This research uses system optimization to assess short, medium, and long-term scenarios to achieve the committed CO₂-emission goals of Ecopetrol while minimizing potential adverse impacts such as incremental operational costs and utility demand. Two Colombian refineries are used as a case study: a medium-complexity and a high-complexity refinery. The study explores whether the level of complexity plays a significant role in the results. Potential technologies were ranked using a multi-criteria decision analysis. The system analysis and optimization were done in Linny-R, a mixed integer linear programming software package developed by TU Delft. In the short-term (2030) scenario, the selected technologies include low-carbon H₂ produced from Steam Methane Reformer units with carbon capture and storage and H₂ produced from renewable electricity sources. The medium and long-term (2050) scenario also included biomass gasification, naphtha reforming, and the cracking unit, all with carbon capture and storage. The refineries were modelled using on-site company data. The results indicate that using low-carbon H₂ and carbon capture and storage to flue gases would allow to reach the net zero target. Furthermore, the results show that the level of complexity in a refinery significantly impacts the decarbonization deployment pathways. The high-complexity refineries benefited from using low-carbon H₂ as feedstock while the medium-complexity refinery relied on a combination of carbon capture and low-carbon H₂ as an alternative fuel. This research highlights the potential to achieve substantial CO₂ emissions reductions with less impact on the total operational cost by using the amount of excess refinery gas generated when H₂ is used as fuel in boilers and process furnaces. A significant challenge remains in identifying suitable applications for surplus refinery fuel gas beyond its conventional use in combustion within boilers and furnaces.

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Self-organized industrial symbiosis (IS) starts with one actor's decision to invest in a waste recovery plant and the other actors' decision to buy the recovered flow. Technical and institutional conditions of the cluster influence actors' decisions. This paper explores the emergence of IS collaborations in industrial clusters under different techno-economic conditions in the long term. We propose a mixed-integer linear programming model that incorporates costs and constraints associated with waste recovery and exchange to study actors' investment decisions and investigate shaped symbiotic exchanges under rising energy prices and limited electricity supply. The approach is implemented in Iran's Persian Gulf Mining and Metals Special Economic Zone as a case study. The results revealed that changes in internal or external condition simultaneously influence the industrial and waste recovery plants. For instance, increasing energy prices without raising product prices significantly decreased the production level of industrial plants and, consequently, heat recovery potential. Furthermore, the waste heat recovery plants' contribution to improving the cluster's economic and environmental performance was not the same. Electricity recovery from a power plant's waste heat can result in 55 PJ grid electricity intake reduction and 720 M€ cluster cash flow increase. Recovered cooling or electricity from the steelmaking plant waste heat was consumed internally rather than shaping IS. These model outcomes show its capability to study IS within the socio-technical structure of the cluster, not a standalone phenomenon. Implemented conceptualization offers a novel system-level approach, which could be adjusted to assess other industrial development strategies.@en

In view of the energy transition, it is important that engineering students are familiar with the concept of exergy and the added value of exergy analysis compared to energy analysis. Exergy analysis tells the truth about energy efficiency and exergy is directly related to sustainable development. This paper focuses on teaching exergy to students at the Delft University of Technology (TU Delft), but the contents are valuable to other engineering students as well. To encourage the teaching of exergy, the basics of exergy and exergy analysis are presented, as well as examples and ideas for teaching exergy to BSc students that are related to the topics of their BSc programme. It is recommended that the contents of this paper be discussed with many teachers of BSc programmes, especially teachers of BSc programmes that do not yet seem to include the teaching of exergy, and that attention be paid to teaching exergy to MSc students as well.@en

Life Cycle Assessment (LCA) is a powerful tool for achieving sustainability. Traditional LCAs analyze well defined and developed industrial systems, but recent developments of LCA focus on analyzing emerging technologies which are not yet optimized with respect to energy and materials. Therefore, LCA results of ex-ante applications can be very different from ex-post applications for the same system. The purpose of this study is to show the different effects of data scales on LCA results regarding global warming, fine particulate matter formation, terrestrial acidification and freshwater eutrophication potentials. For this purpose torrefaction technology was selected as the case study and assessed based on bench scale data, lab scale data, data derived from process simulations, pilot scale data and commercial scale data. Considered environmental impacts were global warming, fine particulate matter formation, terrestrial acidification and freshwater eutrophication. Results showed that process efficiencies improved significantly between the bench scale system and systems with higher technology readiness levels (TRLs), such as pilot, process simulations and commercial scale systems. Furthermore, process simulations result in scores closer to commercial scale regarding all considered environmental impacts. However, if LCA practitioners focus only on global warming impact, then pilot scale is also a good alternative. Finally, due to torrefaction technology being relatively simple in terms of raw materials input, we suggest more complex chemical systems to be assessed with LCA in various TRLs.

