Scientists are working to make the biofuel process more efficient and thus reduce carbon dioxide emissions and mitigate climate change. Oil refiners and biofuels interests squared off in oral arguments before the U.S. Supreme Court on Tuesday in a case with large implications for Iowa and Nebraska. As is usually the case, the justices grilled lawyers from both sides before submitting the case for a decision later, most likely in a couple of months or more. Hollyfrontier Cheyenne Refining LLC v. Renewable Fuels Association addresses questions over whether small refineries can request exemptions to the Renewable Fuel Standard. The standard sets the amount of biofuels that must be blended into gasoline and diesel. Small refineries are granted hardship exemptions in some cases.Â