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Biomass-derived sustainable aviation fuel holds significant potential for decarbonizing the aviation sector. Its long-term viability depends on crop choice, longevity of soil organic carbon (SOC) sequestration, and the biomass-to-biojet fuel conversion efficiency. We explored the impact of fuel price and SOC value on viable biojet fuel production scale by integrating an agroecosystem model with a field-to-biojet fuel production process model for 1,4-dimethylcyclooctane (DMCO), a representative high-performance biojet fuel molecule, from Miscanthus, sorghum, and switchgrass. Assigning monetary value to SOC sequestration results in substantially different outcomes than an increased fuel selling price. If SOC accumulation is valued at $185/ton CO2, planting Miscanthus for conversion to DMCO would be economically cost-competitive across 66% of croplands across the continental United States (US) by 2050 if conventional jet fuel remains at $0.74/L (in 2020 US dollars). Cutting the SOC sequestration value in half reduces the viable area to 54% of cropland, and eliminating any payment for SOC shrinks the viable area to 16%. If future biojet fuel prices increase to $1.24/L-Jet A-equivalent, 48 to 58% of the total cultivated land in the United States could support a more diverse set of feedstocks including Miscanthus, sorghum, or switchgrass. Among these options, only 8-14% of the area would be suitable exclusively for Miscanthus cultivation. These findings highlight the intersection of natural solutions for carbon removal and the use of deep-rooted feedstocks for biofuels and biomanufacturing. The results underscore the need to establish clear and consistent values for SOC sequestration to enable the future bioeconomy.

Our study investigates the impact of nanoparticulate additives--specifically those based on ammonia and water--on the combustion characteristics of Jet-A1 aviation fuel, using a 300-kW liquid swirl combustor. Experiments were conducted at two global equivalence ratios (Φ = 0.24 and Φ = 0.40), focusing on laminar flame speed (LFS) and flame properties through chemiluminescence imaging and modal analysis techniques. The primary objective was to understand how these nano-additives modulate flame dynamics and internal chemical reactions, alongside evaluating the environmental implications of combustion alterations. Results showed that integrating urea and water additives into the fuel matrix affected LFS, enhancing it at the lower equivalence ratio but having detrimental effects at the higher ratio. Modal analysis revealed a notable stabilizing influence on flame behavior, especially under leaner fuel conditions. The addition of water and urea influenced combustion chemistry and spray patterns, leading to more uniform sprays and more complete combustion. Chemiluminescence imaging demonstrated higher emission intensity of NH2* radicals compared to NH* radicals, varying with the global equivalence ratio. The data indicated a significant reduction in NOx emissions, particularly at lower equivalence ratios, accompanied by a slight increase in CO2 and CO emissions. [ABSTRACT FROM AUTHOR]

Based on the demands of compact heat exchangers and micro cooling channels applied for aviation thermal protection on aero-engines, the elbow local flow resistance characteristics for supercritical pressure aviation fuel RP-3 flowing in adiabatic horizontal serpentine tubes with the inner diameter of 1.8 mm and the mass flux of 1179 kg/(m2·s) were experimentally studied. The long-short-tube method was used to obtain the elbow pressure drop from the total serpentine tube pressure drop, and the effects of system pressures (P/Pc = 1.72–2.58) and geometry parameters including bend numbers (n = 5–11), bend diameters (D/d = 16.7–27.8), and bend distances (L/d = 20–60) on elbow pressure drops and local resistance coefficients are analyzed on the basis of the thermal physical property variation. The results show that both the increase in the elbow pressure drop and the decrease in the local resistance coefficient with temperatures speed up at the near pseudo-critical temperature region of T > 0.85Tpc. And the growth of the elbow local pressure drop could be inhibited by the increase of system pressures, while the local resistance coefficient is slightly affected by pressures. The influence of bend diameters on the local resistance coefficient is mild when D/d is larger than 22.2 in the premise of fully developed flow in straight tubes. Furthermore, a piecewise empirical correlation considering the bend diameter and physical property ratio is developed to predict the elbow pressure drop of the serpentine tube and optimize the layout of the cooling tube system on aero-engines.

