It's bad enough for some propeller airplanes to be referred to as being powered by elastic band. Now the skeptics might start 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 increasing oil prices and environmental legislation, the race is on to find viable options to standard kerosene and these so far appear to come down to different kinds of biofuel.

Not surprisingly, the very first trials of alternative fuel were started by British aviation pioneer, Sir Richard Branson, whose Virgin Atlantic started London to Amsterdam flights with restricted biofuel use in 2008. This was quickly followed by Lufthansa and Air New Zealand who each used different blends of regular fuel and bio derivatives including some from made from jatropha curcas which can grow in soil thought about too poor for growing mainstream foods items.

Jatropha is a genus of roughly 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 very best for future biodiesel production. It is resistant to dry spell and pests, and produces seeds containing 27-40% oil.

Recently, US aerospace giant Boeing, Brazilian aerial major Embraer and the Sao Paulo state Research Support Foundation moved 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 strategic experts for the task.

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

One actually encouraging development has been the relocation far from biofuels which complete head on with food customers thereby preventing a price spiral. Not so long ago, a rise in usage of biofuels in cars and trucks triggered a spike in maize rates as US farmers diverted too much corn to fuel processing.

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