarding future circular economy jobs [13], stated that 36 additional jobs will be generated per 10 000 tons of new recycled resources. Also the report highlights the fact that the declining of extracting jobs, the creation of new local economies trough close loop strategies and the embracement of digitalization and automation in manufacturing will drastically transform the job environment. A more in deep report about environmental impacts [14], analyses the impact that CE strategies have in Carbon Dioxide (CO2) emissions in the industry sector, taking in A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 23 consideration four of the main materials of industry, that account for the 66% of industrial CO2 emissions (steel, plastics, aluminum and cement) and two of the main sectors where they are used (passenger cars and buildings). The report indicates that even for an ideal scenario where decabornisation of processes like total electrification of transport, use of zero-carbon electricity, low carbon processes or carbon capture are implemented, the total reduction of CO2 emissions won’t be enough for keeping global warming below the 2ºC target of the Paris Agreement. Nevertheless the report estimates that in an ambitious scenario where CE practices are properly grounded, emissions of heavy industry can be significantly reduced as much as 296 million tons of CO2 per year in the EU by 2050, which will suppose a reduction of 56% from the baseline scenario–and some 3.6 billion tons per year globally Figure 4. Figure 4: EU emissions reductions with Circular Economy [14]. A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 24 The report also points out that by reducing the need for industrial processes associated with substantial air pollution, disease and mortality rate can be reduced. In addition reducing the need for mining will deplete soil and water pollution as well as the destruction of ecosystems. In the same report [14] there is an evaluation of the potential for reducing emissions of three circular strategies: Material recirculation, material-efficient products and new circular business models. The Material recirculation strategy based on the establishment of high value recycling provided more than half of the potential for CO2 emissions reductions. Material efficient products, based on manufacturing with less resources and employing improved production processes, along with circular business models like collaborative consumption or practices that promote long lasting products, accounted for the rest of the potential for reduction of CO2 emissions at equal parts. One of the main reasons for which material recycling holds the biggest potential is due to the fact that the actual levels of recycling particularly in the studied materials are so low. A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 25 Circular Economy enabling factors The transition from a linear to a circular economy requires for significant changes in many different socio-economic areas, involving social, economic and technical factors. A successful transition to CE is dependent on key strategies in certain areas that serve as foundation and generates value for the system. The 2015 European Enviroment Agency report about the Circular Economy [15] aims to raise awareness about the potential benefits and the way through optimal implementation among policymakers, investors, businesses and consumers. In this context the report establish four key enabling factors to consider for a successful transition to CE: Innovative business models Business models play transcendental roles in any particular economic system as they principles have a direct and lasting effect on the system, innovative business model that successfully implement CE practices set the reference for the rest and generate competitiveness accelerating the transition, however this competition will only be possible if policies are adapted consequently. The following paragraphs examine some of the most promising business models for CE. Service and function based business models. Product as service models allows for a more close relation between producers and products along their lifecycle. In a new economy where producers are required to minimize the impacts of the products through their whole lifecycle, service models appear as a suitable way of managing the actions required to meet the market specifications. Whereas the product belongs to the producer or the consumer, the facilitation of maintenance, product upgrades or end of life collection requires for the company to develop a service oriented approach. Industrial companies in Europe are increasingly relating income with service provision. Accordingly to this fact, as [16] points out during a period of twenty years from 1995 to 2015 the income related to production has fallen from two thirds of the total to 56%, being service provision the rest of the total income. Collaborative consumption Collaborative consumption is one of the most consumer oriented approaches of circular Economy and emerging technologies based on digitalization are boosting its potential. Rooted A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 32 they are cheaper to make. Maintenance and repair are avoided, as it is more profitable to sell new products. (intangible) needs of the user with a combination of services and products. Tendency to disregard end-of-life phase There is no economic incentive for product life extension, reuse or remanufacturing as they counteract most linear business models. Internal incentive to incorporate end-of-life phase in business model As products are assets, minimizing life-cycle costs is an implicit incentive for a company, inducing a search for the best economic equilibrium between reusing, repairing, remanufacturing and recycling products. Consumer perspective Consumerism follows marketing Consumers want new products that keep pace with fashion and technological advances. Consumers must match their needs with the product offerings available. Customer satisfaction is an important driver In a service relationship, the customer experience feeds back strongly, raising consumers' awareness of their actual needs. Consumers can become prosumers who cocreate or co-produce the products and services they need. International opportunities for cost reduction Consumers seek the cheapest version of a product on international markets, enabled by e-commerce. Local-first attitude Accessibility to the service provider is part of the service experience, which leads to proximity as a customer choice criterion. Ownership is the norm Owning a product is the normal way to fulfil needs. Over time, previously luxury products become commodity goods due to decreasing production costs. Beyond legal warranty, product repair is too expensive compared with buying a new product. Do-it-yourself repair is considered too difficult due to complex and protective product design. Accessibility is the norm Fulfilling needs is driven by accessibility of a product and its use satisfaction. Different consumer segments can access products of their choice through customized services or by sharing products. Service agreements provide an incentive for product care for the producer and the user. A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 33 Low/no residual value of products End-of-life products are considered a burden, to be disposed of as cheaply as possible by selling on the second-hand market, storing at home, or through regulated waste disposal systems or illegal incineration or dumping. End-of-use incentives incorporated If products are part of a service, there are incentives to return them to the provider after use, avoiding stocks of obsolete products in households, or illegal dumping. Policy perspective Dependence on existing production system Mass production of goods is strongly linked with the focus on cutting costs, and achieving efficiency, often resulting in lower labor costs and less job creation. More focus on facilitating skilled workforce More localized and service-based activities require a skilled but affordable workforce. Policymakers can facilitate this by shifting taxes from labor to resources. Global playing field Competition for economic factors on the international market steers national social and environmental policies. Less risk for outsourcing jobs As management of products as local assets is less likely to be outsourced, there is less incentive for a race-to-the-bottom in social and environmental policies. Balance consumer protection with economic stakes Protection of consumer safety and health is mostly reactive and geared towards protecting existing economic stakes, such as value-added tax (VAT) income. Facilitate safe and healthy services with regulation As safety and consumer health are business incentives for high-quality performance, policies focus on facilitation of these types of services. Action prompted by health or environmental concerns There is no inherent incentive for regulation of the waste phase of products. Only when waste-related health or environmental concerns arise is regulatory action taken to minimize negative impacts. Facilitation of end-of-life management Extended producer responsibility rules create incentives for companies to internalize end-oflife management. Governments provide basic infrastructure and fiscal measures supporting reverse logistics. Table 1: Key mechanisms shaping the role of products in circular and linear economies A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 34 Policies and barriers European policies for Circular Economy Policies are key factors in the development of CE strategies as they will smooth the way for companies to adopt this new idea of business models by promoting or forbidding certain business activities. In order to advance, in an efficient and reliable manner from the actual linear system to the pursued circular one, continental, national and regional policies should pave the way for producers and consumers to adequately integrate themselves into this new system. Setting policies that successfully adapt and align to the demands of the system always require for valuable information of the surrounding circumstances. Current available information about circular economy in Europe, principally concerns data related with material flows and waste generation [25]. For that reason, the majority of environmental related policies focus on the end-of-life stages. Waste statistics do not include details about the quality of the recycled products or the level of material functionality retained, that is why existing policies are rather volume based than value based, this ends up with a system that promotes low–value materials with a low environmental performance [25]. Adequate policies require for proper assessment an evaluation of the progress. If progress wants to be properly assessed more precise product-level rather than material-level information is needed. Indicators that measure the rates of product reuse, repair or remanufacture along with monitoring product share practices, will provide a much deeper understanding of the actual state of progress of the CE practices in the system. That will unleash policies better aligned with the current situations and more effective in the accomplishment of the targets. According to a study of the Circular economy Strategies in Europe [26] the strategies for the transition to a circular economy differ considerably in each territory, as the opportunities and challenges depend on factors such as population density, natural resources, industrial clusters, etc. All across Europe, countries, regions and cities have elaborated or are in the process of elaborating strategies that address the transition from multiple points of view in one document. In the documents, all stages of the value chain are considered and their main topics are: A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 35  Provide a framework for ongoing activities in different sectors, by different players, and at different stages of the value chain.  