It's bad enough for some prop aircrafts to be explained as being powered by elastic band. Now the skeptics could start having a dig at commercial aircraft flying on whatever from cooking oil to liquefied algae.

With the civil air travel market under increasing pressure from rising oil prices and environmental legislation, the race is on to find practical alternatives to standard kerosene and these so far appear to come down to various types of biofuel.

Not surprisingly, the first trials of alternative fuel were started by British air travel pioneer, Sir Richard Branson, whose Virgin Atlantic started London to Amsterdam flights with minimal biofuel use in 2008. This was rapidly followed by Lufthansa and Air New Zealand who each used various blends of routine fuel and bio derivatives consisting of 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 jatropha curcas), from the household Euphorbiaceae.

In 2007 Goldman Sachs mentioned Jatropha curcas as one of the finest prospects for future biodiesel production. It is resistant to dry spell and insects, and produces seeds containing 27-40% oil.

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

The most recent airline company to begin exploring with new fuels is the Alaska Air Group which has carried out internal US flights using a mix of 80 % petroleum based fuel and 20% biofuel made from cooking oil. This mix, it is declared, can cut damaging emissions by 10%.

One truly encouraging development has actually been the move far from biofuels which contend head on with food customers therefore preventing a rate spiral. Not so long ago, a rise in use of biofuels in cars and trucks triggered a spike in maize costs as US farmers diverted too much corn to fuel processing.

Hopefully in the future, airlines and drivers will focus biofuel consumption on non-food sources such as jatropha and algae. It would be a mixed blessing undoubtedly if some people wound up starving just to please another person's green credentials.