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Sustainability is high on the agendas of public and private organizations. Governments are setting targets for reducing the use of virgin raw materials in products and to eliminate waste. To accelerate the transition towards a Circular Economy (CE) policymakers are launching instruments. However, policy instruments, such as financial incentives or new regulatory guidelines, are prone to manipulations when the stakes for the involved stakeholders are high. Therefore, policymakers and government authorities need a solid system to monitor and control the implementation and effectiveness of their CE measures. To this end, digital technologies are key to enabling visibility and monitoring of materials flows. They allow governments and other stakeholders to use data to steer the transition towards a CE. However, data from different materials supply chains reside in a diversity of digital platforms used by a diversity of stakeholders involved. Blockchain-based platforms can support the required visibility by combining data from different stakeholders across different materials supply chains. But connecting all data for CE visibility throughout the entire materials flows into one singular platform is unlikely. With the growing number of blockchain-based platforms that each covers parts of data on CE flows, there is a need to assess the level of visibility they offer and to determine which data is lacking to monitor full CE flows. In this article, the development of a framework to evaluate blockchain-enabled information systems on their ability to act as monitoring systems for CE purposes is presented. The design science research approach was followed to develop the framework. Insights provided by academic literature as well as empirical data from three extant blockchain-enabled platforms were used (i.e., TradeLens, FoodTrust, and Vinturas). The evaluation framework can be deployed by public and private actors (e.g., governments and banks) for monitoring purposes, but also by IT providers to offer CE visibility solutions.@en

This study furthers game-based learning for circular business model innovation (CBMI), the complex, dynamic process of designing business models according to the circular economy principles. The study explores how game-play in an educational setting affects learning progress on the level of business model elements and from the perspective of six learning categories. We experimented with two student groups using our game education package Re-Organise. All students first studied a reader and a game role description and then filled out a circular business model canvas and a learning reflection. The first group, i.e., the game group, updated the canvas and the reflection in an interactive tutorial after gameplay. The control group submitted their updated canvas and reflection directly after the interactive tutorial without playing the game. The results were analyzed using text-mining and qualitative methods such as word co-occurrence and sentiment polarity. The game group created richer business models (using more waste processing technologies) and reflections with stronger sentiments toward the learning experience. Our detailed study results (i.e., per business model element and learning category) enhance understanding of game-based learning for circular business model innovation while providing directions for improving serious games and accompanying educational packages.@en

Natural gas for heating is widespread in the built environment of The Netherlands, where the government aims at limiting heat demand and reducing natural gas consumption over the coming decades. In the owner-occupied residential sector, this transition is complex and requires cooperation and coordination of individuals and groups that make investment decisions. We use agent-based modelling to explore the effect that various financial policies could have in an illustrative neighbourhood, given that households make multi-criteria and group decisions. In the scientific literature, this type of energy model seldom focuses on the adoption of competing technologies by households as individual and collective agents grouped in homeowner associations in multi-family buildings. To address the problem and knowledge gaps, we model individual preferences with a multi-criteria perceived lifetime utility submodel, and decisions as outcomes of individual preferences and a threshold voting system. We explore energy taxes (natural gas and electricity), regulated price of heat from networks, and subsidies (insulation and heat pumps). Under our assumptions, we found that combinations of fiscal policies, regulated heat prices, and subsidies can sometimes create incentives for households to disconnect from natural gas, but that steering the transition mainly with financial policies could prove ineffective. We also found that, in terms of collective CO2 reduction, some transitions in which only some households phase out natural gas could have results similar to some scenarios in which households only improve their dwellings’ insulation levels.@en

Safe-and-sustainable-by-design (SSbD) is a concept that takes a systems approach by integrating safety, sustainability, and functionality throughout a product’s the life cycle. This paper proposes a framework based on a prospective life cycle assessment for early safety and sustainability assessment. The framework’s purpose is to identify environmental sustainability and toxicity hotspots early in the innovation process for future SSbD applicability. If this is impossible, key performance indicators are assessed. Environmental sustainability aspects, such as global warming potential (GWP) and cumulative energy demand (CED), and toxicity aspects, such as human toxicity potential and freshwater ecotoxicity potential, were assessed upon applying the framework on a case study. The case study regarded using nano-titanium dioxide (P25-TiO2) or a modified nano-coated version (Cu2O-coated/P25-TiO2) as photocatalysts to produce hydrogen from water using sunlight. Although there was a decrease in environmental impact (GWP and CED), the modified nano-coated version had a relatively higher level of human toxicity and freshwater eco-toxicity. For the presented case study, SSbD alternatives need to be considered that improve the photocatalytic activity but are not toxic to the environment. This case study illustrates the importance of performing an early safety and environmental sustainability assessment to avoid the development of toxic alternatives.@en

