Aviation Biofuels Research Articles

Evaluation of the Properties and Compositions of Blended Bio-jet Fuels Derived from Fast Pyrolysis Bio-oil made from Wood According to Aging Test

AbstractThe aviation industry has set ambitious goals for reducing carbon emissions, with the International Civil Aviation Organization targeting net-zero carbon emissions by 2050. Bio-jet fuel is expected to play a crucial role in achieving this target, and the demand for bio-jet fuel is projected to rapidly increase. Bio-oil from fast pyrolysis of lignin, such as waste wood, is considered a promising alternative for production of bio-jet fuel through processes such as hydrodeoxygenation. In this study, the physical properties and compositions of bio-jet fuel produced from wood-derived pyrolysis bio-oil blended with petroleum-based jet fuel as well as their changes during 16 weeks storage were investigated. Consistently, 0%, 10%, 50%, and 100% blended bio-jet fuels were prepared. After 16 weeks of aging, the total acid number of the all-blended bio-jet fuel showed a sharp increase from 12 weeks, reaching over 0.1 mg KOH/g. Additionally, kinematic viscosity showed a steady increase over 16 weeks whereas oxidative stability decreased by approximately 20% at 16 weeks for the 100% bio-jet fuel alone. The final boiling point increased by up to 20% in higher blends of bio-jet fuel and the average molecular weight increased. Bio-jet fuel has a high olefin content, which can further increase during storage, leading to a decrease in the combustion characteristics. This study suggests that using up to 10% the bio-jet fuel in aircraft is safe considering storage stability, but further research is required to confirm this finding.

Comparative Analysis of Performance and Exhaust Emissions from Jet A1 Blends with Various Aviation Biofuels

The aviation industry is a significant contributor to greenhouse gas emissions. Given the growing demand for air travel and the unsustainable use of fossil fuels, it is crucial to develop and commercialize renewable fuels to reduce these emissions. Conventional jet fuels like Jet A1 release harmful pollutants such as carbon monoxide (CO) and nitrogen oxides (NOx) into the atmosphere. In contrast, biofuels offer a renewable, biodegradable, and non-toxic alternative that emits fewer pollutants, excluding NOx, and is easier to treat than fossil fuels. Due to their eco-friendly characteristics, biofuels have garnered attention in recent years. This study focuses on producing biofuels from jatropha oil and waste cooking oil. Jatropha oil, aside from its medicinal benefits such as antimicrobial and anticancer properties, can be effectively used in industrial applications, particularly for biofuel production. The production of biofuels from jatropha and waste cooking oil is of growing interest due to their environmental and economic benefits. The study investigates the production of these biofuels using appropriate catalysts under controlled experimental conditions, followed by blending the biofuels with Jet A1 fuel to achieve similar engine performance while mitigating the environmental impact of greenhouse gases from petroleum-based fuels.

Investigating the oxidation characteristic of a hydro-processed bio-jet fuel: Experimental and modeling study

A rapid transition from conventional jet fuels to sustainable aviation fuels (SAFs) is imperative in order to reduce carbon emissions. Hydro-processed esters and fatty acids synthetic paraffinic kerosene (HEFA-SPK), as a type of SAF, exhibits broad applications. In this study, a new HEFA-SPK named ZH-HEFA was investigated. The fuel comprises 14% n-alkanes, 85% iso-alkanes and only 1% cycloalkanes by weight, with the majority of alkanes ranging from C9 to C17. Oxidation experiments of the fuel were conducted using an atmospheric pressure flow reactor at temperatures ranging from 550 K to 1075 K under three equivalence ratios (0.5, 1.0 and 1.5). Species mole fraction profiles were measured by an on-line gas chromatographic (GC). For comparison purposes, an experiment was also performed on RP-3, a conventional jet fuel commonly used in China, under the equivalence of 0.5. Compared to RP-3, ZH-HEFA exhibited significantly stronger low temperature reactivity and higher combustion conversion rates while demonstrating considerably lower yields of aromatics at high temperatures. The kinetic simulation of ZH-HEFA was achieved by proposing two surrogates and their corresponding kinetic models. Surrogate S-1 consisted solely of n-dodecane, while S-2 comprised 35% n-dodecane and 65% 2,6,10-trimethyl dodecane by weight. Both surrogate models were validated by the experimental data. S-1 exhibited a closer resemblance to the global oxidation characteristics of ZH-HEFA, whereas S-2 demonstrated improved accuracy in predicting the formation of small hydrocarbon intermediates during the fuel oxidation. Rate of production analysis revealed that the branched alkane component in S-2 possessed more pathways and greater capability than S-1 in generating C3 intermediates, which are important for the generation of aromatics. Furthermore, both models displayed good predictive performance for the auto-ignition properties of HEFA-SPK fuels.-

