A study paid for by the federal government says biofuels made from the leftovers of harvested corn plants are worse than gasoline for global warming in the short term.
The research published in the journal Nature Climate Change challenges the Obama administration's conclusions that biofuels are a much cleaner oil alternative and will help fight climate change.
The study is being criticized by the biofuels industry and Obama administration as flawed.
Corn residue is one of the most promising ways to make cellulosic biofuels. Biofuels have struggled to reach the volumes required by law.
The administration and biofuel supporters claim biofuels are better for the environment than are gasoline and corn ethanol.
A 2007 law requires that they release 60 percent less carbon than gas to qualify as renewable fuel.