Coal-mine effluent treatment has the potential to both reduce the environmental impact of the effluent and provide economic opportunities by recovering valuable minerals and clean water. In this study, we modeled a novel treatment process, which includes nanofiltration (NF), two-step crystallization, reverse osmosis (RO), electrodialysis (ED), multi-effect distillation (MED), and a NaCl crystallizer, and performed a techno-economic analysis of its full-scale implementation, using a circular economy approach. We estimated the thermal and electrical energy consumption to be 745.5 kWhth/tonNaCland 565.1 kWhel/tonNaCl(or 13.6 kWhthand 10.3 kWhelper m3of feed effluent), respectively. The levelized cost of the NaCl salt that accounts for the revenue from the plant's co-products (Mg(OH)2, CaSO4and, pure water) was estimated to be 203 USD/tonNaCl. The economic viability of the treatment chain can be improved by using renewable electricity sources, reducing the total expenditure on NF and RO, and integrating alternate technologies into the treatment plant@en

The Netherlands aims at reducing natural gas consumption for heating in the housing sector. Although homeowners are responsible for replacing their heating systems and improving dwelling insulation, they are not always able to make individual decisions. Some projects require group decisions within and between buildings. We use an agent-based modelling and simulation approach to explore how these individual and group decisions would influence natural gas consumption and heating costs in an illustrative neighbourhood, under a set of assumptions. We model individual household preferences over combinations of insulation and heating systems as a lifetime cost calculation with implicit discount rates, and we use quorum constraints to represent group decisions. We model three fiscal policies and a policy to disconnect all dwellings from the natural gas network. Results show that the disconnection policy was the only necessary and sufficient condition to incentivize households to replace their heating systems and that group decisions influenced the alternatives that were chosen. Since results were influenced by group decisions within buildings and by the market discount rate, we recommend further research regarding policies around these topics. Future work can apply our approach to case studies, incorporate new empirical knowledge, and explore group decisions in other contexts.

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MSocial Life Cycle Assessment (S-LCA) uses a life cycle perspective to assess social impacts of products, and the S-LCA guidelines describe developing the system boundaries based on a factory-level perspective. However, such a perspective may exclude stakeholders with a negative social performance which are cooperating with a factory but are not directly involved with the product under study, and it can result in a step back on corporate social responsibility (CSR). Our study aimed to align S-LCA with the CSR concept. Therefore, we designed a case study for the manufacturing sector in which we practiced expanding the system boundaries of S-LCA. Our results showed larger social risks after expanding the system boundaries due to subsidiary and supplier companies located in countries with less strict regulations than the Netherlands, which is where the main organizations and parent company existed. We conclude that system boundaries expansion can result in more complete picture of the involved organizations, and lead practitioners to approach S-LCA with the goal of improving social conditions and identify companies which deserve excellent or poor social scores. Its usefulness is mostly expected when S-LCA practitioners aim to identify social hotspots in supply chains in socially sensitive markets.

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Industrial Symbiosis Networks (ISNs) consist of firms that exchange residual materials and energy locally, in order to gain economic, environmental and/or social advantages. In practice, ISNs regularly fail when partners leave and the recovery of residual streams ends. Regarding the current societal need for a shift towards sustainability, it is undesirable that ISNs should fail. Failures of ISNs may be caused by actor behaviour that leads to unanticipated economic losses. In this paper, we explore the effect of these behaviours on ISN robustness by using an agent-based model (ABM). The constructed model is based on insights from both literature and participatory modelling in three real-world cases. It simulates the implementation of synergies for local waste exchange and compost production. The Theory of Planned Behaviour (TPB) was used to model agent behaviour in time-dependent bilateral negotiations and synergy evaluation processes. We explored model behaviour with and without TPB logic across a range of possible TPB input variables. The simulation results show how the modelled planned behaviour affects the cash flow outcomes of the social agents and the robustness of the network. The study contributes to the theoretical development of industrial symbiosis research by providing a quantitative model of all ISN implementation stages, in which various behavioural patterns of entrepreneurs are included. It also contributes to practice by offering insights on how network dynamics and robustness outcomes are not only related to context and ISN design, but also to actor behaviour. @en

