Some concerns over the proliferation of “first generation” ethanol type biofuels include:

Food vs. Fuel:
With the world frequently experiencing food shortages and with many people around the world suffering from severe starvation, it is not wise to convert useful food resources into fuels if other alternatives are available. Much of the proliferation of ethanol has been a consequence of the agricultural industry lobby because a higher margin can be yielded on corn prices for example when global demand rises due to the expansion of fuel related end uses.

Conventional Oil Price Deflation:
The abundant use of biofuels has kept oil prices below where they would otherwise be. Some estimates (WSJ, March 2008) put the deflation at as much as 25%. The concern is that this is artificially inflating the use of conventional oil products as a consequence of the market pricing influence of biofuel availability.

Loss of biodiversity and deforestation:
With more demand for sugarcane and corn which is bred to be high in sugar content, fields will be cleared for this use from what would otherwise have been either natural forests of mature trees or agricultural systems of greater biodiversity.

Pollution:
The combustion of ethanol produces byproducts that are released into the atmosphere such as Formaldehyde and Acetaldehyde which have carcinogenic properties.

Water:
Crops that most easily produce the best performing biofuels require significant irrigation resources.

As a response to these and other issues, many new methods and products have evolved over the past decade in what are known as second, third, and fouth genearation biofuel technologies.