Provide a common objective for each activity setting the ground for assessing progress.  Describe ways to further support the transition to a Circular Economy, documenting instruments and defining roles for making the transition.  Function as source of inspiration to get people involved in the transition by expressing ongoing or prospective ways to contribute. The number of strategies has exponentially grown since the year 2015 and as shown in Figure 6 the implementation along Europe is becoming widespread [26]. Figure 6: Overview of existing and planned circular economy strategies in Europe [26] A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 36 Perceived barriers and current performance of Circular Economy A conducted study concerning the perceived barriers to implement CE practices [27], asked business experts and policy makers which were the most limiting factors in the integration of the concept. The main results exposed that: Cultural factors represent the biggest obstacle to CE, particularly the lack of consumer interest and awareness (47%) and the hesitant company culture (46%). Also the low virgin material prices remain particularly as a barrier in the policymakers’ perspective (62%). In the other hand the ability to deliver high quality remanufactured products (11%) and the limited standardization in the market (14%) where not perceived as challenge. According to these results, the reason CE practices are not currently being implemented is due to the fact that the cultural basis of society about this topic is still weak or is not fully grounded. Furthermore, the technological requirements for developing a circular system are not perceived as a challenge despite how far from reality CE might seem to be. However other studies [28] [29] address technological issues as main barriers. This considerable difference may be explained as the fact that the existing technology can enable particular key operations of CE as recycle, reuse or remanufacture, nevertheless, in a short term vision there is still a lack of technological tools that allows to integrate these operations in a system that works efficiently and can function with guarantees. A recent Eurobarometer conducted among companies across EU28 countries [30], outline some facts of the actual performance of companies in circular economy practices. Large companies are taking actions principally for obtaining resource efficiency, 80% are minimizing waste and 59% recycle by reusing generated waste by the company as these aspects normally lead reductions (53%) in the production costs. However, just 27% of the companies design products that are easy to maintain, repair or reuse and just 30% sell crap to other companies. All these values are slightly reduced for SMEs and considerably change depending on the sector and country where the company works. Other interesting fact highlighted by [30], is that the majority of European SMEs (63%) do not currently offer green services or products, and have no intention to do so in the near future. And those offering green products and services (24%), report that these account just for a small proportion of their annual turnover. A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 37 What can be concluded from these results is that circular practices are normally carried out because they entail economic benefits and do not necessarily mean that companies have a more sustainable attitude towards their businesses. A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 38 Measuring circularity In order to build a solid circular economy system, the measurement of the performance of circular systems and products becomes a key factor, as it enables a process of internal and external evaluation of the involved stake-holders that contributes to the improvement of products and processes. However, the large amount of inputs and outputs of energy and materials that products involve through their whole lifecycle suppose a challenge in the measurement of circularity. In this section some existing methods for measuring circularity will be presented, first at a micro-level measuring the circularity of a product or a business practice and then at a macrolevel as the way of measuring circularity practices in a country. Micro-level circularity evaluation The measurement at a micro-level is supposed to serve as a tool for business to assess their own progress and for third parties to compare the performance of different companies. The authors in [31] analyze three of the existing tools for measuring the product circularity: 1. Material Circularity Indicator (MCI). Developed by the Ellen McArthur foundation to asses European companies about their product and business circularity. Is particularly intended for use in product design and is based on an excel calculation sheet, where the materials are evaluated by introducing information about the material origin and destination and the percentages of recycling reuse and the efficiency related. 2. The Circular Economy Toolkit (CET). An assessment tool to identify potential improvement of product circularity. The necessary inputs are the answers to 33 questions divided into categories related to different product lifecycle stages that evaluate the performance of the product in each stage. 3. The Circular Economy Indicator Prototype (CEIP). Similar to the previous tool aims to evaluate the product performance by answering 15 weighted questions divided into 5 lifecycle stages that provide a score of the product in each different stage. These three tools hold different abilities of measuring circularity as MCI provides a rapid comparison between the performances of two different materials; on the other hand, CET and CEIP are more product-centric and lifecycle thinking oriented [31]. Although the tools serve as a rapid overview of products’ circularity they are still far from accomplishing a robust A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 39 measurement of the paradigm of circular economy as they fail in provide in advance fate of the products and the indicators make use of abstract information. Macro-level circularity evaluation Regarding the analysis of circularity at a macro level intended for the evaluation of countries or regions to serve as tool for the development of efficient policies, The European Commission, through the statistic platform Eurostat, has developed a monitoring framework that pretends to measure the progress of the European countries in terms of circularity [32]. For this purpose, ten indicators where selected as the most representative in the measurement of the progress. The indicators can be classified in 4 different categories and are shown in Figure 7. Figure 7: Circular economy monitoring framework [32]. Some of these indicators are still under development (2-Green public procurement) or their available data is not fully representative (4-Food waste). Analyzing the measurable ones, several findings can be outlined: A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 40  All indicators related with waste measurement can be misleading as the methods of measurement between countries are not exchangeable.  For the majority of indicators the differences between countries are substantial, this is result of an unequal degree of development between the countries and the approach of each country in the field of the indicator.  The overall results from most of the indicators follow a similar trend. An initial improvement of the results is followed by a smooth out or decrease during the more recent years.  The most remarkable good performance indicators are: o 5a) Recycling rate (in %) of municipal waste. Account for a 20% improvement during the last years (2000-2018). o 6-Recycling rates improvemnts (in %) for specific waste streams particularly: b) plastic packaging (17% from 2005 to 2017), d) e-waste (11% from 2010 to 2017) and e) Biowaste (31% from 2000 to 2018). o 10-Number of patents related to recycling and secondary raw materials. Experienced a growth of 17% from 2000 to 2015.  The indicators that did not progress considerably: o 3a) Generation of municipal waste (kg per capita). With a slight reduction form the year 2000 (513kg) to 2018 (492kg) but with an increment from the year 2013 (478kg). o 7b) Circular material use rate (in %). With an increment of 3% from 2004 to 2013, but any more improvement until 2017. As an overall conclusion that can be drawn out from the performance of these indicators: There is a slight improvement in certain areas of circularity in Europe; these improvements differ considerably between countries and the evolution of their performance has been considerably affected by the recent economic crisis. Also, the information that these indicators provide serve as a straightforward account of the actual system performance but is far from precisely measure circularity in countries, so the results must be cautiously taken into consideration. A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 41 A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 48 to an object and RFID reader in charge of identifying the object. The fast and proper identification of the objects allows for many working possibilities in IoT. The design architecture of IoT should be able to bridge the gaps in the operation from physical to digital world. More particularly, service oriented architecture guarantees a proper communication between heterogeneous devices in multiple ways and enables the upgradability of the hardware and software components [38]. A four layer commonly used architecture proposed by [38] is graphically represented in Figure 9and is explained as follows:  Sensing layer consists on tags or sensors that gather data from their environment and exchange it with devices. The advancement on RFID and sensor technology allows for the incorporation of information from new sources and in a more precise way it extends the capability of IoT as every connected thing to the system is uniquely identified.  Network layer is the place where the connections are made. All the connected devices share information with each other and with existing IT infrastructures trough wired or wireless networks; then data is transmitted to decision-making units for the high-level complex services. The network should be able to map the connected things and to assign those roles automatically enabling devices to perform tasks collaboratively. In this context information confidentiality and human privacy security are critical.  Service layer relies on the middleware technology that is the platform which provides support to the services and applications required. The middleware should be able to provide all the aspects required by IoT. Services run directly on the network to locate new services for an application and retrieve metadata dynamically. All of the serviceoriented activities (information exchange and storage, communication, search and management of data…) are performed at the service layer.  