Material Flow Model Research Articles

Analysis of energy, exergy and CO2 emissions in a fiberglass furnace with oxy-fuel combustion

Energy savings and emission reductions in the building materials industry are key components of China’s “dual carbon” goals. A new mathematical model of material, energy, exergy, and carbon flows was established and verified against operational data for an 80600 t/y fiberglass furnace in China. The model enables thermal budget calculation along different paths and analysis of the losses and saving potential of the entire fiberglass melting furnace and its three major subsystems. The results indicated that the selected fiberglass furnace attained a satisfactory performance with a specific energy consumption of 4.63 MJ/kg and an energy efficiency of 74.76%. Oxy-fuel combustion provided a substantial overall fuel reduction relative to air combustion. Moreover, the exergy efficiency and effective exergy efficiency reached 62.85% and 55.23%, respectively. The heat recovery system increased the exergy efficiency by 11.01%. Furthermore, the CO2 emissions associated with glass production, major contributors, CO2 reduction potential, and economic impact were obtained. Finally, a sensitivity analysis of the combustion chamber was conducted. This approach could identify the degree of resource and energy utilization and support the implementation of energy and exergy efficiency improvement and CO2 emission reduction schemes.

Mapping Provincial Stocks and Wastes of Passenger-Vehicle Plastics in China Based on Dynamic Material Flow Analysis and GIS: 1985–2019

As a polymer material, plastic is widely used in passenger vehicles for its light weight and low-cost advantages. China has accumulated a large amount of discarded automotive plastic in recent years, which has put increasing pressure on the environment and the recycling industry. A dynamic material flow model for estimating the plastic stock and waste in passenger vehicles was developed. Additionally, geospatial models were used to study the spatiotemporal evolution trend of passenger vehicle plastics. The results show: (1) passenger-vehicle plastic stock and waste in China increased rapidly from 1985 to 2019. By 2019, the passenger-vehicle plastic stock was 36.94 million tons, and the waste amount was 1.64 million tons, of which polypropylene accounted for the greatest proportion, and polyoxymethylene (POM) accounted for the least. (2) The stock and waste of passenger-vehicle plastics showed spatial dependency. (3) The spatial center of plastic waste was located in Henan Province, and the spatial center is shifting from north to south. (4) The GDP and the annual population are the main driving factors of passenger-vehicle plastic waste. This study will improve plastic waste management, resource recovery, and environmental sustainability decisions.

An integrative and prospective approach to regional material flow analysis: Modeling the decarbonization of the North Rhine‐Westphalian steel industry

AbstractNorth‐Rhine Westphalia is the center of the German and European steel production. Its steel industry is heavily based on the primary production route and emits up to 30 Mt CO2 annually. One possible and increasingly prominent alternative to reduce these emissions is the hydrogen‐based direct reduction. While this technology allows for a near climate‐neutral production of primary steel, it poses substantial impacts on regional energy and material flows. Hence, the aim of this paper is to quantify the alterations in energy and material flows over time via integrating top‐down energy and material flow models with bottom‐up process models. The resulting values of emissions, energy, and material flows are then used to develop prospective scenarios that depict the requirements and consequences of potential pathways toward a climate‐neutral steel production by 2045. The outcomes show that decarbonizing the North Rhine‐Westphalian steel industry leads to an additional demand for renewable energies of up to 52.5 TWh per year, which represents 10% of the current electricity production in Germany. As securing the green electricity demand is a large challenge, the study also analyzes the impact of a partial recourse to natural gas as a reducing agent in combination with other measures like carbon capture and utilization/storage. The results show that such a recourse would reduce the electricity demand to 36.8 TWh. Hence, the paper illustrates relevant implications of the different scenarios, which can be used by policymakers to develop more realistic and resilient strategies for reaching carbon neutrality.

