by Michael Gubisch (FlightGlobal/Flight International)  …Between 15 July and 27 December 2011, Lufthansa deployed a newly delivered Airbus A321 (registration D-AIDG) on the route between Hamburg and Frankfurt, with one of the two International Aero Engines V2500 powerplants running exclusively on a 50:50 synthetic biofuel-kerosene blend and the other using conventional Jet A1. The aircraft made the approximately one-hour journey up to eight times per day and consumed 1,556t of biofuel in total.

The point was not to see whether the alternative fuel burns in gas turbine engines – that had been demonstrated before – but to evaluate its long-term impact on performance as well as powerplant and fuel system health. “We wanted to make sure that we can safely fly on biofuel without problems,” says (Joachim) Buse (vice-president of aviation biofuel). “It makes no sense to plan further steps if biofuel leads, for example, to higher maintenance.”

The test not only confirmed that the jatropha, camelina and animal fat-based mixture has no negative side effects on equipment and operations – it even showed a 1% lead in specific fuel consumption because of its higher energy density over Jet A1. Biofuel is among the most promising means to cut aviation carbon dioxide emissions, with a potential to improve the CO2 balance by up to 60%, says Buse. But it also offers an opportunity to reduce the industry’s dependence on fossil fuels and global oil-price fluctuations in the long term. The challenge is finding a way to supply the future fuel in sufficient quantity.

A member of Buse’s team, which has been working on Lufthansa’s biofuel strategy since three years ago, travelled to Russia in early June to inspect camelina fields in the Volga region, where the oil plant is being tested as a potential future crop. Local farmers tried to grow different sorts of wheat in the region, but abandoned a huge area of farmland over the past 10-15 years after numerous crop failures.

…While the fossil oil industry has a long-established integrated infrastructure – covering all stages from exploration to distribution – the biofuel sector is fragmented. Oil plant growers are not linked up with biofuel refineries, who in turn have little contact with consumers. The existing bio-diesel business for ground vehicles is largely determined by intermediate traders who deal with raw materials in spot markets, says Buse. “Today, the end user is the only one [in the aviation biofuel supply chain] who is able to provide security that the final product will be taken up by the market.”

… Fuel additives are being developed, which should simplify the use of synthetic bio-kerosene in future. The mixture ratio with Jet A1 – currently limited by the standards authority ASTM International to a maximum 50:50 blend – depends on the fossil fuel’s conditioning. If, for example, the Jet A1 sulphur content is low, it may not be mixed half and half with biofuel. Buse expects, however, that additives will become available in the next three to four years, which will allow using 100% bio-kerosene in aircraft. This will not only make the current safety-critical blending step obsolete, but also facilitate combined storage and distribution with conventional Jet A1.  READ MORE