Kudos to Sen. Collins for asking the question. Sure seems like a dubious program to me.
The GAO report, requested by Senators Barbara Boxer (D-Calif.) and Susan Collins (R-Maine), says that a 45-cent-per-gallon federal tax credit is doing nothing to spur production of renewable fuels that government mandates aren't already achieving...
The credit "may no longer be needed to stimulate conventional corn ethanol production because the domestic industry has matured, its processing is well understood, and its capacity is already near the effective RFS limit of15 billion gallons per year for conventional ethanol," the GAO said.
The 45-cent-per-gallon credit available to ethanol blenders is up for renewal next year.