Interface layer is needed to make the interconnection and management of the connected devices easily and intuitively for the user. When large amount of devices provided by different vendors are involved, the compatibility issues must be addressed by the interface layer. A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 49 Figure 9: IoT architecture layer [38] . Now from this understanding of the IoT principles the main particularities that IIoT possess can be summarized as follows:  More requirements of real-time and reliable data, as industrial operations require greater levels of precision, therefore usage of more precise sensors.  Commonly used as part of more complex systems along with technologies like cloud computing or big data. Thus a certain degree of interoperability with other operation technologies is required.  Security issues should be further considered as disruptions may lead to great costs. Cyber-Physical Systems The concept of Cyber-Physical Systems can sometimes appear as exchangeable with IoT, in fact there is not a clear distinction between them as the origin of both concepts emerged from different communities, CPS from a system and control engineering perspective and IoT from a networking and information technology perspective [39] . For this work the concept of CPS would be more associated with the integration of computing capabilities with the physical components and the IoT concept will be more related to the connection of products with the internet. CPS can be defined as the set of technologies that interconnect computational and physical capabilities; it embraces smart elements that communicate with each other and have the ability to perform intelligent tasks like controlling the needs of workpieces or altering the manufacturing strategies by themselves [33]. CPS systems consist on three parts according to [33]: A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 50 1. Communication, wired or wireless connects the CPS to a higher level such as control or lower-level like physical world components. 2. Computation and control, is where the intelligent commands are generated from the received measure. 3. Handling and monitoring components, in charge of the connection with the physical world, using actuators to handle physical components and sensors to monitor them. There is a wide range of applications of Cyber-Physical Systems in the industry sector; authors in [40] list the practices with the highest potential for improvement in the industry sector, as the following table shows some of these applications grouped in categories of different industrial topics. Category Applications Automatization  The context awareness of smart machines allows for particular operations by accessing the information of each material or product.  Machine to machine communication optimizes the sequence in production steps based on previous determined algorithms.  Automated guided vehicles are able to transport components and working materials. Autonomatization (Control and coordination of processes without human intervention)  Upgrade of SCADA system that allows for condition monitoring and situation based system reconfiguration.  Facilitates cost-efficient production of mass-customized products.  Safety related benefits of absence of personal. Human machine interaction  Sensors permit the safe synchronous work between human and machine.  Human machine collaboration reduces the workload and lead to overall optimization.  Robotic exoskeletons enhance human weight lifting related activities.  Decision support systems supplies users with needed information to perform their work. A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 51 Decentralization  Complex event processing can be performed in a leaner and faster way with decentralized computer solutions. Digitization for Process Alignment  Digitalization of warehouse and logistics enables self-organizing production to include real time inventory.  Automated e-procurement improves availability of parts and materials enhancing just-in-time production.  Remote maintenance, repair and operation.  Product lifecycle monitoring. Knowledge Management  The amount of real time information enables value creation in technical processes.  The staff practical knowledge should be recorded. Table 2: CPS applications in industry A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 52 Cloud computing Cloud computing (CC) have become widely implemented in the last years and each day more businesses are making use of this service, from industrial manufacturers to entertainment companies. The basic principle of this tool is to provide access to the user to computing resources and services without the need of owning and managing the entire software infrastructure. A straight definition of the cloud that gathers the main ideas of the concept is the following: Clouds are a large pool of easily usable and accessible virtualized resources (such as hardware, development platforms and/or services). These resources can be dynamically reconfigured to adjust to a variable load (scale), allowing also for an optimum resource utilization. This pool of resources is typically exploited by a pay per-use model in which guarantees are offered by the Infrastructure Provider by means of customized SLAs [41, p. 2]. CC platforms differ in certain features depending on the service they offer, however the majority of them share some common characteristics, [42] present the five essential characteristics that cloud platforms share and are shown in Table 3. Characteristic Description On-demand self-service Consumers can unilaterally provision computing capabilities as needed automatically without the need of human interaction with provider. Broad network access Capabilities are available over the network and accessed through standard mechanisms that promote use by heterogeneous client platforms. Resource pooling The provider’s computing resources are pooled to serve multiple consumers, with different physical and virtual resources dynamically assigned according to consumer demand. Rapid elasticity Capabilities can be elastically provisioned and released to scale rapidly with demand. Measured service Cloud systems automatically control and optimize the use of resources by leveraging a metering capability at some level of abstraction appropriate to the type of service Table 3: Characteristics of CC platforms. A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 53 Cloud Computing platforms can be classified concerning the deployment model and the provided service model structures they offer [33], [42], [41]: Deployment model The model chosen will depend on the business’s needs in terms of costs, data governance regulations and data confidentiality.  Private cloud. The infrastructure is provisioned by a single organization and it offers special benefits for their users as it contains particular services for the organization.  Community cloud. Offers exclusive use to a specific community of consumers of multi organizations that share concerns about the organization’s infrastructure.  Public cloud. Is provisioned for open use by the general public. Usually located in data centers.  Hybrid cloud. The cloud is a composition of two or more distinct cloud infrastructures that remain unique entities, but are bound together by standardized or proprietary technology. Service models  Infrastructure as a service (IaaS). The consumer is provided with computer resources like processing or storage capacity, where users can deploy and run arbitrary software as operating systems applications.  Platform as a service (PaaS). The capability provided to the consumer resides in the access to software platform where consumer-created or acquired applications run on. The consumer does not manage the cloud infrastructure, but control the deployment and configuration settings of the applications.  Software as a Service (SaaS). Consumers are provided with access to applications running in the cloud via interfaces like web browsers or program interfaces. It allows for the elimination of service application on local devices gaining better performance efficiency. Enables software applications such as CAD and ERP to run with a lower total cost ownership. A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 54 Cloud manufacturing In the context of the manufacturing industry, the term of cloud manufacturing refers to the integration of cloud computing technology into the processes of manufacturing. The main purpose of cloud manufacturing is to provide users access to services in all stages of product lifecycles, shifting manufacturing from product-oriented to service-oriented [33]. The manufacturing resources available in the platform can be physical resources (equipment, computers, servers, raw materials, etc.) or manufacturing capabilities (product design capability, simulation capability, maintenance capability, etc.). Pay-as-you-go services, production scaling up and down per demand, and flexibility in deploying and customizing solutions are some of the possibilities that offer the implementation of cloud manufacturing [43]. Fog and Edge computing In a predicted future IoT system where the number of connected devices and the data generated will exceed the network’s capacity. The solution will require a development of the network’s capacities by moving computing and storage capabilities to the edge of the network. This approach known as distributed intelligence will allow to handle the increasing volume of end devices by sending to the cloud center only the necessary information and by doing most of the processing at the remote site, it will also reduce delays and overloads in data transfer and will allow to run operations even when the access to the cloud center is not possible [44]. Fog and Edge computing are two similar often confused concepts that aim to bring cloud services and resources closer to the data generator devices. The main difference between the two is where their processing structures work, as fog computing works with the cloud, placing its computing intelligence at the local area network (LAN) whereas edge computing place it outside the cloud into edge nodes such as embedded automation controllers [45]. A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 55 Big Data analytics The exponential growth in data generation in todays connected world is expected to keep rising with the implementation of IoT and similar technologies. All these generated data holds a lot of value, however the process of sorting out the valuable information requires for adequate proceedings. In this context appears the concept of “Big-Data” that can be often confused, as it not only refers to the definition of the particularities of a type of data, that is characterized by being high-volume, high-velocity and high-variety [46], but it also refers to the field that gather the technologies in charge of analyzing and dealing with this generated data. The data usually comes from heterogeneous sources and in different formats of structured data (digits, symbols, tables…) or unstructured data (text, audio, video…). More particularly in manufacturing processes, according to [47] the data generated can be classified as:  Management data. Collected from manufacturing information systems (e.g.. MES, ERP, CRM) including data related to product planning, material management, inventory management, sales and more management operations.  Equipment data. Generated from the IIoT of the smart factories, including real-time performance, operating conditions or maintenance history of the equipment.  