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Sustainable aviation biofuels
... This fuel is in the ASTM International process for approval. A jet engine test flight was successfully completed using Virent SAK in 2016 [49]. Percent weight values of the six key components in Virent SAK are also shown in Table 4, as well as the values for the 50:50 blend of the two fuels. ...
An array physiologically-based pharmacokinetic (PBPK) model represents a streamlined method to simultaneously quantify dosimetry of multiple compounds. To predict internal dosimetry of jet fuel components simultaneously, an array PBPK model was coded to simulate inhalation exposures to one or more selected compounds: toluene, ethylbenzene, xylenes, n-nonane, n-decane, and naphthalene. The model structure accounts for metabolism of compounds in the lung and liver, as well as kinetics of each compound in multiple tissues, including the cochlea and brain regions associated with auditory signaling (brainstem and temporal lobe). The model can accommodate either diffusion-limited or flow-limited kinetics (or a combination), allowing the same structure to be utilized for compounds with different characteristics. The resulting model satisfactorily simulated blood concentration and tissue dosimetry data from multiple published single chemical rat studies. The model was then utilized to predict tissue kinetics for the jet fuel hearing loss study (JTEH A, 25:1-14). The model was also used to predict rat kinetic comparisons between hypothetical exposures to JP-8 or a Virent Synthesized Aromatic Kerosene (SAK):JP-8 50:50 blend at the occupational exposure limit (200 mg/m3). The array model has proven useful for comparing potential tissue burdens resulting from complex mixture exposures.
e agro waste briquettes produced from sorghum panicle and pearl millet with corn starch as the binder with varied proportions were compared with the other agro briquettes, and the elemental analysis of SP-PM briquettes was compared with the agro waste, palm kernel shell, soybean waste, mango leaves, rice husk, spruce, and co ee husk briquettes. e TGA results of SP-PM briquettes were compared with the corn leaf, baggase, almond shell, banana leaves, banana pseudostem, pineapple leaf, stem and root, low rank coal, bituminous coal, cotton stalk, and wheat straw. e DSC analysis that was carried out for SP-PM briquettes were compared with the rice husk char, spent co ee ground, wood chips, saw dust, wood straw, Tomsk peat, Sukhovskoy peat, Arkadievsky peat, nutshell, and bran. us, the briquettes made out of sorghum panicle and pearl millets are compared with the other biomass briquettes for its e ciency and its quality. us, the briquettes made out of sorghum panicle and pearl millets are compared with the other biomass briquettes for its e ciency and its quality.
As the push for carbon-neutral transport continues, the aviation sector is facing increasing pressure to reduce its carbon footprint. Furthermore, commercial air traffic is expected to resume the continuous growth experienced until the pandemic, highlighting the need for reduced emissions. The use of alternative fuels plays a key role in achieving future emission goals, while also lowering the dependency on fossil fuels. The so-called sustainable aviation fuels (SAF), which encompass bio and synthetic fuels, are currently the most viable option, but hydrogen is also being considered as a long-term solution. The present paper reviews the production methods, logistical and technological barriers, and potential for future mass implementation of these alternative fuels. In general, biofuels currently present higher technological readiness levels than other alternatives. Sustainable mass production faces critical feedstock-related challenges that synthetic fuels, together with other solutions, can overcome. All conventional fuel replacements, though with different scopes, will be important in meeting long-term goals. Government support will play an important role in accelerating and facilitating the transition towards sustainable aviation.
Over the coming years, the world is projected to witness an upsurge in “drop-in” aviation biofuel production as part of the renewable energy and bioeconomy developments. This paper presents a comprehensive review of the current status of biojet fuel development and uptake in global commercial aviation industry, including state-of-the-art certified technologies (i.e. Fischer-Tropsch (FT); hydroprocessed esters and fatty acids (HEFA); alcohol-to-jet (ATJ); and hydroprocessing of fermented sugars (HFS)); potential feedstock that can be deployed; a comparison of techno-economic and environmental performances of biojet fuel production routes; airlines’ commitment in promoting higher biofuel uptake; and global initiatives and policies. This review shows that the HEFA route using oil-based crops is best performing in terms of lowest production cost and greenhouse gas emissions, however it is in competition with the existing road transport biofuel market. Lignocellulosic biomass and waste feedstock should be promoted in view of replacing food/feed crops which have high indirect land use change emissions. Therefore, further improvement should be focused on FT, ATJ and HFS routes to enhance the cost effectiveness of biojet fuel production and promote commercialisation of these technologies. The selection of feedstock and technologies for SAF production should be justified based on production cost and environmental footprint, while avoiding competition with the existing road transport biofuel market. The shortcomings in the SAF policies such as blending mandate and multiplier in RED II should be addressed to reduce the negative impacts of feedstock competition between the road and aviation biofuel sectors and to meet the decarbonisation targets.
Sustainable aviation fuels (SAFs) are expected to play an essential role in achieving the aviation industries’ goal of carbon-neutral growth. However, producing biomass-based SAFs may induce changes in global land use and the associated carbon stock. The induced land use change (ILUC) emissions, as a part of the full life-cycle emissions for SAF pathways, will affect whether and to what extent SAFs reduce emissions compared with petroleum-based jet fuels. Here, we estimate the ILUC emission intensity for seventeen SAF pathways considered by the International Civil Aviation Organization (ICAO), covering five ASTM-certified technologies, nine biomass-based feedstocks, and four geographical regions. We introduce the SAF pathways into a well-established computable general equilibrium (CGE) model, GTAP-BIO, and its coupled emission accounting model, AEZ-EF, to study economy-wide implications of SAF production and estimate ILUC emissions intensity for each pathway. The estimated SAF ILUC emission intensities, using a 25-year amortization period, range from -58.5 g CO2e MJ⁻¹ for the USA miscanthus alcohol (isobutanol)-to-jet (ATJ) pathway to 34.6 g CO2e MJ⁻¹ for the Malaysia & Indonesia palm oil Hydrotreated Esters of Fatty Acids (HEFA) pathway. Notably, the vegetable oil pathways tend to have higher ILUC emission intensities due to their linkage to palm expansion and peatland oxidation in Southeast Asia. The cellulosic pathways studied provide negative ILUC emissions, mainly driven by the high carbon sequestrations in crop biomass and soil. Using the core life-cycle emissions established by ICAO, we show that fifteen of the assessed pathways have a lower full life-cycle emission intensity than petroleum-based jet fuels (89 g CO2e MJ⁻¹), offering promising options to reduce aviation emissions.
Advanced biofuels are among the available options to decarbonise transport in the short to medium term especially for aviation, marine and heavy-duty vehicles that lack immediate alternatives. Their production and market uptake, however, is still very low due to several challenges arising across their value chain. So far policy has established targets and monitoring frameworks for low carbon fuels and improved engine erformance but has not yet been sufficient to facilitate their effective market uptake. Their market roll-out must be immediate if the 2030 targets are to be met. Analysis in this paper reiterates that the future deployment of these fuels, in market shares that can lead to the desired decarbonisation levels, still depends largely on the integration of tailored policy interventions that can overcome challenges and improve upstream and downstream performance.