Abstract Background In October 2023, the U.S. Environmental Protection Agency announced a final endangerment finding that leaded aviation gasoline (avgas) contributes to air pollution that is harmful to public health. This study evaluates the evidence for a link between living in proximity to airports and children’s blood lead levels in Colorado. Methods We analyzed the association between childhood blood lead levels (BLLs) and proximity to airport point locations in children tested for lead in Colorado over a 10-year study period (2011–2020) using a correlated random effects model with bootstrapped standard errors (N = 56,002 observations, 47,322 individuals). Along with distance from airport point locations, we identified the number of days sampled children lived downwind of their nearest airport during the 60 days prior to their test date. We also adjusted the model for age, sex, detection limit, test type, sample order, seasonality, time, proximity to lead-releasing facilities, estimated monthly aircraft traffic, and demographic characteristics of the surrounding neighborhood. Results Our primary model estimates that living one mile (1.6 km) further from airport point locations decreases mean blood lead levels by 0.068 µg/dL. Additional analysis estimates that living one mile further from airport point locations decreases the odds of having a blood lead level ≥ 3.5 µg/dL by 13.2%. Conclusion Our results suggest that lead emissions from aircraft using leaded avgas have a small but statistically significant effect on the BLLs of children living near airport point locations in Colorado. While the risk from proximity to airports is likely less than the risks associated with deteriorating lead paint and dust, our findings highlight the value of lead testing in children who may be at risk of exposure from all sources, including those who live near airports.

Background: In October 2023, the U.S. Environmental Protection Agency announced a final endangerment finding that leaded aviation gasoline (avgas) contributes to air pollution that is harmful to public health. This study evaluates the evidence for a link between living in proximity to airports and children's blood lead levels in Colorado. Methods: We analyzed the association between childhood blood lead levels (BLLs) and proximity to airport point locations in children tested for lead in Colorado over a 10-year study period (2011–2020) using a correlated random effects model with bootstrapped standard errors (N = 56,002 observations, 47,322 individuals). Along with distance from airport point locations, we identified the number of days sampled children lived downwind of their nearest airport during the 60 days prior to their test date. We also adjusted the model for age, sex, detection limit, test type, sample order, seasonality, time, proximity to lead-releasing facilities, estimated monthly aircraft traffic, and demographic characteristics of the surrounding neighborhood. Results: Our primary model estimates that living one mile (1.6 km) further from airport point locations decreases mean blood lead levels by 0.068 µg/dL. Additional analysis estimates that living one mile further from airport point locations decreases the odds of having a blood lead level ≥ 3.5 µg/dL by 13.2%. Conclusion: Our results suggest that lead emissions from aircraft using leaded avgas have a small but statistically significant effect on the BLLs of children living near airport point locations in Colorado. While the risk from proximity to airports is likely less than the risks associated with deteriorating lead paint and dust, our findings highlight the value of lead testing in children who may be at risk of exposure from all sources, including those who live near airports. [ABSTRACT FROM AUTHOR]

The catalytic conversion of renewable biomass-derived aldehydes and ketones to aviation fuels is very attractive for sustainable development. We provided insight into the production of aviation fuel from typical biomass carbonyl platform compounds (furfural, acetone, butanone, and butyraldehyde) by aldol condensation followed with hydrodeoxygenation over bifunctional catalyst Ni/Mg–Al-O/AC, focusing on the mechanism of condensation reaction. It was found that high temperature is not only conducive to aggravate the depth of aldehyde ketone condensation reaction, further convert dimer to trimer, but also promote its self-condensation. The optimal condensation temperature of aldehydes and ketones under this idea was 170 °C, the carbon number range of the jet fuel intermediates was C7–C14, and the yield of condensates reached 79.23%. In order to explore the mechanism in the aldol condensation of aldehydes and ketones, the evolution law of typical products was studied by controlling the reaction time, and seven main condensation pathways were proposed. The ratios of aldehyde/ketone in the reactant and the ratios of each component within the aldehyde and ketone were adjusted, and it was found that the reaction priority of chain aldehydes is the highest in this reaction system, and the reaction priority of small-molecule ketones with low carbon number is higher than that of high carbon number ketones. The presence of long-chain groups in the hydrogenated oil increased the density of jet fuel, and it has a higher calorific value, which are very promising as aviation fuels or additives of aviation bio-fuels. [ABSTRACT FROM AUTHOR]

Summary: Indanone and its analogs are widely used intermediates for many useful chemicals. Decalin and its alkylated analogs are major components of thermal-stable aviation fuels and the additives used to improve the thermal stability of aviation fuel. In this work, we develop an integrated route to selectively produce trimethyl-indanone or alkylated decalin with cellulose. First, cellulose was hydrogenolyzed to 2,5-hexanedione in a biphasic reaction system of toluene/NH4Br aqueous solution over Pd/C catalyst. Under the catalysis of alkali hydroxide, 2,5-hexanedione was converted to a mixture of C12 oxygenates (with trimethyl-indanone as the main component) at room temperature. Trimethyl-indanone can be used as an intermediate for many useful chemicals. Moreover, the C12 oxygenates can be hydrodeoxygenated to a mixture of dimethyl decalin and C12 monocycloalkanes with a low freezing point (200 K) and high density (0.85 g mL−1). This work provides insights on the preparation of indanone or advanced aviation fuel with cellulose. Science for society: The production of valuable chemicals and sustainable aviation fuel (SAF) with renewable, cheap, and abundant lignocellulose has drawn a lot of attention. Indanone and its analogs are widely used as intermediates in the manufacture of many useful chemicals. Currently, these compounds are obtained from fossil resources at low yields. Decalin and alkylated decalins are additives to improve the thermal stability of aviation fuel. Herein, we report an integrated route for the selective preparation of trimethyl-indanone or alkylated decalins with cellulose, the most abundant biomass. Compared with the reported processes to produce indanone analogs or SAF, this new process has several advantages, such as renewable feedstock, mild reaction conditions, fewer steps, and excellent fuel properties (e.g., lower freezing point, higher volumetric heat value, thermal stability of final products, etc.). This work paves a new way for the high-value utilization of cellulose.

