The following article focuses on sustainable aviation fuels, which include first and second generation biofuels and other non-biomass fuels that meet most of environmental, operational and physicochemical requirements. Several of the requirements for sustainable aviation fuels are discussed in this article. The main focus was on researching the alcohol-to-jet (ATJ) alternative fuel. The tests covered the emission of harmful gaseous compounds with the Semtech DS analyzer, as well as the number and mass concentration of particles of three fuels: reference fuel Jet A-1, a mixture of Jet A-1 and 30% of ATJ fuel, and mixture of Jet A-1 and 50% of ATJ fuel. The number concentration of particles allowed us to calculate, inter alia, the corresponding particle number index and particle mass index. The analysis of the results made it possible to determine the effect of the content of alternative fuel in a mixture with conventional fuel on the emission of harmful exhaust compounds and the concentration of particles. One of the main conclusion is that by using a 50% blend of ATJ and Jet A-1, the total number and mass of particulate matter at high engine loads can be reduced by almost 18% and 53%, respectively, relative to pure Jet A-1 fuel.

One of the most promising mid-term solutions for reducing GHG emissions from the aviation sector is alternative aviation fuels, especially sustainable aviation fuels (SAFs). Regulations imposed by the Fit for 55 package to use 38% of SAFs until 2050 require a comprehensive analysis of SAFs and production pathway development with increased blending limits of alternative fuel. Within this review, a summary of key aspects of alternative aviation fuels is presented. The review contains a description of the certification process and certified production pathways with an analysis of feedstocks used for SAF production. SAF emissions also have been analyzed based on available research. SAFs reduce particulate matter emissions significantly, even by 70%, compared to fossil fuels. The emission of gaseous exhaust compounds, such as carbon monoxide, unburned hydrocarbons and nitrogen oxides, also is discussed. Alternative aviation fuels have a lower LCA compared to conventional aviation fuel and the LCAs of specific feedstocks are presented.

The fine particulate matter (PM) emitted from jet aircraft poses a serious threat to the environment and human health which can be mitigated by using biofuels. This paper aims to quantify PM emissions from a small turbofan fueled with the alcohol to jet (ATJ) synthetic kerosene and its various blends (5%, 20%, and 30% of ATJ) with Jet A-1 fuel. Emissions from a turbofan engine (DGEN 380) with a high bypass ratio, applicable in small private jets, were studied. Among the four fuels tested, the PM-number emission index (EI_N) was the lowest for the ATJ 30% blend. EI_N for ATJ 30% dropped from 1.1 × 10¹⁷ to 4.7 × 10¹⁶ particles/kg of fuel. Burning alternative fuel blends reduced the particle mass emissions over the entire range of fuel flow by at least 117 mg/kg of fuel. The particles formed in the nucleation mechanism dominate PM emission, which is characteristic of jet engines. Thus, number-based particle size distributions (PSDs) exhibit a single mode log-normal distribution. The highest values of EI_N were found for Jet A-1 neat compared to other fuels. The use of the ATJ additive did not cause significant changes in the size of the particles from nucleation mode. However, a magnitude reduction of nucleation mode was found with the increase in the ATJ ratio.

The aviation engines homologation process takes place in LTO (Landing and Take-Off) test cycle. Mentioned procedure is good for the approval applications because the test conditions are repeatable and obtained results could be compared between different engines. The authors compared in this article the exhaust emission results obtained in LTO test cycle during selected engine homologation with values obtained in estimations. Two Allied Signal TFE731-2-2B engines with a thrust of 15.6 kN were taken into considerations. The engines are used to propel the popular VLJ (Very Light Jet) aircraft: Dassault Falcon 100. Adopted methodology of emission estimation is very similar to the LTO, because the authors use the emission factors obtained in LTO cycle, specified for selected engines. Also, the duration of take-off, climb-out and approach LTO phases were adopted to the estimations. In the analyzed case, 16 scenarios of taxi phase were selected on the basis of the Warsaw Chopin Airport available runways. Duration of taxi phase in these cases vary between 3.1 to 11.0 minutes which is at least 58% less than in LTO test. Assuming the real taxi times change the exhaust emission results comparing to normal LTO cycle up to about 64%. The proposed methodology could be used for assessing environmental impact of air operations, which can be used to create the reports with more accurate data than with typical LTO times.

Despite the introduction of increasingly restrictive regulations, the air quality in Poland is still considered one of the worst in Europe. Two cities (Wroclaw and Cracow) were selected for this study, so they represent a pair of Polish cities with poor air quality, and at the same time are academic cities, popular with tourists. The article focuses on the emission of particulate matter, which is one of the most dangerous components of air pollution. The focus was on particles less than 10 µm in diameter which are most often neglected at measuring stations. We have identified the sources of particulate emissions in selected locations in Wroclaw and Cracow, and then measured particles in terms of their mass and number distribution. It was noted that the PM₁₀ emission values obtained as a result of the measurements were different from the value specified by the Inspectorate of the Environmental Protection in Poland.