Material Flow Model Research Articles

High-quality recycling through self-learning and resilient recycling networks using a combination of agent-based modelling and life cycle assessment

Especially in the case of long-lived products, the crucial questions about the proper implementation and assurance of high-quality recycling targets often only arise after decades. Furthermore, information about material composition is often not sufficiently known and communicated to the end user. With the presented extended socio-technical approach of a self-learning and resilient recycling network, which should include manufacturers and operators of wind farms, dismantlers, waste processors and recyclers, as well as authorities and players from research and development, such problems can be adequately addressed. On the one hand, this requires knowledge tools to ensure a high-quality material cycle, such as databases in which installed products and their characteristic values for the masses and materials used are documented. In addition, material flow modeling to track material flows generated for the end-of-life (EoL) of products including life cycle assessments of recycling and disposal routes, as well as forecasting tools for expected waste volumes are needed. On the other hand, a simulation tool such as agent-based modeling (ABM) is also needed to map courses of action and their impacts, taking into account stakeholders’ interests in terms of target formulation of the recycling network. The example of wind turbine rotor blades is used to show how such an approach can be used for a meaningful recycling network, which supports the operator responsibility of wind farms as well as the extended producer responsibility of wind turbines with regard to sustainable recycling of long-lived products. The developed tools and especially their active combination are presented. In addition, the example of rotor blades is used to present the concrete possibilities for resource-saving control of the material flows.

How will tramp elements affect future steel recycling in Europe? – A dynamic material flow model for steel in the EU-28 for the period 1910 to 2050

Global steel production has undergone massive growth since WWII. In recent decades, however, affluent regions such as the US and the EU-28 have been experiencing a saturation of the steel market. Stagnant steel production volumes and increased post-consumer scrap volumes are the consequence. The increasing shares of post-consumer scrap provide the opportunity to increase the scrap rate (share of utilized scrap) in crude steel production. However, steel recycling has a major limiting factor: the content of specific tramp elements.In the present study, a dynamic material flow model for steel is used to compare available scrap with crude steel demand on a quantitative and qualitative level (tramp element content of Cu, Ni, Mo, Cr and Sn). The results show that post-consumer scrap increases from 80 Mt/yr (65% of all scrap available) in 2020 to more than 100 Mt/yr (75% of all scrap available) in 2050. Based on the model, the development of the yearly surplus of low purity scrap (for which there is a higher supply than demand) was assessed via material pinch analysis. The low purity scrap surplus rises further, from today's 20 Mt/yr (2020) to 43 Mt/yr in 2050. Assuming that the current handling of scrap continues, the maximal scrap rate is shown to lie at around 55%, while the potential scrap rate (without quality constraints) could reach 75%. The dilution of low purity scrap with high purity resources would allow the utilization of all scrap until 2040 if the current collection scheme remains in place.

Building Circularity Assessment in the Architecture, Engineering, and Construction Industry: A New Framework

Circular Economy (CE) has proved its contribution to addressing environmental impacts in the Architecture, Engineering, and Construction (AEC) industries. Building Circularity (BC) assessment methods have been developed to measure the circularity of building projects. However, there still exists ambiguity and inconsistency in these methods. Based on the reviewed literature, this study proposes a new framework for BC assessment, including a material flow model, a Material Passport (MP), and a BC calculation method. The material flow model redefines the concept of BC assessment, containing three circularity cycles and five indicators. The BC MP defines the data needed for the assessment, and the BC calculation method provides the equations for building circularity scoring. The proposed framework offers a comprehensive basis to support a coherent and consistent implementation of CE in the AEC industry.

