Functional unit and impact calculation methods
This study includes the investigation of two different functional units.
The first is a functional unit of 1 MJ (MJ) of ethanol.
Using a unit of energy is common practice in biofuel LCAs as it allows for the comparison of different types of fuels regardless of their respective energy densities .
The HHV energy densities for ethanol and gasoline are assumed to be 29.8 MJ kg 1 and 46.5 MJ kg 1 respectively.