Private-equity firm Blackstone Group LP won a bankruptcy auction for Optim Energy LLC's Twin Oaks power plant in Texas with a $126 million offer, Dow Jones Daily Bankruptcy Review reported today. Blackstone officials bid against competitors, including Boston-based energy investor ArcLight Capital Partners, to gradually raise the price from an $82 million opening bid for the Robertson County, Texas, power plant, according to a transcript of Monday's auction filed in court yesterday.