GE Aviation has begun jet engine combustor component testing with 100% Gevo renewable alcohol-to-jet fuel (ATJ). The testing is being performed as part of the Federal Aviation Administration’s (FAA) Continuous Lower Energy, Emissions and Noise Program (CLEEN). CLEEN is the FAA’s principal environmental effort to accelerate the development of new aircraft, engine technologies, and to advance sustainable alternative jet fuels, in conjunction with aviation industry leaders such as GE Aviation.
Specifically, this testing is designed to enable the greater displacement of petroleum-based jet fuel by bio-based alternative products. Bio-based hydrocarbon fuels have similar performance characteristics to the petroleum-based fuels used today, albeit with reductions in particulate matter and other air quality related emissions. Some bio-based jet fuels, such as Gevo’s ATJ, have the potential to improve performance, such as providing greater energy density which translates into better mileage.
ASTM’s specification for aviation fuel containing synthesize hydrocarbons (ASTM D7566) includes annexes dealing with different types of synthetic jet fuel. Annex A1 handles Fischer-Tropsch (FT) synthesized paraffinic kerosene (SPK) (50% max blend); Annex A2, hydroprocessed fatty acid esters and fatty acids (HEFA) (50% max blend); Annex 3, SIP (synthesized isoparaffins) (10% max blend); Annex 4, Fischer Tropsch synthesized paraffinic kerosene with aromatics (SPK/A) (50% max blend); and Annex 5, alcohol-to-jet (ATJ) (30% max blend).
Several catalytic upgrading strategies are being pursued for isobutanol to synthetic paraffinic kerosene (ATJ-SPK) approved with Annex 5. These new catalytic conversion strategies are focused on making ATJ blends that include additional hydrocarbon products—such as aromatic content—to allow for greater blending volumes of the AJF product. (Earlier post.)
In October 2017, Gevo announced a partnership with Los Alamos National Laboratory (LANL) on a project to improve the energy density of Gevo ATJ to meet product specifications for tactical fuels for specialized military applications such as RJ-4, RJ-6 and JP-10, which are currently purchased by the US Department of Defense (DoD). ChemCatBio, a consortium within the US Department of Energy, awarded funding to LANL in support of the project.
Gevo and LANL are looking to develop a low-cost, catalytic technology that would be bolted-on to Gevo’s existing isobutanol-to-hydrocarbons process to produce high energy density fuels (HEDFs). With the successful scale-up of this technology, it is believed that Gevo’s HEDFs could be produced at a lower cost than the petroleum-based equivalent, even at current oil prices.
HEDFs are currently used in air and sea-launched cruise missiles used by the US military forces. If this project is successful in scaling HEDFs cost-effectively, there may be an even broader application in the general aviation sector, enabling higher energy density jet fuel that would provide superior mileage to traditional aviation fuels.
GE Aviation is a part of General Electric Company, and is a world-leading provider of jet engines, components and integrated systems for commercial and military aircraft.
If we are truly going to reduce our greenhouse gas (GHG) emissions from aviation, we need to be able to replace larger percentages of petroleum jet fuel with bio-based alternatives such as Gevo’s ATJ. The future is to replace the whole barrel of oil with bio-based hydrocarbons that stimulate the economy, mitigate GHG emissions, draw on abundant resources and enhance sustainability. We want to thank the FAA and GE Aviation for their vision in supporting projects like this one.—Dr. Patrick Gruber, Gevo’s CEO