Alternative sustainable aviation fuel and energy (SAFE)- A Review with selected simulation cases of study

Renewable energy sources are gaining prominence as petroleum-based fuels deplete, necessitating alternative options. The aviation industry, facing increasing demand for both conventional and alternative fuels, is exploring blue hydrogen as a cleaner substitute for traditional jet fuels. This paper evaluates recent advancements in blue hydrogen production methods and hydrogen carriers such as ammonia, metal hydrides, formic acids, carbohydrates, and liquid-organic-hydrogen carriers (LOHC). Developed economies are actively researching biofuels as potential alternatives to petroleum, offering reduced emissions, enhanced fuel security, and improved sustainability. The power-to-liquid (PtL) method is employed to assess a sustainable alternative fuel, chemically matching regular jet fuel using water, CO2, and renewable energy. The study examines various biofuels and their application in aviation, comparing the techno-economic and environmental performance of PtL fuels to fossil and biomass-derived jet fuels. To estimate combustion flue gas properties, a model using Aspen Plus is developed, simulating the performance of a CFM56–7B turbofan engine with alternative fuels. Biodiesel, ethanol, n-butanol, 70% NH3–30% H2, and CH4 are evaluated, demonstrating comparable temperatures to conventional jet fuels. The NH3-H2 blend, while exhibiting lower thrust, limits the aircraft range due to reduced thrust compared to JET-A1 and kerosene-gasoline fuels. Ethanol shows slightly better thrust and range performance than the NH3-H2 blend but still falls short of conventional jet fuels. Biofuel and n-butanol emerge as promising replacements, demonstrating comparable thrust and range performance, with only a 15% reduction in aircraft range compared to JET-A1 fuel. The study provides valuable insights into the potential of these alternative fuels, emphasizing the need to consider combustion flue gas temperatures and their impact on existing power plants.