Circular Strategy Research Articles

Circular strategy assessment for digital services: The CADiS framework

Circular strategy assessment for digital services: The CADiS framework

Sustainable waste-treating-waste strategy: Catalytic recycling of polyethylene terephthalate over reconstructed waste catalysts

Polyethylene terephthalate (PET) is the most widely used polyester plastic, but difficulties associated with PET recycling have led to significant environmental issues. The recycling of PET waste into building monomers and valuable chemicals has attracted increasing attention. Herein, we propose a sustainable circular strategy for efficiently hydrogenolytic depolymerizing the waste PET by using reconstructed spent catalysts from the heavy oil slurry-phase hydrocracking. Two types of molybdenum sulphide/activated petroleum-based carbon compounds, a-MoSx/APC and MoS2/APC, were constructed using waste refining catalyst through the activation and annealing methods, which were used as catalysts for the hydrogenolytic depolymerisation of waste PET. Experimental results revealed that the different active components in the two reconstructed catalysts, molybdenum sulphide clusters, and few-layered molybdenum disulfide, show different activity and selectivity for the catalytic depolymerisation of PET. After the β-scission process of PET, the formed intermediate vinyl-terminated carboxylate units are converted to monoethyl terephthalate (MET) through a CC insertion pathway catalyzed by MoV, while to terephthalic acid (TPA) through a hydrogenolysis pathway catalyzed by MoIV. Therefore, MoS2/APC converts PET to TPA with a yield of 83 % within 24 hours at 270 °C under 1 atmosphere of H2 and solvent-free conditions, without generating any MET products. Moreover, this process is effective for both commercial and waste PET, and the catalyst could be reused for at least ten runs with stable activity. The sustainable waste-treating-waste strategy highlights a potential approach to the circular economy.

Common values for common goods: a circular regeneration model for active citizenship

Regenerating cultural heritage implies adopting a systemic and multi-scalar approach capable of considering the characteristics and flows of relations between the different components of the system. The regeneration project can be a circular strategy to reconnect people and places, generating and regenerating material and immaterial values of cultural heritage as a ‘common good’. The research proposes a circular and participatory regeneration model, validated through an evaluative framework. It supports decision-making and assesses the multidimensional impacts of reuse, redevelopment, maintenance and management practices of the commons, at all stages of the recovery project, and with respect to emerging instances and criteria adopted in existing policies.

Biobased Construction from Agricultural Crops: Paper 1 - A State of Play of Commercial Solutions in Europe

In response to environmental concerns and the global warming issue in particular there is a growing drive to decarbonise the building sector and transition it to more circular practices. Biobased construction materials, products and systems are an important low carbon and circular strategy as they can enable low to negative carbon construction and have strong circularity advantages notably being able to enter the bio cycle, using renewable, low to zero toxic resources and provide a range of other performance benefits, including moisture and vapour regulation. This novel research presents a unique state of play on the commercial application of biobased construction from selected agricultural crops, straw, miscanthus and hemp, focused on the European context. A desk-based review of known biobased material producers and manufacturers is undertaken, supplemented with semi structured interviews and site visits, to provide a comprehensive overview of the sector and detailed account of the types of biobased materials, products and systems that are being applied in buildings across Europe and beyond. The findings show that a diversity of agricultural crops are being utilised at different process, manufacture and construction technology levels, providing a range of tested and certified materials and products for application in mainly timber frame construction, but also some masonry solutions, and a growing number of modular systems. These operate in a diversity of supply chains and are being applied in a wide range of building types, both domestic and non-domestic, including multi story and complex buildings.

A multi-life cycle assessment of external wall insulation strategies in an Irish domestic retrofit

