Search Results (69)

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

Sustainable aviation fuels (SAFs) are vitally important for aviation decarbonization. The laminar burning velocity (LBV), a key parameter reflecting the combustion behavior of fuel/oxidizer mixtures, serves as a fundamental metric for evaluating SAF performance. This paper systematically reviews and evaluates the LBV experiment method and the performance of traditional aviation fuel, SAFs produced via different pathways, and individual components (n-alkanes, iso-alkanes, cycloalkanes, and aromatic hydrocarbons, as well as the impacts of isomers and homologues) in aviation fuels. It is found that LBV values of different SAFs exhibit significant fluctuations, approaching or slightly deviating from those of conventional aviation fuels. Carbon number, branching degree, substituent types, and testing methods in the components all affect LBV performance. Specifically, increased branching in iso-alkanes reduces LBV, cyclohexane and benzene show higher LBV than their methylated counterparts (methylcyclohexane and toluene), and n-alkylcyclohexanes/benzenes with short (C1–C3) side chains demonstrate minimal LBV variation. Spherical flame methods yield more consistent (and generally lower) LBV values than stagnation flame techniques. These findings provide insights for optimizing SAF–conventional fuel blends and enhancing drop-in compatibility while ensuring operational safety and usability. 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

The growing interest in alternative fuels stems from the need to reduce greenhouse gas emissions and promote sustainable development. Despite the dominance of fossil fuels in aviation, pulsejet engines offer a promising platform for testing new fuels due to their simple design and fuel versatility. This study presents a multi-criteria analysis of alternative fuels for use in pulsejet engines, emphasizing environmental impacts. Both gaseous (biogas, ethyne, LPG, and natural gas) and liquid fuels (methanol, ethanol, biodiesel, Jet A-1, and SAF) were examined. Exhaust emissions (CO₂, H₂O, CO) were simulated in Ansys 2025 based on literature data and chemical calculations. Additional factors analyzed included calorific value, production cost, thermal expansion, density, life cycle emissions (LCA), CO₂ emissions per fuel mass, and renewable energy content. Using the zero-unitization method, results were normalized into a single aggregate variable for each fuel. The highest values were recorded for biogas and methanol, respectively, indicating their potential as alternative fuels. The findings support further development of sustainable fuels for pulsejet engines. Future research should address combustion optimization and noise reduction, enhancing viability in aviation and other transport sectors. Integration with the current fuel infrastructure is also recommended to facilitate broader implementation. Full article

Addressing the urgent need to decarbonise aviation and valorise agricultural waste, this paper investigates the production of Sustainable Aviation Fuel (SAF) from corn stover. A preliminary evaluation based on a literature review indicates that among various conversion technologies, fast pyrolysis (FP) emerged as the most promising option, offering the highest fuel yield (22.5%) among various pathways, a competitive potential minimum fuel selling price (MFSP) of 1.78 USD/L, and significant greenhouse gas savings of up to 76%. Leveraging Aspen Plus simulation, SAF production via FP was rigorously designed and optimised, focusing on the heat integration strategy within the process to minimise utility consumption and ultimately the total cost. Consequently, the produced fuel exceeded the American Society for Testing and Materials (ASTM) limit for the final boiling point, rendering it unsuitable as a standalone jet fuel. Nevertheless, it achieves regulatory compliance when blended at a rate of up to 10% with conventional jet fuel, marking a practical route for early adoption. Energy optimisation through pinch analysis integrated four hot–cold stream pairs, eliminating external heating, reducing cooling needs by 55%, and improving sustainability and efficiency. Economic analysis revealed that while heat integration slashed utility costs by 84%, the MFSP only decreased slightly from 2.35 USD/L to 2.29 USD/L due to unchanging material costs. Sensitivity analysis confirmed that hydrogen, catalyst, and feedstock pricing are the most influential variables, suggesting targeted reductions could push the MFSP below 2 USD/L. In summary, this work underscores the technical and economic viability of corn stover-derived SAF, providing a promising pathway for sustainable aviation and waste valorisation. While current limitations restrict fuel quality during full substitution, the results affirm the feasibility of SAF blending and present a scalable, low-carbon pathway for future development. 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

