Biojet fuels have prospects as a future jet fuel source, which is not rigidified and contains nearly zero amounts of aromatics and sulfur, typical to several hundred pieces per million in petroleum-based jet fuel by volume and mass(p.p.m.). This article, therefore, outlines the benefits of biofuel blend jet fuels in preserving the environment and reducing global warming. A blend of Biodiesel and bioethanol is projected to be the most commonly used biofuels in Europe, especially in combination with diesel and petrol, in the short- to medium-term ( Das, 2020) . The effect of this mixture is a significant reduction of pollution and increased fuel efficiency by jets. Blending fossil fuels with biofuels reduces volatile and non-volatile particulates in air cruise conditions by 50 –70%, enabling lower pollution from the aviation industry from the current 5% to halving it by 2020 and achieve carbon-neutral growth by 2050 ( Moore et al., 2017) .
According to the article, the environmental benefits arising from the mitigation of greenhouse gas emissions and reduced carbon footprints have resulted in growing interest and value of biofuel in the aviation industry. The non-volatile (nvPM) airborne emission, known as elemental carbon (EC), leads to both local or universal air pollution as a "soot" in the aerosol or atmospheric sciences or combustion settings. Overall fuel CO2 emissions are projected to double before 2050, and global aviation emissions are expected to rise by 3 to 4 times as they were in 2000 ( Moore et al., 2017) . Elemental carbon aerosols strongly absorb solar radioactivity and decrease surface reflective power, accelerating global warming.
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The development of sustainable biofuels will significantly reduce greenhouse gas emissions from the aviation industry. However, there are challenges to the attainment of emissions reduction goals. There are sustainability and cost challenges because jets require refined fuels than biofuels, and broader adoption of biofuel in other areas of transport could push the prices upwards. But surface transportation modes are more interested in electric batteries and not biofuels which could help in stabilizing biofuel prices. The biofuel comprises a hydrocarbons mixture of animal and plant oils that produce jet fuel with similar properties as petroleum-based jet fuel. The possible fuel source for future aviation is organic fuels derived from bio feedstocks like Camelina, algae, and jatropha due to their capacity to mitigate the concerns of fossil jet fuel.
Biofuel application as the future aviation fuel is due to its low sulfur content and savings in carbon dioxide emissions of up to 80% on its life cycle, unlike fossil fuels. Besides, jet engines require no required modifications to use biofuels, unlike other electric power and solar alternatives. Biofuels also have the advantage of low freezing point and high energy content than the other fuels (HBS Digital Initiative, 2016) . Thus, sustainable biofuels have the potential impact of lowering emissions in airports and the surrounding areas, and the same performance is expected of aircraft at cruising speeds.
National Aeronautics and Space Industry (NASA), in conjunction with agencies from Canada and Germany, conducted an experiment, which forms the basis of the article to examine whether the benefits offered on the ground by bio jet fuels are achieved jets are at cruising speeds. The report covers Alternative Fuel Effects on Contrails and Cruise Emissions Study (ACCESS) on jet engines that used standard jet fuel and blended jet fuel at cruising speeds (NASA, 2017) . The measurements were conducted between 2013 and 2014 and focused on recording data on the effects of blended fuels on emissions, engine performance, and contrails generated by jets at cruising conditions.
The contrails produced by jet engines primarily comprise water in ice particles formed from the cooling of hot exhausts from the jet engines mixing with cold air at cruising altitudes. Contrails form a critical component of the study since they create clouds that would otherwise not form in the atmosphere and play an essential role in influencing globe environment. Levels of soot emitted also affect the properties of formed contrails. Thus, a reduction in the levels of soot particles emitted results in low ice concentrations in the contrails, which lower their impact on the environment.
The variations between the number and mass (volume) emission indices for the two fuel sources are explained by measured particle size distributions. The total and non-fluid particulate amount and volume of the biofuel blend decline markedly as the mode peak is slightly shifting by 3–5 nm in numerical distributions and 8–11 nm in volume distribution. This change tends to be instigated by the most significant decline in the number of organic species and sulphuric acid in the soot-mode aerosols. Since gas-to-particle sediment gauges with particle diameter. However, the decrease in ice crystals in contrails will potentially increase, given the 8% escalation in the hydrogen amount of the blend of biofuel relative to petroleum-based fuel, which complicates the understanding of the consequences of these conclusions on the impact of aircraft on higher troposphere clouds ( Dagaut et al., 2019) .