A bottom‐up ontology‐based approach to monitor circular economy: Aligning user expectations, tools, data and theory

AbstractWith circular economy being high on governmental agendas, there is an increasing request from governing bodies for circularity measurements. Yet, currently existing macro‐level monitoring frameworks are widely criticized for not being able to inform the decision‐making. The criticism includes, among others, a lack of consensus on terminologies and definitions among scholars, politicians, and practitioners, a lack of supporting data and tools and, consequently, a lack of transparency and trustworthiness. To address those needs, a bottom‐up approach to build a shared terminology is suggested as a starting point for monitoring development. The government, data providers, and tool developers are involved in the process of formal ontology development and alignment. The experiment builds upon a use case of the Amsterdam Circular Economy Monitor (2020). First, four ontology development approaches are used to create a theory‐centered, a user‐centered, a tool‐centered, and a data‐centered ontology. The ontologies are later compared, merged, and aligned to arrive at one single ontology which forms the basis of the circular economy monitor. The notes taken during the process have revealed that next to a material flow model, typical of socioeconomic metabolism analysis, policy makers are concerned with actors (i.e., institutions, companies, or groups of people) who participate in the analyzed processes and services. Furthermore, a number of terms used by the decision‐makers lack clear definitions and references to be directly associated with the available data. Finally, a structured terminology alignment process between monitor users, developers, and data providers helps in exposing terminology conflicts and ambiguities.

Insights into circular material and waste flows from c-Si PV industry

A material flow model for the production of Bifacial Selective Emitter 60-cell p-type Cz PERC (Passivated Emitter and Rear Contacted) glass-backsheet modules with aluminium frame was built. The selected module represents mature technologies in the PV industry and their manufacturing is considered to take place in China in a production cluster with an annual module capacity of 5 GWp. In a first step, data acquisition and validation for wafer, cell and module fabs took place. The data were used to generate the reference system lifecycle inventories (LCI) and extended waste databases for the reference wafers, cells and modules. A set of potential circularity actions, such as the vertical integration of the operations and waste revalorisation strategies, had been proposed and their environmental performance and cost assessed by means of a life cycle assessment (LCA) and a total cost of ownership (TCO). Our results show that 87% of the waste can be reduced and revalorised, this represents a circular flow of raw materials of 18,756 Mg per year from a 5GWp PV module production cluster. Environmental impact reductions of 0.6–2.3% are estimated for different impact categories. We also estimate a cost reduction potential of 2.59% from total module costs.

Systematic assessment of food traceability information loss: A case study of the Bangladesh export shrimp supply chain

Traceability information systems in food supply chains (FSCs) can suffer from information loss, and this can cause food safety crises and economic downturns around the world. Information loss happens as a result of inefficiencies in material and information flows caused by the vulnerabilities associated with either the internal traceability systems of individual FSC operators and/or external traceability systems between them. A structured comprehensive approach to identify and analyse these vulnerabilities in an entire FSC encompassing both of its internal and external traceability systems is still absent in the literature. This paper develops a systematic information loss assessment technique, modifying and integrating Failure mode effect and criticality analysis (FMECA) and a traceability modelling tool, Material and information flow modelling technique (MIFMT). To demonstrate the proposed method, the study uses data derived from a primary case study on Bangladesh export shrimp supply chain comprising a farm, a depot and a processor. Providing standardised visualisation and quantitative information loss evaluation, the proposed method offers a systematic approach for analysing vulnerabilities in the food traceability system. The results of this approach are used to make specific reengineering suggestions to improve the existing shrimp traceability system in Bangladesh. The proposed method could be applied widely in various FSCs to support systematic reengineering e.g. blockchain and IoT implementation in existing traceability systems.