User data. From ecommerce and social networking platforms, entailing user demographics, profiles, preferences and behavior.  Product data. From smart products and product-service systems including product performance, context of use, environmental and user biological data.  Public data. From governments, data related to intellectual property, civic infrastructure, scientific infrastructure and development, environmental protection and health care. For guaranteeing manufacturers with the compliment of the regulations and industry standards. In order to extract valuable information from this generated data, it has to be stored, managed and then analyzed. The analytical process is where the real value is created and where organizations need to put the effort to develop efficient ways of working, to turn this great amount of data in valuable knowledge. This information can be translated in systematic guidance for production activities during entire product lifecycles, obtaining less faults and A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 56 more savings during the production processes and helping managers in decisionmaking and problem solving related to operations [33]. Another great resource of Big-Data is Predictive analytics. This tool comprises a variety of techniques that predict future outcomes from current and historical data, allowing predictions in many different work fields from jet engines failures to consumer behaviors. Its basic idea is to uncover patterns and capture relationships in data using statistical methods [46]. Data-driven smart manufacturing is considered to be the process where enterprises utilize Big Data analytics to exploit the data from manufacturing to refine their processes, improving product efficiency and the performance of a product. Data driven smart manufacturing shares the following characteristics [47]: 1. Customer-centric product development focusing on customized product design enabled by the employment of users’ data precisely quantified with Big Data analytics. 2. Self-organization of manufacturing resources and task data for smart production planning. Making use of both internal and external data from the manufacturing sites. 3. Self-execution from a variety of data from the manufacturing process for precise control. Raw materials and parts can be sent to any manufacturing site that requires them. 4. Self-regulation from real-state data for manufacturing process monitoring. Enables generation of automatic responses to unexpected events. 5. Self-learning and self-adaptation from historical and real-time data for proactive maintenance and quality control. There are many existing applications of Big Data in manufacturing and others that are yet to be developed. The following are highlighted in [48] as some of the most valuable ones:  Product design is shifted from experience and inspiration based to data and analysisdriven design. Users’ behaviors and market trends translate consumer needs into new products.  Smart production planning is conducted based on manufacturing resource data. The current availability and capacities condition the strategy.  Real time data allows for optimal operational control strategies during the manufacturing process. A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 57  Making use of the predictive ability of BD, health and fault monitoring are conducted for active preventive. A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 64 operational costs as it improves the utilization of materials, increase production yield, reduces part rejection and increase energy efficiency [44]. Regarding the manufacturing operations of AM, there are different existing working processes of additive manufacturing intended for different materials and applications; The International Organization for Standardization (ISO)/American Society for Testing and Materials (ASTM) 52900:2015 standard classify standard Additive Manufacturing processes into seven categories, furthermore within these categories exist different working procedures and techniques intended for different AM machines, but, it is considered to be out of the scope for the following explanation : 1. Binder Jetting (BJ): This process is mainly characterized by the absence of heating, avoiding residual stresses [54]. In this process a thin layer of powder is glued together using a liquid adhesive spray in the parts specified by the CAD file. 2. Directed Energy Deposition (DED): Usually conceived for the usage of metal wire or powder; high energy heating sources (normally laser beams) merge into the material injector generating the object. 3. Material Extrusion (ME): Is becoming one of the most prominent additive manufacturing processes [54]. The objects are generated by depositing an extruded material layer by layer; normally a thermoplastic filament that is melted and deposited in horizontal or vertical direction. 4. Material Jetting (MJ): Works as a two dimensional ink jet printer, the material is jetted into a platform where it solidifies and the model is built layer by layer. 5. Powder Bed Fusion (PBF): Similar to BJ but in this case the fusion of the powder is fused together using a heat source such a laser or an electron beam (for metal powder). 6. Sheet Lamination (SL): In this process sheets of materials are bonded together using adhesives (Laminated object manufacturing) or a heat source (Ultrasonic additive manufacturing) to form the 3D object. 7. Vat Photopolymerization (VP): Also known as Stereolithography is one of the first and most widely used method of 3D printing; is a liquid based process that cures a photosensitive polymer when a laser beam contacts the resin [52]. The Table 4 shows for each of the above mentioned AM processes some of the main advantages and disadvantages identified by the authors in [54] and [53], along with the A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 65 suitable and commonly used materials according to [53] and the main applications of each process considered by [54]. Type Advantages Disadvantages Materials Applications BJ  Free of support  Design freedom  Large build volume  Low cost  Fragile parts with limited mechanical properties  May require post processing  Polymers  Ceramics  Composi tes  Metals  Hybrid  Prototyping  Tooling DED  High degree control of grain structure  High quality parts  Can operate in open air  Surface quality dependent on speed  Limited to metals/ metal based hybrids  Metals  Hybrids  Repair/build up large volume pieces ME  Economic  Scalable  Fully functional parts  Good structural properties  Vertical anisotropy  Slow building times  Low quality may require post processing  Polymers  Composi tes  Prototyping  Tooling  Office manufacturin g. MJ  High accuracy of droplet deposition  Low waste  Multiple material parts  Multicolor  Support materials often required  Parts may have low strength and durability  Polymers  Ceramics  Composi tes  Hybrid  Biologic al  Electronics  Consumer products  Tooling  High resolution prototypes PBF  Low waste  Relatively inexpensive  Wide range of materials  Powder bed act as support  Lack of structural integrity  High power required  Size limitations  Polymers  Ceramics  Composi tes  Metals  Hybrid  Aerospace  Automotive  Medical products  Tooling  Dental implants SL  Low cost  Strength and integrity of  Polymers  Tooling A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 66  High speed  Ease material handling  Allows combination of materials parts depend on adhesive  May require postprocessing  Difficulties with complex geometries  Ceramics  Metals  Hybrid  Large pieces VP  Large parts  Excellent accuracy  Excellent surface finishing  Limited to photopolymers  Low durability  Expensive precursors  Slow  Polymers  Ceramics  Prototyping  Consumer toys  Electronics  Guides  Fixtures Table 4: Characteristics of the different AM processes. Looking at the actual and potential applications of AM, it can be observed that they are present in the majority of the industry sectors and currently in Europe contribute to 1.6 million jobs and 11% of the EU production [53]. From all the different possible applications of AM the authors in [52] consider the following as the most remarkable ones:  Lightweight Machines. AM as mentioned before allows for the possibility of manufacturing light weight pieces, which is of great interest for the automotive and aerospace industries that are always looking for lightness in their products.  Architecture modelling. The creation of models in architecture is a very important and difficult task, when the model entails complex structures AM is an adequate tool.  Medical applications. The medical world is considered to be one of the most promising ones for AM. As it allows for a high quality and rapid prototyping of bone transplants and models of damaged bones for better analysis of patients’ diagnosis, also better and more adapted prosthesis can be created as the designs are more adapted to each patient. AM has as well great potential in dentist application as the model of a patient’s mouth can be easily build.  Manufacturing cell fuels. This particular technology requires for a very precise deposit of a thin film, a requirement that AM can properly perform.  Art and user services. AM becomes an interesting tool for artists to elaborate complex forms involving fashion, furniture or lighting among others. The low acquisition cost A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 67 of some printers open up opportunities for particulars and nonmanufacturing institutions such as schools or universities to benefit for the possibilities of AM. Additive Manufacturing is not intended, at least in the near future, to replace mass manufacturing; indeed is more suitable for high value low volume products due to its ability to produce shapes and complex products which are not possible or cost-effective for conventional manufacturing processes. Also, AM is not tied to traditional economies of scale or unit labor costs and the replacement of the whole value chain of the products will mean a compression of all the processes of the value chain which will require in-house expertise in materials, metrology, assembly… a knowledge that is normally widespread into many different actors along the value chain [53]. A study conducted among industry experts and researchers about their view of Additive Manufacturing processes in the year 2030 [55], makes a great emphasis in the change of the production system that could be generated regarding spare parts, as the production of spare parts with AM will simplify logistics reducing time expenditure and will also reduce the spare parts stocks. The study also highlights the possibilities of multi-material products that AM will enable and the importance that AM will acquire in a future where products will always remain in continuous modifications and upgrades. Perceived challenges for Industry 4.0 implementation Industry 4.0 is still on its development phase, some of the technologies are grounded and functional others are still being developed to be commercially available, but more importantly A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 68 its degree of implementation in industrial companies is still weak. Through the following chapters some of the challenges that Industry 4.0 implementation faces are presented and analyzed. The challenges for SMEs Companies that want to introduce 4IR technologies in their businesses need to face