Purpose
This work aims to provide insights on the application of social life cycle assessment (S-LCA) in evaluating the social impacts associated with municipal wastewater treatment (WWT). The study assesses the social risks and social performance of two municipal WWT systems in Catalonia, Spain: a conventional wastewater treatment plant (WWTP) (Reference System) and a novel system that recovers water and other valuable resources (Novel System).

Methods
S-LCA was conducted at Generic and Site-Specific levels using 1 m3 of wastewater treatment as the functional unit (FU). The Generic assessment was conducted via the Product Social Impact Life Cycle Assessment (PSILCA) database, while the Site-Specific assessment employed the Subcategory Assessment Method (SAM) with four-level reference scales to assess the social performance of the WWTP operator and its first-tier suppliers. Furthermore, activity variables were calculated based on organizations’ shares in the total costs per FU, and the Novel System’s multifunctionality was solved through economic allocation. Results were aggregated by (i) assigning equal weights to organizations and (ii) factoring in organizations’ weights and the allocation factor, leading to results per FU.

Results and discussion
The Generic analysis results indicated that the Novel System entailed fewer social risks than the Reference System. Most social risks in both systems occurred in the subcategories “Access to material resources,” “Fair salary,” “Freedom of association and collective bargaining,” “Contribution to economic development,” and “Corruption.” In the Site-Specific assessment, the Novel System presented better social performance than the Reference System per 1 m3 of wastewater treatment. The latter’s performance per FU did not meet the basic requirement in four out of eleven subcategories, mainly due to the performance and weight of a chemical supplier. Allocation greatly benefitted the Novel System’s results per FU compared to the results obtained when equal weights were applied.

Conclusions
Activity variables were used to connect organizations’ conduct with particular WWT systems, and multifunctionality was solved. This approach allowed for obtaining results per FU at both assessment levels. However, social performance was also evaluated by calculating the average social performance of each system without considering activity variables and the FU, leading to different results. The social performance of the Novel System per FU was satisfactory across all subcategories but required improvement in four subcategories based on the average results. Given the limitations of using activity variables and allocation in S-LCA, further research is necessary to appropriately evaluate and compare the social effects of novel resource recovery systems.@en

This study assesses the economic and environmental implications of Sustainable Aviation Fuel (SAF) production using Alcohol-to-Jet (ATJ) and Gasification Fischer-Tropsch (GFT) technologies, focusing on Colombian lignocellulosic feedstocks and evaluating key performance indicators such as yield, minimum fuel selling price, and life cycle assessment. GFT demonstrates promising results, yielding and Minimum Fuel Selling Price (MFSP) of about 1.3 USD/L and a Life Cycle Assessment (LCA) of 3.2 to 7.7 gCO2 eq/MJ. However, its scalability is constrained by the volumes it manages. On the other hand, ATJ has an MFSP between 1.9 and 2.4 USD/L. Aligned with aviation industry goals for carbon-neutral growth, this analysis provides valuable insights for policymakers and industry stakeholders, supporting informed decisions toward sustainable aviation fuel adoption in the Colombian context.@en

The production of capital goods is often ignored in the life cycle inventory phase of life cycle assessment studies. In this study, we investigated whether capital goods production, i.e., manufacturing of capital equipment and construction of infrastructure, and operation affect the results of the social life cycle assessment (S-LCA), using a case study of a desalination plant with multiple co-products in Lampedusa, Italy. The assessment was conducted using the PSILCA database to evaluate 20 impact subcategories and four stakeholder categories: Workers, Value chain actors, Society and Local community. Monetary data were collected for the manufacturing of equipment, labor and miscellaneous work during plant construction, working hours of employees during operation, consumed electricity and chemicals, and recovered materials during operation. Furthermore, multi-functionality was addressed through substitution, system expansion, and economic allocation to examine how these approaches affected the results. The functional unit was 1 m³ industrial water. Equipment manufacturing and plant construction contributed up to 15% to stakeholder categories and between 2% and 75% to impact subcategories of the substitution approach, and up to 51% for impact subcategories of system expansion and economic allocation. Equipment manufacturing and plant construction contributed to a high extent to “Health and safety” (of Workers), “Discrimination” and “Local employment” due to the construction and electrical sectors. Credits in substitution lead to a lower contribution of the operational stage and negative societal impact values. If S-LCA practitioners must limit the considered impact subcategories, for generic or site-specific analysis, the “Health and safety” (Workers), “Local employment”, and “Fair salary” should be investigated.

