The growth of biofuel production and consumption for automotive transport is now the subject of a lively debate. This debate has led to revisions of transport biofuel policy in a number of countries, and it is likely that this debate will have further impacts on the development of biofuel production. Major items in this debate are the following.

Energy Security

To the extent that transport biofuels are advocated to provide for energy security, it has been stated that their potential may be very limited. Eaves and Eaves (2007) have argued that devoting 100% of US corn to ethanol, while correcting for fossil fuel inputs, would displace 3.5% of gasoline consumption, ‘only slightly more than the displacement that would follow from properly inflated tires’. Moreover, they have pointed out that historical US corn yields have shown considerable volatility, with corn yields about once every 20 years more than 30% lower than on average, which is not conducive to national energy security (Eaves and Eaves 2007). On the other hand, it has been argued that worldwide biofuels may end the dependence of transport on mineral oil, or even all fossil fuels. As pointed out above, de Vries et al. (2007) suggest that by 2050, up to about 300 EJ (= 300 x 1018 J) of liquid biofuels may be produced worldwide, mainly on abandoned agricultural soils, which would, as pointed out in Sect. 1.1, in all probability be sufficient to power transport.