The aviation sector is a significant contributor to greenhouse gas emissions, and with the increasing demand for air travel these emissions are projected to continue rising in the coming years. Sustainable Aviation Fuel (SAF) could greatly help reduce these emissions and make the aviation industry more eco-friendly. SAF is a renewable, low-carbon alternative to conventional jet fuel produced from sustainable resources. A key step to bringing the fuel into regular use is studying how people view it. Understanding what the public think and feel about biofuels, including aviation fuel, is very important. This is because public opinion can shape consumer interest, demand for products, and the willingness of governments to back green energy policies and invest in clean technologies. The study systematically evaluates the public opinion, perception and awareness of SAF in the South Central United States and its utilization to decarbonize the aviation industry. This is performed through a series of multiple-choice survey questions and interviews. The study results show that while there is some recognition of the environmental impact of aviation and the potential role of biofuels in reducing this impact, there is still a need for greater public education and awareness regarding alternative fuels and their benefits for sustainable aviation. The findings of the study underscore a pivotal challenge in addressing aviation-related carbon emissions: the gap in public knowledge about potential solutions like biofuels and SAF. This gap not only reflects a lack of awareness but also hints at the possible skepticism or uncertainty among the public regarding the effectiveness and viability of these alternatives. Full article

The development of new technologies for the production of renewable energy is fundamental to reducing greenhouse gas emissions. Therefore, the search for new energy generation methods that are environmentally responsible, socially rational, and economically viable is gaining momentum in order to mitigate carbon footprint. The aviation sector is responsible for a significant fraction of greenhouse gas emissions; for this reason, the decarbonisation of this sector must be investigated using biorefinery models. This study presents a mixed-integer linear programming (MILP) model for optimising the design and configuration of the supply chain in different states of Brazil for the production of sustainable aviation fuel (SAF) and green diesel and gasoline, using microalgae cultivated in sugarcane vinasse as the raw material. The technology of hydrothermal liquefaction was assessed in terms of its capacity to convert microalgae without need for the energy-intensive drying step. The MILP model was developed in the LINGO v.20 software using a library of physical and economic process models. We consider the selection of processes based on the object of total minimum cost, with optimal production plant scaling and regional supply chain design, including an assessment of resources and final product distribution. A case study was implemented in Brazil, considering different regions of the country and its local demands for fuels. São Paulo is the most profitable state, with a cash flow of 1071.09 and an IRR of 36.19%, far outperforming the rest. Transport emissions alone represent between 0.6 and 8.6% of emissions generated by the model. The costs of raw materials, mainly hydrogen (57%) and electricity (27%) represent the main costs evaluated in the model. The production cost (MUS$/TJ biofuel) is in the range of 0.009–0.011. Finally, changes in the cost of electricity have the greatest impact on the model. Full article

This study assesses Queensland’s sugar industry potential for sustainable aviation fuel (SAF) production via biomass-to-liquids (BtL) processes. Using surplus sugarcane bagasse, preliminary estimates suggest that individual mills could support 60–130 MW_th gasifiers, while clustered approaches enable larger capacities. Annual BtL syncrude production could reach 440 mL, increasing to ~1000 mL with additional feedstocks. These findings highlight both the industrial-scale viability of SAF production and the logistical and engineering challenges that must be addressed to align with Australia’s renewable energy and fuel security goals. Full article

The aviation industry significantly contributes to global greenhouse gas (GHG) emissions, accounting for approximately 2–3% of total annual CO₂ emissions, with high-altitude operations amplifying radiative forcing effects. This study quantitatively examines aviation’s contributions to global pollution compared to other transportation sectors, such as road and maritime, highlighting the substantial challenges in mitigating its environmental footprint. We focus on emissions of organic compounds, including polycyclic aromatic compounds and dioxins, and analyze key pollutants such as CO₂, NO_X, and ultrafine particles alongside the sector’s indirect effects. Our estimation indicates that dioxin emissions from commercial flights are negligible, at only 0.76 g annually; however, the sector’s broader impact on climate and air quality is significant. The analysis also evaluates current mitigation strategies, including the adoption of sustainable aviation fuels (SAFs), international initiatives like CORSIA, and advancements in aircraft technologies and operational efficiency. Despite these efforts, the projected growth in air traffic, estimated to increase annually by 5% over the next decade, underscores the urgent need for accelerated innovation and robust policy frameworks to achieve sustainable aviation. These findings emphasize the necessity of addressing aviation’s unique environmental challenges through international cooperation, technological advancements, and targeted climate actions. Full article