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The iron and steel industry is responsible for 30% of all industrial CO2 emissions, largely emitted via hot Basic Oxygen Furnace (BOF) gas (CO, H2, CO2). Gas fermentation can convert the BOF gas into valuable chemicals such as the disinfectant and platform chemical isopropyl alcohol (IPA), which is currently only produced with petrochemical cracking. The goal of this research was to model the state-of-the-art industrial-scale BOF gas fermentation to IPA and identify the key process parameters affecting technical performance. The designed and modelled industrial-scale process was based on the published LanzaTech technology with Clostridium autoethanogenum. In the process model, the IPA is purified through extractive distillation with pure glycerol as an entrainer. During sensitivity analysis, eleven process parameters were investigated for their effect on the eighteen chosen technical Key Performance Indicators (KPIs). These process parameters are (product selectivity (YIPA/CO), CO volumetric mass transfer rate (VMTCO), CO conversion, reactor dilution rate (D), temperature off-gas condenser, biomass separation liquid loss, extractive distillation glycerol mole fraction, extractive distillation molar reflux ratio, glycerol recycle purge, broth recycle purge and anaerobic digestion waste conversion). The sensitivity analysis identified that the key technical parameters affecting the KPIs are the gas fermentation parameters (CO conversion, VMTCO, YIPA/CO, and D) as well as the biomass filtration liquid loss. Moreover, increasing CO conversion, VMTCO, YIPA/CO as well as decreasing D and the biomass filtration liquid loss all individually had the greatest positive impact on the KPIs. Thus, this study has successfully synthesised and modelled a state-of-the-art industrial-scale BOF gas fermentation to IPA process and identified the key process parameters to improve its technical process performance. These findings can be used both to optimise the BOF gas fermentation to IPA process, and perform further economic evaluations and environmental impact assessment.@en

The aim of this study is to introduce and showcase the applicability of the ‘Green-by-Design method’, a tool created by the cooperative Cosun that integrates different indicators involving economic, environmental, inherent safety and health aspects for comparative analysis at an early design stage. Two case studies are presented to exemplify the evaluation principles and steps considered along the ‘Green-by-Design method’: ethylene glycol production and fava bean protein isolate extraction. The results indicate that the ‘Green-by-Design method’ provides a comprehensive comparison of different design concepts, by combining various indicators into a single score, enabling sustainability to be an integral aspect in the decision-making during an early design phase.@en

This research explores the optimization of Sustainable Aviation Fuels (SAF) production in Colombia, emphasizing economic and environmental factors. It examines feedstock availability, production technologies Alcohol-to-Jet (ATJ), Fischer-Tropsch (FT), and geographical considerations to determine the Minimum Fuel Selling Price (MFSP) of SAF. The environmental analysis employs a Life Cycle Assessment (LCA), considering CO2 emissions at each value chain step with an energy allocation factor for equitable carbon footprint distribution. Results highlight increased SAF demand in urban centers, necessitating diverse biomass sourcing. Fischer-Tropsch proves efficient but with high energy requirements impacting costs, while Alcohol-to-Jet offers an alternative leveraging existing bioethanol facilities. The study emphasizes data sensitivity importance, addressing limitations and showcasing 0.072 USD/L change for 1% allocation change and 0.03 USD per liter for 1% conversion drop in Gas-to-Liquid Fuel, and 0.04 USD/L for allocation and 0.1 USD/L for 1% conversion drop in Alcohol-to-Jet. Compared to prior work, this research provides detailed economic and environmental insights, extending analysis depth and acknowledging limitations, thereby enhancing research comprehensiveness and applicability.@en

