Alternative fuels pioneers urged to share information

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The results of Airbus's breakthrough A380 demonstration flight powered with a gas-to-liquid (GTL) kerosene blended with standard jet fuel are being made public in a bid to advance industry understanding of alternatives as rapidly as possible.

The Rolls-Royce Trent 900-powered A380 (MSN004) completed the 3h flight between Airbus's Filton and Toulouse plants on 1 February as part of its evaluation of alternative fuels.

The A380 took off with an 11t synthetic fuel uplift one of its engines in a 40% blend of GTL synthetic jet fuel processed from gas fuel provided by Shell International Petroleum.

 © Airbus

Speaking at this week's Future Fuels Summit, Shell aviation technology manager Paul Bogers spoke about the contents of a report to be presented to standard setting organisations such as ASTM International's Subcommittee J for Aviation Fuels and the UK Aviation Fuels Committee, which together preside over jet fuel standards, as well as CAAFI - the Commercial Aviation Fuels Alternative Fuels Initiative - a broad cross-industry group that has worked to evaluate alternative fuels for civil aviation since May 2006.

"The industry is only going to move forward if we share this data," says Bogers.

Details of the report include essential fuel characteristics, such as the fact that density proved to be a limiting factor on the flight which led to the use of a 40% rather than 50% blend

"This was right at the end of the DEF STAN 91-91 properties [jet fuels standard] although all within the spec," he says, adding that samples of the fuel used for the official flight test were comprehensively tested including a blind test sample that was sent to the third-party assessor.

"What we have done is push the boundaries of the fuel, the aircraft and the engine," says R-R fluids specialist Chris Lewis, who adds that the engine manufacturer now plans to run a full suite of alternative fuels engine gaseous emissions tests by mid-2009. "We want to be leaders in this field, although the vision of the partnership was always that we would share the information."

Sébastien Rémy, head of Airbus's alternative fuels research programme agrees: "Everyone will end up using the same fuel so sharing the knowledge simply makes better use of the resources available and avoids duplication."

The A380 flight test pilots "really put the aircraft through its paces" as the flight engineer "insisted that these tests were conducted at the exact margin of the flight envelope", says Rémy.

One interesting aspect was the testing of the gravity feed system where a selected fuel pump system was shut down and fuel flow monitored. "Even though this fuel was of a lower density performance, still there was an acceptable fuel flow," says Rémy, who adds that the immediate next step will be to secure ASTM approval of a protocol which could clear a generic 50% Fischer Tropsch blend at a forthcoming meeting in June in Warsaw.