Alternative Jet Research Articles

Dynamic radius jet clustering algorithm

The study of standard QCD jets produced along with fat jets, which may appear as a result of the decay of a heavy particle, has become an essential part of collider studies. Current jet clustering algorithms, which use a fixed radius parameter for the formation of jets from the hadrons of an event, may be inadequate to capture the differing radius features. In this work, we develop an alternative jet clustering algorithm that allows the radius to vary dynamically based on local kinematics and distribution in the η-ϕ plane inside each evolving jet. We present the usefulness of this dynamic radius clustering algorithm through two Standard Model processes, and thereafter illustrate it for a scenario beyond the Standard Model at the 13 TeV LHC.

Properties of Selected Alternative Petroleum Fractions and Sustainable Aviation Fuels

With regard to speed, comfort, and a dense network of destinations, the popularity of air transport is on the rise. For this reason, jet fuel is a commodity with rapidly growing consumption and interesting refinery margins. At the same time, however, it is becoming a focus of attention in terms of reducing negative environmental impacts. As a response to these trends, it will be necessary to coprocess alternative petroleum fractions with sustainable aviation components in oil refineries. Six alternative jet fuel samples of different origin were used to investigate their jet fuel-specific properties, that is, aromatics (from 0 to 59.7 vol%), smoke point (from 12.2 to >50 mm), freezing point (from −49 to <−80 °C) and net specific energy (41.2–43.7 MJ·kg−1), and these properties were compared to standard hydrotreated straight-run Jet A-1 kerosene. The properties of the components studied differed significantly with respect to each other and to the requirements of Jet A-1. Nevertheless, the properties could be well correlated. This provides an opportunity to study possible synergies in blending these components. It was also found that the current methods and instruments used do not always allow a precise determination of the smoke point (>50 mm) and freezing point (<80 °C).

EXPERIMENTAL STUDY OF PHYSICAL-CHEMICAL PROPERTIES OF ADVANCED ALCOHOL-TO-JET FUELS

The paper presents an analytical review of technological processes of alternative jet fuel production from alcohols and experimental results on the study of its physical-chemical properties. State-of-the-art in the sphere of civil aviation development within the framework of sustainable development and minimization of transport’s negative impact on the environment is presented. The development and implementation of sustainable aviation fuels are considered the main measure for reaching carbon-neutral growth. Two technologies of alcohol-to-jet fuel production are considered, and possible feedstock and processing pathways are presented. Physical-chemical properties of two kinds of alcohol-to-jet fuels are studied experimentally, as well as the properties of conventional jet fuels blended with alternative ones. It is shown that the physical-chemical properties of jet fuels blended with alcohol-to-jet component containing aromatics are very close to conventional jet fuels. All of the studied fuel blends with alcohol-to-jet components completely satisfy the requirements of specifications. Basing on the received results it is expected that alcohol-to-jet component containing aromatics may be successfully used for blending with conventional jet fuel and used as a drop-in fuel.

Skeletal and Compact Validated Mechanisms for Iso-dodecane Using a Decoupling Methodology

Iso-dodecane is an important component in developing surrogate fuel mixtures for conventional and alternative jet fuels. Despite some progress in recent years, there is still a requirement for a compact mechanism that is well validated in both low and high temperatures when compared to the experimental data. This paper develops a new compact mechanism with the aid of a decoupling methodology for iso-dodecane validated against available experimental data over a wide range of pressures and equivalence ratios. The ignition delay results show excellent agreement over a wide range of temperatures from 600 to 1300 K that covers low and high limits compared to the empirical data at 15, 20, and 40 bar and at lean, stoichiometric, and rich conditions. The maximum discrepancy between the simulations and the experiments by a factor of 1.7 was observed for 750 K at the rich condition at 15 bar. Laminar burning velocity simulations at two different pressures were conducted for iso-dodecane, and the results were compared with the available experimental data for alcohol-to-jet (ATJ) fuel, which is mostly composed of iso-dodecane. It was found that there was very good agreement between the modeling results and the experimental data. The final version of the new mechanism includes 158 species and 986 reactions and has potential in further functional kinetic investigations and to use for complex geometries of combustion systems such as Equivalent Reactor Network analyses.

