Thursday: takeoff from Minneapolis/St. Paul (MSP) around 2:00 PM (got there 11:30 AM). Fall asleep (short night's sleep, stayed up packing and awakened early for pre-fast breakfast). Wake up about 2:45 PM to announcement that we've received clearance to land at MSP. mm?? Fellow passengers relay explanation: backup electrical system shortage, but too much fuel weight to land safely, so we've been circling and now will attempt to land. Flight attendant informs us that fire trucks will be awaiting us but are not expected to be needed (they weren't).