### General Background  
Several options are currently implemented to adhere to the environmental targets, electric vehicles being the most well-known type with about 95,000 electric vehicles registered in Germany. Other alternatives include hybrid, fuel cell, and natural gas vehicles, but unfortunately, the aviation sector is not as flexible. The aviation industry solely depends on high-quality paraffinic kerosene as fuel, making it an even more important sector for the overall energy and climate footprint. Direct electrification is highly unlikely for the aviation industry, mainly due to the high amount of energy required between two charging cycles. Long-distance travel would require heavy-weight batteries, large enough to store an adequate amount of energy (1 kg of kerosene is equivalent to 50 kg of battery weight for today's technology [2]). To replace the conventional fossil fuel with alternatives such as hydrogen is still not tempting due to the low energy density of hydrogen (5.7 MJ/L) as compared to kerosene (37 MJ/L), reducing the space for customers and cargo; therefore, liquid fuels cannot be replaced in the near future [3]. Alternative synthetic energy carriers with lower emission rates compared to conventional fossil energy can be a major part of the solution. The four phases of the energy transition plan are shown in Figure 1, where synthetic fuels such as aviation kerosene serve as the transition phase towards the goal of complete defossilization. Whether synthetic kerosene reduces the carbon emissions mainly depends on the source of power used in the P2J production pathway. McKinsey and Company estimate that by 2030 the technology for synthetic fuel could abate roughly 15 Mtpa of CO\({}_{2}\)[4]. Germany's power mix generated 485 g of CO\({}_{2}\)/kWh in 2017 [5], and with this current value, synthetic fuels will contribute to reaching the climate goals only in the long-term future. On the other hand, if synthetic fuels are produced with the curtailed surplus of renewable energy, the current carbon cycle can be balanced [3]. Curtailed electricity occurs at times of very high wind and photovoltaic power generation, where a certain excess of electricity supply cannot be utilized and must be curtailed. This excess amount of power is curtailed before entering the grid due to the insufficient grid transport capacity. The Federal Association of the German Energy and Water Industries estimates a curtailed electricity amount of 40 TWh in 2030 [6]. The Power-to-X concept refers to processes that exploit the environmental as well as the economic potential of renewable electricity (e-production) and convert them into useful final products such as gases, liquids, heat, fuels, or ultimately back to electricity. By adjusting the operation of  
Figure 1: Timeline of the four-energy transition phases [3]. production processes and varying the production level or operational mode, the electricity grid can be stabilized and make use of the fluctuating nature of renewable electricity [7]. The final desired product of the ongoing study is aviation kerosene fuel; thus, all feed quantities are calculated based on the final jet fuel objective. Synthetic fuel provides advantageous chemical and physical properties, thus offering a drop-in replacement for fossil fuel while having a better environmental performance. The ASTM-D7566 (ASTM D7566: Standard Specification for Aviation Turbine Fuel Containing Synthesized Hydrocarbons, ASTM International, 100 Barr Harbor Drive, P.O. Box C700, West Conshohocken, PA 19428-2959, United States) standard already allows 50% blend of synthetic fuel from the Fischer-Tropsch pathway with conventional jet fuel, while the methanol pathway is yet to be approved [8]. The Power-to-Jet (P2J) process (methanol pathway) starts with hydrogen production via electrolysis. In parallel, carbon dioxide is captured and transported. Both raw materials then react, forming the intermediate byproduct methanol.