Is the ethanol tariff a good idea?

You know there is a lot of hype around ethanol right now, just watch a couple of GM ads. You'd think corn is set to save the America from foreign oil dependency. Of course with only 600 ethanol pumps in the U.S. out of around 180,000, ethanol is nowhere near saving America. Nonetheless, ethanol offers great potential. Still, does that mean that the 54 cent tariff on ethanol is a good idea? This tariff, created in 1980 was meant to help build American energy independence. "Ethanol industry groups argue that ethanol supplies are adequate and lifting the tariff is unwarranted." (MSNBC) O.K., so 26 years later, has the tariff helped, or hurt? Has it accomplished anything? What is the purpose of the tariff?