WILMINGTON, Del. (AP) — A Massachusetts company that received a $39 million Department of Energy loan before declaring bankruptcy is asking a Delaware judge for permission to use collateral for the loan to help pay its operating expenses.Beacon Power Corp., which makes flywheel energy storage systems used to keep power frequency steady on electrical grids, filed for bankruptcy protection Sunday.The company now wants to use some $3 million held as collateral for the DOE loan to keep its business going.A Justice Department attorney argued at a hearing Wednesday that the DOE loan was to a Beacon subsidiary for building and operating a 200-flywheel frequency regulation facility in Stephentown, N.Y.The DOE wants assurances the parent company won't use the money for anything not directly related to the Stephentown facility.