The authors regret that an inconsistency was identified between the results presented in Fig. 6 and the inventory data reported in Tables S.11 and S.12 of the Supplementary Information. This discrepancy arose because an additional scenario from a previous version of the manuscript was inadvertently retained in the Supplementary Information, although it was not included in the final published article. As a result, the scenario numbering in the Supplementary Information did not correspond to the scenarios discussed in the main text, leading to apparent inconsistencies for Climate change and Marine ecotoxicity results for Scenario 3. The Supplementary Information has now been corrected by removing the tables related to the excluded scenario and aligning the remaining scenario numbering with the final version of the article. The results presented in the main article remain unchanged. The authors would like to apologise for any inconvenience caused.

This study advances the development of syngas fermentation by presenting the first industrial-scale process design for producing isopropanol (IPA) and acetone from steel mill off-gas, with a total production capacity of 46–50 ktonne per year. The process was rigorously developed in Aspen Plus, with a comprehensive techno-economic assessment and life-cycle analysis performed to evaluate the process performance. The developed process maximizes energy efficiency by utilizing the heat content of steel off-gas and implementing advanced heat pump systems. As a result, the process is thermally self-sufficient and can operate solely on renewable electricity. Efficient utilization of waste gases results in substantial reductions in global warming potential compared with petrochemical-based production (144–160% for IPA and 138–149% for acetone). The unit production cost of 0.58–0.74 $/kg_IPA/Ac and potential profit margins of 49–65% testify to the cost-effectiveness of the developed process. These findings demonstrate the environmental and economic sustainability of syngas fermentation from steel mill off-gas, establishing it as a potentially viable alternative to conventional petrochemical processes. This technology may hold great potential in reducing environmental impacts and carbon emissions in industrial chemical production.

Coffee processing encompasses the conversion of coffee cherries into marketable products, including the removal of outer layers to produce green coffee and, in extended chains, their roasting into roasted coffee, and grinding into ground coffee. Calculating the carbon footprint (CF) in coffee processing is crucial for identifying and mitigating key sources of greenhouse gas (GHG) emissions. Utilizing the Life Cycle Assessment (LCA) methodology, the current study quantifies the CF associated with Robusta dry coffee processing by collecting primary data through interviews with coffee producers and visits to coffee processing units, roasting, and grinding facilities in Wayanad, India. The study identifies GHG emission hotspots across two scenarios. Scenario A includes transportation of dried coffee beans from farm to coffee processing unit, green coffee production, packaging, roasting, and grinding at a local unit, while Scenario B covers local transportation of green coffee beans from India to The Netherlands, green coffee production, packaging, and its transportation from India to The Netherlands. Cultivation and harvesting of coffee cherries, consumer-level preparation and use, and disposal of coffee products are outside the scope of this study. The functional unit is defined as 1 kg of green coffee for both scenarios. Findings show that the CF equals 0.62 and 0.38 kg CO_2eq per kg of green coffee for scenarios A and B, respectively. Roasting (78 % of CF), and sea transportation (66 % of CF) emerged as the main hotspots of GHG emissions for scenario A, and scenario B, respectively.

Alternative fermentation feedstocks such as ethanol can be produced from CO₂ via electrocatalytic processes that coproduce O₂. In this study, industrial-scale fermentation of ethanol with pure O₂ for single cell protein (SCP) production was studied using a modeling approach. This approach considered (i) microbial kinetics, (ii) gas–liquid transfer, and (iii) an exploration of potential operational constraints. The technical feasibility for producing up to 58 kt/y of SCP in a 600 m³ bubble column operating in continuous mode was assessed and attributed mainly to a high O₂ transfer rate of 1.1 mol/(kg h) through the use of pure O₂. However, most of the pure O₂ fed to the fermenter remains unconsumed due to the large gas flows needed to maximize mass transfer. In addition, biomass production may be hampered by high dissolved CO₂ concentrations and by large heat production. The model estimates a microbial biomass concentration of 114 g/kg, with a yield on ethanol of 0.61 g_x/g_ethanol (> 95% (Formula presented.)). Although the large predicted O₂ transfer capacity seems technically feasible, it needs further experimental validation. The model structure allows the analysis of alternative substrates in the same way as identifying the best carbon feedstock.

Synthesis gas fermentation is a promising route for the valorization of steel mill off-gas and for replacing conventional fossil-based isopropyl alcohol (IPA) production. A recent 120 L pilot-scale study reported 85% gas conversion at 90% product selectivity and claimed a negative global warming potential (GWP) without detailed process design. The current paper reports a first-of-a-kind industrial-scale syngas fermentation process that was designed using extractive distillation with glycerol to produce 46 kton year ⁻¹ of 99.1 wt% IPA. The sustainability of an industrial-scale continuous syngas-to-IPA process has not yet been assessed. This study describes the first integrated cradle-to-gate technoeconomic analysis (TEA) and life cycle assessment (LCA), accounting for all emissions scopes, crediting prevented CO ₂ emissions from steel mill off gas, and including steel mill heat replacement. Parametric assessment identified higher CO volumetric mass transfer rate (VMT _CO) and lower dilution rate (D) as key parameters for enhanced sustainability. For improved process design, economic and environmental tradeoffs were observed for lower glycerol bleed and higher VMT _CO. At best, a −44.4% GWP was achieved for a 6.25% increase in VMT _CO to 8.5 g L ⁻¹ h ⁻¹ (12.2 kgCO ₂-eq kg ⁻¹ _IPA; Netherlands case) and a −23.2% in IPA production costs for a 30% decrease in glycerol bleed of 7 wt% (USD 3.28 per kg _IPA, US case) compared with the base-case process.

