Search Results (55)

Aviation contributes approximately 2.4% of global CO₂ emissions and 3.5% of total effective radiative forcing when non-CO₂ effects are included, yet Sustainable Aviation Fuel (SAF) accounts for less than 0.5% of European jet fuel consumption. This paper investigates why the gap between policy ambition and deployment persists, asking (i) how misaligned instruments across ReFuelEU Aviation, RED III, CORSIA, and the UK RTFO impede high-integrity production pathways, and (ii) what convergence mechanisms can reduce fragmentation beyond Hydroprocessed Esters and Fatty Acids (HEFA)-dominated supply. Applying the Multi-Level Perspective framework, the study triangulates comparative policy analysis with a stakeholder survey (n = 45) across SAF producers, airlines, policymakers, and investors. Results identify regulatory fragmentation, capacity constraints, and funding barriers as near-equally weighted obstacles, while disaggregation reveals actor-specific priorities: policymakers emphasise regulatory complexity, airlines emphasise funding, and producers emphasise capacity. Most producers declined to disclose volume projections, interpreted here as strategic ambiguity under regulatory uncertainty. Three convergence mechanisms are proposed: harmonised carbon-intensity registries, standardised book-and-claim accounting, and joint feedstock certification protocols. The findings align aviation decarbonisation with SDGs 7, 9, 12, and 13. Without coherent policy architecture, SAF deployment risks entrenching low-ambition compliance pathways that undermine the EU’s contribution to the 2030 Agenda. Full article

The aviation sector is accelerating the transition toward low-carbon propulsion, and Sustainable Aviation Fuels (SAFs) represent a key leverage to reduce lifecycle emissions without modifying existing turbine architectures. Microturbines offer an effective and low-cost platform for assessing SAF behaviour under engine-representative conditions. In this work, a zero-dimensional performance and emission model of the GTM-140 microturbine was developed in GSP and validated against experimental data at 70,000–112,000 rpm for Jet A-1 and HEFA paraffinic blends. The model reproduces thrust and fuel-flow trends with good fidelity, with deviations typically below 6% across all operating points. Introducing 50% HEFA consistently reduces fuel consumption, leading to a TSFC decrease of 3–6%, with the strongest effect at high rotational speed, where compressor efficiency is highest. CO emission indices decrease by 6–9% at mid-load and converge at full power due to enhanced oxidation, while NO_x increases by 6–15%, driven by the higher adiabatic flame temperature associated with HEFA’s increased H/C ratio and heating value. These results confirm that simplified 0D modelling can reliably capture performance and emission trends of SAF-fuelled microturbines and demonstrate the dual effect of HEFA: improved combustion efficiency and CO reduction, at the expense of moderately higher NO_x formation. Full article

The aviation industry faces increasing pressure to reduce its environmental impact and achieve net-zero emissions by 2050. In this context, sustainable aviation fuels (SAF) have emerged as a critical alternative to conventional jet fuels. This study provides a comprehensive analysis of SAF technologies from a chemical engineering perspective, highlighting key production routes, technological maturity levels, and implementation challenges. A bibliometric analysis using the Scopus database and VOSviewer software was conducted to identify research trends and thematic clusters in SAF literature. The analysis reveals a growing interest in advanced biofuels and physicochemical conversion technologies, particularly those supported by catalytic and thermochemical processes. Certified and emerging SAF pathways were examined with respect to their process efficiency, feedstock availability, and scalability. Additionally, the study explores the potential of Latin America as a strategic region for SAF development, considering its abundant biomass resources and ongoing pilot projects. This critical and holistic analysis aims to support researchers, engineers, and policymakers in understanding the current state and future directions of SAF technologies within the framework of chemical process design and optimization. Overall, Hydroprocessed Esters and Fatty Acids Synthetic Paraffinic Kerosene (HEFA-SPK) and Fischer–Tropsch Synthetic Paraffinic Kerosene (FT-SPK) are identified as the most mature and widely deployed SAF production routes, whereas Alcohol to Jet (ATJ), Synthesized Iso-Paraffins (SIP), and Direct Sugar to Hydrocarbons (DSHC) remain at earlier technological stages despite their long-term potential for feedstock diversification and reduced environmental impacts. The analysis also underscores Latin America, where abundant biomass resources, consolidated agro-industrial systems, and emerging SAF research initiatives create favorable conditions for future development and deployment. Full article