The work presented aims to i) inform on policy relevant challenges that restrict the flexible, reliable and costefficient market uptake of sustainable advanced biofuels for transport, and ii) highlight policy interventions that, have strong potential to overcome the challenges and are relevant to current policy, Green Deal and the Sustainable Development Goals (SDGs).
The present contribution deals with a comprehensive analysis of the available feedstocks and the appropriate technologies to produce advanced biofuels. The analysis is focused on the EU countries, since they adopted policy measures able to promote advanced biofuels as a strategic solution for a competitive and sustainable transport sector. In this regard, four classes of feedstocks have been taken into account: wastes, vegetable oils, agricultural and forestry residues. Their availability is studied with the aim to respect the European targets in terms of emissions without neglecting possible negative impacts on environment and biodiversity. A metric for the classification of the different solutions is proposed on the basis of feedstocks availability, technology readiness levels (TRL), quality of the produced biofuel as well as feedstock and production costs. It is possible to conclude that, even if the several interesting alternatives currently available have a high ranking in the proposed metric and must be taken in consideration, green diesel is today the most convenient solution for producing advanced biofuel without risks of technological failures and feedstocks shortage. This analysis can provide insights to encourage the development of advanced biofuels in EU, especially for some of the Member States as Germany, France and Italy.
Background
Biomass fuels (bio-jet fuel) have recently attracted considerable attention as alternatives to conventional jet fuel. They have become the focus of aircraft manufacturers, engines, oil companies, governments and researchers alike. This study is concerned with the production of biojet fuel using waste cooking oil (WCO). Batch reactor is used for running the experimental study. The catalytic cracking products are investigated by GC mass spectra. Final products from different reaction conditions are subjected to fractional distillation. The (Bio kerosene) fraction was compared with the conventional jet A-1 and showed that it met the basic jet fuel specifications. Optimum reaction conditions are obtained at (450 °C), pressure of (120 bars), catalyst dose (2.5% w/v), reaction time (60 min) and hydrogen pressure 4 atmosphere. The aim of this study is to produce bio aviation fuel according to specifications and with a low freezing point from waste cooking oil in one step using a laboratory prepared catalyst and with a low percentage of hydrogen to complete the process of cracking and deoxygenation in one reactor, which is naturally reflected positively on the price of the final product of bio aviation fuel.
Results
The results indicated that the product obtained from WCO shows promising potential bio aviation fuels, having a low freezing point (− 55 °C) and that all bio kerosene’s specifications obtained at these conditions follow the international standard specifications of aviation turbine fuel.
Conclusion
Biojet fuel obtained from WCO has fairly acceptable physico-chemical properties compared to those of petroleum-based fuel. Adjustment of the hydro catalytic cracking reaction conditions was used to control quantities and characteristics of produced bio aviation fuel. Taking into consideration the economic evaluation WCO is preferable as raw material for bio aviation fuel production due to its low cost and its contribution in environmental pollution abatement. Blend of 5% bio aviation with jet A-1 (by volume) can be used in the engine without any modifications and a successful test of blended aviation fuel with 10% bio aviation has been achieved on Jet-Cat 80/120 engine.
The present work concerns the conversion of coconut oil into hydrocarbons within the chain length range of jet biofuel through the pathway called hydroprocessing of esters and fatty acids (HEFA). The aim is to employ the resulting mixture as an alternative biofuel in the aviation sector. The process involved two steps: (i) hydrodeoxygenation (HDO) over a sulfided NiMo/Al 2 O 3 catalyst, followed by (ii) hydroisomerization (HIS) over a Pt/SAPO-11 catalyst. Preliminary tests were carried out with model compounds: lauric acid and n-dodecane for HDO and HIS, respectively. In both steps, middle processing temperatures (~340-350°C) were low enough to prevent excessive cracking but high enough to provide acceptable reaction rates and to prevent coke formation. The HDO step rendered a mixture constituted basically by n-alkanes. The subsequent HIS permitted to increase the content of branched chains. The final HEFA-SPK (where SPK is the abbreviation for synthetic paraffinic kerosene) had an acidic index zero and a relatively high content of monomethylalkanes. Furthermore, due to the fatty chain composition of the starting oil, the chain length distribution of the resulting biofuel matched well with that of conventional jet fuels, so that subsequent steps of cracking and fractionation, which increase costs and reduce the process yield, were not required. The obtained results are encouraging in terms of using coconut oil-based HEFA-SPK in the formulation of sustainable alternative jet fuels at competitive costs and with relevant environmental and social benefits.
Over 2500 airports worldwide provide critical infrastructure that supports 4 billion annual passengers. To meet changes in capacity and post-COVID-19 passenger processing, airport infrastructure such as terminal buildings, airfields, and ground service equipment require substantial upgrades. Aviation accounts for 2.5% of global greenhouse gas (GHG) emissions, but that estimate excludes airport construction and operation. Metrics that assess an airport’s sustainability, in addition to environmental impacts that are sometimes unaccounted for (e.g. water consumption), are necessary for a more complete environmental accounting of the entire aviation sector.
This review synthesizes the current state of environmental sustainability metrics and methods (e.g. life-cycle assessment, Scope GHG emissions) for airports as identified in 108 peer-reviewed journal articles and technical reports. Articles are grouped according to six
categories (Energy and Atmosphere, Comfort and Health, Water and Wastewater, Site and Habitat, Material and Resources, Multidimensional) of an existing airport sustainability assessment framework.
A case study application of the framework is evaluated for its efficacy in yielding performance objectives. Research interest in airport environmental sustainability is steadily increasing, but there is ample need for more systematic assessment that accounts for a variety of emissions and regional variation. Prominent research themes include analyzing the GHG emissions from airfield pavements and energy management strategies for airport buildings. Research on water conservation, climate change resilience, and waste management is more limited, indicating that airport environmental accounting requires more analysis. A disconnect exists between research efforts and practices implemented by airports. Effective practices such as sourcing low-emission electricity and electrifying ground transportation and gate equipment can in the short term aid airports in moving towards sustainability goals. Future research must emphasize stakeholder involvement, life-cycle assessment, linking environmental impacts with operational outcomes, and global challenges (e.g. resilience, climate change adaptation, mitigation of infectious diseases).
Production of green fuels and chemicals from non-edible corn cob residues presents an excellent opportunity to produce sustainable low carbon energy vectors as an alternative to fossil fuels. The objective of this study was to optimize the fuel physical and chemical properties of torrefied corn cobs bio-oil by investigating the relationship between feedstock pre-treatment (torrefaction) temperatures (240, 260, 280 and 300 °C), and subsequent pyrolysis temperatures (400, 450, 500 and 550 °C). This experimental methodology aimed to improve both yields and properties of bio-oils from corn cobs. Torrefaction was first carried out as a pre-treatment step using a custom-built torrefaction reactor followed by pyrolysis using a continuous fluidized bed reactor. Torrefaction was found to be a promising pre-treatment step because it had the effect of reducing the water content and viscosity within the bio-oil. Corn cobs grinding energy requirements could be reduced by 69% when torrefaction was applied from 240 °C to 260 °C. A maximum bio-oil yield of 51.7% was achieved when the optimal temperatures (torrefaction 260 °C and pyrolysis 450 °C) was applied. Overall, using torrefaction as a pre-treatment step before pyrolysis was shown to be a promising approach for improving some physiochemical properties of bio-oil for its application as a fuel.