European Union (EU) policy and initiatives are driving both building renovation and the uptake of low-embodied carbon and circular design in the construction sector. The European Performance of Buildings Directive (EPBD) recast (2021) introduces global warming potential (GWP) methodology, and the future state will likely be embodied carbon targets for which life cycle assessment (LCA) of buildings will be required. External wall insulation (EWI) will have an important role to play in meeting targets. In this context, this paper compares the carbon emission payoff of three alternative EWI strategies that address conventional, low-carbon and circular solutions to EWI respectively, in the retrofit of an existing dwelling. The circular strategy is based on design for disassembly (DfD). Whereas standard LCA is based on a single building life cycle, the literature reviewed shows that the environmental impact assessment of DfD requires a multi-life cycle approach. In the absence of standardised methods for assessment, four multi-cycle LCA methods are selected and applied holistically in a case study investigation. Three allocation methods, 100:0, linear degressive (LD) and enhanced linear degressive (CELD), provide a range of emissions from ‘conservative’ to ‘best case’ over three building life cycles and the fourth method, the Van Gulck method, assesses the benefits of circularity through the concept of ‘multi-cycling’ based on one building life cycle. As each method of assessment will deliver different results, carbon emission payoff is not a fixed value. Findings show that with multiple use, the circular strategy pays off due to avoided production emissions and benefits from end-of-life (EoL) processes that DfD facilitates, that the upfront carbon cost of the circular strategy is minor relative to the carbon emission savings that reuse brings, and that the margin of improvement relative to the alternative strategies increases with each subsequent reuse.

Exploiting tropical fruit processing coproducts as circular resources to promote the growth and maintain the culturability and functionality of probiotic lactobacilli

This study evaluated the use of acerola (Malpighia glabra L., CACE), cashew (Anacardium occidentale L., CCAS), and guava (Psidium guayaba L., CGUA) fruit processing coproducts as substrates to promote the growth, metabolite production, and maintenance of the viability/metabolic activity of the probiotics Lactobacillus acidophilus LA-05 and Lacticaseibacillus paracasei L-10 during cultivation, freeze-drying, storage, and exposure to simulated gastrointestinal digestion. Probiotic lactobacilli presented high viable counts (≥8.8 log colony-forming units (CFU)/mL) and a short lag phase during 24 h of cultivation in CACE, CCAS, and CGUA. Cultivation of probiotic lactobacilli in fruit coproducts promoted sugar consumption, medium acidification, and production of organic acids over time, besides increasing the of several phenolic compounds and antioxidant activity. Probiotic lactobacilli cultivated in fruit coproducts had increased survival percentages after freeze-drying and during 120 days of refrigerated storage. Moreover, probiotic lactobacilli cultivated and freeze-dried in fruit coproducts had larger subpopulations of live and metabolically active cells when exposed to simulated gastrointestinal digestion. The results showed that fruit coproducts not only improved the growth and helped to maintain the viability and metabolic activity of probiotic strains but also enriched the final fermented products with bioactive compounds, being an innovative circular strategy for producing high-quality probiotic cultures.

Coupling material and energy flow analysis with life cycle assessment to support circular strategies at the urban level

PurposeThis study aims to investigate how the coupling of Material and Energy Flow Analysis (MEFA) with Life Cycle Assessment (LCA) under an urban metabolism (UM) perspective (referred to as the UM-LCA approach) can support the design, evaluation, and monitoring of urban-level circular strategies. For this purpose, we apply the UM-LCA approach to the urban area of Umeå (Sweden) by expanding the goal and scope of a recent MEFA study conducted by the authors of the article.MethodsThe modeling combines MEFA with LCA and is performed both retrospectively and prospectively. The MEFA was performed in the prior study following a bottom-up approach to map and quantify material and energy flows in the urban system at the sectoral level. The quantified flows are used in the present study to construct the life cycle inventory (LCI) model of the urban system. The LCI model is first used as a basis of the retrospective LCA (rLCA), which is conducted to assess the environmental performance of the urban system with its sectors. The LCI model is then modified according to future scenarios and is used as a basis of the prospective LCA (pLCA), which is performed to assess the environmental implications of implementing circular strategies in the future.Results and discussionThe rLCA shows that the construction and household sectors are major drivers of environmental impacts in the urban system, with households being the largest contributors to 11 out of 12 analyzed impact categories. It also reveals the most impacting flows within these sectors, including food in households and steel in the construction sector. These findings indicate that the construction and household sectors and their most impacting flows should be prioritized in a circular strategy. Furthermore, the pLCA highlights that a future circular strategy promoting reductions in the material used in these two sectors could lead to higher reductions in all impact categories, ranging from 4.3 to 8.6%, than a strategy focused only on recycling, which could lead to reductions ranging from 0.2 to 1.2%.ConclusionsThis study concludes that the UM-LCA approach has great potential to comprehensively analyze, both retrospectively and prospectively, the environmental performance of an urban system providing valuable insights that could support policy makers in designing, assessing, and monitoring urban-level circular strategies. However, further research should address identified limitations of the UM-LCA approach (e.g., limited available data, inability to consider social and economic aspects) to facilitate its applicability and enhance its comprehensiveness.

