Costs outweigh the benefits. In Canada, anyway. Between 2008 and 2012 the cost biofuels were $3-$3.5 for every dollar of social and environmental benefit according to a study by the MacDonald-Laurier Institute. “Consequently the policy has failed to deliver value to Canadian taxpayers.”
“The support for ethanol as a partial substitute for gasoline in Canada has been very expensive by any test,’ the study says. “On a per-tonne basis, we estimate that the cost per tonne of CO2 equivalent reduction from production and use of corn ethanol ranges from $400 to $3,300 per tonne, and that from cellulosic ethanol is about $142 per tonne. This far exceeds the conventionally estimated benefits of CO2 reduction of between $0 and $50 per tonne.”
The Renewable Fuels Association disagrees claiming a 62% reduction in GHG emissions from ethanol and up to 99% reduction with biodiesel. [I'd like to see that calculation. Carbonless biodiesel?] The Renewable Fuels Association claims net economic benefits.
I tend to agree with the failure end of the spectrum, but I’m not in the biofuel production and sales business.