Maine utility regulators have approved a long-term energy supply contract for the Rollins wind-power project in Penobscot County. The 20-year contract approved Wednesday by the Public Utilities Commission is between Rollins’ owner, First Wind, and utilities that buy and distribute its power, Central Maine Power and Bangor Hydro-Electric companies. It is the first long-term contract to be approved since electric restructuring in 2000. The 40 turbines in the Rollins project are to be built in Lincoln, Burlington, Lee, Winn and Mattawamkeag. They will produce enough energy for more than 23,000 homes. Federal, state and local permits have been approved. PUC Chair Sharon Reishus said the contract benefits ratepayers, while the company gets the financial assurance to become fully operational.