The aeronautical sector faces challenges in meeting its net-zero ambition by 2050. To achieve this target, much effort has been devoted to exploring sustainable aviation fuels (SAF). Accordingly, we evaluated the technical performance of potential SAF production in an integrated first- and second-generation sugarcane biorefinery focusing on Brazil. The CO2 equivalent and the renewability exergy indexes were used to assess environmental performance and impact throughout the supply chain. In addition, exergy efficiency (ηB) and average unitary exergy costs (AUEC) were used as complementary metrics to carry out a multi-criteria approach to determine the overall performance of the biorefinery pathways. The production capacity assumed for this analysis covers 10% of the fuel demand in 2020 at the international Brazilian airports of São Paulo and Rio de Janeiro, leading to a base capacity of 210 kt jet fuel/y. The process design includes sugarcane bagasse and straw as the feedstock of the biochemical processes, including diverse pre-treatment methods to convert lignocellulosic resources to biojet fuel, and lignin upgrade alternatives (cogeneration, fast pyrolysis, and gasification Fischer-Tropsch). The environmental analysis for all scenarios shows a GHG reduction potential due to a decrease of up to 30% in the CO2 equivalent exergy base emissions compared to fossil-based jet fuel.@en

Compositional data on vegetable biomass is widely available from research papers and online databases. However, the high diversity of biomass characteristics and composition represents a challenge for researchers and companies willing to produce novel substances from residues, and that should decide on the best and most feasible options for their use as feedstocks. The present study constructed a database with information gathered from the proximate, ultimate, and chemical composition of different biomass residues that can be used for data analysis and classification to elucidate better how they can be valorized. Different data clustering techniques were implemented to determine how compositional data can be segmented. The identified groups, that contained residues with similar characteristics, allowed to have an insight into the valorization of these biomasses, which can be used as an initial tool for biorefinery design. The use of data clustering facilitated the identification of different types of biomasses in a systematic way, which until now has not been reported in the literature.@en

The sustainable supply of water is crucial, especially on islands where water is scarce. Our study applied the social life cycle assessment (S-LCA), under the organizational approach, to assess industrial water production on the island of Lampedusa, Italy. A novel plant for industrial water production considering a circular concept was compared with the existing linear production plant based on reverse osmosis. An online survey, brief literature review and generic analysis were conducted to prioritize impact subcategories selection for site-specific analysis that regarded six organizations in the system boundaries. These subcategories were Local employment, Access to material resources, Promoting social responsibility, End-of-life responsibility, Health and safety (Workers), and Public commitment to sustainability issues. The social performance of organizations involved was assessed based on equal weighting and weighting with cost values. The generic analysis showed that wastewater treatment in Italy is underdeveloped, and water scarcity can become a serious problem in the future. The site-specific analysis based on equal weighting showed that the novel water plant results in improving social performance for all considered impact subcategories by 88 % to 91 % due to co-production when compared with the existing plant. Even increasing impacts allocation to industrial water production social benefits are still expected due to co-production. The type of weighting based on cost values showed that two organizations are the main contributors to the social performance of the novel system, and improving their corporate conduct can result in improving impacts up to 25 %, such as Public commitment to sustainability issues. To conclude, the novel plan does provide social benefits but mainly due to co-production, thus, it should be investigated more how to apply the S-LCA to linear production systems as they become more circular.

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To be the first carbon-neutral continent by 2050, the European Union (EU) should decarbonize the aviation sector. According to the ReFuel initiative, sustainable aviation fuels (SAFs) are crucial in reducing carbon emissions from the sector. The Clean Sky 2 program by the EU commission, shortlisted four promising technologies - hydro-processed esters and fatty acids (HEFA), Fischer–Tropsch (FT), fast pyrolysis (FP), and alcohol-to-jet (ATJ) for the production of SAFs from bio-based sources. This study addresses the potential of these four technologies to reduce net and total greenhouse gas (GHG) emissions in the aviation sector. With a focus on mapping feedstock availability in 33 European countries for meeting the national demand in 2030. The investigation identified the best pathway combinations for each country, having the highest GHG emissions reduction while satisfying fuel demand when considering different degrees of biomass competition. Without any political and economic barriers to SAF production and biomass competition, we estimated a sufficient biomass supply exists to support the European SAF demand across all forecasted scenarios in 2030.

