Virgin 747 biofuel trial set for February

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Virgin Atlantic plans to fly one of its Boeing 747s within weeks using biofuel in one of four GE CF6-80C2 engines on a London Heathrow to Amsterdam demonstration flight to evaluate alternative fuel for air transport.

The biofuel selected is not yet known, although Virgin, which has been working with Boeing and engine manufacturer GE Aviation on the initiative since last April, says it is using a "truly sustainable type that does not compete with food and fresh water resources".

GE revealed in August that there were three candidates, each using different sources and processes, one of which would be selected for ground testing in a development engine by the end of 2007. Three biofuels which are thought likely contenders have been developed by Aquaflow Bionomics, Imperium Renewables and Gevo.

Shell Aviation fuel specialist Mike Farmery says any aviation biofuel will need to be a drop-in replacement to mix with standard kerosene. "Imperium looks like a standard biodiesel plant," he says. "It might use proprietary technology to esterify the vegetable oil but it is still producing a methyl ester and nobody believes the methyl esters are realistic options for aviation. I'd be surprised if Aquaflow has found a source of algae oil in sufficient quantities and managed to hydrogenate it."

Virgin Fuels last year invested in Pasadena, California-based Gevo, which produces advanced biofuels including butanol, and this year secured an exclusive licence from UCLA to genetically modify Escherichia coli bacteria to produce an efficient synthesiser.

The flight - on an as-yet undisclosed date in February - will not be in revenue service and the aircraft will be due to go into heavy maintenance. The Civil Aviation Authority says no approval would be granted before it had conducted a full operational and technical assessment.

Another Virgin fuel-saving scheme seems to be stuck at the departure gate, though. An idea to tow aircraft on the ground, rather than driving them under their own power, has been quashed by Boeing. Preliminary analysis for a 747 indicates: "While the concept is feasible, it involves towing operations that would increase loads on the nose gear. These increased loads would reduce the life of the nose gear and increase the cost of maintenance because the gear was not originally designed for these loads."

Virgin is understood to be examining an alternative in-wheel motors concept.