certain technical and economic challenges. Nevertheless as a research conducted among German companies [56] states, companies are willing to face digitalization despite these challenges in which enterprise size plays an important role. SMEs have great importance on the industrial sector, particularly in Europe; moreover they are a crucial factor in the supply chain of big companies. Some of these big companies are already transitioning towards Industry 4.0, however SMEs are experimenting more difficulties in embracing this transition. There is a need of closing the gap between the development of the transformation between big companies and SMEs in order to accelerate the process of transition. Investment requirements are one of the main challenges that SMEs face in the adoption of a 4IR system, the required infrastructure demands a considerable initial investment. Despite the fact that the adoption of these new technologies will entail economic benefits for companies, the price of the deployment of these new technologies is still high and a total transformation of the entire production process can have tremendous costs. Other challenge that particularly affects SMEs is the difficulties they face when it comes to change from the old to the new systems. These companies normally have lack of expertise in these new technologies and they have to turn to third parties. Also businesses rooted in traditional practices may have a lack of willingness to transform their way of working, slowing down the transition. Cybersecurity A fully digitalized system in which every working piece is connected and stores valuable information holds the risk of being exposed to cyber-attacks that can compromise the security in different areas of the company. The supply chain is one of the key areas of the company as it records sensitive information from a considerable number of participants. A digital supply chain should be properly balanced in terms of the transparency that it entails in terms of sharing data from different A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 69 stakeholders and maintaining security for other information that can have privacy risks. Organizations need to consider which data is available, however providing access to certain data can facilitate gaining access to other valuable information for those with malicious intentions [57]. Smart factories rely on a digital infrastructure the performance of all their processes, these infrastructures are supported by commercial software products which introduce a variety of exposure points that can endanger the performance of the system. A cyber-attack that shuts down the production processes of a factory can result in considerable money losses, but the main issue with cyber-attacks is when they affect systems that are in charge of managing the safety of operators [33]. Smart products represent also considerable risks in terms of cybersecurity as they can generate threats even out of the production process. Once the product gets to the customer’s hand the security of connected products cannot be guaranteed as it normally depends on the customer to update security settings or device firmware [57]. The issue of cybersecurity should be addressed in order to effectively transition to Industry 4.0 as its one of the main concerns of companies willing to embrace the transformation. The authors in [57] suggest three main approaches in order to address the problem: 1. Security. Stakeholders need to be certain about which of their vulnerable infrastructures are secure and which aren’t by taking a measured risk-based approach. 2. Vigilant. A continuous monitoring of the systems is required to avoid possible threats. Real-time intelligence and AI are required to understand and predict harmful actions. 3. Resiliency. If an attack occurs how the system responds and how quickly the effects are remediated is of great importance. Energy efficiency Despite the fact that these new technologies will help with the accomplishment of a more energy-efficient and sustainable industry. The massive amount of devices that could be operating in IoT systems in a near future will have a considerable impact in energy consumption. Connected devices with RFID technologies have very low energy consumption levels, however IoT systems can involve a great amount of devices with sensing, processing and communication capabilities that combined can consume a significant amount of energy. A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 70 Particularly are the wireless sensor networks the ones that have the greatest energy consumption rates [58]. The real impact of this energy consumption will depend of the magnitude of the system that in terms of involved devices, a number that is expected to exponentially increment with Industry 4.0. However the authors in [58] explained how the magnitude of this problem can be tackled with the introduction of an energy efficient architecture. They proposed an architecture that as general overview reduces the energy consumption of IoT systems by reducing the time that the sensing devices are communicating with the use of a control layer that enables the communication just when is required. Additive Manufacturing as explained before reports many benefits in the production processes as the reduction of time and operations which is translated in an overall reduction of energy consumption. However the production process itself of AM has a considerable rate of energy consumption, which in some cases could be bigger than the one used in traditional manufacturing processes. A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 71 A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 72 Connecting Circular Economy and Industry 4.0 In the last years the topics of Circular Economy and Industry 4.0 have been addressed from many different points of view, the synergy between the two is a topic that has recently drawn the attention of academia, however due to the scarcity of research papers and industrial applications, is still considered to be in its early phases of development. The wide extent of these two terms difficult the establishment of a specific framework of interrelation, as the synergies between CE and 4IR technologies can take place in multiple areas and the degree and the form of interrelation will certainly depend on the particular applications they are intended for. Nevertheless, in this section the relationship between both terms will be explored, first by presenting the existing literature that analyzes the topic in a more conceptual and broad manner, then the topic would be addressed in a more particular way with the introduction of a series of industrial and academic case studies that provide a more realistic view of the challenges and opportunities that arise with the implementation of this two strategies in various industrial sectors. A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 73 Conceptual framework of the Digital Circular Economy It is reasonable to think that some of the main principles of CE: Dematerialization, share of assets or product multifunctionality; will certainly be enhanced by business practices based in the use of digital technologies, as they encourage these product capabilities. Nevertheless, the benefits that the merge of this two value propositions can generate are not always that obvious, and in some cases involve a combination of different 4IR technologies along entire supply chains and trough whole product lifecycles. The diversity of these possible combinations is far-reaching, thus, through this chapter only some of the most discussed possibilities will be presented. As mentioned before the conceptual framework of the symbiosis of 4IR and CE is not a straight forward concept, hence in the existing literature the given approaches differ considerably. In the following paragraphs several studies will be reviewed in order to outline the most relevant conclusions of the academia. Opportunities of 4IR technologies to promote Circular Economy In a recent book that has the intention to address the challenges and opportunities for the implementation of a global circular economy system [59]. The authors identified the main capabilities of 4IR technologies that enable businesses to decouple production and growth from consumption of natural resources: First, technology developments which implies greater efficiencies in all stages of the product lifecycle and allows for less overall resource and energy consumption, second 4IR technologies help to drive innovation as new entrants will disrupt the existing market forcing companies to turn into new business models. Finally, the implementation of these technologies will increase information transparency through the gathering and analysis of data, allowing companies to access new levels of visibility of the production processes, a greater degree of connectivity trough the supply chain and an upgrade in production flexibility. A recent report that evaluates the opportunities that digital technologies can bring to the implementation of a Circular Economy system [60], indicates that digitalization is designed to address complexities thus is optimal to deal with the challenges that arise with the shift to a CE system. However, [60] also points out that digitalization if not properly managed holds the risk of ending up in unwanted rebound effects, such as the reinforcement of an unsustainable linear take make-dispose economy. The report stablishes three categories in which the A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 80 AM can upgrade current recycling processes, promote reuse/remanufacture or make use of biomaterials.  BigData and analytics. In contrast with AM it has been considered less frequently by experts. BDA is considered to be the easiest way to digitalize the CE. Other considered applications are: Develop automated approaches assessing potential value pathways for secondary materials, develop tools, procedures, open data and services for promoting: reuse, assess innovative business models, manage lifecycle data or implement smart manufacturing practices.  Cyber-physical-systems. Were the less discussed ones. They are mainly related with lifecycle management of products and with the development of new services, especially for maintenance reasons. In few cases were related with remanufacturing practices or multi-agent systems for managing the extraction of natural resources.  Internet of Things. Considered with AM one of the most important technologies that support Circular Economy practices. Apart from papers that focused on the potential use of IoT in extending the information exchange along the product lifecycle. IoT was considered to have many other applications to support CE. It can support strategies for the waste management in cities or connect stakeholders across the value chain. Also it promotes the digitalization of CE practices by implementing smart industrial environments dynamic feedback loops or the creation of new service models or services.  