The CO2 emitted during combustion of biofuels being generally of biogenic origin, is not included in the calculations. However, the methanol used in biodiesel conversion is fossil-based, so this fossil carbon content in the resulting biodiesel contributes to non- biogenic GHG emission and is thus counted (Pleanjai et al., 2009). The non-CO2 GHG emissions are calculated from IPCC (2006) using the global warming potentials from AR5 GWP100 (IPCC, 2013).
The result of TEF assessment of the four fuel types is shown in Fig. 2. The overall impact of biodiesel (21.1 TEP/FU) is about 33% lower than diesel (28.8 TEP/FU). Biodiesel feedstock acquisition (palm oil cultivation) needs to consume a lot of freshwater, while the fossil feedstock acquisition does not. Oil palm is grown in southern Thailand where the rainfall rate is high and climate con- ditions are suitable; however, even then some farmers use irriga- tion water in the dry season in order to maintain productivity. Furthermore, this assessment result includes water embodied in agrochemicals used. The produced water from fossil oil production is calculated, but due to its insignificant amount, it is not shown in Fig. 2. Biodiesel gets the benefit of biomass feedstock because CO2 from biofuel combustion is not accounted. Bioethanol (25.2 TEP/FU) also performs better than gasoline (32.3 TEP/FU). The energy con- tent of biofuels are lower than their counterparts. As a result, TEFs of biofuels are not much lower than their fossil counterparts when compared on a MJ basis.