The impact of climate policy implementation on lithium, cobalt and nickel demand: The case of the Dutch automotive sector up to 2040

The Dutch national climate agreement (‘Klimaatakkoord’), stipulates a 49% decrease in greenhouse gas (GHG) emissions by 2030, relative to the 1990 level. To accommodate this target, the passenger vehicles sector must reduce its GHG emissions by 30% in 2030, which likely will come about by replacing internal combustion engine vehicles with electric vehicles. In this study, a dynamic material flow model combined was applied to investigate the future demand for (and metabolism of) lithium, cobalt, and nickel within various scenarios of Dutch electric vehicle markets stemming from climate policy implementation. Our results show that by 2040 the demand for electric vehicles rapidly grows by an order of magnitude, which expands by two orders of magnitude the annual accumulation of these metals in the Netherlands when compared to the 2019 levels. Lithium and nickel demand will keep increasing through 2040, while the demand trend of cobalt will start to drop after 2030, due to changes in battery technology. Increasing the EV driving range and replacing EV batteries during an EV lifetime will increase the demand for these metals by 10%–19%. Conversely, extending the average battery lifetime to meet the vehicle lifetime could reduce the demand of these metals by 30%. Due to the low open-loop recycling of these metals, policies must seek to minimize their presence in the electric mobility sector, while also stimulating better recycling practices and infrastructure. • The demand for electric vehicles (EV) and Li, Co and Ni used in the EV batteries will be accelerated under the promotion of the Dutch climate policy. • The innovation in battery cathode technology is one of the factors to diversify the requirements of raw materials. • The extension of battery service life is important to lessen the demand for primary materials.

Repercussions of clinical waste co-incineration in municipal solid waste incinerator during COVID-19 pandemic

During coronavirus disease 2019 pandemic, the exponential increase in clinical waste (CW) generation has caused immense burden to CW treatment facilities. Co-incineration of CW in municipal solid waste incinerator (MSWI) is an emergency treatment method. A material flow model was developed to estimate the change in feedstock characteristics and resulting acid gas emission under different CW co-incineration ratios. The ash contents and lower heating values of the feedstocks, as well as HCl concentrations in flue gas showed an upward trend. Subsequently, 72 incineration residue samples were collected from a MSWI performing co-incineration (CW ratio <10 wt%) in Wuhan city, China, followed by 20 incineration residues samples from waste that were not co-incineration. The results showed that the contents of major elements and non-volatile heavy metals in the air pollution control residues increased during co-incineration but were within the reported ranges, whereas those in the bottom ashes revealed no significant changes. The impact of CW co-incineration at a ratio <10 wt% on the distribution of elements in the incineration residues was not significant. However, increase in alkali metals and HCl in flue gas may cause potential boiler corrosion. These results provide valuable insights into pollution control in MSWI during pandemic.

Form-Specific and Probabilistic Environmental Risk Assessment of 3 Engineered Nanomaterials (Nano-Ag, Nano-TiO2 , and Nano-ZnO) in European Freshwaters.

The release of engineered nanomaterials (ENMs) to the environment necessitates an assessment of their environmental risks. The currently available environmental risk assessments (ERA) for ENMs are based on an analysis of the total flows of a specific ENM to the environment and on ecotoxicity studies performed with pristine ENMs. It is known that ENMs undergo transformation during product use and release and in technical systems such as wastewater treatment. The aim of the present study was therefore to perform an ERA of 3 ENMs (nano‐Ag, nano‐TiO2, and nano‐ZnO) based on a form‐specific release model and a form‐specific analysis of ecotoxicological data. Predicted environmental concentration values were derived using a form‐specific material flow model. Species sensitivity distributions were used to derive predicted‐no‐effect concentrations (PNECs) for the pristine ENMs and for dissolved and transformed Ag and ZnO. For all ENMs, the matrix‐embedded form was included in the assessment. A probabilistic assessment was applied, yielding final probability distributions for the risk characterization ratio (RCR). For nano‐Ag, the form‐specific assessment resulted in a decrease of the mean RCR from 0.061 for the approach neglecting the different release forms to 0.034 because of the much lower PNEC of transformed Ag. Likewise, for nano‐ZnO, the form‐specific approach reduced the mean RCR from 1.2 to 0.86. For nano‐TiO2, the form‐specific assessment did not change the mean RCR of 0.026. This analysis shows that a form‐specific approach can have an influence on the assessment of the environmental risks of ENMs and that, given the availability of form‐specific release models, an updated ERA for ENMs can be performed. Environ Toxicol Chem 2021;40:2629–2639. © 2021 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

The multidimensional effects of single-use and packaging plastic strategies on German household waste management.

