The rising cost of Renewable Identification Numbers is driving up retail fuel prices, said Valero Energy CEO Bill Klesse during a Senate Energy and Natural Resources Committee hearing. "We support and believe that ethanol will be part of the fuel mix in this country, but the [Renewable Fuel Standard] is broken," Klesse said. Other witnesses said that despite ramped-up domestic oil production, fuel prices are rising because of refinery outages, transport issues and global market forces. "I don't think it's fair to blame the Renewable Fuel Standard. The policy is helping to wean us off foreign oil, and that is a good thing," said Sen. Al Franken, D-Minn.