Evaluation of Chemical Functional Group Composition of Jet Fuels Using Two-Dimensional Gas Chromatography

The growing interest in fuel property prediction models for simplification of fuel characterization has led to techniques for evaluating the chemical functional group compositions of fuels and mixtures as low-dimensional representations of the more detailed complete fuel composition. A new technique for quantitatively evaluating the UNIFAC group composition, chosen for its predictive versatility, from two-dimensional gas chromatography (GC × GC) analysis of complex real and alternative jet fuels is discussed. GC × GC analysis provides a more detailed and comprehensive chemical composition for the extraction of chemical functional groups when compared to optical spectroscopy-based techniques like Fourier transform infrared and Raman spectroscopy. Furthermore, the operating cost is lower and GC × GC analysis is more direct than the NMR spectroscopic evaluation of functional groups. The conversion of GC × GC, time-of-flight mass spectrometry (TOF-MS), and flame ionization detection (FID) analysis data to UNIFAC group composition is done with a new method and software tool developed in this work. The tool can be decoupled from the fuel analysis method, used independently with other methods, and applied to already available fuel composition databases. Using GC × GC combined with TOF-MS and FID analysis, the UNIFAC group compositions of eleven different complex jet fuels are demonstrated as consisting of 10 groups of lower dimensional yet chemically significant features for data science prediction of fuel properties.

Evaluation of physicochemical variability of sustainable aviation fuels

This study outlines an effort to report on the physicochemical variability of Sustainable Aviation Fuels (SAF), leveraging data from the FAA Alternative Jet Fuels Test Database (AJFTD). The AJFTD, containing fuel sample records of conventional and sustainable aviation fuels to date, was developed by the PIs through the FAA Center of Excellence (ASCENT). With the development of SAF from various feedstocks and processing methods, new approval processes have been developed to accommodate the changing jet fuel landscape. To control for these differences, approval procedures were designed as each new fuel category came through the development pipeline. However, recent studies have suggested that rather than feedstock or processing method, chemical properties and fuel performance can be accurately judged by considering fuel composition characteristics such as carbon chain length, hydrocarbon class, and branching level. To quantify the variability present in recently approved jet fuels, this paper evaluates physicochemical property variability and provides relevant thermophysical property relations for conventional and alternative jet fuels with a discussion of efforts to streamline approval, reducing the time and cost of bringing new SAF to future markets. Findings from this study show that the variability in the composition and properties of SAF as compared to conventional fuels is small enough such that they still satisfy specification requirements outlined by the American Society for Testing and Materials (ASTM) D7566 standards for aviation fuels containing synthesized hydrocarbons.

Rock breaking characteristics by swirling impeller abrasive water jet (SAWJ) on granite

Radial jet drilling technique (RJD) has been identified as a cost-effective way of exploiting geothermal energy from hot dry rock (HDR). The swirling impeller nozzle is expected to drill large diameter radial branches in HDR. However, the swirling impeller water jet (SWJ) is difficult to break hard granite . Here, we investigate swirling impeller abrasive water jet (SAWJ) as an alternative jet type for drilling laterals in HDR reservoirs. We conducted comparative experiments to evaluate its rock-breaking performances on granite. Scanning electron microscope and 3D profiler were performed to observe the macro and micro-morphology of jet-drilled holes. Results show that SAWJ can efficiently create a large and regular hole with smooth walls that completely satisfies the requirements of drilling laterals in granite. The longitudinal sections of the SAWJ-drilled holes were “W” shaped. With the erosion of SAWJ, the generation of the conical bulge reached a state of dynamic balance. A large number of craters were formed through the impact of the abrasive particles . In addition, tensile cracks were found within the craters thereby improving the rock-breaking performance of the SAWJ over the SWJ technique. Interestingly, this is the first study to illustrate the feasibility of SAWJ drilling in hard rocks. The research results are expected to provide a viable alternative for effective RJD operation and optimal exploitation of geothermal resources in HDR.