At the present stage of the development of aviation activity, there is a significant increase in aviation traffic, which in turn puts a significant burden on the supply of jet fuel to civil aviation. On average, 10.9 million tons of aviation kerosene per year are supplied to the domestic market of the country1. In Russia, a significant market share in the supply of aviation fuel is occupied by the leaders, among which now are Lukoil, Rosneft and Gazprom which all together are vertically integrated oil companies (VIOC). Along with the colossal volumes of production and supply of jet fuel, which include many technological operations, starting from the production stage to the direct delivery “to the wing” of the aircraft, the probability of production and supply of not only high quality, but also substandard jet fuel increases. Substandard fuel poses a rather serious threat during the operation of aviation equipment, being one of the many factors leading to failures of aviation equipment, aviation accidents and incidents, thereby reducing the level of flight safety. Oil refining companies, refueling complexes and airlines are interested in the safety of their activities, which have reliable systems and means to ensure it, but nevertheless substandard fuel takes place. One of the important reasons is the lack of a unified integrated flight safety system in terms of aviation fuel supply for air transportation, and therefore, it is necessary to search for new or implement existing adapted methods, solutions, systems and means to ensure the required level of flight safety.

Huge territories of the Russian Federation are occupied by permafrost. Often aviation is the only mode of transport that connects remote north areas of the country with the rest of Russia. The main feature of permafrost regions is the harsh climate, which includes low negative temperatures, an abundance of snow and strong winds. Such conditions make it extremely difficult to operate ground vehicles that service and maintain flights. In recent years, more and more domestic tankers have been exhausting their life span. At present, a significant number of northern refueling complexes have switched to the operation of foreign tankers based on Volvo and Mercedes-Benz tractors. The operation of these vehicles has already revealed a series of shortcomings which extremely complicate the normal procedures. There is an acute need to refine the components and assemblies in order to reduce the failures that affect the regularity and safety of aircraft flights. One of the main problems of fuel tankers operation at low temperatures is the malfunction of the electropneumatic bottom valve, due to its freezing. The paper proposed replacing this problematic node with a mechanical bottom valve, which is not susceptible to low temperatures. In order to avoid cracking of rubber products of the underwing refueling nozzle and to increase the flexibility of the dispensing hoses, it is proposed to carry out heating of the glass of the refueling nozzle and the filling module by means of exhaust gas bypass and pumping hot coolant through the system of nozzles. The most serious problems are the difficulties of operating a diesel-powered tractor at low temperatures. Problems arise already at startup. Diesel fuel at low subzero temperatures can thicken or even solidify, the lubricant also thickens. There have been cases when the startup was complicated by low compression in the cylinders. But even if the engine was able to start, after a while it may start to stall. This is due to oxygen starvation, which occurs because the icy air entrains water, which is deposited as frost on the air filters, thereby blocking the oxygen supply to the engine. After prolonged parking at low temperatures, during the first seconds of starting the piston engine, the parts come into contact with each other without lubrication. The reason is the viscosity of the oil which decreases at extremely low temperatures, therefore, in order for the lubricant to reach the end users through narrow oil pipelines, it takes some time to warm up (about 10 minutes). As a result of such cold starts and the risk of bullying on the parts of the piston group, their durability is reduced by more than 40%. When starting cold, the engine additionally warms up itself at higher idle speeds. To prevent undesirable consequences, as well as to create more favorable conditions for starting the diesel unit, reducing fuel consumption, it is proposed to use a pre-heater with an external power source from the 220 V electrical network. In order to facilitate the start of the diesel engine, it is necessary to provide the heating of the fuel line and fuel pump filters. To eliminate oxygen starvation of the engine, due to the formation of frost on the filter elements, and to increase the stability of the engine, it is necessary to provide the heating of the air filter.

