If a plan approved by the U.S. Senate on June 5 becomes law, drivers in every state but Hawaii and Alaska could be pumping gasoline containing ethanol by 2012. The proposal, included in a broad energy bill, would change the way refiners blend gasoline and how they meet clean-air requirements. It would require doubling the use of ethanol to at least five billion gallons per year.The measure, which was approved by 67 to 29, would also ban the use of methyl tertiary butyl ether (MTBE) in gasoline. MTBE is a derivative of natural gas that can contaminate supplies of drinking water. It has been added to gasoline in many states since the 1970s to increase octane rating and make the fuel burn more cleanly.Backers of ethanol said the bill would help energy independence by displacing up to 250,000 barrels of oil a day by 2012.