Single-use and packaging plastic (SUPP) strategies are intended to transform the linear make-use-dispose economy of SUPPs into a more circular, resource-efficient one. The aim of this study was to identify optimal SUPP management concepts from a circular-economy-perspective by assessing the effects of different SUPP strategies on household waste management. Data on the generation and management of SUPP-containing household waste in Germany in 2017 were compiled and a material flow model was established. Regulatory SUPP strategies were translated into scenarios (with effects on waste generation and waste composition) and implemented in the material flow model. The effects on material efficiency, waste generation and lower heating values were evaluated and trade-offs between these target dimensions were identified. In Germany in 2017, 32kg per person and year of SUPP household waste were generated, of which 28kg per person and year was packaging waste. From a material efficiency perspective, the combination of banning specific non-packaging SUPPs and optimizing source-separation leads to the maximum increase in final recycling rates of SUPPs in household waste, from 38% to 50%. However, in this scenario the amount of SUPP-containing household waste is hardly reduced as compared to the status quo. The trade-offs observed in different waste management target dimensions highlight the importance of understanding the systemic effects of SUPP strategies on waste management in order to identify optimal solutions from a circular-economy-perspective.

Sorting and Recycling of Lightweight Packaging in Germany \u2014 Climate Impacts and Options for Increasing Circularity Using Tracer-Based-Sorting

This paper elaborates an energy and material flow model for conventional lightweight packaging sorting and recycling in Germany based on literature analysis and information provided by industry experts. The model is used to determine specific energy and material demands of particular lightweight packaging fractions and their respective climate impacts. Fluorescent-based identification techniques, tracer-based-sorting in particular, are assessed as an option to increase material circularity due to improved sorting and recycling accuracy. In comparison to primary production of lightweight packaging, conventional sorting and recycling saves 565 kg CO2-eq./Mg of input sorting. A total of four implementation scenarios are considered, reflecting the percentage of mixed plastics and residuals that can be mechanically processed through improved sorting (10%, 50%, 90% and 100%). Using tracer-based-sorting, these savings increase from 578 up to 1227 kg CO2-eq/Mg depending on implementation scenario. This paper concludes that tracer-based-sorting can contribute to an environmentally benign circular economy by yielding high-quality regranulates, which are capable of substituting more carbon-intensive primary production of lightweight packaging.

An Approach to Improving the Mechanical Properties of Friction Stir Spot Welded Joints on the Basis of Hook Formation Mechanism

Background: Partial metallurgical bond (namely 'hook') is formed between the overlapped metal sheets during friction stir spot welding (FSSW). The geometry of hook is found to significantly affect the mechanical performance of FSSWed joints, while that how to adjust hook geometry to a better state remains to be studied. Methods: The conventional FSSW joints under different plunge depths and dwelling time were obtained. The cross-sectional morphology of each spot weld was investigated to clarify the material flow behavior and deduce the formation mechanism of hook. The tensile shear strength and fracture features were examined to reveal the effect of hook geometry on the mechanical properties. Results: The weld geometry affects the tensile shear strength of FSSWed joints by determining their fracture modes. The formation mechanism of hook is deduced by a material flow model. In the toolplunging stage, the faying interface is broken by upward-flowing materials, hook is therefore initiated and driven up gradually. During the tool-dwelling stage, hook continues to migrate to the lowpressure zone, surrounding the stir zone. Conclusion: The uncertainty of crack-propagating endpoint along hook makes it difficult to ensure the mechanical properties of welds. If the hook endpoint has not yet reached the low-pressure zone at the end of welding process, welds with ideal hook geometry can be obtained. Target friction stir spot welds were produced by the use of a tool possessing smaller pin diameter.