Microstructure engineering during directed energy deposition of Al-0.5Sc-0.5Si using heated build platform

Achieving a specific solidification morphology during the directed energy deposition process can be key to desired properties of the deposited part. The careful control of thermal gradient and cooling rates can be utilized to achieve these grain morphologies. The heating of the build platform and post-deposition heat treatment are two ways in which we have shown to control these solidification parameters. Three-dimensional heat transfer and material flow model along with columnar-to-equiaxed transition diagram have been used to model the process and the microstructure evolution during laser directed energy deposition of Al-0.5Sc-0.5Si powder. The computed results have been validated using the experimentally measured thermal cycles and melt pool shape and sizes. The computed thermal gradient and cooling rates are used to predict the solidification morphology compared with the experimentally observed microstructure. For a specific set of deposition parameters, the fraction of equiaxed grains is least in the bottom layers, highest in the middle layers, and reduced in the top layer. The increasing build platform temperature increases the fraction of equiaxed grains in any specific deposited layer. The microhardness of various layers in different specimens as a function of build platform temperature is also shown to be a function of the solidification microstructure. The developed and validated numerical model is able to predict the microstructure evolution and can be a tool for further microstructure engineering during the L-DED process.

Towards a circular economy for PET bottle resin using a system dynamics inspired material flow model

A massive rise in single-use plastic consumption has resulted in uncontrollable terrestrial and marine plastic pollution. Waste management systems currently do not have sufficient capacity to safely dispose of waste plastic. Apart from the plethora of negative environmental impacts due to mismanaged plastic waste both inland and in the oceans, landfilled plastics represents a significant recoverable energy footprint disposed of after a single use or a very short lifetime. Recovering these materials could reduce their carbon footprint by displacing the production of virgin plastic. The goal of this research is to develop a plastics circular economy framework that includes critical technological, economic, and policy constraints to help decision makers compare end of life options and inform investment decisions. In addition to implementing metrics for measuring circularity, the framework employs life cycle assessment to compare the environmental impact of pathways for improving circularity in the plastics economy. A case study exploring the recycling of polyethylene terephthalate (PET) bottles from 2020 to 2049 reveals that chemical recycling using glycolysis along with improved collection systems through drop-off recycling centers will significantly improve the circularity of PET bottles as well as reduce carbon footprints by displacing virgin PET manufacture. While waste incineration rather than recycling shows improved landfill-diversion-based circularity potential, it results in a significant increase of greenhouse gas emissions due to the combustion process.

Material and energy flows of industrial biogas plants in Switzerland in the context of the circular economy

Today, biomass is one of many countries most important renewable energy sources. Anaerobic digestion (AD) is a promising alternative to treating organic wastes from both energy and nutrient perspectives. Here, we develop a material flow model to assess the current utilization of wet biomass in industrial AD installations from mass, energy, and nutrient perspectives in Switzerland. We then identify how the current situation fits into the circular economy concept and develop quantitative scenarios for the future of industrial AD. The nutrient transfer coefficients through AD are >74 %. In the future, this could replace up to 14,000 t/a of chemical fertilizers, saving up to 40,000 t/a of CO2-eq. Today, however, 70 t/a plastic ends up in the fields after AD, which should be improved if AD is to increase in the future. Thus, increased AD of organic wastes could reduce dependence on fossil fuels while promoting a circular economy.

Life Cycle Assessment of the Battery Cell Production: Using a Modular Material and Energy Flow Model to Assess Product and Process Innovations

Battery cells and their production processes are developing continuously toward higher efficiencies. Conventional life cycle inventories (LCIs) applied in life cycle assessment (LCA) studies are either numerical or parametrized, which inhibits their application to changing developments in battery research. Therefore, this article presents an approach to develop modular material and energy flow (MEF) models for battery cell production. The modular MEF model is linked to the Brightway2 framework to generate LCI for six different innovations: 1) extrusion‐based slurry preparation; 2) water‐based electrode production; 3) dry coating; 4) thick electrodes; 5) change of active material; and 6) a combination of innovations. The results reveal that the modeled process and product innovations, particularly the dry coating process, can contribute to a reduction of more than 15% in CO2‐eq emissions. With the presented approach, it is possible to model process and product innovations in a common environment, which enables a comparative analysis under changing model premises with reusable and adaptable models at the process level. This reduces the effort to evaluate process variations significantly and contributes to the use of LCA as an engineering tool.