This study aims to design and evaluate the techno-economic feasibility of socially just and context-specific biohubs for producing marine biofuels based on olive residues with hydrothermal liquefaction (HTL) in Spain, using existing infrastructures. The conceptual process and biohubs design are co-designed using a multi-actor approach, involving local stakeholders through participatory methods, with the help of a Capability-sensitive design. The material and energy balances (from Aspen Plus simulations) are used to evaluate the technical and economic performance (such as capital expenses, operational costs, and minimum fuel selling price) of biohub. 21 possible scenarios are investigated to understand the impact of design aspects (such as scale, distributed configuration, and co-processing) on the minimum fuel selling price (MFSP). The MFSP of the HTL biofuels varied by a factor of 0.6–3.1 compared to the conventional fossil-based fuels. Additionally, co-processing of HTL bio-crude at existing petroleum refineries reduces equipment costs by 16%. The study also recommends that the minimum scale of the HTL facilities should be between 588–882 dry tons per day (DTPD) of crude olive pomace processing capacity, to benefit from economies of scale. Overall, the investigation shows an economically feasible way to develop context-relevant olive residue-based biohubs for marine biofuel production with existing infrastructures in Spain, while ensuring social justice near biomass production sites. We argue this approach can be replicated in the other olive-producing regions in the Mediterranean and conclude that olive residues from the Mediterranean region have a huge potential to provide alternative advanced “drop-in” biofuels for the shipping sector.

As water research and industry shift towards resource recovery plants, comprehensive assessment methods are needed to capture environmental trade-offs. Existing life cycle assessments (LCA) on desalination often neglect key methodological challenges in multi-product zero-liquid-discharge (ZLD) systems, risking misleading conclusions. This study applies LCA to conventional desalination and with three resource recovery scenarios (integrated desalination and brine treatment) in Cyprus: Sc1) maximum water recovery using waste heat (WH), Sc2) integrated desalination plant with brine treatment using WH, Sc3) electricity-based desalination with chemicals recovery, to assess how key methodological decisions influence the results and decisions. Five impact categories were analysed: climate change, human toxicity, marine ecotoxicity, water depletion, and fossil depletion. Without product substitution, multi-product ZLD systems show higher absolute impacts than SWRO due to increased energy and chemical demands. However, when credits for recovered salts and chemicals are considered, Scenarios 2 and 3 achieve large net reductions compared to conventional production, highlighting the sustainability potential of resource recovery. Results proved highly sensitive to methodological choices: functional unit selection (increase up to 59 %), allocation methods (variation from 54 % to 90 %), while excluding WH altered impacts by up to 89 %, emphasizing the need for transparent reporting to support robust decision-making in desalination design. Sensitivity analysis showed that integrating renewable energy could cut climate change and fossil depletion impacts by up to 99 %, though with trade-offs in marine ecotoxicity and water depletion. Rather than proposing new methods, this work provides critical guidance on applying standardized LCA options to complex systems, offering directly relevant insights for practitioners and policy-makers in sustainable desalination design.

Residues from orange processing are being continuously generated in vast amounts due to the increasing demand for this fruit and its byproducts worldwide. The valorization of Orange Residues is challenging in contrast to conventional “lignocellulosic residues” since this fruit-derived biomass contains high amounts of pectin and an extractive fraction rich in sugars, essential oils, and polyphenols. The relative amounts of these fractions are highly influenced by the juice/pulp extraction process. Even though several studies have explored how to produce added value from this biomass, it is necessary to compare how different techniques and operating conditions influence the bioactive compounds that can be recovered and the remnant biomass after processing. This study compares essential oil extraction, solvent extraction, and acid hydrolysis for fermentable sugar and pectin production to elucidate a feasible sequence for a biorefinery from Orange Residues. From our results, it was proposed a technically feasible sequence that maximizes the yields of i) essential oils (0.70 ± 0.05 g/ 100 g DM) from steam distillation (4 h, 1500 W), ii) naringin (0.19 g/100 g DM), hesperidin (1.27 g/100 g DM), and glucose (3.9 g/100 g DM) from solid-liquid extraction (Ethanol 61.6 % (w/v), 45.8 °C, 155.5 min, and 5 % (w/v) biomass load), iii) pectin (25.24 g/100 g DM) from citric acid hydrolysis (pH 1.5, 90 °C, 82.1 min, and 5 % (w/v) biomass load), and iv) glucose (12.41 g/100 g DM) and xylose (10.13 g/100 g DM) from sulfuric acid hydrolysis (Sulfuric acid 0.68 % (w/v), 121 °C, 24.1 min, and 7.32 % (w/v) biomass load), in a biorefinery scheme.

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.