Boeing and Air New Zealand have announced that they will carry out the first flight test of "second generation" sustainable biofuel in an airliner on 3 December.
The planned test will be carried out using an Air New Zealand Boeing 747 flying from Auckland. During the flight, one of the jumbo's four Rolls-Royce engines will run partly on biofuel.
Successful biofuelled airliner tests have already been made, but these used so-called "first generation" fuels made from plants grown on existing cropland. A consensus is developing against such fuels, as they require huge amounts of productive farmland to be produced in significant amounts. As an example, according to Royal Society of Chemistry estimates, much of the UK's arable land would be required merely to supply the fuel requirements of Heathrow airport.
This means that crop biofuels are probably not a practical solution to powering transport, and would almost certainly drive up food prices and cause starvation in the developing world.
The airline industry are aware of this, but remain keen to develop alternative fuels in an era of high oil prices, uncertain supplies and probable carbon taxes and caps. This has led to the quest for "sustainable", starvation-free biofuels.
The juice to be used in next month's Antipodean test will be made from jatropha nuts. The hardy jatropha is said by its advocates to be capable of growing usefully in arid regions unsuitable for food crops, and in this case - according to Boeing - the nuts have been "sourced from nonarable lands in India and Southeastern Africa (Malawi, Mozambique and Tanzania)".
Honeywell subsidiary UOP produced the jatropha jet juice, marking "the world's first large-scale production run of a commercially viable and sustainable biofuel for aviation use", according to Boeing.
"This fuel not only met but exceeded three key criteria for the next generation of jet fuel: higher than expected jet fuel yields, very low freeze point and good energy density," said Boeing Director of Environmental Strategy Billy Glover.
"That tells us we're on the right path to certification and commercial availability."
The plan is that jatropha jetfuel would be blended with ordinary fossil juice, rather as already occurs with motor fuel in many countries. This would ease the airlines' carbon numbers, and potentially their fuel-price headaches.
"The blended fuel meets the essential requirement of being a 'drop-in' fuel," said Chris Lewis of engine maker Rolls-Royce.
"Its properties will be virtually indistinguishable from conventional fuel, Jet A1, which is used in commercial aviation today."
There remain many who are sceptical about jatropha's potential to produce any large proportion of the huge amount of fuel required by today's global aviation, however - especially genuinely sustainable jatropha from unusued deserts.
Boeing themselves have previously said that they see the future more in terms of many different sources of sustainable biofuel, rather than any one kind predominating. Provided that all are "drop-in" suitable, and can be blended together freely to run in any engine, this wouldn't complicate matters too much.
Other ideas for gen-2.0 jetfuel biomass include algae farmed on water, various kinds of fungus, even domestic garbage. ®