The laminar burning velocity of n-decane (an aviation kerosene surrogate) blended with hydrogen is studied using experimental and numerical analysis at the initial conditions of 470 K and 1, 2, and 4 bar over the equivalence ratios of 0.7–1.3 and hydrogen addition ratios of 0 %, 10 %, 20 %, 30 %, 40 %, and 50 %. The burning velocity is investigated using the constant volume method of the spherically expanding flame method. Here, burning velocity at elevated pressure and temperature conditions close to engine-relevant conditions have been established. Thus, using the experimental data at 470 K and 4 bar, burning velocities at the unburnt temperatures of up to 612 K and pressures of up to 11.02 bar are obtained. Also, Polimi and JetSurF2.0 mechanisms were used to simulate the burning velocities and they agreed well with the experimental data. However, as the hydrogen addition increased, especially when the hydrogen addition was 40 % there was a significant deviation between the experiment and the simulation results. The chemical reaction analysis of n-decane-hydrogen shows the flame speed is significantly driven by H + O 2 ⇔ O + OH , CO + OH ⇔ CO 2 + H , CH 3 + H (+ M) ⇔ C H 4 (+ M) , and H + OH + M ⇔ H 2 O + M at the various initial conditions. However, H + O 2 ⇔ O + OH produces more OH, H, and O radicals that accelerate the combustion chemical reaction rate of n-decane-hydrogen. The reaction pathways show that the decomposition of n-decane is mainly controlled by the OH and H radicals. This study's results provide an understanding of the combustion characteristics of aviation fuel-hydrogen blends in internal combustion engines at elevated pressures and temperatures to achieve zero emissions in aviation. • Laminar combustion characteristics of n-decane-hydrogen were studied. • Burning velocity at 11.02 bar and 612 K were obtained for n-decane-hydrogen. • H + O 2 ⇔ O + OH , CH 3 + H (+ M) ⇔ C H 4 (+ M) , and H + OH + M ⇔ H 2 O + M drove the flame speed. • OH, H and O radicals enhanced the combustion reactivity of n-decane-hydrogen. [ABSTRACT FROM AUTHOR]

The article deals with the concept of a new mobile fuel laboratory, which will enable the verification of the quality of JP/F-34 aviation fuel. Using external benchmarking, a multi-criteria analysis and subsequent comparison of analogous solutions at national and international level is performed. Focus is placed on fulfilling the requirements of the Army of the Czech Republic to verify the quality of JP/F-34 type aviation fuel in accordance with the relevant national and international technical standards, including the logistical support of the laboratory. The concept of a set of modular ISO 1C containers with corresponding laboratory equipment and estimation of capacities for practical use in the conditions of the Czech Army is proposed. It includes 3D visualization of the proposed mobile container laboratory - ISO 1C modular container set. [ABSTRACT FROM AUTHOR]

As a potential source of a major accident, aviation fuel tanks represent a potential source of danger not only for the airport but also for businesses in the vicinity of the airport. Fire is one of the main hazards associated with the operation of fuel storage tanks. Depending on the type of storage tanks, there may be a fire in the tank itself or a fire in the bund. An important factor in an actual fire is the influence of wind, which affects the geometry of the flame and thus the range of heat flux and its impact on other equipment in the vicinity of the fire. Another phenomenon known to occur in industrial fire accidents is the domino effect, where the fire can spread to other equipment and cause more severe damage. From this point of view, a systematic risk analysis is needed, where the procedures known within the SEVESO series of directives can be used. The outputs of the risk analysis and impact calculations of the consequences allow better planning for an effective and safe management of the accident. This article describes the possible consequences of an aviation fuel storage accident at an airport near which manufacturing plants and other infrastructure are located. [ABSTRACT FROM AUTHOR]

The challenge of limiting global warming to below 1.5°C requires all industries to implement new technologies and change practices immediately. The aviation industry contributes 2% of human-induced CO2 emissions and 12% of all transport emissions. Decarbonising the aviation industry, which relies heavily on high-density liquid fuels, has been difficult to achieve. The problems are compounded by the continued reliance on so-called sustainable aviation fuels, which use first-generation agricultural feedstocks, creating a trade-off between biomass for food and feed and its use as a feedstock for energy generation. Decarbonising aviation is also challenging because of problems in developing electric aircraft. Alternative feedstocks already exist that provide a more feasible path towards decelerating climate change. One such alternative is to use gas fermentation to convert greenhouse gases (e.g. from food production and food waste) into fuels using microbial acetogens. Acetogens are anaerobic microorganisms capable of producing alcohols from gaseous CO, CO2 and H2. Australia offers feedstock resources for gas fermentation with abundant H2 and CO2 production in proximity to each other. In this review, we put forward the principles, approaches and opportunities offered by gas fermentation technologies to replace our dependency on fossil fuels for aviation fuel production in Australia.