Claviceps purpurea is a specialized phytopathogenic fungus that infects grasses and produces pharmacologically active compounds, attracting considerable interest in genomic research. In this study, we assembled and annotated the complete mitogenomes of 15 C. purpurea strains isolated from different host plants, including seven newly sequenced isolates from China. Analysis of the C. purpurea pan-mitogenome demonstrated that the accessory regions, with an average proportion of 48.23%, are the main contributor to mitogenome variation. Analysis of the 14 protein-coding genes revealed Ka/Ks ratios below 1, indicating strong purifying selection. Notably, the atp9 gene was absent in all strains, suggesting a potential adaptive gene loss. Structural variations were predominantly located in the intergenic region between rns and rnl. Phylogenetic analysis based on concatenated mitochondrial genes placed Claviceps as most closely related to the genus Epichloë. The 15 C. purpurea strains grouped into five well-supported subclades, with Chinese and non-Chinese isolates forming distinct lineages. Among these, the Chinese strains ACCC 37001 and KUNCC 11030 represented the earliest diverging lineages. This study elucidates the intraspecific variation and evolutionary patterns of the mitogenome in C. purpurea and highlights the value of mitogenome in resolving phylogenetic relationships. Full article

Background/Objectives: Helicobacter pylori is a cause of chronic gastric infections and gastrointestinal carcinogenesis, with a prevalence of 20–90% around the world. Its eradication is increasingly challenged by clarithromycin resistance, particularly in regions with high rates of antibiotic resistance. While clarithromycin resistance is primarily attributed to 23S rRNA mutations, secondary mechanisms such as efflux pumps remain understudied. The present study reports a high prevalence of hefA efflux pump overexpression as a main molecular basis of clarithromycin resistance in H. pylori isolates from southern Chile. Materials and Methods: A total of 102 H. pylori isolates were obtained from gastric biopsy cultures. Isolates were analyzed for clarithromycin susceptibility by MIC, the 23S rRNA mutations A2142G/A2143G by PCR-RFLP followed by sequencing, and hefA relative expression by qPCR. Results: Clarithromycin resistance was detected in 38% of isolates. Resistance was significantly associated with therapeutic failure and urban residence. While 44% of resistant isolates harbored A2142G/A2143G mutations, 56% did not, suggesting alternative resistance mechanisms. Mutation C2182T was identified in 11% resistant isolates, and increased hefA expression was observed in resistant strains without 23S rRNA mutations, indicating efflux pump dysregulation as a resistance mechanism. Conclusions: Our findings reveal a shift in epidemiology of clarithromycin resistance mechanisms in H. pylori that extends beyond classical 23S rRNA mutations to include efflux-mediated adaptive resistance as a contributing mechanism. The positive correlation between hefA overexpression and MIC elevation underscores its role in resistance. These findings have important implications for the efficacy of clarithromycin-based therapies and highlight the need to reassess empirical treatment strategies in response to emerging resistance patterns. Full article