Mathematical Modelling of Marine Power Plants with Thermochemical Fuel Treatment

Abstract The article considers the methodological aspects of the theoretical investigation of marine power plants with thermochemical fuel treatment. The results of the study of the complex influence of temperature, pressure, and the ratio of steam / base fuel on the thermochemical treatment efficiency are presented. The adequacy of the obtained regression dependences was confirmed by the physical modelling of thermochemical fuel treatment processes. For a gas turbine power complex with a thermochemical fuel treatment system, the characteristics of the power equipment were determined separately with further merging of the obtained results and a combination of material and energy flow models. Algorithms, which provide settings for the mathematical models of structural and functional blocks, the optimisation of thermochemical energy transformations, and verification of developed models according to the indicators of existing gas turbine engines, were created. The influence of mechanical energy consumption during the organisation of thermochemical processing of fuel on the efficiency of thermochemical recuperation is analysed.

Hazardous waste from the global shipbreaking industry: Historical inventory and future pathways

Shipbreaking activities release hazardous wastes (namely, oil, asbestos, other landfillable wastes, and incinerable wastes) that harm both workers' health and the environment. However, an accurate and detailed emission inventory to support policy design of the greening reform remains lacking. By developing a framework that combines dynamic material flow model, global change assessment model and scenario analysis, this study carries out historical analysis and future projection of global ship scrap and pollutant emissions, based on ship scrap datasets. Our results show that shipbreaking sites have gradually shifted from more developed regions such as Taiwan, the European Union (EU), Japan, and Russia to the three less developed Southern Asian countries, Bangladesh, India, and Pakistan, in the past four decades. Waste emissions in these three countries have increased significantly by 6.5 times between 1990 and 2019. Although the volume of scrapped ships is expected to reach 75–95 million gross tons per year by 2050, the cumulative waste emissions from 2020 to 2050 will be reduced by 92% and 79% under the EU Convention and the Hong Kong Convention scenario, respectively. Lastly, policy implications such as how to mitigate the adverse impact of shipbreaking activities after the international conventions enter into force are comprehensively discussed.

Environmental benefits of circular economy approach to use of cobalt

Cobalt is an important critical material and a constituent of a broad range of products such as batteries, electronics, superalloys, and hard metals. Effective recycling of cobalt is considered one of the most pivotal processes in alleviating its criticality. In this paper, using the dynamic modelling of material, energy, and water flows in cobalt supply chain, we show that by 2050 around 25% of the total demand for cobalt could be supplied by recycling. Our results indicate that, compared to the primary production of cobalt, its recycling might lead to a reduction of energy consumption by 46% associated with the global cobalt supply chain and the corresponding fall in the use of water by 40%. In addition, recycling of cobalt is estimated to mitigate around 59% of the total emissions of greenhouse gases and 98% of the total emissions of sulfur oxides. Finally, we present the regionally distributed projections of cobalt-related energy and water use from 2020 to 2050.

Material flow analysis of a post-consumer plastic packaging recycling system in The Netherlands: a focus on beverage carton

AbstractDeveloping material flow models of waste and recycling streams can be crucial to determining the inefficiencies of post-consumer plastic packaging recycling systems. Currently, there is no such material flow model of beverage carton packaging waste in The Netherlands because beverage carton management is inherently difficult to measure and calculate. This paper presents a material flow model of beverage carton packaging waste in The Netherlands by calculating potential, collected, sorted, and recycled beverage carton dry weight. The results show that of a potential 60,000 tons of beverage carton material, 47,124 tons are recycled while 12,876 tons end up incinerated. This quantification does not only serve as a starting point for additional research and environmental policy considerations to improve the sustainability of the post-consumer plastic packaging recycling system, but it can also contribute to research in similar settings, leading to a more complete overview of the municipal solid waste recycling system. Graphical abstract

The evaluation of energy consumption in transportation and processing of municipal waste for recovery in a waste-to-energy plant: a case study of Poland.

