It's bad enough for some prop planes to be described as being powered by rubber bands. Now the skeptics could begin having a dig at commercial aircraft flying on everything from cooking oil to liquefied algae.

With the civil air travel market under increasing pressure from rising oil costs and environmental legislation, the race is on to discover viable alternatives to standard kerosene and these so far seem to come down to various kinds of biofuel.

Not remarkably, the first trials of alternative fuel were started by British aviation leader, Sir Richard Branson, whose Virgin Atlantic began London to Amsterdam flights with limited biofuel usage in 2008. This was quickly followed by Lufthansa and Air New Zealand who each used various blends of routine fuel and bio derivatives including some from made from jatropha which can grow in soil considered too poor for growing mainstream foods.

Jatropha is a genus of approximately 175 succulent plants, shrubs and trees (some are deciduous, like Jatropha curcas), from the household Euphorbiaceae.

In 2007 Goldman Sachs mentioned Jatropha curcas as one of the finest candidates for future biodiesel production. It is resistant to drought and pests, and produces seeds consisting of 27-40% oil.

Recently, US aerospace giant Boeing, Brazilian aeronautical significant Embraer and the Sao Paulo state Research Support Foundation transferred to bring out research study and advancement into making use of biofuels to power jet airliners. It was reported that Brazilian airline companies Azul, Gol, TAM and Trip would serve as strategic experts for the task.

The current airline to start experimenting with new fuels is the Alaska Air Group which has carried out internal US using a mix of 80 % petroleum based fuel and 20% biofuel made from cooking oil. This mix, it is claimed, can cut hazardous emissions by 10%.

One actually encouraging development has been the relocation away from biofuels which compete head on with food consumers thereby avoiding a price spiral. Not so long earlier, a surge in use of biofuels in vehicles triggered a spike in maize costs as US farmers diverted excessive corn to fuel processing.

Hopefully in the future, airline companies and motorists will focus biofuel consumption on non-food sources such as jatropha curcas and algae. It would be a mixed true blessing certainly if some individuals wound up starving just to satisfy somebody else's green credentials.