Fuel Lubricity Assessment of Fossil and Synthetic Paraffinic Kerosene to Be Used in Reciprocating Engines

Fuel Lubricity Assessment of Fossil and Synthetic Paraffinic Kerosene to Be Used in Reciprocating Engines

Comparative analysis of the combustion and emission characteristics of biojet and conventional Jet A‐1 fuel: a review

AbstractConventional jet fuels derived from fossil sources contribute to greenhouse gas emissions and air pollution, leading to climate change. Recent studies have shown that biobased jet fuels from different feedstocks offer a more sustainable alternative to conventional fuels as they are derived from renewable biomass, reducing greenhouse gas emissions. The major feedstocks reviewed are jatropha curcas, camelina, karanja oil, waste cooking oil, and municipal solid waste. They offer diverse benefits for sustainable aviation fuel development. As a comparative analysis, this review examined jet fuel characteristics based on their physicochemical properties, namely energy content, viscosity, calorific value, cetane number, and freezing and flash points. The objective was to understand the influence of the properties on performance evaluation, environmental impact, and combustion characteristics. The properties of biojet fuels are compared with their fossil counterparts to validate their suitability as renewable alternatives and their benefits in terms of emissions reduction and engine performance. Biojet fuels perform better in terms of lower sulfur content, lower soot content, and a lower freezing point, their aromatic content, and their high cetane number. This study enhances the understanding of biojet fuels and their quality, and supports the development of sustainable fuel options. Overall, adherence to the American Society for Testing and Materials (ASTM) D7566‐18 standard is crucial for the acceptance and integration of biojet fuels into the aviation sector. Future research should explore feedstocks such as wood biomass, wastepaper, and agricultural residues for biojet fuels. It should also investigate the combustion and emission characteristics of biosourced aviation fuel at higher blending ratios (>50% by volume) with fossil Jet A‐1.

Exploring genetic diversity, population structure, and subgenome differences in the allopolyploid Camelina sativa: implications for future breeding and research studies

Abstract Camelina (Camelina sativa), an allohexaploid species, is an emerging aviation biofuel crop that has been the focus of resurgent interest in recent decades. To guide future breeding and crop improvement efforts, the community requires a deeper comprehension of subgenome dominance, often noted in allopolyploid species, alongside and understanding of the genetic diversity and population structure of material present within breeding programs. We conducted population genetic analyses of a C. sativa diversity panel, leveraging a new genome, to estimate nucleotide diversity and population structure, and analyzed for patterns of subgenome expression dominance among different organs. Our analyses confirm that C. sativa has relatively low genetic diversity, and show that the SG3 subgenome has substantially lower genetic diversity compared to the other two subgenomes. Despite the low genetic diversity, our analyses identified thirteen distinct subpopulations including two distinct wild populations and others putatively representing founders in existing breeding populations. When analyzing for subgenome composition of long non-coding RNAs, which are known to play important roles in (a)biotic stress tolerance, we found that the SG3 subgenome contained significantly more lincRNAs compared to other subgenomes. Similarly, transcriptome analyses revealed that expression dominance of SG3 is not as strong as previously reported, and may not be universal across all organ-types. From a global analysis, SG3 was only significant higher expressed in flower, flower bud, and fruit organs, which is an important discovery given that the crop yield is associated with these organs. Collectively, these results will be valuable for guiding future breeding efforts in camelina.

