Really? Do you know how much corn it would take and how much land that corn needs to grow? What do you consider a "significant dent"?
All you would ever want to know about ethanol here -
http://www.ethanol.org/documents/EthanolFAQs_000.pdf
(PDF)
Their main website -
http://www.ethanol.org
Maybe the kids from Mater Dei can do the math.