Sesquiterpenes have been identified as promising ingredients for aviation fuels due to their high energy density and combustion heat properties. Despite the characterization of numerous sesquiterpene structures, studies testing their performance properties and feasibility as fuels are scarce. In this study, 122 sesquiterpenoid skeleton compounds, obtained from existing literature reports, are tested using group contribution and gaussian quantum chemistry methods to assess their potential as high‐energy aviation fuels. Seventeen sesquiterpene compounds exhibit good predictive performance and nine compounds are further selected for overproduction in yeast. Through fed‐batch fermentation, all compounds achieve the highest reported titers to date. Subsequently, three representative products, pentalenene, presilphiperfol‐1‐ene, and α‐farnesene, are selected, produced, purified in large quantities, and tested for use as potential fuels. The performance of pentalenene, presilphiperfol‐1‐ene, and their derivatives reveals favorable prospects as high‐energy aviation fuels. [ABSTRACT FROM AUTHOR]

2,3‐Butanediol (BDO) is a bio‐derived building block available from biomass through biochemical methods in high titers (>120 g L−1) making it an attractive target for production and further upgrading to chemical products and fuels such as sustainable aviation fuel. A key challenge to enable the adoption of BDO as a precursor is the effective separation and isolation of this molecule from the fermentation broth. 2,3‐Butanediol has a boiling point higher than that of water (177°C), and as a consequence, separation via distillation methods is an energy‐intensive and therefore costly approach. We have improved the BDO separation through conversion to a 1,3‐dioxolane directly in fermentation broth via reaction with bio‐derived aldehydes catalyzed by a solid acid catalyst. The resulting dioxolane phase separates from the fermentation broth, allowing for easy decantation and isolation in >90% isolated yield. Isolated dioxolane can be used directly as a compression iginition fuel, trans‐acetalized to recover high‐purity BDO or used directly in a catalytic process as a BDO synthon to produce methyl ethyl ketone with aldehyde recovery in near quantitative yield. [ABSTRACT FROM AUTHOR]

This study aimed to understand the health-seeking behaviors of the child migrants, commonly known as Chokola, who live along the Uganda–Kenya border at the town of Busia. The study used qualitative data collection methods: in-depth interviews, life-histories, focus group discussions, and key informant interviews. At the border, Chokola are accorded a marginal status and identity, limiting their health rights. Chokola face many health challenges, some of which arise from risky sexual behaviors and practices. Their health problems include gonorrhea, HIV, malaria, and cholera. The Chokola in our study exhibited specific health-seeking behaviors, with sniffing aviation fuel being the most pronounced. Although this practice was intended to alleviate common ailments and discomfort, it was also reported to have side effects ranging from loss of appetite to early death. Sniffing aviation fuel as a health-seeking behavior is a construction of individuals. Chokola constructions of the efficacy of aviation fuel are inculcated during socialization and are supported by a shared belief in the fuel as a panacea. Scientific views regarding the risks of side effects are irrelevant to them. In terms of access to health services, Chokola are vulnerable and require affirmative action and targeted interventions. [ABSTRACT FROM AUTHOR]

Fuel vapor concentration is a key parameter for assessing the flammability of aircraft fuel tanks. However, the current research on RP-3 (Rocket Propellant-3) fuel vapor concentration is inadequate. This study categorizes fuel components by the number of carbon atoms and utilizes Raoult's law to estimate the gas–liquid equilibrium relationship of each constituent element under equilibrium conditions. The equilibrium-state model is experimentally validated, and the differences in the constituents and fuel vapor concentrations of RP-3 and Jet-A (Jet Fuel-A) fuels are analyzed. In addition, an empirical correlation between the overall hydrocarbon concentration of RP-3 fuel vapor and the temperature and pressure in the equilibrium state is established, providing a theoretical basis for determining RP-3 fuel vapor concentration in related investigations. Furthermore, a transient prediction model of fuel vapor concentration is developed using the lumped parameter approach that considers the heat exchange among the fuel, gas, wall, and environment. The model's accuracy is confirmed by comparing it to existing literature. Then, the temperature and fuel vapor concentration variation patterns in the fuel tank are calculated and evaluated under two typical flight scenarios. The results show a significant difference between the calculated fuel vapor concentration values obtained through equilibrium-state and transient models. Therefore, in the design of fuel vapor catalytic inerting systems, it is crucial to consider both the equilibrium and transient fuel vapor concentration values rather than relying solely on the former. Throughout the flight envelope, gas phase and fuel phase temperatures in RP-3, Jet-A, and C10H22 fuel tanks exhibit minimal differences. However, significant variations in fuel vapor concentration exist depending on the flight state and envelope. Hence, regarding RP-3 as equivalent to C10H22 is inappropriate. Additionally, fuel vapor concentration is a more suitable metric than fuel temperature for assessing fuel tank flammability. [ABSTRACT FROM AUTHOR]