Spatial segregation of catalytic sites within Pd doped H-ZSM-5 for fatty acid hydrodeoxygenation to alkanes

Spatial control over features within multifunctional catalysts can unlock efficient one-pot cascade reactions, which are themselves a pathway to aviation biofuels via hydrodeoxygenation. A synthesis strategy that encompasses spatial orthogonality, i.e., one in which different catalytic species are deposited exclusively within discrete locations of a support architecture, is one solution that permits control over potential interactions between different sites and the cascade process. Here, we report a Pd doped hierarchical zeolite, in which Pd nanoparticles are selectively deposited within the mesopores, while acidity is retained solely within the micropores of ZSM-5. This spatial segregation facilitates hydrodeoxygenation while suppressing undesirable decarboxylation and decarbonation, yielding significant enhancements in activity (30.6 vs 3.6 moldodecane molPd−1 h−1) and selectivity (C12:C11 5.2 vs 1.9) relative to a conventionally prepared counterpart (via wet impregnation). Herein, multifunctional material design can realise efficient fatty acid hydrodeoxygenation, thus advancing the field and inspiring future developments in rationalised catalyst design.

A surrogate fuel emulating the physical and chemical properties of aviation biofuels

AbstractThe development of aviation biofuels is a key strategy for reducing carbon emissions in the aviation industry. This study aimed to establish a surrogate model for aviation biofuels using a hybrid approach that combined explicit equations with an artificial neural network (ANN). The low heating value was calculated using an explicit equation, whereas the ANN predicted changes in density, viscosity, surface tension with temperature, and the distillation curve of the surrogate model. An optimization algorithm was then employed to identify suitable substitutes, which consisted of 11.44% n‐decane, 43.43% n‐dodecane, 43.11% n‐tetradecane, and 2.02% methylcyclohexane. The maximum error between the physical properties of the surrogate components and the measured biofuels did not exceed 7%. The ignition delay time of the substitute components matched that of real aviation biofuels at an equivalence ratio of 1.0 and a pressure of 10 bar.

Enhancing corn stover to bio-jet fuel process: Valorizing lignin-enriched residue for energy, economic, and environmental benefits

Bio-jet fuels are considered as a highly promising strategy for minimizing carbon emissions in the aviation sector. This study presents a scheme for producing bio-jet fuel from corn stover through aqueous phase conversion, focusing on the economics and environmental performance of various lignin utilization technologies. Three scenarios were simulated using Aspen Plus, each integrating a different approach: lignin hydrothermal conversion to jet fuel range arenes (LtoA), lignin gasification-syngas fermentation to ethanol (LtoE), and lignin direct combustion (LC). The energy conversion rates of the three cases are 32.75 %, 32.67 %, and 31.44 %, in that order. Technical-economic analysis and life cycle assessment were conducted for each scenario. The minimum jet fuel selling prices (MJFSP) for the three scenarios range between 2050 and 2562 $/t, 2095–2620 $/t, and 2024–2529 $/t, with greenhouse gas (GHG) emissions reduced by 33 %, 383 %, and 37 % compared to fossil jet fuel, respectively. Steam stripping for furfural production is the largest energy consumer, hindering economic improvement and GHG emission reduction due to inefficient furfural yield. The use of sulfuric acid and NaOH as catalysts contributes significantly to 37 % of greenhouse gas (GHG) emissions and 79 % of human toxicity emissions among other environmental impacts. The development of green solvents and the enhancement of lignin conversion rates could further improve the economic and environmental performance of bio-jet fuel.

In-situ preparation of MnFeCoNiCu/C for the sustainable co-production of bio-jet fuel and green diesel under solvent-free and low hydrogen pressure conditions

The conversion of non-edible oils such as fatty acid methyl esters (FAME) into green and renewable liquid fuels align with the current trend of sustainable development. However, traditional processes often involve multi-step process to prepare catalyst and require high-pressure hydrogen. This study reports a strategy for the in-situ preparation of MnFeCoNiCu/C catalyst, enabling the one-step conversion of FAME into bio-jet fuels and hydrocarbon-based diesel under solvent-free and low-pressure conditions. The effect of active metal loading, reaction temperature, hydrogen pressure, and ZSM-5 zeolite addition on the catalytic performance was investigated. Under the conditions of reaction temperature 350 ℃ and hydrogen pressure 2 MPa, the conversion rate of FAME reaches 100 %, and the selectivity of bio-jet fuel and green diesel is 48.35 % and 51.05 %, respectively. A small number of olefins, cycloalkanes, and aromatics can also be detected in the products. After the 4 cycles of AC-15 catalyst, the selectivity of bio-jet fuel and diesel are 40.09 % and 39.81 %, respectively. The above research work provides a mild and efficient method for the preparation of renewable bio-jet fuel and green diesel.