Future modeling research should look at how the concentration of the ice volume of contrails will rise, and changes in cloud optical depth, lifespan and exposure, and the general ice-reduction radiation force. The determination of motor exhaust particles at cruise times is a crucial first stage ( Das, 2020) . Data were so far negligible for engines that burn bio-jet fuel mixes and are scarce for traditional petroleum fuel fuels.
Method and Discussion
Measurements were taken from NASA's HU-25 falcon aircraft using NASA Langley Aerosol Research Group, which had previously been used in numerous airborne programs. The instruments on the aircraft were characterized based on fright age, and their results were taken. The concentration of the particles was measured using a condensation particle counter onboard the aircraft. The volatility and non-volatility of the particles were measured after the samples were treated with a thermal denuder at 350°C.
The sample of particles was conducted at a rate of 37 lm−1 in a tube of 4.35mm that is supposed to have parallel airflow (mean aerial velocity of approximately 200m s−1) ( Moore et al., 2017) . The inlet tube is covered, which facilitates parallel screening but decreases local airspeed by an unknown quantity. A systemic black carbon characterization developed by a gas turbine engine is presented at different thrust and different fuel conditions to examine the changes in morphology, aggregate size, and nanostructure with the composition and thrust of the turbine; HRTEM descriptions are studied ( Dagaut et al., 2019) . The aggregate increases with energy, the dependency is smaller with fossil fuels with a higher biofuel content, and with an increased biofuel content decreases with any power aggregate. Both fuels are correlated by their primary particle size and aggregate scale. The sample then crosses roughly 0,34 m of tubes with an internal diameter of 4.45 mm and an internal diameter of roughly 5 m of tubes of 7,9 mm until the instrumentation is analyzed in the cockpit on the radar reflector.
The principal difference between HEFA fuel and conventional oil is that the fuel does not contain any sulfur. In contrast, standard jet fuel usually contains 18%-25% aromatic content. Fuel aromatics, according to the article, are restricted to under 25% to limit the solvent degradation of nitrile elastomers in accumulation to strict requirements relating to the density of fuel, viscosity, and freezing behavior affecting flight safety; in the meantime, the slightest aromatic level of 8% has been developed to increase the elastomer levels in some existing fuel systems ( Dagaut et al., 2019) .
According to the author, biofuel blends in jets reduce particle emissions. This article is convincing since the author has speculated that this kind of fuel would reduce the soot produced by jets. When designing this study, the authors made an indefensible assumption, and they clearly explained the results, which makes this report convincing. Also, the methodology use by the authors was appropriate and valid. The authors gave examples of some countries that have become successful, like European countries, in adopting biofuel blending. This fuel contains a low concentration of Sulphur.
Conclusion
A comprehensive characterization of soot from a gas engine is viewed at different engine power and fuel levels. An analysis of the variance in aggregate size, nanostructures, and morphology with a motor thrust and gas structure is done on the HRTEM images. The overall size increases with strength, the reliance on fuel mixtures with higher biofuel content is lower, and the combined size decreases with increased biofuel content for any power. Both fuels are correlated by the magnitude of the main particle and the aggregate.
References
Dagaut, P., Bedjanian, Y., Dayma, G., Foucher, F., Grosselin, B., Romanias, M., & Shahla, R. (2019). Emission of Carbonyl and Polyaromatic Hydrocarbon Pollutants From the Combustion of Liquid Fuels: Impact of Biofuel Blending. Journal of Engineering for Gas Turbines and Power , 141 (3).
Das, S. (2020). The National Policy of biofuels of India–A perspective. Energy Policy , 143 , 111595.
Moore, R. H., Thornhill, K. L., Weinzierl, B., Sauer, D., D’Ascoli, E., Kim, J., ... & Anderson, B. E. (2017). Biofuel blending reduces particle emissions from aircraft engines at cruise conditions. Nature , 543 (7645), 411-415.
NASA Study Confirms Biofuels Reduce Jet Engine Pollution . NASA. (2017). https://www.nasa.gov/press-release/nasa-study-confirms-biofuels-reduce-jet-engine-pollution .
Will Sustainable Biofuel Power the Airplanes of the Future? - Technology and Operations Management . HBS Digital Initiative. (2016). https://digital.hbs.edu/platform-rctom/submission/will-sustainable-biofuel-power-the-airplanes-of-the-future/.
