where GWP savings is the difference between GWP of gasoline displaced and GWP of ethanol (t ha 1 ), energy yield ethanol is the annual energy yield in ethanol product produced from one hectare of land (MJ ha 1 ), GWP gasoline is the GWP of gasoline per MJ of energy (g MJ 1 ), and GWPethanolis the GWP of ethanol per MJ of energy (g MJ 1).
The energy yieldethanolis the amount of fuel energy yielded from feedstock grown on a hectare of land converted to ethanol in a candidate conversion process. It is calculated using:
where biomass yield is the average annual bone dry biomass yield from one hectare of land (t ha 1 ), ethanol yield is the fuel yield per tonne of biomass (L t 1 ), and ɸis the HHV of ethanol (MJ L 1 ) (23.4 MJ L 1 ).