The undeniable environmental ramifications of continued dependence on oil-derived jet fuel have spurred international efforts in the aviation sector toward alternative solutions. Due to the limited options for decarbonization, the successful implementation of bio-aviation fuel is crucial in contributing to the roster of greenhouse gas emissions mitigation strategies for the aviation sector. Since fleet replacement with low-carbon technologies may not be a feasible option, due to the long lifetime and significant capital cost of aircraft, “drop-in” alternatives, which can be used in the engines of existing aircraft in a seamless transition, may be required. This paper presents a detailed analysis of the supply chain components of bio-aviation fuel provision: feedstocks, production pathways, storage, and transport. The economic and environmental performance of different potential bio-feedstocks and technologies are investigated and compared in order to make recommendations on short- and long-term strategies that could be employed internationally. Hydroprocessed esters and fatty acids production pathway, utilizing second-generation oil-seed crops and waste oils, could be an effective immediate solution with the potential for substantial greenhouse gas emissions savings. Microalgal oil could potentially offer far greater yields of bio-aviation fuel and reductions in greenhouse gas emissions, but the technology for large-scale algae cultivation is inadequately mature at present. Fischer-Tropsch production pathway using lignocellulosic biomass has the potential for the highest greenhouse gas emissions savings, which could potentially be the solution within the medium- to long-term plans of the aviation industry, but further research and optimization are required prior to its large-scale implementation due to its limited technological maturity and high capital costs. In practice, the “ideal” feedstocks and technologies of the supply chains are heavily dependent on spatial and temporal criteria. Moreover, many of the parameters investigated are interlinked to each other and the measures that are effective in greenhouse gases emissions reduction are largely associated with increased cost. Hence, policies must be streamlined across the supply chain components that could help in the cost-effective and sustainable deployment of bio-aviation fuel.
The utilization of bio-oil could be an attractive option in the future, attributed to its high bulk energy density and ease of transportation. However, the primary challenge in promoting the commercialization of technologies using bio-oil is high capital investment and operating costs. The key to resolve this challenge is to maximize the value of products that can be extracted from bio-oil through realizing a flexible, multiple product generation and integrated system configuration, known as polygeneration system. In this study, an integrated bio-oil steam reforming and hydrodeoxygenation (BOSR-HDO) system, with simultaneous production of hydrogen, chemicals, heat, and power, is proposed. A systematic design framework was adopted in the present case for maximizing resource utilization and hence the economic potential of the system. The system has shown a positive economic potential (i.e., £120 million/year) at a bio-oil cost of £166/t. On the other hand, the netback of bio-oil, i.e., the maximum acceptable market price, was determined to be £301.9/t (£19.4/GJ). The study has also demonstrated that the adoption of heat integration strategy could improve the economic potential of the BOSR-HDO system by 24.6% (i.e., £29 million/year). Furthermore, the study has recommended that the utilization of excess hydrogen in the HDO process should be limited below a hydrogen-to-oil ratio of 4.3 for an economically viable processing.
Aviation fuel demand is expected to continue to grow over the next decades and continue to rely heavily on kerosene fuel for use in jet engines. While efficiency and operational improvements are possible ways to reduce GHG emissions, decarbonisation will need to heavily rely on low carbon kerosene drop-in alternatives. Currently, alternative fuels make up a very small share of fuel used in aviation, but their commercialisation is making good progress. Hydrogen offers a longer term alternative fuel option but requires aircraft design and fuelling infrastructure changes. Electrification is emerging as an option for providing propulsion in aircraft, either in pure form in small aircraft or in hybrid mode in larger aircraft. This paper reviews the status, challenges and prospects of alternative fuels and electrification in aviation.
Aquatic ecosystems are the ultimate sinks for the contaminants. Water contamination is the outcome of human activities such as urbanization, industrialization, and agricultural activities. The overuse of pesticides and fertilizers and sewage from residential and industrial areas ultimately find its way to aquatic environment. Thus results in the degradation of the water quality and leads to the spread of infectious diseases such as dysentery, diarrhea, and jaundice. Contamination in aquatic environs is one of the leading types of pollution which has significant negative health issues and mortality. Water has a natural capacity to neutralize the contamination, but when contamination becomes uncontrolled, water will lose its self-generating capacity. Therefore, there is a need for regular monitoring and controlling of pollutant discharge into the nearby aquatic environs.
Aviation industry has the challenge of halving CO2 emissions by 2050, as compared to 2005. An alternative are drop-in biofuels, which are sustainable and fully compatible with aircraft engines and also can be mixed with fossil jet fuel. Among the feedstock for biojet fuel production, licuri (Syagrus coronata) can be highlighted as most of its fatty acids are in the jet fuel range. Thereby, this work investigated the composition and physicochemical characterization of licuri oil and licuri biodiesel, both with satisfactory results according to international standards, with the purpose of obtaining hydrocarbons in the range of jet fuel from these feedstock, by catalytic deoxygenation. The semi-batch reaction, using a 5% Pd/C catalyst at 300 °C and 207 psi, produced n-alkanes with a conversion of up to 39.2%. The n-alkane selectivity was 80.7%, in addition to CO2 selectivity of 83.4% for biodiesel, indicating the preference for the decarboxylation pathway and also confirming licuri as a potential raw material for biojet fuel.
This paper assesses the biojet fuel production potential in Brazil. It evaluates feedstock availability by applying a georeferencing analysis, and determines the cost‐effectiveness and greenhouse gas (GHG) emissions of selected production routes throughout their entire life cycle. This study identifies and locates Brazilian hotspots in terms of bioenergy availability and proximity to the main sites of fuel consumption and handling in the country. Findings show that the biomass availability for each crop in the hotspots would be sufficient to feed the biojet conversion plants proposed in this study. The biojet production potential in the hotspots would represent 48% of the country's jet fuel consumption in 2014, allowing the current certificated 50% blend with conventional fuel. The major biomass hotspots are close to airport and fuel logistic basis. However, even with a US$ 200.tCO–1 2 tax, hydroprocessed esters and fatty acids (HEFA) biojet is far from being competitive with petroleum‐based jet fuel, whereas the Fischer–Tropsch synthetic paraffinic kerosene (FT‐SPK) route may produce a competitive biojet. One possible pathway to incentivize biojet fuel production in Brazil would be, first, to implement carbon taxes that would allow the development of smaller plants. Then, with technological learning and larger production scales, it would be possible to reduce or even eliminate the carbon taxes. © 2019 Society of Chemical Industry and John Wiley & Sons, Ltd.
The production of fuel from the hydrodeoxygenation of vegetable oils has been extensively investigated on account of the decline of petroleum-based fuels and increase of ecological problems. The conversion of jatropha oil over Al-MCM-41-supported Ni, W, and Ni–W catalysts was studied at 3 MPa and 360 °C. Over the monometallic Ni and W catalysts, the biofuel yield was low, about 19.3 and 12.5 wt %, respectively, whereas the highest biofuel yield reached 63.5 wt % over the Ni–W bimetallic catalysts. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and high-resolution TEM results suggested that the proper amount of Ni and W would form a Ni17W3 active phase, the particle size of which varied with the content of Ni and W or preparation methods. The crystalline Ni17W3 phase formed when the content of both Ni and W reached 10%. With further increase of the content of W or Ni to 15%, the crystal size of Ni17W3 grew from 7 to 14 nm or to 20 nm, whereas the biofuel yield decreased with the increase of the Ni17W3 crystal size. The 10Ni–10W/Al-MCM-41 catalyst with the Ni17W3 crystal size of 7 nm showed the best performance for the transformation of jatropha oil into high-grade biofuel.