Representation, Propagation, and Interpretation of Uncertain Knowledge in Dynamic Probabilistic Material Flow Models

The determination of the environmental concentration of a pollutant is a crucial step in the risk assessment of anthropogenic substances. Dynamic probabilistic material flow analysis (DPMFA) is a method to predict flows of substances to the environment that can be converted into environmental concentrations. In cases where direct quantitative measurements of concentrations are impossible, environmental stocks are predicted by reproducing the flow processes creating these stocks in a mathematical model. Incomplete parameter knowledge is represented in the form of stochastic distributions and propagated through the model using Monte Carlo simulation. This work discusses suitable means for the model design and the representation of system knowledge from several information sources of varying credibility as model parameter distributions, further evaluation of the simulation outcomes using sensitivity analyses, and the impacts of parameter uncertainty on the total uncertainty of the simulation output. Based on a model developed in a case study of carbon nanotubes in Switzerland, the modeling process, the representation and interpretation of the simulation results are described and approaches to sensitivity and uncertainty analyses are demonstrated. Finally, the overall approach is summarized and provided in the form of a set of modelling and evaluation rules for DPMFA studies.

Effective Designing of Order Picking Systems Using Dynamic Simulation

In this article, we describe the use of dynamic simulation when designing an effective system for order picking within a distribution warehouse. The simulation model was created in the Witness software environment for discrete dynamic simulation and is a modification of a general simulation model of material flows in supplier systems. Using the example of a batch system for picking orders in a drugstore goods warehouse, we discuss the possibilities of using a general simulation model of material flows as an effective framework for the development of system support for warehouse processes using WMS. The simulation model is based on the possibility of dividing any material flow in the supply system into a finite number of movements with the possibility of using one of the sources and fulfilment of certain conditions. In order to achieve the required optimisation of the order picking system, which depends, in particular, on the unknown duration of goods collection at the picking location, and on the duration of goods sorting in consolidation, the &#8220;what-if&#8221; analysis has been used as a tool to measure the impact of uncertainty of one or more variables entering the model on the uncertainty of output variables. The study showed that minimisation of the number of physical elements in the model leads to a significantly higher speed of its operation. By means of dynamic simulation, it is possible to test a large number of variants of the picking system layout in a relatively short time and minimise the risk of erroneous decisions associated with the implementation of a suitable WMS.

Study on in-situ material flow behaviour during friction stir welding via a novel material tracing technology

• The proper tracer materials were used to reflect the real material flow rule in friction stir welding process. • The material flow characteristics in different positions of stir zone has been extensively studied in terms of displacement,flow path, rotation angle and driving force. • The material flow model in different horizontal planes of the welds were established. A novel material tracing technology was proposed using ER2319 aluminium alloy welding wire as the tracer material to study the material flow behaviour at different positions of friction stir welded 6061-T6 aluminium alloy joint. Having been influenced by temperature and driving force of the tool, the displacement of all the tracer materials deposited behind the original position during welding decreased gradually from top to bottom of the stir zone (SZ). The advancing side (AS) and the retreating side (RS) of the SZ are dominated by the shear action and the extrusion action, respectively. The extrusion force and friction force are the driving forces for material flow during friction stir welding. The material flowed downward at the AS and upward at the RS in the vertical plane of the joint, while the material of the SZ flowed to the back of the tool through the RS in all the horizontal planes of the joint. The flow path of tracer material in most positions of the SZ is arc shaped, however, it is a complex curve in the SZ bottom at the AS due to the poor material flowability. The rotation angle of the tracer material decreased from AS to RS of the SZ and from top to bottom of the SZ.