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Purpose: Gold mining has historically and significantly contributed to the Colombian economy. Gold extraction in Colombia is mainly done through two techniques: open-pit and alluvial mining. In this study, the environmental impacts of both these mining systems were analyzed using the life cycle assessment (LCA) framework, including identification of the system components that contribute most to impacts. Methods: Inventory data were obtained for two medium-scale mines in Colombia, one representing the open-pit method and the other the alluvial method. Environmental impacts were classified and characterized by mid-point impact categories and further aggregated into end-point indicators through the ReCiPe (v. 1.11) methodology, which uses a hierarchist perspective. Results: Results for end-point indicators show that the open-pit mining presents higher values in the human health damage category, influenced primarily by tailings and by the excavation process. For the alluvial mining, the overall impacts were an order of magnitude lower, with ecosystem quality as the most significant contributor due to the stripping of soil and vegetation. In the case of mid-point indicators, freshwater and marine ecotoxicity contribute the most to open-pit mining, while for alluvial mining, metal depletion and natural land transformation contribute the most. Climate change is also a significant impact category for alluvial and open-pit mining. Conclusions: The is a substantial difference in environmental impacts between the two mining systems: the quantified total environmental impact was 1.0 × 10⁰⁴ points for the open-pit mine and 2.4 × 10⁰³ points for the alluvial mine. Since these mines represent specific Colombian operational conditions, this conclusion cannot be confidently extended to other operational contexts. For example, results in other cases may depend on the local geological features and natural environment conditions. Knowing the critical mining supply chain stages for environmental performance will allow the decision-makers to provide the tools for more sustainable extraction and production.

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This article reviews the current scenario and the main uncertainties and challenges associated with implementing Sustainable Aviation Fuel (SAF) in Colombia, from which it determines the possible certified technologies under the ASTM D 7566 standard as well as co-processing technologies contemplated within the ASTM D 1655 standard, more suitable for the implementation of SAF production. Likewise, through the PESTEL tool (Political, Economic, Social, Technological, Environmental, and Legal), a diagnosis is made in order to obtain an updated overview of the implementation of SAF in Colombia. Based on the above, it provides recommendations to mitigate the uncertainties identified, and it is complemented by the ECOCANVAS tool, which applies to businesses related to the circular economy, and also include the net production potential of SAF in Colombia, considering the production of feedstock, in agricultural residue of sugarcane, oil palm, corn, and coffee. This study concludes with some policy recommendations that can make SAF implementation viable and allow responsible institutions to organize themselves for better strategic action and identify the fields of research and the need for investment in R + D + i to strengthen the supply chain.@en

Integrating low-carbon technologies within biorefineries, with applications targeting energyefficient separation systems, is essential to achieving net zero emissions in the coming years. To address this target, we investigated potential biorefinery pathways featuring process intensification in the bioethanol and biodiesel industries. The role of separation technologies was determined, and a methodological tool to design biorefinery systems with improved economic and environmental performance was developed. A thermodynamic analysis, comprising an energy and exergy assessment, of all scenarios showed a 10% reduction in the irreversibility rates, and the steam consumption decreased by 20% compared to conventional bioenergy configurations when considering intensified ethanol and biodiesel processes. The renewability exergy index and the average unitary exergy cost were defined as key parameters to assess the efficiency and impact since they represent appropriate metrics to determine the environmental impact and the global performance throughout the configurations’ supply chain. Lastly, promising ethanol-derived products (e.g., 1,3-propanediol, diethyl ether, n-butanol, 1,3- butadiene, D-lactic acid, and succinic acid) were evaluated based on the biofuel conversion performance, aiming to diversify biorefinery systems through chemical production and add value to the technological pathways toward lower carbon fuels/products. Among the alternatives, 1,3- propanediol was ranked as the most promising ethanol-derived chemical based on exergy efficiency and λindex.@en

In the last few years, healthy foods have increasingly attracted consumers' interest, leading to an increase in sales worldwide. Using by-products from the agroindustry to produce healthy/fortified foods is a promising approach since peels and seeds of fruits have significant amounts of bioactive compounds. In this sense, this work evaluated the possibility to add fractions recovered from residues of orange, lime, and peach palm in a food product. First, the proximate, ultimate, and chemical composition of the residues was determined to identify the main substances that could be valorized. Then, the selected high-value-added molecules extracted from fruit residues were used to formulate a high-fiber brownie. A Box-Behnken experimental design was used to determine if fat replacement, flour replacement, and the addition of encapsulated extracts influenced the food product's color, texture, and humidity which were determined from the analysis of the texture profile of the samples. It was possible to identify with the help of an electronic tongue a formulation with similar properties to a commercial brownie but with enhanced functional properties due to the novel ingredients added, which could potentially improve consumers' health.

