I always find it grating the way some armchair environmentalists love to lash out at frequent flyers (and/or travel writers) who, in confessing to have hopped a plane, are made to feel like sinners for sullying the atmosphere with nasty carbon footprints.

The global aviation industry is responsible for producing 2 percent of all the carbon dioxide that spews into the atmosphere.

That said, I’ve also always wondered why, in this era of sustainable this, that, and the other, nobody seems to be coming up with a sustainable alternative for airplane fuel (which, admittedly, is a major pollutant; the global aviation industry is responsible for producing 2 percent of all the carbon dioxide that spews into the atmosphere).

Moreover, since Brazil is a notorious pioneer in the development and use of renewable biofuels – Brazilian automobiles have been running on ethanol derived from sugar cane since the 1973 oil crisis – I always idly wondered why no enterprising Brazilians ever tried using sugar cane to fly planes as well.

To my happy surprise, it turns out they just did.

During the recent United Nations Sustainable Development Conference (Rio+20), Brazil’s third largest airline, Azul, made history when one of its E195 Embraer jets flew from Campinas (on the outskirts of São Paulo) to Rio de Janeiro, using a revolutionary bio-kerosene made from sugar cane.

The landmark flight was a result of the Azul+Verde (Blue+Green) project developed by Azul in conjunction with Amyris Inc., Embraer, and General Electric. The partners were fired up by the findings of a study carried out by the Instituto de Estudos do Comércio e Negociações Internacionais (ICONE), which confirmed that kerosene derived from sugar cane could reduce gas emissions by 82 percent compared to those produced by fossil fuels.

It took three years of research to come up with AMJ 700, an innovative biofuel that relies upon modified microorganisms to convert sugar into pure hydrocarbons. Via this process, for every 2 tons of sugar cane, it’s possible to obtain 100 million liters of renewable kerosene that (once certified) will comply with the rigorous aviation standards set forth by the American Society for Testing and Materials (ASTM).

The experimental Azul flight was fueled by a 50:50 mixture of regular jet fuel and biofuel, but eventually planes will be able to fly using 100 percent bio-kerosene. A major advantage of AMJ 700 is that it can be used just like traditional kerosene; there is no need to adapt any part of the aircraft or modify any part of the fueling process.

While discussions are already underway for the eventual commercialization of AMJ 700, the biggest challenge now is to be able to produce sugar cane on a large commercial scale at a cost that can compete with – or undercut – the price of traditional jet fuel. Until that happens, it will probably be some time before you can hop a sugar-fueled flight sustainable enough to appease the armchair environmentalists.