The benefit of a higher ethanol yield in the AP makes up for the GWP penalty associated with hydrogen production by producing more fuel per hectare.
These GWP savings of 8.6 t ha 1 and 7.9 t ha 1 for the EP and AP, respectively, are in the higher end of the range of savings reported by other studies of 2 t ha 1 to 11 t ha 1 for lignocellulosic ethanol via bioconversion.
The GWP reduction per hectare is significant because land for bioenergy crop production is limited.
Estimates place the amount of marginal/abandoned land available for biofuels at 3.2 million square kilometers to 11.07 million square kilometers worldwide.
Using second generation biofuel production methods (like the ethanologen pathway describe in this research), this amount of land would enable ethanol fuel production to meet 26%-55% of the current world liquid fuel demand