U.S. refiners such as Valero Energy Corp and Marathon Petroleum Corp are bracing for stricter, smog-busting gasoline regulations set to hit in January, threatening more headwinds for an industry that has just endured its least profitable year since the shale boom started five years ago. Many refiners are grappling with record costs to meet U.S. biofuel standards and the prospects of rising crude prices in the wake of the decision by OPEC and other oil producers to cut production. “The new rules are certainly going to increase costs and impact margins. But how much, we’ll have to wait and see,” said Ed Hirs, an energy economist at the University of Houston. The Obama administration’s so-called Tier 3 standards require all but the smallest refiners to produce gasoline with an […]