Parametric LCA integrating a product's State of Health: A decision-making tool based on environmental impact in the context of circular strategy.

Circular processes such as remanufacturing, reuse, recycling, make it possible to extend the life of products and thus reduce their environmental impact. However, they introduce uncertainties of quantities and qualities that bring significant challenges for manufacturers and others stakeholders. To reduce such uncertainties and give decision-makers more information for selecting a circular strategy driven by the environment, a parametric life cycle analysis method is essential. The aim of this article is to propose a method based on the performance parameters of each process of product closed-loop to calculate the environmental impact of a product in different closed loops, considering the product's state of health. To achieve this objective, the product life cycle process with closed circular processes were first specified. Then, its parameterization was completed to simulate different scenarios. Based on parameters defined, formulas to facilitate the simulation of several circular scenarios for a given product has been defined. This allows identifying the circular strategies with the lowest environmental footprint. Illustrated by a case study on an electric circuit breaker, our approach demonstrates its effectiveness in supporting eco-responsible decisions.

Revalorization of degraded maguey pulquero substrate for Lycopersicon esculentum germination

The bagasse of Agave salmiana (maguey pulquero) is a residue generated during the exploitation of the plant to obtain pulque, inulin, honey, etc. Due to its chemical composition, it can be used for the cultivation of fungi of the Pleurotus genus and the subsequent use of the degraded material "degraded substrate (DS)" as a support for the germination of vegetables. The objective of the study was to characterize the bagasse of maguey pulquero biodegraded by Pleurotus djamor as a new perspective in its value chain, and subsequent use for the germination of Lycopersicon esculetum (tomato). The DS was recovered at 60 d from the P. djamor culture, characterized physicochemically and the conformation of the plant tissue was observed by scanning electron microscopy. The DS showed a decrease in protein (4.8–3.3 %) content and fibrous fraction (54–36 %), but dry matter digestibility increased from 47 to 71 %; in addition, changes in mineral composition were observed, mainly in calcium concentration (6 %). Due to its composition, it is possible to revalue DS in the germination of L. esculetum to reduce the use of peat moss (commercial peat). The results show that up to 25 % of maguey DS mixed with 75 % peat moss can be used (25:75), reaching a germination percentage of 85 % and increasing the seedling emergence speed index from 0.96 – 1.25. Concluding that it is possible to implement a circular strategy in which agave bagasse is used for mushroom cultivation and the subsequent recovery of the spent substrate for tomato germination.

SSCT-Net: A Semisupervised Circular Teacher Network for Defect Detection With Limited Labeled Multiview MFL Samples

Deep learning methods have demonstrated promising performance in magnetic flux leakage (MFL) defect detection under adequate amounts of labeled samples. However, in industrial occasions, obtaining adequate amounts of labeled samples is time-consuming and expensive, and applying only limited labeled samples can lead to unsatisfactory defect detection accuracy. To address the above issues, a defect detection method named semi-supervised circular teacher network (SSCT-Net) is proposed in this article. First, a parallel feature extraction network with hybrid attention is proposed in SSCT-Net so that the useful features of multi-view MFL signals can be extracted simultaneously. Second, semi-supervised circular learning is proposed for the first time. In semi-supervised circular learning, a distinguishable feature embedding space is constructed, and two structurally identical deep networks co-supervise and collaborate through the proposed consistent circular strategy so that the decision bias of unlabeled samples can be reduced. Finally, the trained model is applied for defect detection in practice. The proposed method can establish a potential connection between multi-view MFL signals and fully utilize labeled and unlabeled MFL signals. The experiments in simulations and real-world applications demonstrate that SSCT-Net can reach 92% detection accuracy with only 20% labeled samples, which is more effective than the state-of-the-art methods and leads to a promising practical utility of the proposed method.

