It is useful to compare the potential of microalgal biodiesel with
bioethanol from sugarcane, because on an equal energy basis, sugarcane
bioethanol can be produced at a price comparable to that of
gasoline [69]. Bioethanol is well established for use as a transport
fuel [70] and sugarcane is the most productive source of bioethanol.
For example, in Brazil, the best bioethanol yield from sugarcane
is 7.5 m3 per hectare [69]. However, bioethanol has only
64% of the energy content of biodiesel. Therefore, if all the energy
associated with 0.53 billion m3 of biodiesel that the US needs
annually [14] was to be provided by bioethanol, nearly 828 million
m3 of bioethanol would be needed. This would require planting
sugarcane over an area of 111 M hectares or 61% of the total
available cropping area of the United States.