Cellulases are the enzymes decaying cellulose and related polysaccharides and are produced by organisms like fungi, bacteria, algae, and protozoans. Fungi are the pioneers behind cellulose degradation, and the fungal cellulases are simpler compared to the bacterial cellulase. Increased usage of fossil fuels causes catastrophic destruction to the environment and the health of the population worldwide, which calls for exploring new avenues of fuel generation to save the environment from CO2 emission. Biofuels from fungi are extensively explored, and among the diverse fungal biofuels, fungal cellulase-based biofuels seem to be a promising option. Besides the production of bioethanol, fungal cellulases are widely envisaged in paper and pulp industry, textile industry, food industry, brewery industry, and agriculture sector. An elaborate work on fungal cellulase is indeed needed for their rapid utilization as biofuel sources. Advancements in the fungal cellulase technology and the yield enhancements will make way for establishing the biofuel production as a sustainable solution to the prevalent energy crisis and the associated environmental pollution issues worldwide.
Fossil fuels have solved our energy problems since the beginning of the industrial revolution that started in the eighteenth century. However, from past few decades, the world has seen an unprecedented and uncontrolled use of fossil fuels. In the current era, we heavily rely on fossil fuels for energy demands. It is undeniably true that fossil fuels hold the credit of shaping our world, but on the cost of environmental and related hazards. The negative environmental impacts of fossil usage are now being realized, and the search for alternative energy sources has begun. Bioenergy crops are one such energy source that could positively impact the environment to reduce the level of carbon dioxide, emission of greenhouse gases and soil erosion. The biofuel generation using fast growing and photosynthetically efficient bioenergy crops is emerging as a reliable alternative to fossil fuels. Bioenergy plants increase soil carbon and fix atmospheric carbon. In addition, bioenergy crops (miscanthus, sorghum and poplar) could also be used for the phytoremediation of heavy metal-contaminated soils. The bioenergy crops include specific plants that are grown and maintained at lower costs for biofuel production. The bioenergy crops are classified into five types namely, first-, second- and third-generation bioenergy crops, dedicated energy crops and halophytes. The first-generation bioenergy crops include corn, sorghum, rapeseed and sugarcane, whereas the second-generation bioenergy crops are comprised of switchgrass, miscanthus, alfalfa, reed canary grass, Napier grass and other plants. The third-generation bioenergy crops contain boreal plants, crassulacean acid metabolism (CAM) plants, eucalyptus and microalgae. Bioenergy halophytes are comprised of the genera Acacia, Eucalyptus, Casuarina, Melaleuca, Prosopis, Rhizophora and Tamarix. The dedicated energy crops include perennial herbaceous and woody plant species as giant miscanthus, switchgrass, jatropha and algae.
Aviation is steadily growing worldwide as well as in the European Union (EU). Overall, EU transports increased their GreenHouse Gas (GHG) Emissions since 1990, while the other energy sectors succeeded in achieving a constant reduction over the same period. In this context, air transport is the most critical area to decarbonize, given the limited number of options that can be implemented, such as optimization of flight routes, increase of jet engine energy efficiency, and few others. Switching to renewable or low carbon fuels is thus the main opportunity for aviation. Large scale deployment of Sustainable Aviation Fuels (SAF) is however a real challenge, as it requires large investments in new production facilities, strong reduction in production costs (over the entire value chain, i.e. including feedstock production, collection and delivery), and considerable investments in ASTM certification. The present work shortly reviews the perspectives of aviation fuel in terms of demand and GHG emission trends, possible routes to jet fuel production, and the status of ASTM certified routes to jet fuel as of today.
According to Energy outlook 2020, the aviation fuel consumption is expected to increase 13% by year 2050, as compared to year 2019. Increased cost of petroleum fuels and growing environmental concerns have made the aviationAviation biofuels industry to include biofuel as a possible fuel source. Non-edible oils, energy crops and algae are the common feedstock for jet fuel production. There are several biomasses-to-jet fuel conversionBiomass-to-jet fuel conversion pathways such as lipid hydro-processing, Fischer–Tropsch synthesisFischer-Tropsch synthesis (F-T), alcohol-to-jet fuel, pyrolysis processPyrolysis process, hydrothermal liquefactionHydroThermal Liquefaction (HTL) and blending of fatty acid methyl esterFatty Acid Methyl Ester (FAME). However, the sustainable production of jet biofuel is still under research. This chapter discusses the opportunities and challenges of these technologies from sustainable development perspective.
Lignocellulosic agricultural wastes are the most widely utilized resource for bioethanol production due to several advantages. Removal of hemicellulose and lignin is a prerequired step during bioethanol production from lignocellulosic biomass to upgrade cellulose recovery and the substrate porosity for saccharification. Chemical pretreatment of corncob was performed in the current research applying binary acids (H2SO4 + CH3COOH) in different ratios. The attained maximum removal of lignin and hemicellulose were 81.41 ± 2.3% and 85.6 ± 1.8%, respectively, with enhanced cellulose recovery of 93.5 ± 1.3% at the optimum conditions of binary acids concentration (3%, v/v), biomass loading ratio (0.1 g/mL), pretreatment temperature (120 °C) and time (60 min). The SEM, FTIR and XRD results revealed the removal of hemicelluloses and lignin from the corncob biomass by binary acids pretreatment and confirmed a change in the crystallinity index of corncob biomass. Ethanol fermentation was accomplished at 30 °C at 200 rpm for 4 days with the hydrolysates using Saccharomyces cerevisiae and obtained a maximum bioethanol concentration of 24.6 mg/mL. This study demonstrates that binary acids pretreatment is an alternative approach for the pretreatment of lignocellulosic biomass. The optimized process conditions could also increase cellulose recovery and bioethanol yield.
Bioethanol can be produced by cellulolytic and ethanogenic bacterial species could efficiently degrade lignocelluloses and have potential for biofuels production through consolidated bioprocessing (CBP). In this study, on-site cellulase production followed by saccharification and fermentation of pre-treated Allium ascalonicum leaves to bioethanol in a single reactor using Hangateiclostridium thermocellum KSMK1203 and consortium of Cellulomonas fimi MTCC 24 and Zymomonas mobilis MTCC 92. A. ascalonicum leaf pre-treatment with different alkalis and different pre-treatment conditions such as alkali dosage and time for proficient removal of hemicellulose and cellulose recovery was optimized using RSM method with the maximum hemicellulose removal of 85.25%. The essential medium components were screened through PBD and further optimized using RSM method for H. thermocellum KSMK1203 and the consortium for maximized bioethanol yield. Hence, this study proposed that wild-type H. thermocellum KSMK1203 strain and consortium could be used for cellulase secretion and simultaneous bioethanol conversion.