In-flame soot structure of a jet fuel with 24% aromatics in a small-bore optical compression-ignition engine

This study applies a multi-location soot sampling method in a small-bore optical compression ignition engine to show in-flame particle evolution of a surrogate jet fuel with 24% aromatics (AR24) and a conventional diesel fuel. Four soot sampling probes are installed on the piston-bowl wall with 60° spacing angles for simultaneous sampling from the same firing cycle. These sampling locations represent a jet-wall impingement point (JW), an up-swirl point (US), a down-swirl point 1 (DS1) and a down-swirl point 2 (DS2) along the sooting flame path identified by high-speed soot luminosity images and planar laser induced incandescence (PLII) images. The sampled soot particles are examined with transmission electron microscope (TEM) and the images are post processed for the analysis of morphology. The results showed both fuels produce a large amount of small soot aggregates at JW point due to fuel-rich mixtures while AR24 soot aggregate number count is much less than diesel, indicating less soot formation for AR24. They grow as the flame travels along the bowl wall through aggregation, which is more significant at DS1 point than that of US point. Simultaneously, some small soot aggregates disappear due to oxidation, which is more significant at US point. As the sooting flame reaches DS2 point, only large aggregates with compact structures survived intense oxidation. The soot sampling performed for high resolution TEM and internal structure analysis of AR24 showed that the core-shell particle structure becomes clearer and the carbon-layer fringe-to-fringe gap decreases during the flame penetration, indicating the soot oxidation continued. From the results, the in-flame soot evolution is characterised by high formation of small aggregates at JW point, simultaneous aggregation and oxidation at US and DS1 point with the latter more prone to aggregation, and significant oxidation at DS2 point.

Experimental and molding study of the vaporization process of newly developed and well-established jet fuel surrogates

Real jet fuels have hundreds of individual hydrocarbon species with varying physical and chemical properties. Surrogate fuels containing mixtures of a small number of components have been developed to emulate the behaviors of the parent fuels. Often surrogates are derived solely based on the gas-phase combustion behavior and thus are not constrained to match physical phenomena, such as atomization and vaporization. Thus, these fuels can subsequently exhibit different behaviors than the parent fuel they are designed to emulate, especially when introduced in a two-phase system. This work explores the ability of selected established and newly developed/proposed surrogate jet fuels to mimic the properties necessary for the two-phase conversion process, including the vaporization behavior of real fuel spray. The droplet lifetime/vaporization dynamics is measured using a single droplet levitating device (acoustic levitator). The newly developed surrogates show a satisfying emulation of the parent jet fuel's physical and chemical properties, including SMD, CN, LHV, MW, and vaporization evolution. Most notably, the binary solution consisting of n-dodecane and toluene predicted the physical and chemical properties of the parent fuel closely, with a total maximum deviation from the selected targeted fuel properties ∼12.6% compared to ∼52% of the well-established previously developed Dooley 1st surrogate.

On the use of extended-wavelength FTIR spectra for the prediction of combustion properties of jet fuels and their constituent species

A Fourier transform infrared (FTIR) spectra-based strategy was developed for estimating three important combustion properties of jet fuels and their constituent hydrocarbon species: ignition delay time (IDT), net heat of combustion (NHC), and derived cetane number (DCN). This approach leverages the strong sensitivity of combustion behavior to the different infrared absorption features of hydrocarbon fuels. Gas-phase FTIR spectra of pure hydrocarbons and jet fuels in the 2–15.38 μm wavelength range were used to train elastic-net regularized linear models, with the model parameters optimized separately for each property. The results from these models were compared with the results from previous models, which utilized only a limited spectral region in the wavelength range 3.3–3.55 μm. The new, optimized models developed in this work show significant improvement in predictive performance compared to the previous models for all three properties. The models’ prediction errors on test data (blends of conventional and alternative jet fuels) are found to be comparable to the standard property measurement uncertainties, demonstrating the value of infrared spectral analysis as a low-volume prescreening tool for accurate property estimation of both conventional and alternative jet fuels.