The increasing carbon footprint of civil aviation has made the use of Sustainable Aviation Fuel (SAF) a strategic necessity in line with the sector’s sustainability goals. This study evaluates the existing SAF types based on environmental, economic, technical and social criteria, determines the criteria weights with Fuzzy-Step-Wise Weight Assessment Ratio Analysis (F-SWARA) and selects the most suitable alternative through Spherical Fuzzy-Multi Objective Optimization on the basis of Ratio Analysis plus full MULTIplicative form (SF-MULTIMOORA) method. The alternative evaluation process was carried out on a Python-based online platform and sensitivity analysis was performed on five different scenarios. According to the findings, the Hydroprocessed Esters and Fatty Acids (HEFA-SPK) alternative stands out as the most suitable option in all scenarios, followed by the Fischer-Tropsch Synthetic Paraffinic Kerosene (FT-SPK) alternative. In contrast, Alcohol-to-Jet (ATJ-SPK) and Power-to-Liquid (PtL) options seem to be more variable and less stable. The study provides methodological contributions for the evaluation of SAF alternatives with fuzzy multi-criteria decision making (MCDM) methods and provides strategic implications for manufacturers and airlines in achieving the low-carbon targets of the aviation sector. Full article

The global energy transition is pushing the development of advanced biofuels to reduce greenhouse gas (GHG) emissions in the aviation industry. This study thoroughly evaluates the potential of the Colombian crude palm oil (CPO) sector to support sustainable aviation fuel (SAF) production. Extensive primary data from 53 palm oil mills and 269 palm plantations were examined. The methodology included a carbon footprint analysis of SAF produced from Colombian CPO through the HEFA pathway, an economic aspects analysis, a review of renewable fuel standards, and an assessment of market access for low-CO₂-emitting feedstocks. The results show that the carbon footprint of the Colombian palm oil-SAF is 16.11 g CO₂eq MJ⁻¹ SAF, which is significantly lower than the 89.2 g CO₂eq MJ⁻¹ reference value for traditional jet fuel. This figure considers current direct Land Use-Change (DLUC) emissions and existing methane capture practices within the Colombian palm oil agro-industry. A sensitivity analysis indicated that this SAF’s carbon footprint could decrease to negative values of −4.58 g CO₂eq MJ⁻¹ if all surveyed palm oil mills implement methane capture. Conversely, excluding DLUC emissions from the assessment raised the values to 47.46 g CO₂eq MJ⁻¹, highlighting Colombia’s favorable DLUC profile as a major factor in its low overall CPO carbon footprint. These findings also emphasize that methane capture is a key low-carbon practice for reducing the environmental impact of sustainable fuel production, as outlined by the CORSIA methodology. Based on the economic analysis, investing in Colombian CPO-based SAF production is a financially sound decision. However, the project’s profitability is highly susceptible to the volatility of SAF sales prices and raw material costs, underscoring the need for meticulous risk management. Overall, these results demonstrate the strong potential of Colombian palm oil for producing sustainable aviation fuels that comply with CORSIA requirements. Full article

Hydrotreated ester and fatty acids to jet (HEFA-tJ) is presently the most developed and economically attractive pathway to produce sustainable aviation fuel (SAF). An ongoing systematic study of the critical variables of different pathways to SAF has revealed significantly lower greenhouse gas (GHG) reduction potential for the HEFA-tJ pathway compared to competing markets using the same resources for road diesel production. Moderate yield variations between air and road pathways lead to several hundred thousand tons less GHG reduction per project, which is generally not evaluated thoroughly in standard environmental assessments. This work demonstrates that, although the HEFA-tJ market seems to have more attractive features than biodiesel/renewable diesel, considerable viability risks might manifest as HEFA-tJ fuel market integration rises. The need for more transparent data and effort in this regard, before envisaging making decisions regarding the volume of HEFA-tJ production, is emphasized. Overall, reducing the carbon intensity of road diesel appears to be less capital-intensive, less risky, and several times more efficient in reducing GHG emissions. Full article