The viability of novel network-level circular business models (CBMs) is debated heavily. Many companies are hesitant to implement CBMs in their daily practice, because of the various roles, stakes and opinions and the resulting uncertainties. Testing novel CBMs prior to implementation is needed. Some scholars have used digital simulation models to test elements of business models, but this this has not yet been done systematically for CBMs. To address this knowledge gap, this paper presents a systematic iterative method to explore and improve CBMs prior to actual implementation by means of agent-based modelling and simulation. An agent-based model (ABM) was co-created with case study participants in three Industrial Symbiosis networks. The ABM was used to simulate and explore the viability effects of two CBMs in different scenarios. The simulation results show which CBM in combination with which scenario led to the highest network survival rate and highest value captured. In addition, we were able to explore the influence of design options and establish a design that is correlated to the highest CBM viability. Based on these findings, concrete proposals were made to further improve the CBM design, from company level to network level. This study thus contributes to the development of systematic CBM experimentation methods. The novel approach provided in this work shows that agent-based modelling and simulation is a powerful method to study and improve circular business models prior to implementation.@en

Industrial Symbiosis (IS) is a collaboration between nearby industrial plants to exchange waste material and energy and achieve economic and environmental benefits that cannot be obtained individually. IS emergence in a cluster requires both technical potentials for material and energy exchange and social readiness for collaboration. In this paper, to gain insight into IS dynamics in emerging industrial clusters; we investigate shared concepts governing actors' behavior in the form of rules and regulations, and social norms and practices. We implemented the IS dynamics framework to reveal which dynamics are supported either by the legislation or actors' preferences. The Persian Gulf Mining and Metal Industries Special Economic Zone in Iran is used as a case study. The case study revealed that previous successful collaborations in the cluster were often self-organized, but stakeholders preferred to initiate new IS collaborations if financial incentives and infrastructure are provided. Meanwhile, the institutional analysis showed that institutional arrangements (e.g., pricing and penalties) are not in favor of IS emergence. Even though stakeholders might engage in self-organized IS because of inherent problems such as resource scarcity, the lack of clear and effective institutions could hinder IS. This understanding can help both the government and stakeholders in their strategies for future collaborations under different economic and environmental policies.

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Environmental pollution, resource scarcity, and freshwater shortage are critical world challenges facing humanity. Process industry produces large amounts of brine, a waste water with a high salinity level and often critical raw materials. This study applies the social life cycle assessment (S-LCA) to quantify societal benefits and risks in developing brine treatment systems. S-LCA is implemented for hotspot and site-specific levels on four case studies of the Zero Brine project. Hotspot analysis focused on the major commodities. Social Hotspot Database was used as source for data and endpoint indicators. In addition, site-specific analysis regarded the social performance of the case studies companies; interviews and questionnaires were performed with representatives of the four case studies. The collected data were converted to scores with subcategory assessment method and performance reference points. The results show that for all case studies “Labor rights and decent work” and “Health and safety” indicators result in the largest impacts due to imports of commodities from developing countries. Site-specific results show that the overall social sustainability performance of the case study companies is at a good level. The only potential areas for improvement are the “Occupational accidents” and “Contribution to the local community”. The former are minimally higher for silica plant and higher for coal mine in relation to these sectors average accidents rates. Furthermore, the coal mine company can contribute more to the local community and reduce conflicts concerning environmental impacts at the city level. Common identified hotspots among the case studies are: China, India and Congo. Reducing imports from these countries will significantly improve the societal performance of the brine systems.

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Industrial Symbiosis (IS) is a means for sustainable cluster development. The first consideration for implementing IS in a cluster is to identify technical opportunities for exchanging waste material and or energy. However, the definition and methods for assessing the technical potential of IS are not elaborated in the literature. This research proposes a method to evaluate IS potential that considers different system boundaries. The method allows for explicitly reflecting current and expected developments at plant and cluster level. The suggested method was applied to the Persian Gulf Mining and Metals Special Economic Zone (PGSEZ) in Iran. The case study shows that expanding the system boundaries to include the waste flows inside steelmaking and direct reduction plants could result in an 8% increase in available waste heat. Heat recovery possibilities outside the cluster boundaries offered 118 MW cooling plus 368 MW heating potential compared to 158 MW demand for electricity in the cluster. Furthermore, less than 20% of generated by-products could currently be reused in the cluster, while theoretically all by-products could be utilized today in other industries such as cement and ceramic. These findings support the use of IS as a way to open new perspectives for EIC development policies.