The present paper is a review of the use of different types of blends of Jet A aviation fuel with biodiesel and alcohols, respectively, as sustainable aviation fuels (SAF). The scientific literature published from 2017 to 2024 was addressed and highlighted that the use of Jet A fuel blended with alcohols and biodiesel has gained attention as a potential pathway to reducing aviation emissions and enhancing sustainability. Alcohol-blended Jet A fuels, such as ethanol and methanol mixtures, offer advantages including lower carbon monoxide (CO) and unburned hydrocarbon (HC) emissions due to their improved combustion efficiency. Similarly, biodiesel blends contribute to reduced particulate matter (PM) and CO emissions, while their oxygen content promotes cleaner combustion. Both types of blends have the potential to decrease the aviation sector’s carbon footprint and enhance fuel diversification. However, several gaps and limitations remain, including lower energy density leading to increased fuel consumption, material compatibility issues, increased nitrogen oxide (NO_x) emissions, and concerns over fuel stability. Further research is needed to optimize blend ratios, improve combustion control strategies, and ensure the safe and efficient integration of these alternative fuels in aviation. Full article

Reducing CO₂ emissions is an increasingly important goal in general aviation. The dual-fuel hydrogen–kerosene combustion process has proven to be a suitable technology for use in small aircraft. This robust and reliable technology significantly reduces CO₂ emissions due to the carbon-free combustion of hydrogen during operation, while pure kerosene or sustainable aviation fuel (SAF) can be used in safety-critical situations or in the event of fuel supply issues. Previous studies have demonstrated the potential of this technology in terms of emissions, performance, and efficiency, while also highlighting challenges related to abnormal combustion phenomena, such as knocking and pre-ignition, which limit the maximum achievable hydrogen energy share. However, the causes of such phenomena—especially regarding the role of lubricating oils—have not yet been sufficiently investigated in hydrogen engines, making this a crucial area for further development. In this paper, investigations at the TU Wien, Institute of Powertrain and Automotive Technology, concerning the role of different engine oils in influencing pre-ignition tendencies in a hydrogen–kerosene dual-fuel engine are described. A specialized test procedure was developed to account for the unique combustion characteristics of the dual-fuel process, along with a detailed purge procedure to minimize oil carryover. Multiple engine oils with varying compositions were tested to evaluate their influence on pre-ignition tendencies, with a particular focus on additives containing calcium, magnesium, and molybdenum, known for their roles in detergent and anti-wear properties. Additionally, the study addressed the contribution of particles to pre-ignition occurrences. The results indicate that calcium and magnesium exhibit no notable impact on pre-ignition behavior; however, the addition of molybdenum results in a pronounced reduction in pre-ignition events, which could enable a higher hydrogen energy share and thus decrease CO₂ emissions in the context of hydrogen dual-fuel aviation applications. Full article

The production of sustainable aviation fuel (SAF) has gained more attention in recent years due to the initiative to implement new technologies to improve the decarbonization of the energy and transport industry, especially the aviation sector, in different countries. In Mexico, the production of SAF has been promoted as a sustainable initiative to boost the agro-industrial sector, the nation’s self-sufficiency, and compliance with national and international CO₂ emission reduction goals. Nowadays, there are two technologies with a high level of technological readiness ready to be implemented as a solution to produce SAF, which are hydrotreating esters and fatty acids (HEFA) and Alcohol to Jet (ATJ). These technologies use biomass as a source of feedstock and are described as possible sustainable solutions to reduce the CO₂ emissions from conventional aviation fuels. This work analyses the feasibility of implementing these two technologies as a strategy to promote the use of SAF in Mexico from the biomass available in the country based on a techno-economic analysis and a life cycle assessment of each technology. Based on this study on SAF production, a return on investment of 10.2% for HEFA-SPK technology and 13.7% for ATJ-SPK technology was obtained. Full article

Adverse climate change has forced a deeper reflection on the scale of pollution related to human activity, including in the aviation industry. As a result, fundamental questions have arisen about the characteristics of these pollutants, the mechanisms of their formation and potential strategies for reducing them. This paper provides a comprehensive overview of key technical solutions to minimize the environmental impact of aircraft engines. The solutions presented range from fuel innovations to advanced design changes and drive concepts. Particular attention was paid to sustainable aviation fuels (SAFs), which are currently an important element of the environmental strategy regulated by the European Union. It also discusses the potential use of hydrogen as a potential alternative fuel to replace traditional aviation fuels in the long term. The analysis in the article made it possible to characterize in detail possible modifications in the functioning of aircraft engines, based both on the current state of technical knowledge and on the anticipated directions of its development, which has not been a frequent issue in comprehensive research so far. The analysis shows that the type of raw material used to create SAF has a strong impact on its physical and chemical parameters and the degree of greenhouse gas emissions. This necessitates a broader analysis of the legitimacy of using a given type of fuel from the SAF group in the direction of selected air operations and areas with a higher risk of severe atmospheric pollution. These results provide the basis for further research into sustainable solutions in the aviation sector that can contribute to significantly reducing its impact on climate change. Full article