Simulation. Most of the papers addressed the relation between circular business models and lifecycle management with simulation tools. Other discussed topic is the supply change management where simulation could optimize the performance through probabilistic neural networks or modelling of the material flows. Simulation can enhance remanufacturing processes with the use of decision-support tools and the efficiency in exploiting natural resources trough eco-efficiency indexes. The authors in [64] also analyzed the relation between 4IR technologies and CE by identifying which are the technologies that better fits or have more potential in certain CErelated areas. AM, BDA and IoT were the most frequently described technologies for the digitalization of the CE. When it comes to support innovative lifecycle management strategies CPS is the term with more appearances followed by AM, IoT and simulation. BDA is the most related with A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 81 new forms of disassembly and AM is suitable for new types of reuse and recycling processes and remanufacture along with Simulation. Efficient exploitation of resources is mainly related with IoT and BDA. The development of circular business models and new services can be associated with all of the technologies except from AM. Finally when it comes to the management of complex processes and supply chains simulation and IoT appear as the most mentioned. A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 82 Case studies In this section some selected case studies will be presented, the cases are aimed to represent how Industry 4.0 technologies are used in both real and academic cases, in which sustainable practices encouraged by Circular Economy strategies are generated intentionally or as consequence of the technological applications. The studied examples are selected from three of the industry sectors that are considered by the European Circular Economy Action Plan of 2020 [65] as priorities in the application of Circular Economy measures along their supply chains. The industry sectors will first be shortly described addressing the main challenges they face in meeting sustainable requirements, then the case studies will be presented. A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 83 Resource efficiency in the textile industry The actual society in developed countries is surrounded by rapid changing trends in many aspects of people’s lives, from new music rhythms to fresh exotic dishes; the world of clothing and textiles is probably the most influenced in this matter as it is exposed to the introduction of new fashion styles constantly, changing the way people dress quite rapidly. This ends up with an over consumption of clothes, as people are buying more items and keeping them for a shorter period of time even though they are still in their useful life. The textile industry is considered as one of the most resource intensive industries only after food, housing and transport [65]. The current linear system is strongly reliant on virgin materials from non-renewable sources, the choice of material is considered as one of the most relevant factors to determine the impact that the clothes have on the environment; from cultivation (land, fertilizer, water use…) to processing (energy, chemical and water use…) [59]. Conventional cotton that along with polyester are the most used materials in the textile industry, consumes significant amount of inputs in its production process, in fact, the manufacture of a single T-shirt and pair of jeans requires for almost 20,000 liters of water [59]. Human resources are also a great malfunction part of this industry, the low margins and the rapid changes in market trends have led to delocalized manufacturing activities in developing countries where the salaries are lower and the total investment of the textile companies in the manufacturing processes are substantially reduced. This have sometimes degenerated in companies involved with exploitive labor practices [66]. The sector is evolving into more sustainable businesses models, many fashion brands are implementing eco-design principles working in the creation of products that can be recycled, reused or biodegraded, however all this added value is lost in the system as the infrastructure and the processes of the recovery sector are not developed enough to accomplish these operations [66]. The actual recycling processes of conventional textiles are not efficient enough to properly manage the amount of disposed clothes generated; also the majority of countries have not yet developed a proper collection system in their municipalities able to handle the textile waste, as they have with standard municipal waste. As a result of these challenges, the disposed clothes are not adequately collected ending up in landfill or as a form of energy recovery and A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 84 when properly sorted the profitability of the system is lowered due to the low efficiencies of the recycling processes. In fact, in the European Countries 73% of all the clothes (5.8 tons annually) that reaches their end-of life end up being landfilled. Innovative ideas are required in order to transform the textile industry and 4IR technologies appear as great tools for doing so, as the following paragraphs demonstrate. CircularID initiative The company EON has developed a project that aims to solve the challenges of the implementation of circular practices in the fashion sector by connecting the products with IoT technologies. The aim is to create a protocol for product identification in which the manufactured garments are identified and characterized all along their lifecycle. Currently there are some existing companies that are recovering and recycling textile products enhancing circular economy practices, however some challenges arise in these practices. The sorting process is normally performed by hand relying on the information presented in a label that can sometimes have a lack of information or even may no longer be attached to the product. If high volumes of textiles are meant to be collected a better scalable recognition system is needed to move goods in a faster way through the supply chain. Also, another great challenge when it comes to textile recycling is the difficulty of separation of the blend of materials that exist in the garments, the new promising solutions that are able to properly recycle these products require for a precise quantification of the material input to the process, which again requires for a better process of material recognition. The CircularID protocols will be able to provide the necessary specifications for each item validating its true content and aiding the sorting process by recognizing the product category and material content of collected textiles. The process of sorting will speed up and the possibilities for recovery practices will be enhanced. When recovered products are put again into the market the information about the “new” product is not accessible, CircularID will facilitate brands the process of reselling their items as the product information could be easily accessed and provided to the customers. How does CircularID works? The connected product is digitally identified and connected to its characteristic data through IoT parameters. To link the physical product to IoT a digital identifier (RFID, QR, NFC…) is A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 85 attached and the digital profile is accessed through interactions with the identifiers bias appropriate lectors. The digital representation of the connected product as shown in Figure 12 will consist on the following components:  Digital birth certificate. Is created for the finished product and includes data fields that as the product brand, name, color, material content and factory identification number among others.  Digital passport. It includes the record of interactions of the product through its lifecycle, the interactions occur when the product identifier is read by an appropriate device. The passport serves as valuable tool for stakeholders to capture the valuable insights of the product usage, durability and movement in the value chain.  Identifier. Consists on the physical device in charge of connecting the product with its digital profile. The identifier must remain attached to the garments along all its lifecycle to allow for access, verification and expansion of the digital information contained on the product. RFID, NFC, QR or UPC are the main examples of usable identifiers that should always be designed to remain intact for the full lifetime of the product. The introduction of the CircularID protocol will entail a considerable number of benefits among the textile industry stakeholders as the ones appearing in Table 1, which are mainly due to the two primary functions enabled by the CircularID protocol: Identification of products that allows for a continued identification and monetization of the product trough circular business models and identification of materials that enables a better performance of the recovery activities mainly disassembly and recycling processes. A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 86 Figure 12: CircularID connected product components [66] A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 87 Stakeholder group Roles Impact & Value of CircularID™ Protocol for Targeted User Groups Circulators Collectors, Sorters, Resellers, Renters, Peer-to-Peer reselling, Repairer, Digital Wardrobe  Enables transactions  Identifies products and materials for reverse logistics, collections and sorting  Enables efficient economy and marketplace  Creates economic viability  Communicates embedded value  Captures maximum value of products  Improves sorting efficiencies Regenerators Recyclers (includes ALL types of recyclers)  Captures maximum value of materials  Provides accurate data and specification about materials to inform disassembly and recycling  Unlocks possibility for materials to meet unique technology specifications  Improves sorting efficiencies Product Owner Brands, Retailers  Creates economic viability and visibility  Creates opportunity for ongoing revenue from existing product  Builds circular brand integrity and equity  Unlocks transparency across the product lifecycle  Creates the ability to share, exchange and access data with circular economy partners  Facilitates measurement of circular economy goals Customer Individual who uses product  Helps customers maximize the use and value of product  Helps customers make intelligent decisions about purchases  Enables ease of sustainable quality and narrative  Allows customers to connect with brands after purchase to build more meaningful connections. Table 6: CircularID Protocol value creation among stakeholders [66]. A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 88 Modeclix Modeclix is a patented innovative way of applying additive manufacturing to the textile industry developed in the University of Hertfordshire, UK. The model is based on printing a flexible material that is able to create a great variety of shapes and structures perfect for clothing. The main innovation that characterizes this process is the ability to be infinitely deconstructed and then reconstructed by hand after the material is printed. The AM process has been successfully tested using the Selective Laser Sintering technique and employing white Nylon powder as the working material. The structure consists of a system of links that can be additively manufactured as linked panels. The design of the links allows for the panels to be de-constructed and reassembled by hand to easily create the desired forms and shapes [67]. The links consists of 4 connected spiral arms connected on the top face but open on the reverse Figure 13, enabling the links to be disconnected and reconnected to other links creating garments with no size restrictions by connecting the printed panels of links. The links shapes are designed