The precise synthesis of non-precious metal single-atom electrocatalysts is crucial for enhancing the yield of highly active reactive oxygen species (ROSs). Conventional oxidation methods, such as Fenton or NaClO processes, suffer from poor efficiency, high energy demand, and secondary pollution. In contrast, heterogeneous electro-Fenton systems based on cascade oxygen reduction reactions (ORRs), which require low operational voltage and cause pollutant degradation through both direct electron transfer and ROS generation, have emerged as a promising alternative. Recent studies showed that carbon cathodes decorated with atomically dispersed transition metals can effectively integrate the excellent conductivity of carbon supports with the tunable surface chemistry of metal centers. However, the electronic structure of active sites intrinsically hinders the simultaneous achievement of high activity and selectivity in cascade ORRs. This review summarizes the advances, specifically from 2020 to 2025, in understanding the mechanism of cascade ORRs and the synthesis of transition metal-based single-atom catalysts in cathode electrocatalysis for efficient wastewater treatment, and discusses the key factors affecting treatment performance. While employing atomically engineered cathodes is a promising approach for energy-efficient wastewater treatment, future efforts should overcome the barriers in active site control and long-term stability of the catalysts to fully exploit their potential in addressing water pollution challenges. Full article

Sustainable aviation fuels (SAFs) are currently considered a key element in the decarbonization of the aviation sector, offering a feasible solution to reduce life cycle greenhouse gas emissions without requiring fundamental changes in aircraft or infrastructure. This article provides a comprehensive overview of the current state of SAFs, including their classification, production technologies, economic aspects, and environmental performance. The analysis covers both currently certified SAF pathways, such as HEFA and FT-SPK, and emerging technologies like alcohol-to-jet and power-to-liquid, assessing their technological maturity, feedstock availability, and scalability. Economic challenges related to high production costs, investment risks, and policy dependencies are discussed, alongside potential mechanisms to support market deployment. Furthermore, the article reviews SAFs’ emission performance, including CO₂ and non-CO₂ effects, based on existing life cycle assessment (LCA) studies, with an emphasis on variability caused by feedstock type and production method. The findings highlight that, while SAFs can significantly reduce aviation-related emissions compared to fossil jet fuels, the magnitude of benefits depends strongly on supply chain design and sustainability criteria. There are various certified pathways for SAF production, as well as new technologies that can further contribute to the development of the industry. Properly selected biomass sources and production technologies can reduce greenhouse gas emissions by more than 70% compared to conventional fuels. The implementation of SAFs faces obstacles related to cost, infrastructure, and regulations, which hinder its widespread adoption. The study concludes that although SAFs represent a promising pathway for aviation climate mitigation, substantial scaling efforts, regulatory support, and continued technological innovation are essential to achieve their full potential. Full article

This work concerns the preparation of Pt/AC catalysts (Pt supported on activated carbon) and their application to the synthesis of hydrocarbon biofuels through the HEFA (hydroprocessing of esters and fatty acids) route. The key motivation for the work was that catalysts based on sulfided Mo supported on γ-Al₂O₃, traditionally employed in the hydroprocessing of petroleum derivatives, (i) are unstable in the HDO (hydrodeoxygenation) of biomass-derived feedstocks and (ii) can contaminate the resulting biofuels with sulfur. In this context, a systematic study on the effects of preparation conditions on the properties of the resulting Pt/AC catalysts and their performance in HEFA was carried out for the first time. Efficient catalysts were obtained, which led to the complete deoxygenation of lauric acid and coconut oil, yielding products composed primarily of n-alkanes. The highest HDO activity was verified for the catalyst prepared using as a support an AC previously subjected to thermal treatment up to 800 °C in a H₂ atmosphere (which removed most of the surface acidic oxygenated groups), depositing Pt over the surface of this support via wet impregnation using a H₂PtCl₆ solution acidified with HCl. The obtained results showed the great potential of the Pt/AC catalysts for the production of hydrocarbon biofuels through the HEFA route. Full article

Modern aviation is one of the main consumers of petroleum-based fuels, consuming nearly 100 million gallons of fuel per year, and this consumption continues to grow. On the other hand, airlines have committed to achieving net-zero carbon dioxide (CO₂) emissions in the industry by 2050. Fulfilling this commitment necessitates the investigation of new and the optimization of existing processes for the production of alternative, renewable, and environmentally safe feedstocks. This article was prepared as part of the research project “Development of Technological Solutions for Obtaining Composite Motor Fuels from Secondary Raw Materials to Enhance Energy Security”. Full article