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Mussels cooking wastewater (MCW) and fish processing wastewater (FPW) were utilized as feedstocks for the production of polyhydroxyalkanoates (PHA) and triacylglycerides (TAG) at the laboratory scale. This study presents a comparison of the techno-economic and environmental performance of ten circular economy-based and innovative processes, in which PHA/TAG are produced using Mixed Microbial Cultures (MMC), with benchmark wastewater treatments for MCW and FPW. The innovative systems were modeled based on the upscaling of lab-scale data using mass balances, and a centralized downstream processing (DSP) plant was proposed for PHA/TAG extraction. This study is the first to conduct a techno-economic and environmental analysis of a system with a centralized DSP. Consequently, the most favorable operational options were selected based on the techno-economic and environmental performance of the ten proposed scenarios. The techno-economic evaluations demonstrate that treatment costs for MCW and FPW could be reduced by 10% and 40%, respectively, compared to the benchmark treatment. Furthermore, environmental impacts could be significantly reduced (e.g., 10–70% for global warming potential) compared to the baseline scenario by implementing a system expansion approach. Regarding the centralized DSP, the production cost of PHA from MCW falls within a competitive market threshold, ranging from 0.95 to 1.18 €/kg. However, the production costs of PHA and TAG from FPW (1.40–2.21 €/kg PHA and 0.51–0.69 €/kg TAG) are hindered by the lower biomass concentration achieved. Hence, this study demonstrates, for the first time, the potential feasibility of circular economy-based strategies for valorizing saline industrial wastewaters through a centralized DSP approach.

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Syngas fermentation is an up-and-coming technology that uses acetogenic microorganisms to produce ethanol at the commercial scale. Acetogens can produce many different types of products via their metabolic pathway called the Wood Ljugdahl Pathway (WLP). The WLP can natively produce many different fatty acids and alcohols, and with metabolic engineering, other molecules could be produced through syngas fermentation that are not native to the WLP. In this work isopropanol, 3-hydroxybutyric acid, hexanol, octanol, hexanoic acid, butyric acid and lactic acid were assessed for their feasibility to be produced through syngas fermentation. Two syngas cases were analysed; bio-syngas (H₂:CO of 1:1.907) and basic oxygen furnace gas (H₂:CO of 1:21.667). The feedstock capacity was fixed at 350 ktons/yr based on its availability. Using thermodynamic values, process reactions from the substrate to the product were found. To verify the metabolic feasibility, ATP yields were calculated based on the respective WLPs from the literature. Sensitivity studies of H₂:CO ratios on the carbon yield are carried out to check its effect on the production yields of the product, biomass, and CO₂. Sensitivity analysis showed that a higher H₂:CO ratio in the feedstock will lead to higher production.

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Most gasoline currently consumed in Mexico continues to be oxygenated with Methyl Tert-Butyl Ether (MTBE) despite its proven effects on the environment and human health. Hence, the existence of a regulatory framework on biofuels and various institutional efforts have not been sufficient to develop a national market for anhydrous ethanol use as biofuel. The goal of this research is twofold: one, to review and analyze the governmental actions taken to incorporate bioethanol as a gasoline oxygenate, and, two, to design a tool to estimate the bioethanol price at the Storage and Distribution Terminals of PEMEX (Mexico’s state-owned oil company). A price estimation model for bioethanol was developed through the microeconomic theory of the producer and the indifference price of a product methodology, which calculates the daily price of ethanol in the period 2015–2022; additionally, an MS Excel-based support tool was created for this analysis (namely: the Price-CEM). The analysis showed that incorporating bioethanol into the Mexican energy matrix would require policies of fiscal support for R&D, agricultural waste management and bioethanol production, as well as a new regulatory framework to both gradually eliminate MTBE and establish bioethanol/gasoline blending targets. Furthermore, institutional efforts would also be required to integrate all links in the biofuel production chain, including primary feedstock producers. The cost estimation method and tool have also shown to be valuable instruments to calculate both the prices at which a local bioethanol market would be competitive (with respect to the international market) and the most important cost contributions for local supply chains. This is the first tool to estimate the price of anhydrous ethanol at the local level, which can contribute to identifying opportunities and economic thresholds for the successful development of feasible bioethanol markets in Mexico.