Actual agricultural practices produce about 998 million tonnes of agricultural waste per year. Therefore, converting lignocellulosic wastes into energy, chemicals, and other products is a major goal for the future circular economy. The major challenge of lignocellulosic biorefineries is to transform individual components of lignocellulosic biomass into valuable products. Here we review lignocellulosic biomasses such as coffee husk, wheat straw, rice straw, corn cob, and banana pseudostem. We present pretreatment technologies such as milling, microwave irradiation, acidic, alkaline, ionic liquid, organosolv, ozonolysis, steam explosion, ammonia fiber explosion, and CO2 explosion methods. These methods convert biomass into monomers and polymers. For that, the concoction pretreatment methods appear promising.
As the population is increasing at a rapid pace, we now find ourselves in a position where cities are using a growing amount of renewable energy. Renewable energy is the key to help avert climate change and this approach must be sustainable. At the juncture, this review analyses the potential of wind, biomass and hybrid systems in the field of renewable energy production. Initially, the manuscript addressed the feedstocks and their potential for different biofuels such as bioethanol, biodiesel, biomethane, biohydrogen and biohythane from the biomass. With a focus on long-term energy sustainability, this article investigates performance analysis and sustainability of wind energy systems and biomass-based hybrid configurations with wind and its various design factors, problems, and gaps were examined. According to the findings, biomass-based hybrid energy systems can provide a cost-effective and environmentally beneficial alternative, particularly for off-grid rural electrification. The study provides designers, academicians, and policymakers with vital information on the most recent design restrictions and other factors related to biomass-wind hybrid energy systems.
Bio-jet fuels have great potentials in decreasing the reliance on fossil-based jet fuels and decrease CO2 discharges. The International Air Transport Association (IATA) reported with the aim of bio-jet fuels created by that using sustainable sources like biomass to produce bio-jet fuels is a promising strategy to develop and industrialize an alternative aviation fuel to encounter the sustainable growth in the aviation sector. Bio-jet fuels chemical compositions have a significant impact on their performance characteristics. The main performance characteristics of bio-jet fuel performance characteristics include are thermal oxidation Stability of Thermal thermal oxidation, the bio-based jet fuels compatibility with the current system of aviation, low-temperature fluidity, combustion characteristics, fuel metering, and fuel volatility are the bio-jet fuel performance characteristics. Bio-jet fuels These characteristics have been evaluated by the ASTM standards. The conversion technologies of bio-based feed stock can be classified by alcohol to jet (ATJ) alcohol to jet, sugar to jet (STJ), oil to jet (OTJ), and gas to jet (GTJ). Hydrogenated esters and fatty acids Fatty acids (HEFA), Hydrogenated esters, and catalytic hydro- thermolysis (CH) are the common pathways for bio-jet fuel production. The impact of bio-jet fuels delivered from different feedstock, including algae, on jet engine performance was the focus of the researcher by numerical modeling and virtual simulation. Researchers found that the thermodynamic behavior, fuel consumption level of the aircraft and emissions characteristics have been improved by using Biobio-jet fuel as compared with the conventional Jet-A fuel. The mean focus of the current chapter is to summaries summarize the most available study studies of the algae-based bio-jet fuels conversion technologies, characteristics, performance, and process simulation.
This chapter provides perspective on “Bioresources and Biofuels” based on three platforms of bioresource feedstock, i.e., amorphous sugar, lipid, and lignocellulosics. A comprehensive scheme of various possibilities of biofuel production in the three platforms of feedstock that are already commercialized or under development is proposed. At present, only lipid platform dominates the production of “drop-in” biofuel in large volume. However, a coming electric vehicle revolution, disruptive technology, could be a threat to biofuel industries either electricity is produced from renewable energy or having carbon capture and sequestration (CCS) or not. Different alleviation approaches are discussed, for examples (1) shifting from ethanol to “Alcohol to jet, AtJ” or “Direct sugar to hydrocarbon, DSHC” in the amorphous sugar platform; (2) shifting from biodiesel or even bio-hydrotreated diesel (BHD) (also called Hydrogenated Esters and Fatty Acids, HEFA) to HEFA—Synthetic Paraffinic Kerosene (HEFA-SPK) in the lipid platform; and (3) shifting from Fischer-Tropsch (FT) to FT-Synthetic Paraffinic Kerosene (FT-SPK) and FT-SPK with Aromatics (FT-SPK/A) in the lignocellulosic biomass platform. Another interesting choice is on biofuel allocation to produce hydrogen and hydrogen carrier fuel for state-of-the-art fuel cell vehicle application. Last but not least, by using biorefinery concept, lipid/oleochemical biorefinery is specially emphasized and some current typical technologies such as fatty acid methyl ester biodiesel as well as coproduct glycerol should be shifted to more valuable oleochemicals are also mentioned in this chapter. Obviously, economic viability for biofuels and oleochemicals production is still a challenge today. Process intensification which aims to improve process performance substantially (with respect to equipment size, time, energy, etc.) is encouraged and illustrated as an example along the chapter.
Microalgal biomass produced from the inexpensive nutrient medium is a potential raw source for manufacturing different essential products covering a broad spectrum of applications. In this study, six separate microalgal strains were isolated from lake freshwater and screened based on their growth and biomass productivity in 10% raw dairy wastewater (DWW). Statistically optimized growth parameters of microalga using CCD-RSM were light intensity 65 μE m⁻²s⁻¹, pH 7, temperature 35 °C and agitation 150 rpm with maximum dry biomass yield 16.35 ± 0.34 g/L in ultrasonic pre-treated DWW (UPDWW) (75%, v/v). The physicochemical properties of 75% UPDWW were observed pre- and post-algal cultivation and found 94.8% COD removal, indicating the strain's potential phycoremediation. At optimal conditions, hydrolysate of C. sorokiniana NITTS3 biomass yielded 13.67 g/L of bioethanol using selected yeast. The findings of this investigation suggest that C. sorokiniana NITTS3 isolated from freshwater could effectively be used for phycoremediation of DWW with concomitant biomass production as an appropriate feedstock for bioethanol production.
The Brazilian aviation sector aiming to reduce its greenhouse emissions up to 37% by 2030 and up to 43% by 2050 (compared to 2005) using alternative fuels. For this reason, the evaluation of potential feedstock was made for the biojet fuel production focused in the Brazilian context. Four biomass types were proposed (Sugarcane, Jatropha, Soybeans and Eucalyptus), considering three factors: feedstock abundance (without negative impact in population foods), advances in conversion technology, and blend limit already approved by the ASTM International for the use of biojet fuels into fossil jet fuel. Based on this study, it is concluded that Brazil has a great number of available lands for the culture of feedstock from which aviation alternative fuel can be produced, with possible substitution of up to 10% vol. Of fossil jet fuel consumed in the country. However, conversion technologies are still a challenge. Only, Synthetic Paraffinic Kerosene (SPK) obtained by both Fischer Tropsch (FT) process and Alcohol to Jet (ATJ) process offer competitive prices compared to petroleum-based jet fuel. Considering sugarcane as the main feedstock, a self-sustained integrated process was evaluated aiming to increase the production performance of biojet fuel. Four biojet fuels were obtained by this process (ATJ – SPK, FT – SPK, Farnesane and Hexanol), allowing the reduction of up to 19.16% in the number of cultivated lands for sugarcane and up to 56.12% for its forest residues. Finally, the payload versus range ratio was described using the Breguet range equation applied to a possible commercial flight, taking into account all biojet fuels produced from the proposed feedstock including their blends.
