Lufthansa is to begin using bio fuel to power commercial flights for a six-month test phase, dpa quoted the airline as announcing today. Flight LH013 from Hamburg to Frankfurt at 11:15 am (0915 GMT) on Friday will be the first to take off under what Lufthansa says is the world\'s first commercial test of bio fuel for such a long period. Four times a day, the Airbus A-321 being used for the test will fly the 450 kilometres from Hamburg to Frankfurt and back again. One engine will operate on regular fuel and the other will run on a mix of kerosene and bio fuel, to test the effect of the latter on engine durability and maintenance. \"In the six months, around 1,500 tonnes of CO2 (carbon dioxide) will be saved,\" Lufthansa said. It was not yet certain what would happen after the test phase. The aeroplane can only be refueled in Hamburg, where the Finnish-produced bio fuel is being stored. The test was supposed to begin three months ago, but was delayed due to authorization problems for the bio fuel, which is made from a mixture of plant and animal fats. The test will cost 6.5 million euros (9.3 million dollars), of which the German government is contributing 2.5 million euros in research funds.