Novel quota and tax regime design approach for green transition: A case study on Switzerland's aviation industry

In the present study, a novel approach for calculating optimal quota and tax regimes is investigated. A meta-heuristic framework has been developed to find the optimal quota regime for the national or worldwide aviation industry. The minimization of ticket prices and CO2 emissions are considered to be objective functions. The results of the current study indicate that implementing optimized quotas is more effective than intensive tax regimes. To elaborate, much more important than the value of the carbon price is the shape (convexity or concavity) of the tax regime. The optimal tax regime shape is also obtained. Based on the optimal quota and tax regime, the concept of golden time and value is introduced. In the golden time window, investing in Sustainable Aviation Fuels (SAFs) will be the most cost-effective. Furthermore, the results demonstrate that neither the sole introduction of quotas nor the imposition of high carbon taxes are beneficial from an economic and decarbonization standpoint. Thus, an optimized quota regime should be employed. These quotas should be introduced as soon as possible, and their implementation should be combined with political efforts to introduce a carbon tax and policies supporting the development of an alternative jet fuel industry.

Chemical Characterization and Quantitation of Phenols in Fuel Extracts by Using Gas Chromatography/Methane Chemical Ionization Triple Quadrupole Mass Spectrometry

The ability to detect, characterize, and quantify phenols in aviation fuels is critical as these compounds can negatively affect the storage stability of the fuel. However, some phenols inhibit free-radical autoxidation and hence are beneficial. The development of a method based on gas chromatography coupled with positive-ion-mode methane chemical ionization/triple quadrupole mass spectrometry [GC/(methane CI) QqQ] for the characterization and quantitation of phenols in fuels is reported here. Sixteen phenols, ranging from phenol to phenols with up to three alkyl groups of different chain lengths, were studied. Natural phenols (defined as phenols without tert-butyl groups) were protonated upon methane CI, which was associated with diagnostic fragmentation. For example, upon protonation, 2-, 3-, and 4-ethylphenols fragmented via the loss of ethylene, which facilitated their distinction from the isomeric 2,4-, 2,5-, and 3,4-dimethylphenols. Furthermore, the natural phenols formed stable adducts with C2H5+ and C3H5+ ions generated from methane upon CI. In contrast, additive phenols (with one or more tert-butyl groups) were predominantly ionized via electron abstraction to yield molecular radical cations and did not form adduct ions and generated some diagnostic fragment ions, such as ions of m/z 57 (tert-butyl cation). Most of the molecular radical cations of additive phenols also exhibited a methyl radical loss, while protonated additive phenols exhibited water loss. The limit of detection and the limit of quantitation were determined to be 1.3 μM (0.33 ppm) and 4.2 μM (1.08 ppm), respectively, and the linearity of quantitation was between 5 and 160 μM. Measurements of equimolar mixtures composed of additive and natural phenols demonstrated similar (within 10%) but not identical ionization efficiencies for these two compound types. Intra- and interday measurements of the signal intensities of the phenols were highly repeatable, with average relative standard deviations of 1.7 and 5.2%, respectively. The same method was employed to successfully characterize and quantify unknown phenols in alternative and petroleum-based jet fuel extracts. The petroleum-based Jet A fuel was found to contain a 1.5 times greater concentration of phenols than the alternative fuel. Jet A contained monomethylated phenols (108 Da), while the alternative fuel did not. Several phenols with molecular weights of 122, 136, and 150 Da were detected in both Jet A and the alternative fuel. The CI mass spectra suggested that some of these phenols had multiple methyl substituents. The information that can be acquired by using the GC/(CI) QqQ method will facilitate establishing links between the chemical compositions of fuels and fuel properties. Overall, the method was found to be robust and repeatable.

