Some of the explanations offered by the authorities of Brazil regarding the lack of impact of Brazilian biofuels on food prices, biodiversity and related issues (based on recent news reports), include:
1) "Relative stability of sugar prices"
2) "Sugar cane plantations 2000 km away from rainforests"
It is easy to accept explanations that US corn-derived bio-ethanol having a much larger effect on food prices than sugar cane, in the present shorter-term scenario. But at what scale does this remain true? Increased demands over time for bioethanol from current sources will inevitable have an effect on sugar, further to which increased demand for sugar cane plantations will also increase the competition for additional land resources (still under forest cover). But then again, the shrinking or receding boundaries of where the forest "begins" may very well be the reason for the plantations remaining spatially remote from the forest...
Related:
Don't blame Brazilian biofuels - guardian.co.uk - World of Renewables