As aviation is a rapidly growing sector, many actions must be taken to significantly reduce the emission of harmful gases such as CO₂, CO, HC, NOx, and particulate matter (PM). One accessible solution is the use of drop-in sustainable aviation fuels (SAFs), which do not require any changes in the engine or infrastructure construction. The aim of this research was to analyze changes in non-volatile particulate matter (nvPM) emissions for SAF blends compared to Jet A-1 using a miniature jet engine, as there is still limited research on particulate matter emissions from miniature engines, especially for SAFs. This study focuses on non-volatile particle emissions from HEFA-SPK fuel, with comprehensive analyses of particle number and particulate mass-emission indices, as well as number-based and volume-based particle-size distribution (PSD). The tests were conducted on the miniature GTM 400 engine, which was specially designed for SAF testing. The tested fuels were 30/70%v and 50/50%v blends of HEFA-SPK/Jet A-1, as well as neat Jet A-1 as a reference fuel. The results showed that the use of 50%v HEFA-SPK can reduce non-volatile particulate mass emissions up to 59% at low engine loads, and non-volatile particle number emissions by up to 56% at maximum thrust, compared to Jet A-1. Full article

Commercial organic fertilizers (COFs), as an alternative to chemical fertilizers, have been widely promoted and applied to agricultural soils to improve soil fertility and develop green agriculture. However, the residues of veterinary antimicrobials in COFs could be transferred to agricultural soils and pose ecological risk that should not be ignored. This study quantified the occurrence of fifty-seven veterinary antimicrobials, covering five classes (i.e., twenty-three sulfonamides, nineteen quinolones, seven macrolides, six tetracyclines, and two lincosamides) in ninety-three COFs collected from five provinces in China. Twenty-two veterinary antimicrobials, including eleven quinolones, six sulfonamides, four macrolides, and one lincosamide, were detected in the COFs with total contents up to 3870 ng/g. The contents of individual antimicrobials ranged from 0.66 to 3310 ng/g, and their detection frequencies were between 2% and 49%. The composition and contents of antimicrobials in the COFs varied significantly, depending on their raw materials, production processes, and source regions. Seven antimicrobials, including ciprofloxacin, enrofloxacin, and tilmicosin, could pose low to medium potential ecological risk to soil organisms in the amended soils. The wide occurrence of antimicrobials in COFs and their potential ecological risk indicate the urgent need to establish regulatory limits of antimicrobial residues in COFs to control and prevent antimicrobial pollution in agricultural soils brought by their amendment. Full article

The production of hydrocarbon-based biofuels has been the target of intense research worldwide. In this context, the core goal of the present work was to investigate the use of mesopore-rich activated carbons (ACs) as support for sulfided Mo-based catalysts intended for the hydroprocessing of lipidic feedstocks. The key motivations for the work were that, in comparison to traditional inorganic supports such as Al₂O₃, ACs are less propense to form coke, due to their lower acidity, and are highly resistant to hydrolysis, which is a very important aspect in the hydroprocessing of lipidic feedstocks because water is abundantly produced during the process. Furthermore, the porosity of ACs can be tailored to give rise to a high mesopore content, which is important for improving the access of bulky triglyceride molecules to metallic active sites located inside the pores network. A systematic study on the effects of the preparation conditions on the properties and performance of the obtained catalysts was carried out for the first time. The highest hydrodeoxygenation (HDO) activity was verified for the catalyst prepared through sequential deposition of Mo and Ni by wet impregnation. The prepared catalyst presented better performance for coconut oil HDO than an industrial sulfided NiMo/Al₂O₃ catalyst. Furthermore, it presented good stability, provided that the sulfidation degree was kept high. The obtained results evidenced that ACs have great potential to replace inorganic support in sulfided Mo-based catalysts. Full article