Environmental and economic issues for renewable production of bio-jet fuel: A global prospective

Given how quickly the aviation sector is growing, it is crucial to find sustainable ways to supply the demand. Modern technological developments and the creation of alternative jet fuels are crucial elements that could help eliminate greenhouse gases (GHGs) like CO2 emissions. Traditional jet fuel produces a sizable amount of GHG emissions, which has raised concern on a global scale. Compared to conventional jet fuel, biofuel is thought to be more renewable and less polluting. Biojet fuels might work as an effective substitute. The varieties of bio jet fuel, manufacturing procedures (including alcohol-to-jet, oil-to-jet, syngas-to-jet, and sugar-to-jet ways), existing regulations, and the effects of bio jet fuels on the environment and the economy are all covered in length in this overview. These are the techniques that are most frequently used to create bio-jet fuel from both edible and inedible feedstock. The main conclusions of this review indicate that the most popular method for producing biofuel is hydrogenated esters and fatty acids (HEFA). The Fischer-Tropsch (FT) approaches cost more to install even though they produce fewer GHGs. Environmentally beneficial and technologically advanced, second-generation biofuels are a great choice. It has been revealed that jatropha is a crop that produces a lot of energy. The price of feedstock and the lack of bio-jet fuel are the two biggest obstacles to substituting conventional fuel. To increase the power and quality of energy, further in-depth research on optimal feedstocks is necessary. In order to address the needs of both commercial and military aircraft, biomass jet fuel has a lot of potential to replace conventional jet fuel. High yield should be one of the properties of the feedstock without affecting food production.

Laminar flame speed and autoignition characteristics of surrogate jet fuel blended with hydrogen

Hydrogen combustion has emerged as one promising option toward the achievement of carbon-neutral in aviation. In this study, the effects of hydrogen addition on laminar flame speeds, autoignition, and the coupling of autoignition and flame propagation for surrogate jet fuel n-dodecane are numerically investigated at representative engine conditions to elucidate the potential challenges for flame stabilization and the autoignition risks in combustor design. Results show that the normalized flame speed increases almost linearly with hydrogen addition for fuel-lean conditions, while for fuel-rich conditions it increases nonlinearly and can be up to 20. This poses great challenges for avoiding flameholding and flashback, particularly for fuel-rich mixtures. Results further show that flame speed enhancement due to the increased flame temperature can be neglected under fuel-lean conditions, but not for fuel-rich mixtures. For the dependence of ignition delay time on temperature, there exists a unique intersection between pure n-dodecane/air and H2/air mixtures. Near the intersection temperature, there exists subtle kinetic coupling of the two fuels, leading to different H2 roles, e.g., accelerator or inhibitor, for the autoignition process of n-dodecane/H2/air mixtures. With this intersection temperature, the diagram for autoignition risks is constructed, which demonstrates that H2 acts as an inhibitor under subsonic cruise conditions while either an inhibitor or an accelerator under supersonic cruise conditions depending on the combustor inlet temperature and the amount of hydrogen addition. With the potential coupling of autoignition and flame propagation, the 1-D autoignition-assisted flame calculations show that hydrogen addition can alleviate or even eliminate the two-stage ignition characteristics for pure n-dodecane/air flames. For n-dodecane blended with hydrogen, the autoignition-assisted flame propagation speed, as well as the global transition from flame propagation to autoignition, can still be described by an analytic scaling parameterized by the ignition Damkӧhler number.

