E-fuels, technical and economic analysis of the production of synthetic kerosene precursor as sustainable aviation fuel

In the context of European and national energy policies to pursue the energy transition process, the issue of alternative-renewable liquid fuels is clearly addressed, whose purpose is to support the growth of sustainable mobility towards the goal of net zero emissions. On the base of the goals to be achieved in the medium and long term in relation to the theme of decarbonization and the development of new sustainable technologies, the present work deals with the e-fuels, which are produced by hydrogen from water electrolysis driven by renewable energy and CO2 captured from air or industrial sources. In particular, the attention is focused on the production of synthetic kerosene with the purpose to decarbonize the aviation sector, which is one of the most difficult electrifiable sectors due to logistical problems. The main objective of this work is the techno-economic analysis of the production of synthetic kerosene starting from green H2 and CO2 from direct air capture. The study of two main process schemes is carried out for the production of a synthetic crude oil, also called syncrude, rich in the kerosene fraction of interest. In the first scheme, called two-stage or indirect process, the incoming carbon dioxide and hydrogen are transformed through the Reverse-Water-Gas-Shift (RWGS) reaction in a syngas which allows to produce, by means of the Fischer-Tropsch (FT) reaction, the product of interest. The second scheme, referred to as single-stage or direct process, involves the direct formation of syncrude (direct FT-CO2) starting from carbon dioxide and hydrogen. In both cases, kinetic models representative of the considered reactions are selected in order to carry out an accurate process analysis. Through sensitivity analysis and process evaluations, some process optimizations like material recycle and heat integration are performed in order to increasing the efficiency and carry out a cost comparison to evaluate economic feasibility. Regarding the indirect and direct processes, 66.18 bbl/d and 38.46 bbl/d are produced respectively. Considering all the results and scenarios with and without optimizations, the range of the product cost is from 460 to 1435 €/bbl for the indirect process and from 752 to 2364 €/bbl for the direct process. These values strongly depend on the considered prices of power energy and hydrogen used for the present work.