|Three pathways to renewable jet fuel: FT (left); hydrogenated oil (center); ATJ (right). Source: Gevo. Click to enlarge.|
The US Air Force (USAF) last week flew the first test flight using “alcohol-to-jet” (ATJ) fuel. (Earlier post.) Gevo, Inc., the provider of the fuel, worked with the Air Force Research Laboratories (AFRL), the Air Force Alternative Fuels Certification Division (AFCD) and the 40 Flight-Test Squadron, provided the isobutanol-derived renewable kerosene fuel for the successful flight.
Gevo produced the ATJ fuel from isobutanol at its hydrocarbon processing demonstration plant near Houston, Texas, in partnership with South Hampton Resources.
The USAF flew an A-10 Thunderbolt jet powered by a Gevo-produced blend of 50% ATJ fuel and 50% JP-8. A series of flight test maneuvers, throttle bodies, auxiliary power unit (APU) starts and engine assisted starts were performed. The A-10 is a single-seat aircraft powered by two high-bypass GE TF34 turbofan engines. A Honeywell 36-50 APU is used for engine starting and in flight emergency power generation.
Last week’s test flight represented an accumulation of more than 4,000 hours of hard work involving innovative testing, multiple players and years of research on everyone’s part. Together, we have proven that ATJ fuel is a technically viable and promising alternative for both military and commercial applications.—Gevo President and COO Chris Ryan
Gevo, a leading renewable chemicals and next-generation biofuels company, was put on contract last year to provide the USAF 11,000 gallons of its ATJ fuel derived from isobutanol for testing by the AFCD. Gevo’s patented ATJ fuel is a drop-in fuel, deliberately designed to be fully compliant with aviation fuel specifications and provide equal performance, including fit-for-purpose properties.
The Air Force previously ran a series of engine ground tests, using the 50/50 blend of the ATJ and JP-8, said Jeffrey Braun, Division Chief of AFCD. The engineers then compared data with previous results from JP-8 baseline testing. Engine performance parameters monitored during the testing remained unchanged when utilizing the ATJ fuel blend, said Braun.
ASTM has assembled an alcohol to jet (ATJ) task force (D02J006 Alcohol to Jet TF) to investigate the requirements for this third major pathway--the conversion of alcohols—to renewable drop-in jet fuel. The first two synthetic fuel pathways approved by ASTM are gas-to-liquids and hydroprocessed oils. (Earlier post.) Gevo expects ASTM certification of its ATJ biofuel by 2013.
Gevo converts isobutanol into aliphatic and aromatic hydrocarbons using known chemistry and existing refinery infrastructure in a process involving the dehydration of isobutanol—which Gevo produces via fermentation—followed by oligomerization and hydrogenation. The Gevo bio-kerosene is the same as that conventionally produced from butylenes. Gevo’s value proposition is that it can cost-effectively produce and purify isobutanol to serve as the feedstock for this established process.
In its prospectus filed for its public offering, Gevo estimated the global market for ATJ to be approximately 75 BGPY, or approximately $200 billion annually.