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

With the civil air travel industry under increasing pressure from rising oil prices and ecological legislation, the race is on to discover practical alternatives to traditional kerosene and these up until now appear to boil down to different kinds of biofuel.

Not surprisingly, the very first trials of alternative fuel were initiated by British air travel leader, Sir Richard Branson, whose Virgin Atlantic began London to Amsterdam flights with restricted biofuel usage 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 curcas which can grow in soil considered too poor for growing mainstream foodstuffs.

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

In 2007 Goldman Sachs cited Jatropha curcas as one of the very best candidates for future biodiesel production. It is resistant to drought and insects, 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 relocated to perform research and development into using biofuels to power jet airliners. It was reported that Brazilian airlines Azul, Gol, TAM and Trip would serve as tactical consultants for the task.

The current airline to start experimenting with new fuels is the Group which has conducted internal US flights utilizing a blend of 80 % petroleum based fuel and 20% biofuel made from cooking oil. This mix, it is declared, can cut hazardous emissions by 10%.

One truly motivating development has been the relocation away from biofuels which contend head on with food consumers therefore avoiding a cost spiral. Not so long ago, a rise in usage of biofuels in cars caused a spike in maize rates 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 indeed if some people ended up starving just to please somebody else's green credentials.