A drop-in aviation biofuel that relies on the direct fermentation of sugar has been approved for use, further boosting wider industry hopes of achieving a target of supplying up to 1% of the global annual production of jet fuel from non-fossil or sustainable sources by the end of 2015.

The process, developed by energy company Total and California-based renewable products specialist Amyris, becomes the third method of biofuel production to be approved by industry standards developer ASTM along with the Fischer-Tropsch and HEFA (hydroprocessed esters and fatty acids) processes. Based largely on work initially done in Brazil, the fuel called farnesane is produced as a byproduct of the fermentation of sugarcane using a special Amyris-produced yeast. The yeast separates oxygen and produces hydrogen while turning sugar into alcohol, and generates a fuel that will be blended 10% with standard jet fuel.

"We think it is going to cost less than HEFA because it removes an extra step out of the process," says Julie Felgar, managing director of Environmental Strategy and Integration at Boeing, which is supporting the development of multiple alternative fuel sources. "This method takes oxygen off right away whereas with HEFA you have to go through multiple steps."

Total and Amyris say qualifying the renewable fuel for the ASTM standard involved an in-depth evaluation program to verify its compatibility with aircraft and engine components and systems. The test program ranged from verifying the fuel’s low freezing point, high thermostability and high net heat of combustion to evaluation of performance including multiple engine and flight tests. The two energy companies say Brazilian fuels regulator ANP "has indicated it will include this renewable fuel as an option among the other alternative aviation fuels already allowed in the national specification."