The GWP is also assessed using a functional unit of one hectare (ha) of land.
This functional unit is used to assess the absolute reduction in GWP of the two fermentation pathways if the ethanol
produced is used to replace gasoline. Fewer biofuel LCAs have used feedstock land area as the functional unit , but it provides valuable insight into the best use of limited land resources to reduce greenhouse gas emissions.
The benefit of an increased ethanol yield may not be fully captured when emissions are referenced to a MJ of fuel and then used to make relative comparisons to gasoline.