Aviation sector discharges approximately 2% of the global anthropogenic CO 2, and the proportion is growing. The search for cost-effective and environmental-friendly bio-jet fuels derived from natural resources is gaining momentum. The microalgae cultivation conditions including temperature, pH, light intensity and nutrients have shown significant influence on the microalgae growth rate and chemical composition, which create the opportunities to enhance the yield and quality of microalgae bio-jet fuel. This review is focused on the hydroprocessing method for converting microalgae oil into bio-jet fuel, as well as the novel conceptual approaches for bio-jet fuel production such as gasification with Fischer-Tropsch and sugar-to-jet. Fischer-Tropsch synthesis of biomass is one of the best alternative ways to replace natural aviation fuel due to the high maximum energy efficiency and low emission of greenhouse gas. In addition, hydroprocessing with the aid of Ni and zeolites catalysts has successfully converted the microalgae biodiesel to bio-jet fuel with high yield and alkane selectivity. Among these techniques, hydroprocessing used the lowest production cost with the longest duration, whereas the bio-jet fuel with high selectivity (C 8-C 16) could be produced by using gasification with the Fischer-Tropsch process. Consequently, gasification and Fischer-Tropsch and sugar-to-jet can become the future alternative process to convert microalgae to bio-jet fuel. The development of microalgae bio-jet fuel will increase the security of energy supply and reduce the fuel expenses in aviation industry.
Sugarcane is the base of a successful agroindustrial system in several tropical and subtropical regions of the world. This industry is evolving towards diversification of its product portfolio and valorization of the vast amounts of lignocellulosic feedstocks: bagasse and straw. These trends make the sugarcane industry a learning ground for the utilization of agricultural residues and herbaceous biomass for bioenergy and biorefining. The presence of inorganics in sugarcane bagasse and straw, constitutive of the plant as well as originated from contamination, impacts several of the current and potential uses of the biomass. Although many studies refer broadly to terms like “inorganics”, “ash”, “silica”, “sand” or “mineral impurity”, there is a lack of a coherent and nuanced presentation of the inorganics of bagasse and straw: what they are, how variable they can be, and how they can impact different processes and products in biorefineries. This review article aims at filling this gap. Bagasse and straw inorganics are discussed considering their agroindustrial context and how they can impact processes such as combustion, pyrolysis, production of cellulosic ethanol and biomaterials. Prospects for valorization of the biomass inorganics are also discussed, beyond nutrient recycling. In the vision of this review, inorganics are not a marginal concern for biorefineries, as the percentage of inorganic content in biomass may seem to suggest. On the contrary, proper understanding and management of inorganics is key for the design of processes for advanced biorefineries.
Nannochloropsis gaditana is a microalga, constituting cellulose 33 ± 1.3% and hemicellulose 18.2 ± 0.8%; used for the biofuel production. The cellulose in microalgal biomass would contribute to protecting the environment and constitute an attractive renewable raw material for bioethanol production. Ethanol production from N. gaditana microalgal biomass was investigated through Consolidated Bioprocessing (CBP) using Hangateiclostridium thermocellum KSMK1203 bacterial isolate. Screening and optimization of biomass pretreatment with different acids in different dosages, various hydrolysis time at 100 °C were performed and statistically validated using one-way ANOVA for efficient hemicellulose removal from NaClO2-treated N. gaditana biomass. Medium components and process parameters were statistically optimized by Response Surface Methodology. The maximum cellulase of 13.96 ± 1.354 IU/mL and ethanol of 12.90 ± 0.987 g/L were obtained in pretreated N.gaditana biomass. This study demonstrates that N. gaditana is a substitution for vegetal cellulose and these optimized conditions could be successfully used for commercial ethanol production using H. thermocellum KSMK1203.
Given both the ongoing expansion of world population and development of climate change conditions, it is increasingly imperative to develop and deploy sustainable biomass production methods to allow establishment of a flourishing and sustainable bioeconomy. Green technologies, including biofuels and bioproducts, are among the most effective strategies for decreasing greenhouse gas emissions and global warming, while meeting humanity's energy requirements. Biomass now provides a measure of energy to many countries, however supporting technologies are not widely accepted, largely because of low returns for biomass producers. This paper provides an overview of world biomass production and utilization. It also indicates potential approaches for enhancing biomass production: agronomic practices, associated microorganisms, genome editing, selection of optimal technologies, best combination approaches for feeding global human and animal populations, while, decreasing greenhouse gas emissions and replacing demand for fossil energy with bioenergy. A more novel concept is proposed, microbe-to-plant signal compounds, as the potential approach to address the challenges we are facing. These compounds (e.g., lipo-chitooligosaccharide and thuricin 17) have been shown to increase growth for diverse plant species, particularly when they are growing under stressful conditions, however, their commercial development/utilization is far from complete. This review paper will expand the understanding of using the signal interaction between crop and beneficial microorganisms not only to enhance plant growth but also promote agricultural sustainability and a stronger bioeconomy.
Microalgae biomass is considered by many as a most promising renewable source for future generation feedstock for simultaneous production of biodiesel and bioethanol due to the accumulation of considerable amounts of lipids and carbohydrates, respectively. In this work, defatted green microalga, Chlorella sorokiniana NITTS3 biomass was ultrasonic pretreated and effectively used as a culture medium for ethanol production through fermentation using Saccharomyces cerevisiae NITTS1. The ultrasonic pretreatment improved ethanol yield by 25.83 g/L than untreated defatted microalgal biomass. Carbohydrate content of hydrolysate of defatted microalgal biomass after ultrasonic pretreatment was analyzed and found that hydrolysate primarily possessed simple sugars, namely glucose and xylose. Maximally 52.10 ± 0.12 g/L (86.70 ± 0.52 mg bioethanol/g DMB) of ethanol was produced at optimum fermentation conditions of 30 ℃, pH 4 and 200 rpm. This study results show that pretreated microalgal biomass could be used as a cheap, sustainable feedstock for enhanced ethanol production.
The aviation sector relies on petroleum jet fuel because it is the most efficient energy carrier. Due to environmental and economic concerns a strong demand for alternative fuels is emerging. There is a need for diversification of energy sources from natural resources. These resources must be environmentally friendly and costs effective. Environmental impacts of fossil fuels on global warming and climate change are being a major concern today. Furthermore, the fluctuations of oil prices and need for sustainable fuel supply are the strong drivers for the economies of fuel users. In the aviation sector, Jet fuel from microalgae is one of the alternatives receiving considerable attention; it offers the potential to diversify energy sources. Microalgae species can produce lipids; they do not require high use of land, do not need freshwater, can grow in marine water or wastewater, grow faster in very short period of time, the produced oil is not a threat to food security. Similarly, the effect of climate change and global warming due to the generation of greenhouse gases (GHG) from petroleum jet fuel can be considerably reduced due to low carbon footprint generated by algae based fuels. Therefore, algae based aviation fuels can be considered as an alternative to produce an efficient fuel compared to conventional fuels. Conversely, the key challenge is: many algae species have lower lipid content. Harvesting and drying processes are costly as well as upstream processes to convert microalgae oil into Jet fuel. Although algae biofuels are still small players in the aviation industry, there is a potential for the future. This review analyses some routes to be explored or already explored, their strengths and weaknesses, the current trends and possible conceptual approaches to get aviation fuel from microalgae oil.