to obtain flexibility for elongation of the textile piece and to be firm enough so that the degree of stretch is achievable without breaking; also, a certain degree of strength is needed to withstand the manual process of reconstruction [67]. Figure 13: Modeclix printed links and panels [67]. The garments prototypes have been constructed from small panels of 22 x 22 links and assembled on a small workshop as traditional dress making. The garments are seamless and do not require the usual pattern making techniques, the material can be easily manipulated by everyone just by becoming familiar with the technique of connecting the links. Once the procedure is learned the connection of 50 links just takes approximately 1 minute [67]. The material can also be properly dyed making use of commercial textile dying processes. A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 89 Figure 14: Modeclix chocolate mint dress [68] Sustainable manufacturing The model of Modeclix offers significant advantages for the development of a more sustainable textile industry with the employment of Circular Economy principles. The AM process allows for an on demand manufacture of material, the scalability of the process efficiently meets the economic requirements and extends the lifetime of the products with the option of re-configure and re-purpose the material at any time during the product lifecyle. The re-configuration process enables the creation of garments that perfectly fit the customers by simply removing or adding links which entails considerable material savings in the manufacturing process, it also creates a greater sense of comfortability between the customer and the product as it perfectly adapts to the body shape, the possibility of changing the clothes in length or shape would also be available when required. The recovery activities as repair, remanufacture and recycle are easily performed in the Modeclix manufactured products. The interchangeable links enables a straight forward repair process, if a piece of the product is damaged at any time of the product’s lifecyle only the required links are substituted for new ones keeping the rest unaltered. The recycling of the material is performed as a reuse process as the used material can be incorporated in the A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 96 be assembled [74]. This allows the company to print the houses in situ anywhere without the need of a factory or similar. The report of the company technology description [74] summarizes the construction process of the mains structure of a printed residence Figure 17in 6 steps: 1. The model of the residence is designed using any 3D design program and then the model is sliced to obtain the necessary input for the printer. 2. The terrain where the model will be constructed is set up by degrubbin and land levelling. Then a reinforced concrete base is placed that will serve as foundation and zero level mark. 3. The machine is assembled in the previous spot and the required materials are stockpiled. 4. The concrete adequate mix is prepared and the material is supplied trough a concrete pump from the mixer to the printer. 5. The material is extruded layer by layer making sure the planned facade voids are left open and stopping when lintels and framework are required to be placed. For the doors, wooden frames will be placed and on top steel will be placed as support. 6. Finally the desired deck is placed with the building installations above and a compression concrete layer is applied. Figure 17: Construction process BE MORE 3D [74] A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 97 BIM and Augmented reality for waste reduction As previously mentioned the generation of waste in the construction activities is one of the great concerns for the achievement of sustainability in the sector. The waste generation is produced manly at the end of life in the demolition process; however, due to inefficient planning, poor quality of materials, low skilled workers or bad site management activities, a considerable amount of waste is generated during the construction process. Digital technologies represent a great opportunity for the management of waste, providing tools for reducing the waste along the lifecycle of buildings. A well-known simulation tool in the construction sector that is becoming essential for all the construction sector stakeholders is the Building Information Modelling (BIM), it can be defined as the digital representation of the physical and functional characteristics of a facility that allows for design, construction and operation process that forms a reliable basis for decision-making during its lifecycle [75]. Augmented Realty applications shows as well a great potential for construction operations particularly combined with BIM systems as it will be shown in the following paragraphs. BIM and AR application for improving construction performance The construction industry is based on project works usually subjected to cost overruns and schedule deviations; in fact 70% of the projects are affected by time delays, with 14% of the project contract sum consumed by cost overruns and 10% of project materials ending up as waste [75]. The main cause of this misalignment is mainly due to problems and deficiencies in the management of construction processes, the authors in [75] identified the following as the main ones:  Low labor productivity causing costs and time overruns.  Low productivity caused by waste generation due to inefficient construction planning and site management, poor quality, ineffective control and lack of information.  Lack of automation in controlling and monitoring construction works, as managers often use paper-based or simple IT tools that do not efficiently control the progress and performance.  Lack of information, which often leads to communication issues and construction errors. In order to address some of the previous problems the development of the AR4C tool started, a BIM-based application enhanced with AR technology and combined with a location based A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 98 management system. Developers have already created similar applications and some of them are already available in the market, however AR4C is characterized for providing a one field tool that is able to support lean construction on site and the visualization of content to streamline information related to the project and the construction process, it allows for a monitoring of project evolution according to the lean methodology and a location based visualization of construction progress and performance [75]. Figure 18: AR4C application used in construction site [75]. The proposed solution of AR4C aims to improve performance of construction such as productivity, quality of work and information flow. Productivity will be enhanced by implementing monitoring of the construction on a daily basis in a specific location of the project. By overlaying a 3D BIM model on the real world using AR according to [75] the following tasks will be achieved:  Project control via rapid identification of deviation from project schedule as well as variation in performance and progress.  Increment in quality of construction work by providing context specific information on tasks, building components and materials anywhere and anytime.  Verification of construction work by linking quality checklists to each construction task.  Streamline the information flow by displaying tailored information for each construction task. The AR4C application prototype is still in its development phase and it is already showing promising results, when used for the construction of a school according to the architects and A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 99 site managers the construction progress and performance metrics reduced the time needed by 50% compared with conventional procedures, however it has also revealed some problems in the alignment of the 3D building in AR as the model was not always perfectly superimposed above the real objects [75], a feature that should be improved in order to deliver an efficient application. BIM for buildings’ End-of-Life scenarios Building Information Modelling is an adequate tool for implementing circular economy practices into the building sector, as it has the capability to accumulate lifecycle information about a building facilitating the whole life management of a building from planning to operation. When it comes to the proper assessment of the End-of-life phase of the buildings, BIM has shown a considerable potential mainly in the reduction and management of the waste generated during the demolition and dismantling process. BIM allows for the introduction of new layers of information to each object in order to prepare them for future EoL operations such as deconstruction guidelines, environmental assessments or legal requirements [76]. For deconstruction activities having a digital model of the building helps with monitoring the overall status and health of the components as well as getting access to the planned deconstruction guidelines. Moreover, deconstruction is an activity that can take place 50 years or more from the time the building is designed and constructed, normally new parties that didn’t took place in the Beginning of Life phase of the building will require information about the quantities and qualities of materials as well as the need to perform necessary measures, BIM provides access to all this required information whenever needed [76]. In order to obtain the maximum value from the EoL of a building by recycling or reusing its materials the building components must be effectively retrieved after the lifecycle of the building is finished. Design for Deconstruction (DfD) has proven to be the best strategy to effectively maintain the value of the building materials at the end of the building’s lifecycle; nevertheless DfD is not a guarantee for a successful deconstruction process as it is dependent on technical and non-technical success factors. Some studies appearing in [76] have proven how the implementation of BIM models for DfD strategies certainly enhance the deconstruction process, as BIM helps with the estimation of EoL properties of materials while improving the disassembly process. A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 100 Recycling and recovery in the Electronics and ICT sector The massive increase in the usage of new technologies has led to an over production of electronic and electrical equipment, fast product upgrades and technological trends are incrementing product obsolescence, driving shorter product life usage and generation of waste. In fact, in the EU this source of waste has become one of the fastest growing ones with an annual increment of 2% and an estimated recycling rate of less than 40% [65]. This particular waste named as ’e-waste’ or Waste Electrical and Electronic Equipment (WEEE), is of particular value as electronic devices have high demand for earth elements and precious metals. In particular ‘smartphones’ as shown in Figure 19 can be made of 30 different elements of the periodic table some of them being in serious threat for their availability like Yttrium (Y) or Arsenic (As), and others considered hazardous as they suppose a threat to the environment if the products are not adequately treated before ending up in a landfill. Figure 19: Phones’ elements periodic table [77] In the last years European countries, United States or Japan have implemented strict measures