Achieving the circular economy through environmental policies: Packaging strategies for more sustainable business models in the wine industry

AbstractThe environmental and economic benefits of adopting a circular economy (CE) approach could be significant for firms. The CE and packaging constitute a fundamental binomial for our economy, yet there are still few studies of the advantages for food value chains, especially in the wine sector. Therefore, in this paper, we address this research gap by measuring the environmental and economic performance of a circular business model (CBM) adopting the wine industry as a reference. We apply a combination of Life Cycle Assessment (LCA) and Life Cycle Costing (LCC) methods to a small Italian winemaking firm, which implements a circular strategy through the take‐back and refurbishment of wine packaging components. Results show that by implementing this sustainable and CBM, a firm can reduce greenhouse gas (GHG) emissions from 8 to 90% and save from 6 to 63% of its economic costs.

Technology transfer adoption to achieve a circular economy model under resource-based view: A high-tech firm

This study explores technology transfer with public expectations and expert guidance to achieve a circular economy model under resource-based view. This study aims to (1) build a model to apply technology transfer to achieve circular economy principles under public expectations and expert guidance, (2) construct a valid theoretical structure using experts’ perspectives, and (3) provide practical criteria for improvement under resource constraints. High-tech firms seek to apply technology transfer to achieve circular economy principles under resource constraints and to meet public expectations. However, there is always a discrepancy between expectations and expert guidance. Exploratory factor analysis is used to confirm the reliability and validity of the attributes. The linguistic preferences are converted into crisp values using the fuzzy synthesis method. Finally, the decision-making trial and evaluation laboratory is applied to understand the gaps between public expectations and expert guidance in technology transfer adoption to achieve a circular economy model under resource constraints. The results show that technology collaboration in line with a circular strategy, digital workforce skill development, technology sharing to achieve circular co-benefits, and stakeholder engagement for technology transfer are important aspects.

Designing a digital platform to foster data-enhanced circular practices in the European solar industry

Enhanced data exchange among different actors and stages of the value chain (VC) is key to mastering the transition toward a circular solar industry. Data on in-use products and assets enable early assessments of the adequate circular strategy at the end of the first life cycle, which includes the reuse of photovoltaic (PV) modules in a second life cycle. In this context, digital platforms represent a proven technology to facilitate information exchange between different actors along the VC. However, digital platforms that are targeted specifically at fostering the circular economy (CE) the solar industry are under-researched. We apply Design Science Research to build and evaluate an artefact for a digital platform that enables collecting comprehensive PV data at different life cycle stages by involving different solar value chain stakeholders. Data enrichment is incentivized by two platform use cases that represent the outcome of our study: (i) an assessment schema (devised in collaboration with a third-party certifier) designed to gather information relevant to creating a digital product passport; and (ii) a photovoltaic reuse online marketplace designed to match the supply and demand for second life panels (supported by a standardized testing and repurposing infrastructure). Initial insights from Switzerland (our pilot area) pave the way for implementing the proposed concept. Future studies should investigate scalability to the European context.

Transitioning from green to circular procurement in developing countries: a conceptual framework for Ghana’s construction sector

ABSTRACT Circular procurement (CP) systems are fast evolving and recently, regarded as a ‘golden-ring’ to be leveraged in promoting the circular economy. However, it appears that the construction sector of developing countries is yet to make any significant adaptions and improvements to its existing procurement practice. In this paper, we examine the state of procurement practice in such countries for opportunities to develop and implement CP. Using case analysis from the Ghanaian context, evidence on the status quo of existing green procurement system is sought to ascertain gaps and similarities between practice, policy and targets needed for CP implementation. Qualitative methods comprising the use of secondary data and interviews with stakeholders from three public tendered projects were adopted, and results analysed to develop a conceptual framework for CP. The findings of the study reveal that government policy, circular strategy, circular sourcing and platforms are essential components that need to be developed for CP implementation. Hence, the developed framework proposes an integration of these aspects through the four-lenses of people, process, policy and technology. The output of this research provides a collective roadmap for policymakers, practitioners and academicians towards the attainment of more circular consumption patterns in emerging construction markets.