The aviation industry is one of the most rapidly growing transportation sectors, and contributes 2% of anthropogenic greenhouse gas emissions. Next decades, sustainable aviation fuels will play a key role in achieving reductions in aviation emissions. This study was aimed at investigating the potential of sustainable aviation fuel production from waste materials such as municipal solid waste, including food waste and waste cooking oils, as well as agricultural and forestry residues using current conversion technologies, based on data from recent literature. A systematic review was conducted using PRISMA analysis. Results showed that catalytic hydro-processing of waste lipid feedstocks is the most widely used conversion method for bio-jet fuel production. Moreover, waste plastic catalytic pyrolysis and co-pyrolysis with solid biomass residues can contribute to the implementation of effective policy support and improvement of current technologies to reduce production costs. Besides, gasification combined with Fischer–Tropsch and alcohol-to-jet processes revealed as interesting pathway for sustainable aviation fuel production. Although solid waste materials are promising alternative feedstocks for the production of biofuel, including aviation-range hydrocarbons, more research and development is required, as most of these advanced technologies have yet to be commercialised. [Display omitted] • Solid waste biomass is a promising feedstock for bio-jet fuel production meeting ASTM requirements. • Thermochemical production methods contribute to SAF demand. • Lignocellulosic materials and plastic waste can be used as potential feedstocks for producing SAF. • Sustainable aviation fuels (SAFs) play a key role in decarbonization of the aviation sector. [ABSTRACT FROM AUTHOR]

The paper is devoted to the study of the physicochemical properties of aviation biofuels, in particular, to the substantiation of the influence of bio-additives based on various vegetable oils on the properties of jet fuels and to the assessment of the possibility of using new bio-additives to produce aviation biofuels. The aviation industry’s current state is considered and its development’s key directions are presented. Considering the tasks of minimizing the environmental impact of aviation, decarbonizing the aviation sector and increasing its energy efficiency, one of the industry’s main priorities is the development of technologies for the production of alternative aviation fuels and their practical use. This paper considers alternative aviation fuels (biofuels), which are a mixture of traditional aviation fuels and bio-additives derived from various vegetable oils. Taking into account the trends of active transition from first-generation biofuels to second- and third-generation biofuels, the article considers new types of plant raw materials for obtaining bio-additives to fuels. In particular, the possibilities of using bio-additives based on palm kernel and coconut oils to produce second-generation biofuels are considered. The chemical composition and physicochemical properties of bio-additives based on various vegetable oils were investigated and analyzed. It is shown that the quantitative and qualitative composition of bio-additives determines their physicochemical properties. Further, the physicochemical properties of aviation biofuel samples based on petroleum aviation fuel and bio-additives were investigated. It is shown that the introduction of bio-additives into the composition of petroleum aviation fuels leads to changes in their properties, in particular, to an increase in density, viscosity, and crystallization temperature. The experimental results substantiate that bio-additives based on palm kernel and coconut oils have better characteristics than the previously studied bio-additives (based on rapeseed and castor oils), in particular, regarding the possibility of their use as components of aviation biofuels. Thus, the new bio-additives can be successfully used for further research on the development of alternative aviation fuels. [ABSTRACT FROM AUTHOR]

There are three main fuel brands for jet engines of civil aviation used: domestic TS-1 and RT and foreign, produced in relatively small volumes in Russia, JET A-1 (JET A-1). Since the end of the 2000s, foreign manufacturers have made claims to the quality of the mass-used domestic fuel brand TS-1, and these claims have not been specified. However, the service life of a number of foreign engines operating on TS-1 fuel has been reduced by 50%. This circumstance can be caused by both subjective reasons – commercial and political interests of equipment manufacturers, and the objective ones. The main objective reason may be that recently several Russian plants producing TS-1 fuel have begun to produce composite propellant under the same name, where products of secondary oil refining processes are added to the straight-run fractions. These fuels meet the requirements of the standard (GOST 10227-86), which does not contain an indicator that characterizes the anti-wear properties of jet fuels. In the standard for JET A-1 fuel, anti-wear properties are normalized, and they are also normalized in the standard for domestic fuels for supersonic aviation. The article presents comparative tests of anti-wear properties of samples of jet fuels used in the civil aviation. The article substantiates the relevance of the anti-wear properties indicator in the standard for domestic brands of jet fuels for subsonic aircraft introduction, as well as the comparative analysis of the anti-wear properties of fuels produced by various Russian oil refineries. Indicators and methods for assessing the anti-wear properties of aviation fuels can be different. As such an indicator, it is proposed to use the anti-wear properties indicator calculated after testing fuel samples on a four-ball friction machine.