The effect of used cooking oil composition on the specific CO2e emissions embodied in HEFA‐SPK production

AbstractIn this study, the correlation between the composition, hydrogen/carbon (H/C) ratio, and hydrogen/oxygen (H/O) ratio of a used cooking oil (UCO) and the specific emissions embodied in the derived hydroprocessed esters and fatty acids synthetic paraffinic kerosene (HEFA‐SPK) is investigated. It is shown that HEFA‐SPK produced from UCOs with low concentrations of C18:1, high concentrations of C18:2, and low H/C ratios utilize less energy and more hydrogen during Fuel Production. Hence, HEFA‐SPK produced from such UCOs will embody higher gCO2e for fossil hydrogen utilization scenarios, and lower gCO2e for green hydrogen utilization scenarios compared with other UCOs. Conversely, it is shown that HEFA‐SPK produced from UCOs with high concentrations of C18:1, low concentrations of C18:2 and high H/C ratios utilize more energy and less hydrogen during Fuel Production. Hence, HEFA‐SPK derived from such UCOs will embody lower gCO2e for fossil hydrogen utilization scenarios, and higher gCO2e for green hydrogen utilization scenarios compared with other UCOs. Monte Carlo simulation gives the emissions embodied in Fuel Production a 95% confidence interval for all UCO‐derived HEFA‐SPK, showing a similar uncertainty for all compositions. A maximum of +1.1 gCO2e/MJSAF and −1.0 gCO2e/MJSAF is obtained for the upper and lower bounds respectively for the emissions embodied during HEFA‐SPK production from UCO. The application of the correlations founded in this study allows for the prediction of the specific emissions embodied in the feedstock‐to‐fuel conversion of any UCO, providing the C18:1 concentration, C18:2 concentration, H/C ratio and H/O ratio of the UCO is known.

Sustainable bio-jet fuel synthesis techniques for the aviation industry

Abstract In the near future, the aviation industry is expected to significantly increase the usage of “drop-in” bio-jet fuel as the technologies in biofuel production advances and matures. Given the high rate of growth in the aviation sector, the demand for aerial transportation of passenger and cargo is projected to increase by two-fold in the next twenty years. This will raise the global aviation fuel consumption to an estimated 22.48 quadrillion British thermal unit (BTU) by 2040. To meet these high energy demands, it is necessary to develop alternative and sustainable methods to produce jet fuel. In light of this, intense research and numerous fundings have been allocated into developing efficient production methods for bio-jet fuel. Conventional jet fuel emits a considerable amount of greenhouse gases (GHGs) when combusted, which contributes to global warming. Compared to traditional jet fuel, bio-jet fuel is a renewable energy source and regarded to emit less GHGs. Bio-jet fuel can be produced using a diverse range of both edible (food crops such as soybean, corn, and sugar cane) and inedible (such as energy crops, agricultural wastes, and lignocellulosic biomass) feedstocks. There are various promising technologies that can produce aviation biofuel, which includes oil-to-jet [hydroprocessed ester and fatty acids (HEFA)], alcohol-to-jet, sugar-to-jet [hydroprocessing of fermented sugars (HFS)], and syngas-to-jet [Fisher-Tropsch (FT)]. Compared to the other techniques, HEFA bio-jet fuel can be sold at a lower price because HEFA requires less capital investment, capital cost, and energy cost. Although FT technique require high capital investment, FT bio-jet fuel can be sold at medium price due to its matured technology. The breakeven cost of ATJ and HFS bio-jet fuel varies greatly due to the supply and cost of sugar-rich feedstocks, as well as short lifespan of enzymes. Although bio-jet fuel has the potential to replace petroleum jet fuel in the future, there are still many technological and socio-economic challenges that must be overcome. Therefore, this paper aims to highlight the current status, technological advances, and economic challenges of bio-jet fuel production for energy transition in the aviation industry.

