5. Conclusion
The acetogen pathway (AP) to produce ethanol does not achieve the large reductions in GWP and fossil fuel use observed in the Ethanologen Pathway (EP) when assessed using an energy (MJ) functional unit.
However, when assessed on an area basis, the GWP savings of the AP process is comparable to the EP process.
The AP may be considered as a viable option to produce more ethanol while still achieving GWP savings similar to the EP if available land is limited.
The large amount of freshwater needed to produce these biofuels is of concern and warrants further research.