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To reduce greenhouse gas emissions to 80% below 1990 levels by 2050, an energy transition is taking place in the European Union. Achieving these targets requires changes in the heating and cooling sector (H&C). Designing and implementing this energy transition is not trivial, as technology, actors, and institutions interact in complex ways. We provide an illustrative example of the development and use of an agent-based model (ABM) for thermal energy transitions in the built environment, from the perspective of sociotechnical systems (STS) and complex adaptive systems (CAS). In our illustrative example, we studied the transition of a simplified residential neighborhood to heating without natural gas. We used the ABM to explore socioeconomic conditions that could support the neighborhoods’ transition over 20 years while meeting the neighborhoods’ heat demand. Our illustrative example showed that through the use of STS, CAS, and an ABM, we can account for technology, actors, institutions, and their interactions while designing for thermal energy transitions in the built environment.@en

Social life cycle assessment (SLCA) was developed to complement the environmental life cycle assessment (LCA) and economic assessment. Contrary to LCA, SLCA is not yet standardized, and the consequential approach is little discussed in literature. This study aims to perform a consequential SLCA and investigate the applicability of the method in industrial decision making. The aforementioned assessment is done within the Zero Brine project, which works on zero liquid discharge technology for water, salt, and magnesium recovery from brine efluents. The developed SLCA systems are gate-to-gate, and the analysis is performed at two levels: Hotspot and site-specific. The system boundaries consist of a demineralized water (DW) production company, a chlor-alkali company, an electricity provider, a magnesium distributor in the Netherlands, and a Russian mining company. The latter exists only in the boundaries before the change due to the Zero Brine project, because recovered magnesium is expected to replace the Russian magnesium imported in the Netherlands. Within the system boundaries, the stakeholders contributing the most are the DW and the magnesium distributor companies. The former produces the brine and thus recovers the magnesium and salt. The latter is the exclusive distributor of Russian magnesium in the Netherlands. Overall, we find that the recovered magnesium results in improving social performance mainly in "Freedom of association and collective bargaining", "Fair salary", and "Health and Safety" due to decreasing the dependency of the Netherlands on Russia, while increasing operation in a country with much stronger environmental regulation and corporate commitment to sustainability issues. Modelling with SLCA may not result in the expected societal benefits, as the Russian community and workers may not benefit due to the large geographical boundaries of the system under study. Nevertheless, the application of the consequential approach can be considered suitable, yet complicated, for offering decision makers adequate social information. We recommend that decision makers in the DW company invest in magnesium recovery and that decision makers in the magnesium distributor company distribute the recovered magnesium.

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Industrial Symbiosis (IS) is a collective approach to competitive advantage in which separate industries create a cooperative network to exchange materials, energy, water and/or by-products. By addressing issues related to resource depletion, waste management and pollution, IS plays an important role in the transition towards sustainable development. In the literature, two conceptual perspectives on IS can be identified: the Industrial Ecology (IE) and the Circular Economy (CE) perspective. Despite the recognition of these two perspectives, their relationship remains unclear and explicit attempts to develop an integrated perspective have not been made yet. Consequently, the goal of this research is to highlight and start addressing this critical gap of knowledge in order to support future research and practice geared towards the design of new IS clusters. We pose the following research question: How can the IE and CE perspectives on IS be combined in order to support the design of IS clusters? To this end, we first investigate the two perspectives more in depth and compare them in terms of nature, features and relevance for the study of IS. This is done by applying them as conceptual lenses for the analysis of the same case study, an existing IS cluster. The comparative analysis provides insights into how the two perspectives differ, ultimately demonstrating that they are complimentary and both necessary to fully describe an IS cluster. While the CE perspective is more suitable to explain how a cluster functions from a business standpoint in the operating phase, the IE perspective is more suitable to explain its development over time and its impacts on the environment, the economy and society. Building upon the outcomes of the comparative analysis, we leverage on the discipline of Strategic Design and integrate the two perspectives into a process for designing new IS clusters. We suggest two directions for future research. First, improving our comparative analysis of the two perspectives by looking at a wider sample of IS clusters of different sizes and in different contexts. Second, focusing with more specificity on the issue of how IS clusters can be designed, potentially by trying to apply the process we propose on a real case aimed at designing a new IS cluster.

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