Combining Process Modelling and LCA to Assess the Environmental Impacts of Wastewater Treatment Innovations

Alternative wastewater treatment (WWT) technologies with lower environmental impacts seem to be the way forward in the pursuit of sustainable wastewater treatment plants (WWTPs). Process modelling of material and energy flows together with life-cycle assessment (LCA) can help to better understand these impacts and show the right direction for their development. Here, we apply this combined approach to three scenarios: conventional WWT; conventional WWT + chemically enhanced primary treatment (CEPT); conventional WWT + CEPT + side stream partial nitritation/anammox (PN/A). For each scenario, equations were developed to calculate chemical oxygen demand and nitrogen flow (solid and dissolved form) through the WWTP and to estimate the energy demands of its unit operations. LCA showed that the main environmental impact categories for all scenarios were global warming potential (GWP), eutrophication potential (EP) and marine aquatic eco-toxicity potential (MAETP). Compared with conventional WWT, CEPT and CEPT combined with PN/A resulted in a higher sum of normalized and weighed environmental indicators, by 19.5% and 16.4%, respectively (20.0% and 18.3% including biogenic carbon). Interestingly, the environmentally positive features of the alternative scenarios were often traded-off against other increased negative impacts. This suggests that further development is needed to consider these technologies a sustainable alternative.

Towards biofuel generation III+: A sustainable industrial symbiosis design of co-producing algal and cellulosic biofuels

The emergence of environmental and sustainability regulations as well as the limited availability of fossil fuels have brought the notion of gradually substituting petroleum products with biofuels into the limelight. The commercialization and large-scale adoption of cellulosic biofuel (second-generation biofuel) and microalgae biofuel (third-generation biofuel) have been hampered by their poor economic performance. Although the production wastes of biofuel can be utilized as input materials to enhance resource utilization efficiency, environmental sustainability and economic viability in each generation, rarely existing research has been conducted on the integration between these two generations. To fill this research gap, a novel industrial symbiosis (IS) design for the co-production of second- and third-generation biofuels is proposed in this paper. The material flow, energy flow, cost performance, and environmental impact models are established considering the interactions of stakeholders in the IS system. Four scenarios, consisting of the baseline case without IS and three IS cases with different microalgae species, are comprehensively compared in terms of various economic and sustainability performance indicators. Compared to the baseline case, the results reveal that the synergies in the bioenergy IS system render an annual manufacturing cost reduction of >10% in all IS scenarios. It is also discovered that the symbiotic design can lead to a 36% reduction in greenhouse gas (GHG) emissions, a 9.4% decrease in eutrophication potential (EP), and a 7.5% reduction in acidification potential (AP) when adopting the same species of microalgae. The synergies among the bioenergy IS system stakeholders are proved to be viable and beneficial to enhance the economic viability and environmental sustainability.

Modeling of material flow in dissimilar friction stir lap welding of aluminum and brass using coupled Eulerian and Lagrangian method

Dissimilar friction stir welding of metals is crucial in terms of inter-material mixing and the intermetallic compound formation which affects the achieving a sound joint with fine mechanical properties. In this investigation, the formation of intermetallic compounds along with the material flow during friction stir lap welding (FSLW) of aluminum and brass is studied. First, the experimental investigations were performed using SEM, EDS, and XRD to probe the chemical compositions and intermetallic formation in the stir zone (SZ). Experimental results show the presence of Al2Cu and Al4Cu9 intermetallics in the SZ while are dispersed in separated zones. Moreover, to study further the material mixing, the coupled Eulerian-Lagrangian (CEL) method is employed to simulate the SZ formation during the FSLW of aluminum and brass. The model successfully predicts the SZ formation and material mixing in the Al/CuZn34 interface with penetration of Al into brass at the center and penetration of earring shape brass into Al sheet at the periphery of the SZ. Results show that two distinct zones inside the SZ could be observed, in which one is filled mostly by Al2Cu intermetallics near the Al sheet and the other is filled mostly by Al4Cu9 near the brass sheet. Additionally, by increasing the tool traverse speed, the amount of inter-material mixing significantly decreases, but on the other hand, the formation of intermetallic phases, which reduces the mechanical properties of the joint, is restricted.