Refuse-derived fuel (RDF) can be produced from combustible materials contained in municipal waste. This article investigates energy and material flow of waste in different scenarios for production of RDF from bulky waste, separately collected waste, and mixed municipal solid waste (MSW). We compare the proportion of energy consumption in transportation, handling waste, and processing using data from the waste collection company in South Poland. The findings show the components of the reverse supply chain consuming the highest value of energy. A model of material and energy flow has taken into consideration collection of waste and transportation by two categories of waste collection vehicles: light commercial vehicles and garbage trucks. The shipping of RDF from pre-treatment facilities uses tipper semi-trailers and walking floor trailers. The findings of the study show production of RDF from municipal solid waste consumes almost 10% of energy potential in RDF. Less energy is required for the production of RDF from bulky waste (2.2-4.8%) or separately collected waste (1.7-4.1%) depending on the efficiency of collection and selected vehicles. Transportation consumes the greatest portion of energy. For mixed municipal solid waste (MSW), it can reach 79%; for separated collection waste, 90%; and for bulky waste, up to 92% of the total energy consumed. Comparing emissions for two categories of the collection vehicles, no significant difference was found for the bulky waste collections. For mixed MSW and separately collected waste, the emissions are higher for garbage trucks. A recommendation for practitioners is optimization of routing to achieve a higher collection rate at a minimized route length. For transportation of RDF to WtE plants, vehicles with higher loading capacity are essential.

Material flow analysis of the nitrogen loading to surface water of Miyun reservoir watershed under uncertainty

Nitrogen (N) was one of the primary causes to water environment depravation, having a thorough understanding of N loading to water body is important for reducing the N pollution purposefully. In this research, we took the Miyun reservoir watershed as a typical area, of which a material flow model of the N metabolism was built. Afterwards, the material flow analysis (MFA) was conducted to identify the main pathways that generated N loading. And then the Monte Carlo (MC) method was applied to make uncertainty analysis of the N loading calculated through the MFA. The MFA results showed that the total N loading to surface water of the Miyun reservoir watershed was 5505.42 × 103 kg N, of which about 74.89% was originated from the agriculture subsystem (i.e., crop planting, fruit planting and vegetable planting subsystems). The main pathways of the agriculture subsystem that generated N loading were recognized as maize, chestnut, apple, pear, cabbage, cucumber and tomato planting. The uncertainty analysis results revealed that the N loading calculated from the MFA had some uncertainty, of which the fruit planting and industry subsystem had the biggest uncertainty, while the N loading from the fish farming subsystem had the lowest uncertainty. To make directed actions to protect the water quality of the Miyun reservoir watershed, the main pathways of each subsystem that generated N loading need to be regulated. This study provided a new framework of combing the MFA and MC method to simulate N loading to surface water at watershed scale, and was of vital significance to provide decision support for the watershed N pollution management globally.

Quantity and fate of synthetic microfiber emissions from apparel washing in California and strategies for their reduction

Synthetic microfibers have been identified as the most prevalent type of microplastic in samples from aquatic, atmospheric, and terrestrial environments across the globe. Apparel washing has shown to be a major source of microfiber pollution. We used California as a case study to estimate the magnitude and fate of microfiber emissions, and to evaluate potential mitigation approaches. First, we quantified synthetic microfiber emissions and fate from apparel washing in California by developing a material flow model which connects California-specific data on synthetic fiber consumption, apparel washing, microfiber generation, and wastewater and biosolid management practices. Next, we used the model to assess the effectiveness of different interventions to reduce microfiber emissions to natural environments.We estimate that in 2019 as much as 2.2 kilotons (kt) of synthetic microfibers were generated by apparel washing in California, a 26% increase since 2008. The majority entered terrestrial environments (1.6 kt), followed by landfills (0.4 kt), waterbodies (0.1 kt), and incineration (0.1 kt). California's wastewater treatment network was estimated to divert 95% of microfibers from waterbodies, mainly to terrestrial environments and primarily via land application of biosolids. Our analysis also reveals that application of biosolids on agricultural lands facilitates a directional flow of microfibers from higher-income urban counties to lower-income rural communities.Without interventions, annual synthetic microfiber emissions to California's natural environments are expected to increase by 17% to 2.1 kt by 2026. Further increasing the microfiber retention efficiency at the wastewater treatment plant would increase emissions to terrestrial environments, which suggests that microfibers should be removed before entering the wastewater system. In our model, full adoption of in-line filters in washing machines decreased annual synthetic microfiber emissions to natural environments by 79% to 0.5 kt and offered the largest reduction of all modeled scenarios.