Bio-Jet Fuel from Vegetable Oils: Production Process and Perspective on Modeling and Simulation

Bio-Jet Fuel from Vegetable Oils: Production Process and Perspective on Modeling and Simulation

Efficient Self-Condensation of Cyclohexanone into Biojet Fuel Precursors over Sulfonic Acid-Modified Silicas: Insights on the Effect of Pore Size and Structure.

Mesoporous silica materials with different pore structures and sizes have been used for supporting aryl sulfonic acid catalytic sites via a postsynthetic grafting approach. The synthesized materials have been evaluated in the solventless acid-catalyzed self-condensation of cyclohexanone (CHO) to obtain the corresponding C12 adducts. These compounds display great potential as oxygenated fuel precursors as they can be transformed into jet fuel range alkanes in a subsequent hydrodeoxygenation process. In this work, the synthesized catalysts have displayed high selectivity values toward monocondensed compounds (>95%), thus limiting the formation of undesired heavier condensation products, together with CHO conversion values in the range 20-40% after 2 h of reaction at 100 °C. The structural and textural properties of the supports play an important role in the catalytic performance. Moreover, the activity per acid center is correlated with the textural properties of the supports, indicating that a lower surface density of the anchored aryl sulfonic groups affords an improvement in their specific activity. Finally, the benefit of using supports with large pore sizes and open structures, which limit the fouling of the catalysts by organic deposits, is demonstrated in a stability and reusability test.

Optimization of Aviation Biofuel Development as Sustainable Energy Through Simulation of System Dynamics Modeling

This study aims to optimize the development of aviation biofuel as a sustainable energy source by simulating system dynamics modeling. This study is based on the System Dynamics modeling approach, which is a set of conceptual tools designed to understand the structure and dynamics of complex systems. This study used the system dynamics method specifically designed to analyze complex systems. It has been applied to various sustainability-related issues, including urban area sustainable development modeling, sustainability of water resources, environmental management, and sustainable urbanization. The result obtained using the quantitative modeling showed that the contribution of aviation biofuel to flight intensity in Indonesia is still insignificant. The practical implications of this study are that palm oil has the potential to be a viable raw material for aviation biofuel production in Indonesia, and implementing policies to mitigate negative consequences and optimize land use for aviation biofuel fuel production can contribute to sustainable urban development. The originality of this study lies in its use of System Dynamics modeling to analyze the potential of palm oil as a raw material for aviation biofuel production and identify the various social, economic, environmental, and technological factors that impact it.

Technological Processes in the Production of Sustainable Aviation Fuels

Abstract Air transport expansion in recent decades has been continuous. The main aviation fuels used so far are mainly petroleum products, the annual consumption of which (2017) amounts to approximately 300 Mt. The gases emitted by the aviation industry (carbon dioxide CO2, nitrogen oxides, sulfur dioxide) exert a powerful pressure on the environment. The development of the aviation industry will also provoke a growing demand for fuels, and the fuels used will deepen the environmental, social and economic effects. This necessitates the implementation of the concept of sustainability of aviation transport and the replacement of conventional with sustainable aviation fuels (SAF). In the coming years, the production of aviation biofuels will increase as part of the use of renewable energy and the development of the circular economy-bioeconomy. This report briefly presents the current status of developed and deployed bioreactive fuels in aviation; certified technologies; the potential raw materials that can be used and an assessment of the economic and environmental characteristics of biokerosenes. The report also indicates global initiatives and policies to promote the use of biofuels, as well as the commitments made by the airlines.

