Biojet fuel production from oleaginous crop residues: thermoeconomic, life cycle and flight performance analysis

This study assesses an integrated biorefinery model's efficiency for biojet fuel production as Jet A1 blending component through the Alcohol-to-Jet (ATJ) and Hydroprocessed Esters and Fatty Acids (HEFA) thermochemical routes, employing lignocellulosic biomass from oleaginous crops. The ATJ process involved cellulosic ethanol production through steam explosion hydrolysis, simultaneous saccharification and co-fermentation. The anhydrous ethanol was sequentially dehydrated, oligomerized, and hydrotreated. On the other hand, the HEFA process upgraded vegetable oil from residues and fatty acid distillates. The vegetable oil was thermally hydrolyzed, decarboxylated and hydrotreated. The models were simulated in AspenPlus (R) v.11, achieving a specific biojet fuel production of 48 wt% for the ATJ and 87 wt% for the HEFA. In both cases, a biojet fuel mixture primarily composed of C9 to C12 isoalkanes was produced. The minimum selling price ranged between 1.01 euro/kg to 1.43 euro/kg. The studied routes were evaluated through exergetic and thermoeconomic analyses for optimizing. The life cycle assessment was carried out in SimaPro (R) v.9.0. The estimated net GHG emissions were 75 gCO2eq/ MJ for the ATJ and 18 gCO2eq/MJ for the HEFA; nevertheless, significant improvements were achieved from byproduct displacement credits. In both cases, the GHG emissions are under those from petroleum-derived Jet A1 production. Finally, the physico-chemical properties fulfilled the ASTM D7566 specifications, and the calculated payload vs range showed a better performance for an intermediate-range flight.

Automated summary

By utilizing different thermochemical routes for biojet fuel production, simulations showed differences between the ATJ and HEFA processes in terms of biojet fuel production rate, GHG emissions, and selling price. Both routes met the requirements for producing qualified biojet fuels.