Dynamic flow and pollution of antimony from polyethylene terephthalate (PET) fibers in China

Antimony (Sb), a regulated contaminant, is added as a catalyst in the process of polyethylene terephthalate (PET) synthesis. Previously, Sb release from PET bottles and films was studied. However, Sb release from PET fibers (the most common form of PET) is limited. Therefore, a network model of material flow for PET fibers in China is developed, and the anthropogenic Sb flow and release entering into the hydrosphere, pedosphere, and atmosphere are studied based on microexperiments and macromodels. To compensate for the uncertainty caused by material flow analysis, Sb pollution in the surrounding areas (the drinking water of nearby residents and sediments of nearby river area) is further explored by combining field investigations and sample analysis. The results are as follows: 1) the manufacture stage of PET fibers is the main source of Sb release (2926 t), followed by the dyeing (2223 t) and weaving (908 t) stages; 2) Sb release (1108 t) from waste PET fibers subjected to landfill disposal is the highest. Sb release (872 t) from discarded fiber waste is second highest. Sb release from PET fibers subjected to mechanical recycling, incineration, and chemical recycling is 784, 284, and 25 t, respectively; and 3) an obvious source-sink relationship is found between anthropogenic Sb in the rivers and sediments and the intensity of the industries. This study suggests that Sb from PET fibers should be properly managed to prevent widespread dispersion in the hydrosphere, pedosphere, and atmosphere.

Justification of vibrating hopper hole parameters during fine grained bulk material unloading

Purpose. The leakage process of the fine grained bulk material (BM) from the unloading hopper is considered. As known the BM behaviour during the unloading process is directly related to the material stress state (active or passive) inside the hopper, which depends on the physical and mechanical bulk material properties, as well as hopper geometric parameters. At the boundary of the transition from the cylindrical part to the conical part of the unloading hopper hole, the horizontal stresses that precede the leakage of the material increase sharply. The use of vibration reduces horizontal stresses in the hopper and thus improves the bulk product fluidity. Also, the use of vibration reduces the probability of the free-fall arch formation over the outlet. Therefore, the present paper is aimed at developing the mathematical model of the fine grained bulk material flow under the vibration action from the conical hopper hole. Methodology. It is used one of the methods of studying the BM behavior, namely the analysis of the stress state of the conditionally stationary (pseudo-stationary) layer of the product and the force balance equation in the free-fall arch is made for further study of the geometric parameters of the unloading hole. Findings. In this paper, the mathematical model of the BM behavior in the conical hopper hole is developed. Since the most determining factor influencing the hopper productivity is the outlet diameter, so based on the developed model, it is established relationships that allow determining all parameters that affect the diameter. Graphical dependences are obtained, which allow to estimate the influence of the angle inclination of the hopper hole walls on the value of the hopper outlet size at active and passive stress states. The dependence of the diameter of the unloading hopper hole on the BM properties is also established. The BM properties directly affect the initial shear resistance of the material. The influence of vibration on the unloading hole geometry is presented. Originality. The pseudo-immobile layer of bulk product is considered in the developed mathematical model, and it is investigated how vibration affects the BM behavior in this layer. Practical value. The practical value of this paper lies in the possibility of further mathematical modeling of the influence of the BM properties, hopper geometric dimensions and vibration on the product behavior in the material leakage process from the hopper. The results of the studies, presented in the form of graphs, can be used during the vibrating hopper design and the selection of rational modes of hopper operation.

