It's bad enough for some propeller airplanes to be referred to as being powered by rubber bands. Now the skeptics could start having a dig at business aircraft flying on everything from cooking oil to liquefied algae.

With the civil aviation market under increasing pressure from increasing oil costs and ecological legislation, the race is on to find practical alternatives to standard kerosene and these so far appear to boil down to various types of biofuel.

Not surprisingly, the very first trials of alternative fuel were started by British aviation leader, 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 regular fuel and bio derivatives consisting of some from made from jatropha which can grow in soil thought about too poor for growing mainstream foodstuffs.

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

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

Recently, US aerospace giant Boeing, Brazilian aeronautical major Embraer and the Sao Paulo state Research Support Foundation moved to perform research and development into the usage of biofuels to power jet airliners. It was reported that Brazilian airlines Azul, Gol, TAM and Trip would function as strategic specialists for the task.

The latest airline to begin try out brand-new fuels is the Alaska Air Group which has conducted internal US flights using a mix of 80 % petroleum based fuel and 20% biofuel made from cooking oil. This mix, it is claimed, can cut harmful emissions by 10%.

One really motivating advancement has been the move far from biofuels which contend head on with food customers therefore avoiding a cost spiral. Not so long ago, a surge in usage of biofuels in cars and trucks caused a spike in maize prices as US farmers diverted too much corn to fuel processing.

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