While the certification of renewable jet fuel derived from natural plant oils and animal fat was the talk of 2011, the big story in 2012 is expected to be the progress of alcohol-to-jet (ATJ) fuels towards obtaining the green light for commercial use.
Kevin Weiss, chief executive of California-based biofuels company Byogy Renewables, believes that ATJ fuels will be the next big thing in terms of reducing the aviation industry's reliance on petroleum and improving its carbon footprint. "This is going to be very public over the next four months - it's going to be a hot topic," says Weiss, who claims to have developed the world's first 100% synthetic replacement for jet kerosene.
"We've invented a process that converts alcohol to jet fuel. Most companies take the alcohol to someone else to turn into jet fuel." Byogy uses sugar-based feedstocks, which it pre-treats, ferments and distils into ethanol. The ethanol is then converted into jet fuel by catalytic synthesis.
One of the key advantages ATJ fuels have over fuels derived from hydroprocessed esters and fatty acids (HEFA) - which were certified for commercial use by ASTM International on 1 July - is that they do not have to be blended with kerosene because they already contain aromatics. A number of airlines began operating commercial flights running on a mixture of HEFA fuels and kerosene during 2011.
"This is a 100% replacement jet fuel from the most abundant feedstock in the world: sugar," says Weiss. "HEFA fuels require massive hydroprocessing - the fuel has to be taken to an oil refinery. We're completely different - the fuel is made at our site and is ready for distribution at a fraction of the cost." Weiss is hopeful that ASTM certification for ATJ fuels can be achieved either by the end of 2013 or the middle of 2014. "It's not a matter of if ATJ will get approved, it's a matter of when."
Richard Altman, executive director of the Commercial Aviation Alternative Fuels Initiative (CAAFI), believes the certification process for alcohol-based jet fuels will likely take "two to three years", judging by the amount of time it took for HEFA fuels and fuels developed through the Fischer-Tropsch process to be approved.
"We need to be combining the forces of all the global entities working on this to get the data [required for the certification process to begin] in a timely manner - that's the challenge," said Altman. "We understand the scale-up. Alcohol should be readily available, and it's then just a matter of how quickly it can be commercialised."
Another key project to look out for on the ATJ front is the collaboration unveiled in October between Virgin Atlantic and Chicago-based energy company LanzaTech. The latter generates fuel-grade ethanol through a gas-to-liquid process, which involves capturing vented gases from steel, cement and chemical factories and fermenting it. The ethanol produced is then sent to Swedish Biofuels, which converts it into synthetic jet fuel.
Virgin Atlantic is hopeful that it will be able to conduct flights from Shanghai and Delhi to London using the fuel produced through this venture within three years, provided ASTM certification can be achieved in the coming two years. Altman sees LanzaTech's solution as a win-win situation: "In the case of LanzaTech, the steel mills will pay you to take away their carbon."