The feedstock conversion stage contributes -34.5 and -39.9 g CO2e×MJ -1 to total SAF CIs according to CFR and LCFS methods, respectively. The key driver for negative emissions from feedstock conversion is excess electricity production at the biorefinery. According to spatially explicit LCA and hybrid allocation, this stage contributes a median of -62.0 g CO2e×MJ -1 (Table ). One explanation for the difference in CIs is that the Fuel LCA Model used to calculate CIs for CFR participation uses one model for the conversion of various feedstocks (including agricultural residues, animal fats, and wood chips, among others) to SAF; users are only required to input quantities of hydrogen used for production, as opposed to the more rigorous process model and life cycle inventory employed for this spatially explicit LCA (Table ).