Investigation of temperature distribution and solidification morphology in multilayered directed energy deposition of Al-0.5Sc-0.5Si alloy

The temperature distribution, geometry and size of the melt pool, and solidification parameters were computed using the heat transfer and material flow model for the directed energy deposition process. The thermal cycle and melt pool size were computed for different process parameters such as laser power, deposition speed, and laser beam radius across the multiple layers for deposition of Al-0.5Sc-0.5Si alloy. The computed thermal cycles at various locations from the centerline and melt pool size showed fair agreement with the experimentally measured result. The computed thermal gradient and solidification rate were mapped over the solidification map, which was in agreement with the experimentally observed microstructure. The transition in solidification morphology with varying melt pool depth and process parameters were fairly observed inside the melt pool. The fraction of equiaxed solidification morphology increases with the reduction in a thermal gradient.

An assessment of the European regulation on battery recycling for electric vehicles

This paper investigates the design of a recent regulatory proposal aimed at favoring the emergence of a battery recycling industry in Europe. Electric mobility is deemed necessary to cut CO2 emissions in the transport sector but the industrial and environmental impacts of lithium-ion battery manufacturing are controversial. A recent regulatory proposal from the European Commission introduces the obligation to attain a series of minimum thresholds of recycled materials for the new batteries to be manufactured after 2030. This paper discusses the conditions required for that obligation to be fulfilled. It develops a material flow model that projects battery wastes and their recycling potential. Our findings indicate that the feasibility of proposed thresholds is not very sensitive to changes of material intensities from battery technology shifts, recycling efficiencies, or the faster uptake of demand. On the contrary, battery lifetimes are the most crucial parameters for recycling potential. We believe that this result could jeopardize avenues for extending battery lifetimes such as second-life battery usage. Our policy recommendations are twofold. First, we recommend lower thresholds to improve the regulation credibility. Second, the regulation should integrate other objectives that address the lifetime of batteries.

Energy-orientated material flow simulation with stochastic optimisation for peak load management

With rising energy prices, it becomes increasingly important for industrial companies to consider energy costs in the activity of production planning and control. Reduced energy costs can both be realised through lower consumption and higher energy efficiency. Furthermore, the ability to flexibly consume energy, while adapting consumption to electricity availability or variable energy prices, as often referred to as ‘demand response’, might bring significant benefits. Two important requirements for demand response are the ability to predict consumption and the ability to precisely determine the potential flexible approaches available. For this purpose, a material flow model was implemented that simulates both the production process and the energy consumed by it. This model was parameterised based on real production data and energy consumption. Initial analysis reveals that manufacturing processes generally undergo interruptions, which cannot be predicted at the stage of production planning. These interruptions significantly reduce the accuracy of the model and were considered by means of probability density functions.In this paper, the forging shop of an automotive supplier is used as a use case. The main power consumption in this concrete case is caused by induction furnaces, which require different amounts of electricity, depending on the workpiece. Consequently, the loads can be adjusted by adapting the sequence of production orders. Using the simulation model developed, the peak loads of the forging shop were analysed, and an energy-orientated production plan was created and optimised using a genetic algorithm.Results show that the peak loads of the plant can be reduced significantly (by more than 10 %), despite the uncertainties of production, by means of stochastic modelling and optimisation. The application of these findings might contribute to both the stability of the electricity grid and the reliability of operations.