This study aims to evaluate various waste-to-energy conversion scenarios in terms of their potential to reduce greenhouse gas (GHG) emissions and improve sustainability based on economic and environmental outcomes. To achieve this, a comprehensive waste management model was developed using the system dynamics approach in the Vensim software to predict waste generation and composition and compare pyrolysis, incineration, gasification, and sanitary landfill scenarios with the baseline scenario over 25 years (2025–2050). The analysis of different waste management scenarios highlights the superior performance of pyrolysis in terms of energy recovery, economic profit, GHG emissions reduction, environmental outcomes, and long-term sustainability. Results show that the pyrolysis scenario generates the highest electricity, with a cumulative net electricity output of 10,469 GWh. Although pyrolysis has GHG emissions due to energy consumption and direct process emissions, it results in the largest net reduction in GHG emissions, primarily due to avoided emissions from increased electricity generation, leading to a 346% reduction compared to the baseline scenario. Furthermore, the pyrolysis scenario demonstrates the highest economic profit at 354 million USD and the highest sustainability index (SI) at 499 million USD. The cumulative SI from 2025 to 2050 shows a 503% increase compared to the business-as-usual scenario, highlighting its superior sustainability performance. This study highlights the importance of strategic waste-to-energy planning in reducing GHG emissions and promoting sustainability. It also offers valuable insights for policymakers and researchers, supporting the development of sustainable waste management strategies and effective efforts for climate change mitigation.

Operationalizing sustainability transitions is associated with, for example, complexity-related challenges. This article describes an approach designed to facilitate handling such challenges, including compilation of the different perspectives of actors and facilitating analysis of interactions between interventions, in a manner suitable for integration of results in policy development contexts. Building on systems thinking and understanding of transitions, it is designed to support dialogue on (i) problems motivating policy interventions to enable a desired shift, (ii) priority areas for interventions, (iii) possible paths toward enabling transitions including interactions between priority areas for interventions, as well as (iv) chains of reasoning for policy interventions. The approach was piloted to explore how shifts toward sustainable circulation of materials in Swedish transportation infrastructure could be enabled. Semi-structured interviews were used to collect actors' assumptions on system failures as well as drivers and possible interventions, supported by the system failures framework of Weber and Rohracher. Seven priority areas for interventions were suggested. A causal loop diagram as well as a simplified version here referred to as "transition logics" were then prepared and used to explore paths toward enabling the desired shift, including possible near-term priorities considering interactions between suggested priority areas for interventions. The causal loop diagram was also used as a basis to develop a chain of reasoning for policy interventions. Results shall be seen as a basis for further dialogue and analysis. Finally, possibilities for further development of the approach are also discussed.

This study provides a comparative analysis of the biophysical economic structures of four developed economies—Sweden, the United States, the United Kingdom, and Canada. We draw upon results from input–output models to map and analyze capital, energy, and carbon relationships in each economy. The capital stock of each country is divided into four sectors: (i) energy production and distribution, (ii) production of goods and services for consumption, (iii) residential, and (iv) construction and manufacture of capital. The findings reveal diverse strengths and challenges in decarbonization efforts across the countries. Sweden excels in “energy production and distribution” and “residential” sectors, owing to its commitment to renewable energy and energy efficiency, but requires attention in goods and services production where carbon intensity is high. The United Kingdom stands out for its high greenhouse gas intensity in residential capital stock and in the consumption of goods and services, underscoring the need for targeted low-carbon investments. The United States and Canada display high GHG intensities across all sectors, necessitating a more robust transition toward renewable and low-carbon energy solutions. In particular, the United States’ carbon intensity in its energy sector and Canada's industry dominated by fossil fuel extraction offer specific areas for intervention. The study concludes that focusing on sectors with the highest carbon intensity and adopting both sector-specific and broader strategies can significantly accelerate each country's decarbonization efforts, thereby contributing to global climate change mitigation. This article met the requirements for a gold-gold JIE data openness badge described at http://jie.click/badges.

With the circular economy (CE) gaining more traction worldwide, local authorities are engaging in efforts to develop circular strategies at the urban level. Developing and monitoring such strategies require detailed quantitative information on material and energy flows, which can be obtained through an urban metabolism (UM) analysis. This study demonstrates a bottom-up approach to analyze UM at the sectoral level based on material and energy flow analysis (MEFA), aiming to examine its utility within the context of the CE. The analysis is performed for Umeå urban area (Sweden) with a 5-year timeframe (2017–2021). The application of MEFA provides a detailed quantitative description of material and energy flows per sector, indicating the critical sectors in terms of resource consumption and waste generation and the most significant flows. More specifically, it reveals that the construction sector and households are key sectors within Umeå’s UM and that construction materials, food products, fossil fuels, and drinking water are significant metabolic flows. Furthermore, the application of MEFA with a multi-year timeframe uncovers trends in consumption rates of materials and generation rates of waste and emissions, revealing, for example, the correlation of material consumption and waste generation with the level of construction activity. Overall, by illustrating the potential of MEFA to provide a detailed quantitative analysis of material and energy flows, this study emphasizes its utility in supporting the design and monitoring of circular strategies at the urban level. At the same time, it highlights limitations of the method and suggests areas for future research.