regarding the dispose of consumer electronics, however this has ended up with illegal transportation of waste from developed to non-developed countries, where the so called informal recycling is performed. The reasons for this movement of waste through the world is mainly due to economic reasons; less developed countries as India, China or Nigeria are A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 101 becoming the perfect places for these practices as their status of labor, the economies of scale and the lack of regulations and taxes are ideal supporters of this situation [78]. Even though the process of recycling is still conducted in these countries, the fact that these countries have less environmental regulations and the recycling process are inefficiently performed, suppose a real threat to the sustainability of the process. Another critical issue is the low collection rate of WEEE, which as identified by [78] is mainly related with the lack of information about the production, consumption and disposal of the electronic products. This ends up with a legislation based on statistical data that in most cases is quite far from reality, generating inefficient measures and also overlooking the environmental impacts that informal recycling could be generating. The last design improvements that generate better marketability and durability of the products also create recycling challenges in the separation of the components and material recovery, for example lamination of components in Printed Circuit Boards (PCB) increase durability of components while reducing their size but hinder the disassembly and recovery of materials [79]. The authors in [80] according to experts’ opinions identified the following barriers as the most common ones for implementing component recovery and material recycling of e-waste:  Quantity recovery processes. The volume and diversity of WEEE, difficult the establishment of universal operations. Disassembly processes are hinder by product miniaturization and materials are hardly differentiated.  Lifetime. Products’ lifetime are unpredictable, used materials are easily broken during material recovery and their status is not easily recognizable. The fast evolution of the market is an obstacle in reallocation of recovered products.  Recovery cost. In some cases the recovery process is more expensive than the purchasing of new products due to the special facilities and skilled operators required. Transportation is also a drawback as in many countries hazardous materials need specific permissions for being transported.  Awareness. The current markets lack of awareness of social and environmental factors is a barrier for resource recovery activities. Consumers usually prefer brand new products than the ones made from recovered products. Disposal points are unfamiliar for many consumers and in many countries are just parts of the municipal waste. A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 102  WEEE chain. The recovery network involves many participants and its complex to manage without proper information; particularly end users are the less involved ones. Some of these above mentioned barriers could certainly be minimized with the implementation of eco-design strategies that will reduce the hazardous material compositions and will ease product disassembly and recovery processes, also adequate legislations and policies will make producers and consumers more aware of the existing problems and will mitigate risky activities. In the next section some proposed solutions involving the adoption of new industry 4.0 technologies tacking the challenges in disassembly process and WEEE chain management will be analyzed. Apple’s Daisy robot Autonomous Robots have not been included in the previous chapter of the key Industry 4.0 technologies as they are considered to be a quite well known and settled technology, nevertheless they are significantly important in the implementation of this new industry. Autonomous Robots are essential for achieving flexibility in the production system and when supported with smart ecosystems they can enhance the production processes to the next level. The following case study exemplifies how a robot can support a recovery process almost impossible for manual work. With the ambition of achieving a usage of only recycled and renewable materials in the near future, Apple among other initiatives has designed a robot capable of separating components and recovering materials of a total of 15 different iPhone models. Daisy, the new model of this robot is capable of disassemble 200 phones per hour and in the year 2017, a model of the robot located in Austin processed 1 million in total. The principal aim of the robot is to remove and sort components in a way that materials can be recovered with a higher quality and quantity than traditional recyclers. As mentioned before the disassembly process is one of the main problems of material recovery in the electronic products, Daisy is able to successfully sort the components which then are sent to the recycling plants where the materials are easily separated and recycled [81]. The robot starts by separating the screen and the phone body by introducing a set of prongs between them, then the screws are removed and the battery that is glued to the A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 103 phone’s body is removed by blasting the glue with freezing air and then knocking it with enough force. After that the logic board is separated by punching out the screws that hold it, for doing so the robot has to first identify the phone model. Finally, Daisy removes the cameras, haptics, speakers and other bits. Figure 20 shows the final disassembled pieces after the process, indicating the material of each piece and the potential for material recovery of every 100,000 phones. Figure 20: Components and materials disassembly robot Daisy recovers [81] A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 104 Digital Twin and Cloud Computing for WEEE chain management The supply chain management of e-waste is as mentioned before, one of the main challenges in the deployment of an efficient recovery system. Researchers have been working in several solutions for these problems by implementing digital systems into the management structures, for instance in [78] the researchers proposed a system based on BigData applications where IoT devices are used to record and collect information along the product lifecycle allowing for a full monitoring of the waste and the recycling activities. A similar but more complex approach based on the capabilities of Digital Twins is provided by [82] and is introduced in the following chapters. Tracking products’ status along their value chain is of great importance as remanufacturers and recyclers need deep knowledge of the product to effectively perform the required operations. However, in practice the actual system does not enable the acquisition of this information. A big portion of the product lifecycle information is lost during the product development and manufacturing, also the information flow is almost stopped when the product arrives to the end user, examination of products performed by product collectors can recover some amount of lost information but still the system remains ineffective in communication terms [82]. System integration, data utilization and connectivity are identified as the main challenges in the development of a WEEE management system; Digital Twin according to [82] shows high potential in solving these challenges by merging the data from the physical world and the software into a cyber world. DT can be assumed as the key to achieve a cyber-physical system bridging the cloud systems and the data from physical objects (IoT) or from other historical or software sources (BigData). The proposed scheme or system architecture provided by [82] for data integration of the DT model is structured as follows: 1. Product design. The digital twin is initiated based on the knowledge from the product design and development phase. Geometry, components, materials and hazardous substances are the data input for the model. 2. Product status. When the product is sold to the end users, they have to update the product status via mobile apps, smart tags, websites or similar tools. Changes in product location and ownership or performed upgrades and repair operations are loaded in the model. A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 105 3. Logistics and exam results. Once the product comes to the end of its life the consumer dispose the product in an adequate collection point that is indicated trough the mobile app or website. After the collection the product can be examined and updated in consequence, with all the available information of the model the recovery operations are planned. 4. Recovered materials or components. The recycler or remanufacturer initiates the operations without the need of additional test or evaluation as all the needed information is stored in the DT. All the information of the recovered or reconditioned components is recorded in the new product’s model. The architecture model of the proposed Cyber Physical Systems is shown in Figure 21 where the computing resources needed and the information exchange along the different product lifecycle phases is characterized. Figure 21: WEEE digital twin-enabled cyber-physical system [82]. The computing capabilities of the system are supported by a Cloud Computing environment that contains and provides the computing modules when needed. Through the product beginning of life all the operations and data gathering is coordinated by the Product Lifecycle Management (PLM) and Enterprise Resource Planning (ERP) systems. The product design begins with the CAD module where functional and environmental features of the products are documented. 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A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 119 Appendix 1 In this appendix the lifecycle design strategies proposed in [21] are showed A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 120 A review of Industry 4.0 potential to accelerate the transition to a Circular Economy 2020 121 Appendix 2 This appendix gathers the information about the circular economy drivers proposed in [61]:  Extending the use cycle. Extending the lifetime of products, components and materials enables the reduction of raw materials in production processes and reduces the overall need for new assets. As previously mentioned most of the potential for extending the life of assets comes from the design phases where activities that cycle back materials and components and repair or maintenance activities are planned.  Increasing the utilization. The utilization of an asset can be maximized either by sharing the access or by increasing resource productivity in operations. Into this value driver it is also includes designing out negative externalities and the use of renewable resources.  Looping trough additional use cycles. Assets coming to their end-of-life can be cycled back with reuse strategies where the asset is use by a new user, remanufacturing process that enables the user to reenter the cycle or recycling where the materials of the used asset replace virgin ones.  Regeneration of natural capital. Natural ecosystems should maintain and enhance their long term productivity by undertake the necessary actions. This preservation serves as foundation to maintain the value of natural resources and support sustainability.