Using a hedging strategy to stabilize fuel price is very important for airline companies in order to reduce the cost of their main business. In this paper, we construct models for managing the risk of the hedging strategy. First, we use conditional value at risk (CVaR) to measure the risk of an airline company's hedging strategy. Compared with the value at risk (VaR), CVaR satisfies subadditivity, positive homogeneity, monotonicity, and transfer invariance. Therefore, CVaR is a consistent method of risk measurement. Second, time-varying state transition probability is introduced into our model in order to build a Markov Switching-GARCH (MS-GARCH). MS-GARCH takes dynamic changes of market state into account, a feature which has obvious advantages over the traditional constant state model. Additionally, we use a Markov chain Monte Carlo (MCMC) algorithm to estimate the parameters of MS-GARCH based on Gibbs sampling. We use fuel oil futures data from the Shanghai Futures Stock Exchange to implement and evaluate our model. In this paper, we empirically estimate the risk of airlines' hedging strategy and draw the conclusion that our model is obviously effective in terms of the risk management of hedging, a use which has a certain guiding significance for reality. [ABSTRACT FROM AUTHOR]

As the demand for alternative fuels to solve environmental problems increases worldwide due to the greenhouse gas problem, this study predicted the demand for liquid hydrogen fuel in aviation to achieve 'zero-emission flight'. The liquid hydrogen fuel models of an aircraft and all aviation sectors were produced based on the prediction of aviation fleet growth through the classification of currently operated aircraft. Using these models, the required amount of liquid hydrogen fuel and the total cost of liquid hydrogen were also calculated when various environmental regulations were satisfied. As a result, it was found to be necessary to convert approximately 66% to 100% of all aircraft from existing aircraft to liquid hydrogen aircraft in 2050, according to regulations. The annual liquid hydrogen cost was 4.7–5.2 times higher in the beginning due to the high production cost, but after 2030, it will be maintained at almost the same price, and it was found that the cost was rather low compared to jet fuel. [ABSTRACT FROM AUTHOR]

The surface deposition of aviation fuel is a crucial and challenging issue in the application of air-to-fuel heat exchangers in aero-engines. The present study investigated the effect of pressure on the surface deposition of aviation fuel in a horizontal tube. Surface deposition distributions of aviation fuel RP-3 under different pressures (from 1.5 to 5.5 MPa) and different heat fluxes (from 0.08 to 0.4 MW/m2) were measured. Some experimental cases were numerically simulated to analyze the intrinsic mechanism of pressure affecting deposit formation. It was shown that pressure affects oxidative and pyrolytic deposition differently. Elevated pressure promotes the formation of pyrolytic deposits, whereas the oxidative deposition rate increases as pressure decreases. Pressure affects surface deposit formation via the physical properties of aviation fuel, especially density. The phase transition of fuel from liquid to vapor greatly accelerates the precipitation and deposition of insoluble substances under subcritical pressure. The deposition acceleration mechanism caused by the radial density gradient also plays a role under supercritical pressures, especially when pressure approaches the critical value. In addition, surface deposition depends more strongly on wall temperature than on bulk temperature. [ABSTRACT FROM AUTHOR]

Abstract A promising feedstock for large‐scale production of sustainable jet biofuel is the inedible oilseed Brassica carinata (referred to simply as “carinata”), but transitioning to large‐scale fuel production entails significant economic uncertainty and requires substantial up‐front capital requirements for biorefinery construction. Furthermore, for carinata and other feedstocks attempting to compete within the established fossil jet fuel market, historically volatile aviation fuel prices affect the economic feasibility and return of biorefinery investments. In this study, we assess the impact of jet fuel price volatility on the return on investment in a carinata biorefinery employing a real options analysis (ROA). The key advantage of ROA over traditional net present value (NPV) analysis is that it simultaneously assesses the optimal timing for investments and the impact of jet fuel price dynamics on the likelihood of positive economic returns from investments in processing plants. Given the nonstationary nature of jet fuel prices and the presence of structural breaks, the price series are modeled as a geometric Brownian motion. Taking into account the volatility of jet fuel price, the ROA price threshold for a profitable investment is 45% greater than the NPV threshold. The ROA model identifies the necessary market conditions for a profitable investment and highlights the importance of considering market price dynamics before making substantial capital investments in a carinata biorefinery.