Wax esters (WEs) synthesized by Euglena gracilis are potential sources for alternative fuels because of their high productivity, recent success in mass cultivation, and low energy consumption in extraction. In this study, deoxygenation of Euglena WE and conversion to hydrocarbons in a catalytic cracking process under a hydrogen-free atmosphere was investigated using a residue fluid catalytic cracking equilibrium catalyst with enhanced hydrogen-transfer activity. The deoxygenation of Euglena WE proceeded more rapidly with higher H2O selectivity than that of saturated triglycerides. This is because initial β-elimination of WEs produces saturated fatty acids and higher olefins; the higher olefins rapidly release hydrogen species during cracking, cyclization and aromatization, and the hydrogen species accelerate hydrodeoxygenation of the saturated fatty acids. Furthermore, the cracking of Euglena WE produced large amounts of paraffins and olefins instead of aromatics. Therefore, Euglena WE was confirmed to be a preferable feedstock for the catalytic cracking process for hydrocarbon fuel production.
The increase in human consumption of plant and animal oils has led to the rise in waste cooking oil (WCO) production. Instead of disposing the used cooking oil as waste, recent technological advance has enabled the use of WCO as a sustainable feedstock for biofuels production, thereby maximising the value of biowastes via energy recovery while concomitantly solving the disposal issue. The current regulatory frameworks for WCO collection and recycling practices imposed by major WCO producing countries are reviewed, followed by the overview of the progress in biodiesel conversion techniques, along with novel methods to improve the feasibility for upscaling. The factors which influence the efficiency of the reactions such as properties of feedstock, heterog-enous catalytic processes, cost effectiveness and selectivity of reaction product are discussed. Ultrasonic-assisted transesterification is found to be the least energy intensive method for producing biodiesel. The production of bio-jet fuels from WCO, while scarce, provide diversity in waste utilisation if problems such as carbon chain length, requirements of bio-jet fuel properties, extreme reaction conditions and effectiveness of selected catalyst-support system can be solved. Technoeconomic studies revealed that WCO biofuels is financially viable with benefit of mitigating carbon emissions, provided that the price gap between the produced fuel and commercial fuels, sufficient supply of WCO and variation in the oil properties are addressed. This review shows that WCO is a biowaste with high potential for advanced transportation fuel production for ground and aviation industries. The advancement in fuel production technology and relevant policies would accelerate the application of sustainable WCO biofuels.
This paper reviews the technological and economical feasibilities as well as sustainable assessment of approaches (thermochemical and biochemical) applied for sustainable “drop-in” fuel production from lignocellulosic sources. The challenges for each pathway to produce “drop-in” fuels are covered. Currently “drop-in” fuel production cost is approximately 2 times (~5–6/gallon), especially with the use of 2nd generation feedstocks. The primary sources of cost with “drop-in” fuel production are feedstock cost (40–60% of the total production cost), syngas cleaning and conditioning to meet Fischer-Tropsch synthesis requirement (12–15% of the total production cost) and bio oil upgrading (14–18% of the total production cost) in the case of pyrolysis and hydrothermal liquefaction (HTL). The most influential factors on the life cycle analysis (LCA) were biomass cultivation, harvesting, biomass pre-treatment, and transportation. Therefore, robust processes that can use local waste biomass are far more environmental and economically viable, especially as biofuel from second generation have a greater potential to reduce greenhouse gas emissions (50–100%) than first generation biofuels (50–90%) when land use changes are omitted in the LCA. The sustainability of biofuels is pre-dominantly dependant on the sustainability of the initial biomass, with 2nd generation feedstocks being more sustainable than 1st generation. Gasification-FTS is considered as the most promising technique for “drop-in” fuel production over pyrolysis and HTL due to its flexibility towards feedstock acceptance and the ability to produced high yields of liquid fuel together with other economically viable biofuels such as electricity and heat. Biochemical routes (i.e.fermentation) to “drop-in” fuels are still in their early development stages, and therefore require more studies and pilot-scale experiments in order to discover an economic and sustainable means of using these methods.
The optimization of cobalt oxide (Co3O4) loading on silica for the low-temperature Fischer-Tropsch (LTFT) synthesis process employing simulated nitrogen-rich syngas (50 vol%) to produce highly paraffinic biodiesel is studied. Four different amounts of Co3O4 varying from 15 to 36 wt% were loaded on silica in order to examine the catalytic performance of Co/SiO2 catalysts. The supported catalysts were characterized using XRF, nitrogen physisorption, XRD, TPR, DRIFT and SEM fixed with EDS analysis. The performances of the catalysts were examined in a single channel fixed bed reactor employing simulated nitrogen-rich syngas (CO:H2:N2 = 17:33:50 vol%). The reactor was operated at P = 20 bar, T = 237 °C and WHSV = 3.0 Nl/h.gcat. The active site concentration was maximized by (i) utilizing all the available surface area of the sphere's porous support, (ii) using ethanolic impregnation solution to hinder sintering of Co3O4 phases due to presence of ethoxyl groups, and (iii) connecting oxide crystallites to the neighbouring pores by increasing the active metal content. As a result, the production of heavy hydrocarbons per unit of time was maximized with 36 wt% cobalt loading on silica (CO conversion and C5+ selectivity were 87.65 and 81.78 mol%, respectively, and also paraffin: olefin ratio was 98:2).
Fuel is one of the most important basic elements in the field of aeronautics and astronautics. In this chapter the development history and achievement of American military jet fuels are reviewed on basis of two series of fuels, i.e. jet propellant (JP) and rocket propellant (RP). The basic requirements of fuel properties are discussed. Two special fuels, high‐density fuels and high‐thermal‐oxidative‐stability fuels, are introduced. The development history and recent progress in fuel field are comprehensively summarized. Moreover, owing to the restrain of resource and environment, the development of non‐petroleum fuel is introduced. Finally, the development prospect and research direction in the future are proposed on the basis of environmental concern, operability, and logistics supportability.
Utilization of fuel oil from biomass (i.e., bio-oil) reduces emission of greenhouse gases. This paper discusses the different pyrolyis processes, physiochemical properties of pyrolysis products, upgrading techniques for safe storage and application in transportation and industrial activities. The production of bio-oil is challenging and requires inclusion of modern technologies. Pyrolysis plays a key role in the production of solid, liquid, and gaseous fuels from biomass. About 60–65% yield of bio-oil produced through the pyrolysis process using fluidized bed reactor has been reported. Among the all pyrolysis technologies vacuum pyrolysis was found a well suitable not only for bio-oil production, but also for improving the physicochemical properties of biochar such as surface area, porosity (macro/micro), functional groups, etc. In bio-oil upgrading, catalytic cracking process was observed as a most promising technique for the upgrading of bio-crude in to liquid fuel. Pyrolysis based synthetic fuels are considered as one of the key to saving the potential greenhouse gas emission up to 60—80% as compared to fossil fuels.
