Two major problems have kept biofuelled flights grounded -- biofuels tend to freeze at high altitudes and growing crops for biofuels mess up the crops we need for eating. Looks like these two hurdles have been partially dealt with. An Air New Zealand test flight that was half powered by biofuel took off without a hitch today.

The jatropha nut creates a biofuel that doesn't freeze at high altitudes. The crop also comes from trees that grow in a lot of places and don't need to compete with the crops that we need to feed ourselves.

More good news for crop-fuel fans -- Continental will be testing fuels that come from algae along with jatropha nuts. A test flight over the Gulf of Mexico will be conducted using half regular jet fuel plus these algae and nut-based fuels.

This sounds like a huge step from a previous test of a biofuel flight from Virgin Atlantic. That test successfully used 20% biofuel on a Boeing 747 flight between London and Amsterdam.

While this sounds amazing, much more testing is required before flying becomes environmentally cool. Greenpeace has noted that the amount of jatropha biofuel needed for current levels of flying would not be sustainable, especially because flights use such a wasteful amount of fuel. So, guilt-free air travel could still be a distance away.