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Advanced biofuels from thermochemical liquefaction, such as pyrolysis (PY) and Hydrothermal liquefaction (HTL), of olive residues in the Andalusian region of Spain (specifically in the province of Jaen) can potentially play a crucial role in the reduction of greenhouse gas (GHG) emissions in the maritime sector. In this study, an attributional life-cycle assessment (ALCA) was performed to estimate and compare the GHG emissions for producing marine biofuels via pyrolysis and HTL from olive pomace (COP) and pruning biomass (OTPB), to provide 1 megajoule (MJ) of marine biofuel, as a functional unit. For convenience, the different technology-feedstock combination scenarios are represented as scenario 1 (PY_COP), scenario 2 (PY_OTPB), scenario 3 (HTL_COP), and scenario 4 (HTL_OTPB). The life-cycle GHG emissions of the biofuels were 42.0, 44.1, 22.1, and 32.1 g CO₂-eq/MJ for PY_COP, PY_OTPB, HTL_COP and HTL_OTPB scenarios, respectively, corresponding to 47–73% GHG emissions reduction compared with petroleum fuels. The scenarios were also evaluated based on other impact categories such as Sulphur dioxide in the air, Nitrogen oxides in the air, Particulates in the air, and Non-methane volatile organic compounds (NMVOCs) in the air. The scenarios reduced the SO₂ emissions, Nitrogen emissions, NVMOCs, and particulates in the air by at least 50%, 90%, 20%, and 25% respectively in comparison to fossil fuels. A contribution analysis revealed that olive cultivation and upgrading as hot spots for emission in pyrolysis-based systems. Likewise, HTL conversion and upgrading steps were emitting more emissions for an HTL-based system. Therefore, marine biofuel obtained through the thermochemical conversion of olive residues has better environmental performance on a life cycle basis, with a preference for HTL based system over pyrolysis.

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Syngas fermentation is a biochemical pathway to produce ethanol and has been commercialized successfully. The economic viability of this process could be further improved to become more competitive in the existing ethanol market. Improving gas utilization is the key, and can be done by recycling the unreacted syngas. This work is an early-stage techno-economic assessment of recycling in producing ethanol from Basic Oxygen Furnace (BOF) gas. Economic viability is measured in terms of Relative Competitive Percentage (RCP) and is a measure of closeness to the current market. Two scenarios, firstly a once-through process, and secondly a process with recycling (0.9 split ratio: recycle/purge) of gas is considered. None of them showed a positive RCP as compared to the current ethanol market. Comparing these scenarios, beyond the single pass conversion of 60%, the additional production costs due to recycling become dominating and lead to a lower RCP compared to once-through systems.

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Aviation biofuels are promising to reduce carbon emissions in the aviation sector. However, emerging concerns over biofuels indicate a need for sustainability analyses that take into consideration the context around biofuel production. Here, we present a novel ex-ante sustainability analysis of production alternatives for aviation biofuel in Southeast Brazil. Considering local stakeholders’ concerns, the analysis is focused on climate change, commercial acceptability, efficiency, energy security, investment security, profitability, social development, and soil sustainability. By identifying tensions between production alternatives and these sustainability aspects, we discuss opportunities for further developments, such as sugarcane ethanol-to-jet production in the short term, and in-house production of hydrogen and power with renewable energy. Additionally, producer–operator partnerships and opening the decision-making to stakeholder participation are suggested to stimulate social cohesion, and reconcile diverging interests with biobased production. Analyzing sustainability with consideration of the local context can contribute to identify opportunities for more sustainable decarbonization alternatives.

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