This article reviews the production of renewable aviation fuels from biomass and residual wastes using gasification followed by syngas conditioning and Fischer-Tropsch catalytic synthesis. The challenges involved with gasifying wastes are discussed along with a summary conventional and emerging gasification technologies. The techniques for conditioning syngas including removal of particulate matter, tars, sulphur, carbon dioxide and compounds of nitrogen, chlorine and alkali metals are reported. Recent developments in Fischer-Tropsch synthesis, such as new catalyst formulations are described alongside reactor technologies for producing renewable aviation fuels. The energy efficiency and capital cost of converting biomass and residual wastes to aviation fuels are major barriers to widespread adoption. Therefore, further development of advanced technologies will be critical for the aviation industry to achieve their stated greenhouse gas reduction targets by 2050.
The generation of reliable experimental data in any experimental scale requires proper procedures not only for the reaction step but also for the feed preparation, separation, and characterization of products as well as calculations of conversion and product yields. Batch reactor is the most used experimental setup for carrying out exploratory studies for catalyst screening and development. This review is focused on describing and discussing a step-by-step methodology for conducting experiments for catalytic hydrotreating of vegetable oils in batch reactor. The proposed methodology considers literature and own experiences on advantages and disadvantages of different feed types, catalysts, experimental setup and procedures, effect of reaction parameters, separation and characterization of products, and calculations.
Because of increasing consumption and the environmental impacts, the search for alternatives to fossil-fuel-based kerosene is crucial. Plastic waste cracking and subsequent co‑hydrogenation can be a promising way to produce jet fuels. The aim of this study was to investigate the feasibility of production of standard jet fuel from mixtures of cracked fractions of polyethylene (PE) or polypropylene (PP) and straight-run kerosene on commercial NiMo/Al2O3/P catalyst (10–30% cracked fraction content). The effects of process parameters (T = 200–300 °C, P = 40 bar, Liquid Hourly Space velocity (LHSV) = 1.0–3.0 h⁻¹, H2/hydrocarbon ratio = 400 Nm³/m³) and the feedstock composition on the hydrodesulphurisation and hydrodearomatisation efficiencies and the main product properties were investigated. It was found that, olefins affect the hydrodesulphurisation and the hydrodearomatisation reactions until 220 °C and 240 °C, respectively. At the most favourable process parameters (T = 300 °C, LHSV = 1.0–3.0 h⁻¹) practically sulphur and olefin-free jet products with reduced aromatic contents (7.2–11.2%) were produced. The freezing points of the jet fuel (−60.3 to −56.4 °C) produced from the 10–30% cracked PP fraction containing feedstocks were significantly lower than the required −47 °C, but in the case of the products containing the cracked PE fraction one further step (hydroisomerisation) is needed before the application.
Steam reforming of biomass pyrolysis oil or bio-oil derivatives is one of the attractive approaches for hydrogen production. The current research focused on the development of promising catalysts with favorable catalytic activity and high coke resistance. Noble metal such as Rh has been proven to achieve promising reforming reaction efficiencies. However, Ni has attracted considerable attention owing to its stability, cost effectiveness, and good activity in breaking C–C and C–H bonds. Nevertheless, Ni-based catalysts have serious carbon deposition problems arising from chemical poisoning, metal sintering, and poor metal dispersion. This paper attempted to review the current trends in catalyst development considering the aspects of supports, metals, and promoters as an effort to find possible solutions for the limitations of Ni-based catalysts. The present review also covered the current understanding on the reaction mechanisms as well as the future prospects in the field of steam reforming catalysts.
Due to excessive greenhouse gas emissions and high dependence on traditional petroleum jet fuel, the sustainable development of the aviation industry has drawn increasing attention worldwide. One of the most promising strategies is to develop and industrialize alternative aviation fuels produced from renewable resources, e.g. biomass. Renewable bio-jet fuel has the potential to reduce CO2 emissions over their life cycle, which make bio-jet fuels an attractive substitution for aviation fuels. This paper provided an overview on the conversion technologies, economic assessment, environmental influence and development status of bio-jet fuels. The results suggested that hydrogenated esters and fatty acids, and Fischer-Tropsch synthesis can be the most promising technologies for bio-jet fuels production in near term. Future works, such as searching for more suitable feedstock, improving competitiveness for alternative jet fuels, meeting emission reduction targets in large-scale production and making measures for the indirect impact are needed for further investigation. The large-scale deployment of bio-jet fuels could achieve significant potentials of both bio-jet fuels production and CO2 emissions reduction based on future available biomass feedstock.
The Fischer–Tropsch (FT) synthesis has been investigated over decades as an alternative route to obtain synthetic fuels from synthesis gas. FT is a high-performance synthesis based on metallic catalysis, mainly using ruthenium, cobalt and iron catalysts, which converts syngas in hydrocarbons and chemical precursors. This work presents a review on the aspects of the syngas production from biomass gasification and its subsequent conversion into fuels through the Fischer-Tropsch synthesis. The usage of biomass, including lignocellulosic residues, as a raw material in the gasification process. Biosyngas is highlighted as a synthetic fuel source to replace nonrenewable, conventional fossil fuels. Lignocellulosic material must be considered a low-cost feedstock to the liquid biofuel production on a large scale. Studies on syngas cleaning to attain the purity required by the FT process is revised. Recent understanding of reaction kinetics and thermodynamics has contributed to increasing the FT performance and economic viability. This paper includes also the debate on main catalysts, industrial process requirements, and chemical reaction kinetics and mechanisms of Fischer–Tropsch synthesis.
Research has intensified towards the production of biofuels due to increased economic uncertainty and environmental issues associated with petroleum fuel production. A fifth of the global energy demand is derived from transportation fuels such as diesel, jet fuel and gasoline. Most of the research in literature focuses on the production of biodiesel to supplement petroleum-based diesel. This review evaluates and compares three methods, (1) hydroprocessing, (2) pyrolysis (catalytic cracking), and (3) transesterification to determine the ideal, and simultaneous, bio-gasoline and bio-jet fuel production technique from castor oil, a non-edible vegetable oil. The methods are compared on the ability to produce biofuels to be used in spark-ignition engine or/and aviation. Edible oils have been thoroughly investigated as biofuel feedstock, which competes with food sources, hence the requirement to switch focus to non-edible oils. From the extensive research, it is clear that transesterification is not adequate on its own. Hydrocracking is the ideal solution as it can simultaneously produce high quality bio-jet fuel and bio-gasoline using one catalyst.
The paper and pulp industry is the sixth largest consumer of energy in the UK. Furthermore, the industry produces a significant amount of fibrous sludge and reject waste material, containing high amounts of useful energy. Currently the majority of these waste fractions are disposed of by landfill, land-spread, or incineration. These disposal methods not only present environmental problems, but are also very costly. This review explores how paper industry wastes can be valorized into useful energy vectors via advanced thermal conversion routes thus providing not only a solution for waste disposal but also a means of producing useful sustainable energy at paper mill sites. The scope of this work explores the application of advanced thermal conversion methods (gasification and pyrolysis) for the conversion of secondary fibre paper mill wastes into energy vectors. The order of the paper follows a specific structure. Initially, a detailed description is given concerning which wastes are generated from secondary fibre paper mills. This is followed by a brief review of the state of the art in waste management and energy systems currently used by paper mills. Then a review on advanced thermal conversion pathways as a solution to the dual issue of waste management and energy generation for secondary fibre paper mills is given, including details regarding the feasibility of integrating them into the current mill infrastructure. Finally, a discussion of the challenges associated with the proposed conversion pathways is given.