Biofuels in Aviation: Exploring the Impact of Sustainable Aviation Fuels in Aircraft Engines

This comprehensive review examines the role of sustainable aviation fuels (SAFs) in promoting a more environmentally responsible aviation industry. This study explores various types of biofuels, including hydroprocessed esters and fatty acids (HEFAs), Fischer–Tropsch (FT) fuels, alcohol-to-jet (ATJ) fuels, and oil derived from algae. Technological advancements in production and processing have enabled SAF to offer significant reductions in greenhouse gas emissions and other pollutants, contributing to a cleaner environment and better air quality. The review addresses the environmental, economic, and technical benefits of SAF, as well as the challenges associated with their adoption. Lifecycle analyses are used to assess the net environmental benefits of SAF, with a focus on feedstock sustainability, energy efficiency, and potential impacts on biodiversity and land use. Challenges such as economic viability, scalability, and regulatory compliance are discussed, with emphasis on the need for supportive policies and international collaboration to ensure the long-term sustainability of SAF. This study also explores current applications of SAF in commercial airlines and military settings, highlighting successful case studies and regional differences driven by policy frameworks and government incentives. By promoting technological innovation and addressing regulatory and economic barriers, SAF has the potential to play a crucial role in the aviation industry’s transition toward sustainability.

Integrated catalytic approach for advanced biofuel production from renewable ABE fermentation

This study focuses on advancing the production of sustainable aviation biofuels by employing a one-pot integrated catalytic approach to convert Clostridium beijerinckii strain SR-44 ABE fermentation products into higher-value compounds, specifically ketones, using Pd/Ni@BNNS bimetallic catalysts. The influence of various parameters, such as salting-out agents, temperature, catalyst loading, and reaction time, significantly improved the ABE conversion to 98% with 86% higher ketone (C5–C11) selectivity. Furthermore, the heterogeneity and recyclability of the Pd/Ni @BNNSs catalyst were investigated, confirming its suitability for industrial-scale applications. By advancing biofuel synthesis technology and overcoming the drawbacks of conventional biofuels, this study contributes to the mitigation of the environmental and energy challenges facing the aviation industry.

Wastewater-grown microalgae biomass as a source of sustainable aviation fuel: Life cycle assessment comparing hydrothermal routes

The present paper compared, through life cycle assessment (LCA), the production of aviation biofuel from two hydrothermal routes of microalgae cultivated in wastewater. Hydrothermal liquefaction (HTL) and gasification followed by Fischer-Tropsch synthesis (G + FT) were compared. Both routes included biomass production, hydrotreatment for biofuel upgrading, and product fractionation. Secondary data obtained from the literature were used for the cradle-to-gate LCA. G + FT had a higher impact than HTL in the 18 impact categories assessed, with human carcinogenic toxicity exerting the most harmful pressure on the environment. The catalysts were the inputs that caused the most adverse emissions. The solvent used for bio-oil separation also stood out in terms of impacts. In HTL, emissions for global warming were −51.6 g CO2 eq/MJ, while in G + FT, they were 250 g CO2 eq/MJ. At the Endpoint level, HTL resulted in benefits to human health and ecosystems, while G + FT caused environmental damage in these two categories, as well as in the resources category. In the improvement scenarios, besides considering solid, aqueous, and gaseous products as co-products rather than just as waste/emissions, a 20% reduction in catalyst consumption and 90% recovery were applied. Thus, in HTL, 39.47 kg CO2 eq was avoided, compared to 35.44 kg CO2 eq in the base scenario. In G + FT, emissions decreased from 147.55 kg CO2 eq to the capture of 8.60 kg CO2 eq.

Arginine Acts as both Co-Solvent and Catalyst in Regioselective Eutectic-Mediated Dimerization of Levulinic Acid.

A simple, solvent-free arginine-catalyzed aldol dimerization of levulinic acid was achieved via the simultaneous formation of a eutectic mixture. Dimers of levulinic acid are valued as biomass-derived fine chemical precursors, with potential to upgrade to bio-jet fuels or N-containing functional chemicals. Typically, these dimers are produced as isomeric mixtures using high temperatures and a variety of solid inorganic catalysts or mineral acids. In this study, an organocatalytic and regioselective dimerization was achieved at 22 % conversion on either a bench or kilogram scale using mild temperatures and only L-arginine as both a co-solvent and catalyst. The intricate H-bonding network comprising the eutectic solvent was harnessed to produce only one product, minimizing side reactivity and preserving the reactants for recycling.