In the US and in Brazil, biofuels have grown and been introduced to consumers. In US, corn is used to make ethanol to displace some fossil fuel usage. This lowers price, increases national security, and decreases vehicular emissions. In Brazil, sugar cane is used to do the same thing on a much larger scale. Cars sold in Brazil are almost required to be fuel-flex, that is able to use both bio-ethanol as well as oil and many run purely on ethanol due to political issues in the past century. 
But how sustainable are these biofuels? Although we can see the benefits, do they out weigh the costs? Can we even quantify the costs?
Although the apparent benefits and immediate costs are measurable, we’re not able to see the full effect of the costs. With all commercial agriculture, the use of fertilizers, pesticides, and/or genetically modified organisms is apparent when we cannot see how they affect the surrounding environment. If these are allowed to permeate the earth and society without knowing the full effect, we will have to find a solution to reverse a problem we could avoid.
With the increase in scale and ability to model, better research capabilities, and better knowledge of how these products affect their surroundings, better results and better ways of quantifying these issues paired with specific goals will more clearly define the sustainability of biofuels. 
 Off-Balance by Matthew Kelly