Commercial aviation is primarily reliant on fossil fuels, yet the depletion of these sources and the consequences of climate change necessitates the exploration of sustainable alternatives. The pyrolysis process offers a viable method for producing biofuels from various feedstocks. This research examines the combustion, emission, and performance characteristics of biofuels derived from agricultural residues, waste tyres, and plastics using pyrolysis. Pyrolysis oils derived from forestry or agricultural products exhibit high viscosity and moisture content, which impairs combustion efficiency and increases carbon monoxide (CO) from 70 % to 187 % and unburned hydrocarbon (UHC) emissions. Conversely, pyrolysis oils from plastics and waste tyres provide stable combustion with carbon monoxide and total hydrocarbon emissions (THC) comparable to those of commercial jet fuel. However, nitrogen oxide (NO X) emissions are significantly elevated from 57 % to 157 %. Engine performance tests demonstrated that forestry pyrolysis oils result in thrust loss due to their high viscosity value (14.3–113 mm2/s) and low calorific value (17.3–31.7 MJ/kg). In contrast, plastic and tyre pyrolysis oil perform similarly to commercial jet fuels but may potentially cause performance loss due to their high aromatic content (>47.67 %). Overall, upgrading the viscosity, moisture, and aromatic content of pyrolysis oils can enhance their suitability as alternative aviation fuels. These improvements could assist the aviation sector in achieving its carbon-neutral goals by making pyrolysis oils competitive with conventional jet fuels. [Display omitted] • FPO decreases combustion efficiency and increases CO and UHC emissions. • TPO and PPO are comparable to commercial jet fuel in combustion efficiency and CO and THC emissions. • FPO causes significant thrust loss, while TPO and PPO have thrust losses of less than 5 %. • Fuel upgrading may lead to an increased attraction to pyrolysis oils. [ABSTRACT FROM AUTHOR]

Recently, Sustainable Aviation Fuel (SAF) blends and novel combustion technologies have been introduced to reduce aircraft engine emissions. However, there is limited knowledge about the impact of combustion technology and fuel composition on toxicity of primary Particulate Matter (PM) emissions, comparable to regulated non-volatile PM (nvPM). In this study, primary PM was collected on filters using a standardised approach, from both a Rich-Quench-Lean (RQL) combustion rig and a bespoke liquid fuelled Combustion Aerosol Standard (CAST) Generator burning 12 aviation fuels including conventional Jet-A, SAFs, and blends thereof. The fuels varied in aromatics (0–25.2%), sulphur (0–3000 ppm) and hydrogen (13.43–15.31%) contents. Toxicity of the collected primary PM was studied in vitro utilising Air-Liquid Interface (ALI) exposure of lung epithelial cells (Calu-3) in monoculture and co-culture with macrophages (differentiated THP-1 cells). Cells were exposed to PM extracted from filters and nebulised from suspensions using a cloud-based ALI exposure system. Toxicity readout parameters were analysed 24 h after exposure. Results showed presence of genotoxicity and changes in gene expression at dose levels which did not induce cytotoxicity. DNA damage was detected through Comet assay in cells exposed to CAST generated samples. Real-Time PCR performed to investigate the expression profile of genes involved in oxidative stress and DNA repair pathways showed different behaviours after exposure to the various PM samples. No differences were found in pro-inflammatory interleukin-8 secretion. This study indicates that primary PM toxicity is driven by wider factors than fuel composition, highlighting that further work is needed to substantiate the full toxicity of aircraft exhaust PM inclusive of secondary PM emanating from numerous engine technologies across the power range burning conventional Jet-A and SAF. [Display omitted] • Human lung cells were exposed to primary PM from combustion of aviation fuels. • Toxicity depended on combustion technology but did not correlate with fuel properties. • Genotoxicity induced even at the relatively low PM deposition doses. • Strategies of lowering aromatic content may result in less harmful PM emissions. [ABSTRACT FROM AUTHOR]

[Display omitted] • HDPE pyrolysis under multi-stage setups produced jet-fuel-range hydrocarbons. • Condensation was suggested for selective recovery of aviation fuels in plastic oil. • Thermodynamic modeling for HDPE-derived oils in ideal turbojet cycle was evaluated. • HDPE-derived oils at 600 °C showed similar engine performance with jet fuels. Despite the calorific value of plastic waste being comparable to that of fossil fuels, its direct utilisation in the internal combustion engine is not a viable option due to a technical difficulty in optimising the equivalence ratio. To address this issue, this study proposes a pyrolysis system for the conversion of plastic waste, especially high density polyethylene (HDPE), into liquid fuels compatible with aircraft turbojet engines. Given a broad spectrum of pyrogenic hydrocarbons (HCs) derived from HDPE, it is important to shorten the chain length to produce aviation fuel-like products with carbon numbers ranging from 8 to 16. To this end, this study modified the typical pyrolysis setup by additionally adopting a heating element, isothermally operated at 500–800 °C. Also, the condensation system for collecting the pyrogenic HCs was designed using two consecutive units (set as 20 and −40 °C) for the selective recovery of jet-fuel-range HCs. The reaction temperature of 600 °C exhibited the similar composition of HDPE-derived fuel with commercial aviation fuels (Jet-A, JP-8, and JP-5). Subsequently, thermodynamic calculations of HCs collected in the second trap were performed in an ideal turbojet engine cycle. It was confirmed that the fuel performances of HDPE-derived fuel (produced at 600 °C) were comparable to commercial ones. Therefore, this study proposed that modification of pyrolysis and condensation system facilitated the production of jet-fuel-range HCs derived from HDPE. [ABSTRACT FROM AUTHOR]