A novel approach to determine residual stress field during FSW of AZ91 Mg alloy using combined smoothed particle hydrodynamics/neuro-fuzzy computations and ultrasonic testing

The faults in welding design and process every so often yield defective parts during friction stir welding (FSW). The development of numerical approaches including the finite element method (FEM) provides a way to draw a process paradigm before any physical implementation. It is not practical to simulate all possible designs to identify the optimal FSW practice due to the inefficiency associated with concurrent modeling of material flow and heat dissipation throughout the FSW. This study intends to develop a computational workflow based on the mesh-free FEM framework named smoothed particle hydrodynamics (SPH) which was integrated with adaptive neuro-fuzzy inference system (ANFIS) to evaluate the residual stress in the FSW process. An integrated SPH and ANFIS methodology was established and the well-trained ANIS was then used to predict how the FSW process depends on its parameters. To verify the SPH calculation, an itemized FSW case was performed on AZ91 Mg alloy and the induced residual stress was measured by ultrasonic testing. The suggested methodology can efficiently predict the residual stress distribution throughout friction stir welding of AZ91 alloy.

Development of an automated industrial dynamics system

The object of research is the process of determining the main indicators of the functioning of a manufacturing enterprise using the method of system dynamics. Any enterprise for the production and sale of products is a complex socio-economic system that is closely related to the external environment through input and output channels. The external environment determines the conditions for the functioning of the enterprise and can be described by a set of a large number of different parameters, the values of which will dynamically change and are fundamentally indeterminate.Coordination and control over material and financial flows at a manufacturing enterprise is often a separate problem. The interaction of financial resources and material flows, which are selected by the enterprise as the main ones in accordance with market requirements and the specifics of the activity, must be coordinated accordingly to achieve a more efficient operation of the enterprise. Therefore, the task of the presented study is to develop a model of material and financial flows of a production enterprise with its further software implementation. The purpose of the software implementation is to further conduct experiments with the model to determine the main indicators of the production enterprise, depending on changes in the functioning parameters due to the external environment.All the variety of modeling methods considered in modeling theory can be conditionally divided into two groups: analytical and simulation modeling. To solve the problem of this study, simulation modeling was used, which provides for the construction of a model with characteristics adequate to the original on the basis of a certain information principle.In the course of the research, a model of material and financial flows of a production enterprise was built. The mathematical model of flows was developed using the system dynamics method by J. Forrester. An automated system was also developed, which is a software implementation of the proposed model.The automated system of industrial dynamics of a production enterprise developed in the study will significantly increase the efficiency and scientific validity of decisions regarding the management of material and financial resources.

Decarbonization pathways of the Swiss cement industry towards net zero emissions

The present study investigates long-term energy consumption and CO2 emission pathways of the Swiss cement industry, including pathways towards net zero CO2 emissions by 2050. Cement production accounts for 8% (12.8 PJ) of the final energy consumption and 36% (2.5 Mt) of the CO2 emissions in the Swiss industrial sector in 2015. Using a techno-economic bottom-up optimization model based on the TIMES (The Integrated MARKAL-EFOM System) modeling framework, this study applies an advanced modeling technique for the Swiss TIMES Energy system Model (STEM) that expands the modeling of energy flows with additional material and product flow modeling. This allows a more detailed technology representation as well as to account for process related emissions in the cement sector. This modeling framework is applied for a scenario analysis focusing on energy efficiency as well as decarbonization, which ultimately contributes to an improved understanding of energy technology development and identifies policy strategies for the realization of a decarbonized cement industry. The results show that, in accordance with current trends, future cement production reduces its specific energy consumption from 3.0 GJ/tcement in 2015 to 2.3 GJ/tcement in 2050. Simultaneously, cement production decreases its CO2 emission intensity from 579 kgCO2/tcement in 2015 to 466 kgCO2/tcement in 2050 due to the decreasing average clinker content in cement and energy efficiency improvements. Even without major climate policy intervention in the future, it is economically beneficial to replace and improve the existing equipment with more energy efficient technologies. However, our results show that for a drastic reduction of the CO2 emissions in order to comply with the goals of the Paris Agreement, the cement sectors relies on CO2 capture because of the process related emissions. The results show that a minimum CO2 tax of 70 EUR/tCO2 is required for the CO2 capture technologies to become economically competitive.