The Woracle

Try as I might to track developments in alternative jet fuels, there is a bewildering array of initiatives under way and it can be hard to separate the hydrocarbons from the hogwash. But if Boeing is involved, you have to assume there is something more than hype in the tank.

Boeing, Air New Zealand and Rolls-Royce have signed a memorandum of understanding to conduct a biofuel demonstration flight using a 747-400 in the second half of 2008. This will follow the Boeing/Virgin Atlantic/General Electric biofuel flight trial early next year, also on a 747-400. Both involve running just one of the aircraft's four engines on a biofuel blend.

Which biofuel will be tested has not been announced in either case. GE says selection of a fuel for the Virgin trial is imminent, while Boeing says it is still working to identify suitable biofuels available in sufficient quantities for the Air NZ trial.

Air NZ's involvement is interesting because several reports have linked both trials with New Zealand company Aquaflow Bionomics, which produces biofuel from pond scum - sorry, algae. But there are lots of other "potential" bio-jet fuels out there, so it will be interesting to see which are picked by Boeing, GE and R-R.

Airbus has flown an A380 from Bristol in the UK and Toulouse in France on alternative fuel. The synthetic jet fuel was supplied by Shell and produced from natural gas in Qatar using the Fischer-Tropsch process. It's the first test of gas-to-liquid (GTL) fuel in an airliner, but similar synthetic jet fuel is already being qualified by the US Air Force across all of its aircraft.

So what was the point of the flight, other than to steal some thunder from Boeing and the much-hyped Virgin Atlantic biofuel demonstration planned later in February? A cynic would say Airbus is trying to convince a concerned public it is going green, but there is almost no difference in the CO2 produced by GTL jet fuel and kerosene. Okay, it does burn cleaner, cutting NOx, sulphur and soot emissions, and a slightly higher energy content should trim the fuel consumed per trip.

But when it comes to tackling aviation's evironmental impact, GTL is a bit of a non-starter - or, at best, an interim step. Cleaner-burning jet fuel is a good thing, but CO2 is the issue haunting the industry and only biofuel appears to offer a long-term solution. But bio-jet fuel is years away, whatever Sir Richard Branson might claim after his 747-400 flies from London to Amsterdam with one of its GE engines running on processed pond scum, or whatever it is.

GTL will be useful in diversifying the sources of jet fuel, and it may stimulate the development of "designer" fuels with better properties than kerosene, but aviation needs to keep up the pressure to develop sustainable, renewable sources of bio-jet fuel.