Purpose: This 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.

Methods: The 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 discussion: The 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%.

Conclusions: This 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.

The study examines the governance of low trophic species mariculture (LTM) using Sweden as a case study. LTM, involving species such as seaweeds and mollusks, offers ecosystem services and nutritious foods. Despite its potential to contribute to blue growth and Sustainable Development Goals, LTM development in the EU and OECD countries has stagnated. A framework for mapping governance elements (institutions, structures, and processes) and analyzing governance objective (effective, equitable, responsive, and robust) was combined with surveys addressed to the private entrepreneurs in the sector. Analysis reveals ineffective institutions due to lack of updated legislation and guidance, resulting in ambiguous interpretations. Governance structures include multiple decision-making bodies without a clear coordination agency. Licensing processes were lengthy and costly for the private entrepreneurs, and the outcomes were uncertain. To support Sweden’s blue bioeconomy, LTM governance requires policy integration, clearer direction, coordinated decision-making, and mechanisms for conflict resolution and learning.

This study aims to develop a comprehensive model for life cycle assessment and environmental damage cost calculations considering avoided emissions in different waste management scenarios using the system dynamics (SD) approach. Our analysis reveals that under the business-as-usual (BAU) scenario for the period 2020-2050, the total net greenhouse gas (GHG) emissions reach 12.5 Mt, with the highest environmental damage cost being USD 689 million. In contrast, an integrated management strategy encompassing recycling, composting, anaerobic digestion, and incineration results in a 195% reduction in net GHG emissions compared to the BAU Scenario. Concurrently, the environmental damage cost drops to USD 277 million, incorporating USD 347 million in savings, leading to a net environmental damage cost of USD -71 million. The findings affirm that accounting for emissions avoided across various treatment methods offers a more accurate estimate of environmental damage costs. Additionally, policies centered on integrated waste management are more likely to achieve sustainability. The study also demonstrates the utility of the SD approach in providing a holistic view of waste management systems and in evaluating the effectiveness of various policy strategies for sustainable waste management.

Harvesting beach-cast can help mitigate marine eutrophication by closing land-marine nutrient loops and provide a blue biomass raw material for the bioeconomy. Cost–benefit analysis was applied to harvest activities during 2009–2018 on the island of Gotland in the Baltic Sea, highlighting benefits such as nutrient removal from the marine system and improved recreational opportunities as well as costs of using inputs necessary for harvest. The results indicate that the activities entailed a net gain to society, lending substance to continued funding for harvests on Gotland and assessments of upscaling of harvest activities to other areas in Sweden and elsewhere. The lessons learnt from the considerable harvest experience on Gotland should be utilized for developing concrete guidelines for carrying out sustainable harvest practice, paying due attention to local conditions but also to what can be generalized to a wider national and international context.

A blue-green bioeconomy revolution is underway in Europe, with particular attention being paid to the development of new or underutilized marine biomass resources. The wild harvest and mariculture of low-trophic non-fed species of marine biomass may be contributing to circular economies, the mitigation of environmental problems such as eutrophication and climate change through the uptake of nutrients and carbon, while also recovering finite phosphorus from marine coastal environments, thus contributing to food security. The present study provides a cradle-to-gate life cycle perspective on seven established or innovative/emerging marine biomass utilization cases in Sweden: mariculture of sugar kelp, blue mussels, and ascidians and the harvest of invasive Pacific oysters along the Skagerrak coast, the mariculture of blue mussels in the Baltic sea, the harvest of common reed in the Stockholm archipelago, and the harvest of beach-cast seaweed in Gotland. Results showed that the mariculture cases were found to contribute to eutrophication and climate impact mitigation (at gate). All cases were found to contribute to closing the loop on phosphorus by enabling recovery from marine or coastal environments, bridging marine–land flows, all while performing well from an environmental perspective with a relatively low cumulative energy demand and low carbon and nutrient footprints. This highlights the potential of low-trophic biomass to contribute to phosphorus security in the future, and demonstrates the value of industrial ecology tools such as LCA in support of this imminent Decade of Ocean Science for Sustainable Development. 

As cities worldwide implement strategies to accelerate the transition toward a circular economy (CE), there is an increasing need for tools to monitor progress. However, a standardised metric for CE monitoring in urban areas is lacking. This study examines the potential of the EU Circular Economy Monitoring Framework (CEMF), an established indicator-based framework for measuring national- and EU-level circularity performance, as a monitoring tool for urban areas. For this purpose, available data sources that can support the framework's application at the urban level are mapped, and data quality is assessed following the pedigree matrix approach. Next, the CEMF indicators are computed for the urban area of Umeå, Sweden. The mapping showed limited availability of urban-level data, necessitating the downscaling of national-level data using proxy factors. Most available urban-level data are of high quality, while the quality of national-level data is reduced when used to compute indicators at the urban level. The application of the CEMF in Umeå indicates that there are areas where the municipality performs well, though further improvements are needed. We conclude that the CEMF has potential as a monitoring tool for urban areas. However, improvements in CEMF...s scope and data availability are recommended.