Studying of different supported metal catalysts for bio-JET production

Since 2011, the volume of passenger air transport grew nearly 7.5%/year, while freight air transport grew 3.6%/year regarding to the performed kilometers. The expansion of the aviation sector resulted increasing fuel consumption, too. The growing usage of fossil-based jet fuel results significant particle and carbon dioxide emissions, which causes remarkable environment pollution. This emission can only be reduced with using alternative jet fuels, especially those are originated from natural/waste fatty acid/-ester triglyceride sources. The aim of the experimental work was to compare industrially applied sulfide-state catalysts containing different transition metals from the aspect of catalytic conversion of mixtures of waste coconut oil and unrefined kerosene to produce jet fuel at various process parameters (temperature = 280–360 °C, liquid hourly space velocity = 1.0–3.0 h−1, pressure = 30 bar, hydrogen/hydrocarbon volume ratio = 600 Nm3/m3) in a continuous down-flow tubular reactor system. The obtained products contributes to decrease in particle and carbon dioxide emission of aircrafts due to their lower aromatic content. The smoke point of the products obtained at favorable process parameters was higher than 30 mm, while the requirement in ASTM D 1655 standard is minimum 25 mm.

New approach for bio-jet fuels production by hydrodeoxygenation of higher alcohols derived from C-C coupling of bio-ethanol

A new approach for the synthesis of jet fuel hydrocarbon from bio-ethanol was developed, the integrated catalytic process of ethanol C-C coupling and heavy alcohols hydrodeoxygenation (HDO) was reported. The initial bio-ethanol C-C coupling process was fulfilled directly in aqueous environment over Na/Ni@C catalyst. The obtained high-carbon alcohols can be separated into C4-C7 and C8-C16 alcohols respectively through convenient fractional distillation. The obtained C8-C16 alcohols mainly consist of β-branched primary alcohol, which are desired precursors for jet fuel hydrocarbons. To maintain the branched carbon skeleton in the subsequent alcohol HDO process, the Co-Mo2C catalyst with excellent C-O bonds cleavage and carbon skeleton retention ability were developed. Jet fuel hydrocarbons of 56.7% yield obtained from this approach is mainly C8-C16 branched alkanes, which is beneficial for the cold flow properties. This strategy creates new opportunities for producing alternative jet fuel from the mature bio-ethanol industry.

Life-Cycle Assessment of Power-to-Liquid Kerosene Produced from Renewable Electricity and CO2 from Direct Air Capture in Germany

Decarbonization of the aviation sector is crucial to reaching the global climate targets. We quantified the environmental impacts of Power-to-Liquid kerosene produced via Fischer-Tropsch Synthesis from electricity and carbon dioxide from air as one broadly discussed alternative liquid jet fuel. We applied a life-cycle assessment considering a well-to-wake boundary for five impact categories including climate change and two inventory indicators. Three different electricity production mixes and four different kerosene production pathways in Germany were analyzed, including two Direct Air Capture technologies, and compared to fossil jet fuel. The environmental impacts of Power-to-Liquid kerosene varied significantly across the production pathways. E.g., when electricity from wind power was used, the reduction in CO2-eq. compared to fossil jet fuel varied between 27.6–46.2% (with non-CO2 effects) and between 52.6–88.9% (without non-CO2 effects). The reduction potential regarding CO2-eq. of the layout using low-temperature electrolysis and high-temperature Direct Air Capture was lower compared to the high-temperature electrolysis and low-temperature Direct Air Capture. Overall, the layout causing the lowest environmental impacts uses high-temperature electrolysis, low-temperature Direct Air Capture and electricity from wind power. This paper showed that PtL-kerosene produced with renewable energy could play an important role in decarbonizing the aviation sector.