Repair as a circular strategy for increasing resource availability and health system resilience during a crisis

BackgroundHealthcare is a complex socio-technical system where nations regularly struggle with the misalignment between public needs and available resources. The advent of COVID-19 further exacerbated shortcomings, as evidenced by the global panic to find ventilators and beyond. However, the pandemic catalysed a successful Brazilian public-private voluntary partnership that united key industry players, industrial training centres and several volunteers, who, in the absence of a supportive government, could repair ventilators in record time, giving the health system means to succeed. ObjectivesCharacterise how a voluntary public-private partnership came into existence and codify recommendations on how it effectively used repair as a circular strategy to increase ventilator availability and bolster health system resilience. MethodsCase study using multiple data sources collected over 10 months, including national data, semi-structured interviews, daily reports, and internal communications. Sampling, research instruments, and subsequent qualitative data analysis and theory development grounded in repair strategy, resilience, and supply chain literature. ResultsA successful public-private voluntary partnership delivered 2,514 repaired ventilators, approximately 3% of the total ventilators in use in Brazil and impacting around 24,700 lives. Furthermore, effectively functioned as a first-responder bringing to hospitals approximately 500 repaired units as early as April 2020, surpassing the government's procurement and doing so just-in-time for Brazil's COVID 1st wave. More than 70 institutions and 700 professionals helped hospitals in 25 out of 27 Brazilian states. This case documents how the initiative persevered through adversity, including inadequate policies representing a widespread difficulty in enforcing the “right to repair”. Public interest summaryIn Brazil, automakers, the National Industrial Training Service and other organisations formed a voluntary and temporary alliance to repair broken ventilators that had accumulated in hospitals. This initiative took place at the beginning of the COVID-19 pandemic and returned 2,514 ventilators to hospitals, supporting patient care and partially alleviating the shortage of ventilators. This repair depended on the training of technical staff who had never worked with health equipment before. In addition to training, there was a need to share information and manuals, calibrate repaired equipment, procure spare parts, organise logistics and find funding, amongst other activities, meaning that it was a wide scale operation involving several organisations - both within and outside the health system. This research demonstrates the role of ventilator repair in making a health system more resilient in the event of a health emergency, and the urgent need to develop strategies to make repair an everyday commitment.

Computational modeling of laser welding for aluminum–copper joints using a circular strategy

Dissimilar metal welding poses a significant challenge for researchers in the welding and materials science communities due to the different properties of the metals involved. In this study, we present a novel approach for determining the optimal processing parameters for continuous laser welding (CLW) of dissimilar metals, specifically aluminum and copper, using a circular strategy. The approach utilizes computational fluid dynamics (CFD) simulations to model the welding process and predict joint quality. We validated a CFD-based numerical model for predicting the melt-pool shape across a range of laser power and circular welding speed values. Additionally, we developed artificial neural network (ANN) models that can predict melt pool interface width, penetration depth, and copper concentration for any combination of processing conditions. Using surrogate modeling, we identified the optimal values of laser power and welding speed that result in the highest quality joint. Our results showed that the optimal processing conditions were a laser power of 2950W and a circular speed of 55 mm/s, which resulted in a high-quality Al–Cu joint with maximum shear strength of 2200 N. Microstructural analysis and tensile-shear strength testing confirmed that the optimal conditions resulted in a low degree of intermixing and the absence of large intermetallic compounds (IMCs) in the weld seam. Overall, study offers a valuable contribution to the welding and materials science communities by presenting a novel approach to address a common challenge in dissimilar metal welding. Our approach can be applied to other types of dissimilar metal welding and may inform the development of new welding techniques in the future.

Is repair of energy using products environmentally beneficial? The case of high voltage electric motors

Repair is advocated as a circular strategy to improve the environmental performance of products. Whether this holds for very long-lived and energy intensive products has not been addressed. This study compares environmental impacts of two high voltage motors of different energy efficiency and assesses their use extension by repair with life cycle assessment (LCA). Due to high energy use, long lifetime and intensive use, the use phase dominates all environmental impacts, even resource depletion. Therefore, a higher energy efficiency is more beneficial than extending the use by repair, and if the energy efficiency is slightly reduced, the repair is not beneficial. Therefore, product requirements and users and manufacturers of such products should ensure designs with high energy efficiency rather than making the product repairable. Finally, the results highlight the importance of including resource use from electricity production and transmission in LCA of the use extension of energy using products.

Circular economy through waste reverse logistics under extended producer responsibility in Finland.