Role of Ni–Fe/ZSM-5/SAPO-11 bifunctional catalyst on hydrodeoxygenation of palm oil and triolein for alternative jet fuel production

This study aims to investigate the effect of four bifunctional catalysts S1 = (ZSM-5/SAPO-11), S2 = (5%Ni/ZSM-5/SAPO-11), S3 = (5%Fe/ZSM-5/SAPO-11), and S4 = (5%Ni–Fe/ZSM-5/SAPO-11) on the hydrodeoxygenation of palm oil and triolein for alternative jet fuel production. All catalysts were synthesized in situ via wet impregnation method and characterized using BET, XRD, H2-TPR, FESEM, NH3-TPD, Pyridine-FTIR, and TGA analyses. Hydrodeoxygenation was found to progress via the removal of carboxyl group in the fatty acid structure as CO2 and CO. However, the formation of alkanes (C11–C29) and aromatics (C18–C24) were obtained by additional cracking of fatty acids over the bifunctional catalysts. The novelty of the present work lies in finding appropriate catalyst and yields of alkanes and aromatics from palm oil and triolein hydrodeoxygenation. Maximum alternative jet fuel yields from palm oil and triolein were 81.74% and 63.41% with higher heating values of 49.9 MJ/kg and 49.5 MJ/kg, respectively via the use of S4 catalyst. These results showed that with the proper tuning of Ni–Fe synergy and physicochemical properties of Ni–Fe/ZSM-5/SAPO-11 bifunctional catalyst, it is possible to produce alternative jet fuel from palm oil and triolein HDO with low water and oxygen contents and comparable higher heating value with conventional jet fuel.

Effects of alternative jet fuel blends on aerospace-grade carbon/epoxy composites

The effects of Jet A fuel and four alternative fuel blends on different carbon/epoxy composites were investigated. The alternative fuel blends consisted of 50/50 or 90/10 vol% blends of Jet A fuel with low aromatic content non-petroleum sourced fuels. These alternative fuel blends had previously passed the Federal Aviation Administration (FAA) certification process as drop-in fuels with the aim of reducing the environmental imprint of conventional jet fuels. The time-dependent absorption behavior of Jet A and these alternative fuel blends into three different types of carbon/epoxy composites were studied, and no significant differences in fuel absorption were observed for different fuels for a similar composite. The fuel uptakes were low for all three composites, varying from 0.04 to 0.36 wt%. However, the arrangement of fiber tows and individual filaments within plies appeared to affect fuel uptake. Additionally, the effects of the absorption of all five fuels on the composites' glass transition temperature (Tg) were investigated. The composite Tg values decreased in the range of 3.1–19 °C for Tg and 1.8–20.6 °C for Tt for all specimens after fuel absorption. The alternative fuel blends exhibited similar results to that of Jet A for equilibrium fuel uptake amounts, uptake rates, and effects on the composites' Tg.

Alternative fuels’ blending model to facilitate the implementation of carbon offsetting and reduction Scheme for International Aviation

The aviation sector contributes 4.1% to the global economy, although it was responsible for 2.8% of the net global CO2 emissions in 2019, and it contributed around 12% of the CO2 emissions produced from the transportation sector alone in 2018. Hence, the UN’s Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA) can serve as a cost-effective mechanism to promote low carbon fuels and mitigate CO2 emissions, where integrating alternative jet fuels may reduce the cost associated with CORSIA's offsetting requirements. Therefore, this study considers the following alternative production pathways; Gas to Liquid, Oil to Jet, Gas to Jet, Sugar to Jet, Catalytic Hydro-thermolysis Jet and Alcohol to Jet; for the development of an optimal fuel blending model. A multi-objective model is developed and transformed into a singular objective function for a convenient minimisation of the total fuel-related costs for operators under CORSIA. The model considered the reclaiming possibility of offsetting costs when a CORSIA's eligible fuel is utilised. The results demonstrated that an increase in carbon price increases the total net cost of fuel purchasing and carbon taxing, therefore, enhancing the opportunity for airlines to integrate larger shares of alternative fuels. In addition, the presented model managed to select optimal fuels' blending ratios considering carbon credit approach, which achieved a total cost reduction by 0.13% to 8.08%, assuming a carbon tax range of 3–180 $/tonne CO2.