Extended producer responsibility (EPR) is commonly implemented as a strategy in waste management. The core of the concept itself is a waste reverse logistics (WRL), which dictates how the collection, inspection and processing of end-of-life products are performed. Existing studies of EPR mainly focused on single products instead of using broader perspective on national level. Its contribution towards circular economy through slowing and closing the loops also has not been widely discussed. This study examined the system architecture of the policy instruments used in the EPR and the similarities of the WRL networks across different products. A case study was used to investigate six products: portable batteries and accumulators, paper, packaging, vehicles, electrical and electronic equipment (EEE) and tyres. The study generated a WRL framework. It is also observed that closing the loop through recycling is the primary circular strategy and is found in all products, whereas closing and slowing the loop strategy through reuse/repair, remanufacture and repurposing is found in packaging, tyres, vehicles and EEE. This study shows that EPR can close the material loop, although improvement in design for the environment is necessary. It creates challenges and opportunities for the government, producer responsibility organization and producers to improve existing conditions by implementing new initiatives such as design for the environment indicators, standardization, tax and subsidy systems and tariffs for disposal fees.

Ensuring circular strategy implementation: The development of circular economy indicators for ports

Port clusters are expected to play a significant role in the transition towards a circular economy, both at the level of facilitating regional and global transport within circular production chains, as well as hosting circular activities in port areas. There is strong evidence that significant investments in the circular economy (CE) are being made in port areas, albeit without much knowledge on their impacts. To ensure an efficient use of port resources in view of this transition, these impacts should be adequately monitored. Research on circular economy indicators for ports is still in an exploratory stage, characterized by an absence of in-depth research on the development of port-related circular economy indicators. This paper focuses on the development of a comprehensive set of relevant and feasible CE indicators, which aim to support port managing bodies (PMBs) as well as port stakeholders to monitor the CE transition taking place. Through multimethod qualitative research, including content analysis, focus groups, a gap analysis and a qualitative survey, an actionable list of CE 12 indicators for ports was developed. Seven of which are highly feasible and five of which have medium feasibility in terms of stakeholder relevance and ease of implementation. Findings related to (1) the overall limited CE ambition levels of PMBs and (2) the difference in the values of some indicators for different port typologies are also discussed. The value of this study for practitioners lies in providing them with an actionable set of KPIs which can support their efforts and communication related to their CE transition.

Circular Business Strategy of Early Stage Fashion Brand in Indonesia

Business with a purpose has become a very popular thing lately. The intended goal is not just profit but what impact a business can have on society. This was agreed collectively at the world level by the UN by implementing the Sustainable Development Goals (SDGs) in 17 sub-values. This has an impact on shifting the mindset of consumers who are more concerned with the environment and sustainable business and this has occurred in the fashion industry, both global and local brands. The market value for sustainable fashion is increasing, global brands are adopting campaigns and competing to make circular products, local brands are also joining in with various approaches to adopting sustainable fashion. This is of course an opportunity for businesses on a micro scale or for brands in the early stage. GNDT as a local fashion brand in Indonesia that presents clothing solutions for obese or plus size men has implemented inclusivity in clothing, in line with existing trends and opportunities, business transformation must be carried out to make it more circular. With limited resources and a small business scale, GNDT must determine what approaches and strategies are most effective in turning their business into a more circular one and how to implement it. Value hills are used as a framework for this research in carrying out the stages of business transformation and adoption of a circular business strategy. Focusing on three stages, namely pre-use, use and post-use, businesses are expected to be able to map their business model position on the value hill to be able to identify the initial position of their business (uphill), how to optimize the products they sell (tophill) and how far what is the possibility that the product can be returned after use. Furthermore, businesses can identify gaps and opportunities in value hills and determine what strategic options are fit that can be carried out at this time in accordance with the resources they have. This research was conducted qualitatively using observation and brainstorming methods with business owners. The results of the business model assessment and placement on value hills indicate that GNDT must implement a circular strategy at each stage. At the uphill stage, circular design is determined as the most effective strategy, followed by a product as a service strategy for the tophill phase and upcycling for the downhill phase. All of this is wrapped up in a fundamental network organization strategy where GNDT must prepare internal organizations and potential collaboration with partners to realize this strategy.