|Comparison of synthetic BUFF fractions for Sasol and Syntroleum JP-5 products. Click to enlarge. Source: Sasol|
The Office of the US Secretary of Defense (OSD) has been working on an Assured Fuels Initiative since 2001, the goal of which is to catalyze commercial industry to produce cleaner-burning fuels for the military from alternative sources—Fischer Tropsch fuels being the primary example. (Earlier post.)
The recent ground- and flight-testing of a B-52 using a 50:50 blend of military JP-8 and a Fischer-Tropsch (FT) version (S-8 from Syntroleum) (earlier post) is a component of the multi-year project, which is beginning to accelerate. One aspect of the fuels initiative is a program to develop a Joint Battlespace-Use Fuel of the Future (J-BUFF)—a single fuel for all the military’s gas-turbine and tactical diesel engine applications.
The single battlefield fuel must currently comply with Jet Propulsion 8 (JP-8) or JP-5 fuel specifications. JP-8 is virtually identical to Jet A-1 commercial aviation turbine fuel except for the requirement of additional additives, such as fuel-system-icing inhibitors. The exception to the use of JP-8 is the fuel for use on aircraft carriers, which require conformance to JP-5 specifications. JP-5 is essentially the same as JP-8 but has a higher flash point than JP-8 to provide an additional degree of safety in handling fuels on aircraft carriers.
The Department of Defense invited Sasol Synfuels International (Pty) Ltd. and Sasol Chevron Holdings Ltd., among others, to participate in the program with the objective to supply the DoD with a FT BUFF conforming to JP-8 and JP-5 fuel volatility and low-temperature fluidity requirements.
Although DoD is more interested in coal-to-liquid (CTL) technology, and possibly biomass-to-liquid (BTL), Sasol used the product from a gas-to-liquid (GTL) Products Work-Up Demonstration Unit in Sasolburg, South Africa, to evaluate (on a bench scale) the possibility of producing a BUFF fraction from the Sasol Slurry Phase Distillate (Sasol SPD) low-temperature FT (LTFT) process and Chevron Isocracking technology.
Sasol concluded from the study that the production of a synthetic FT BUFF is feasible using the Sasol SPD LTFT technology together with the current Chevron isocracking technology. The product yield for a BUFF conforming to JP-8 requirements is 30 vol% of the fractionator feed, whereas the product yield for a BUFF conforming to the JP-5 volatility requirement is slightly less than 22 vol% of the fractionator feed. Sasol reports on the process and the results in an upcoming issue of Energy & Fuels.
Sasol has been providing a semi-synthetic (50:50 blend of petroleum and synthetic fuels) for commercial aviation since 1999; the fuel has been used routinely at Johannesburg International Airport in South Africa. The company has applied for approval of a 100% synthetic fuel that includes synthetic aromatics. If the test results are acceptable, this fuel could be approved this year.
“Fischer-Tropsch Fuel for Use by the US Military as Battlefield-Use Fuel of the Future”; Delanie Lamprecht; Energy Fuels, ASAP Article 10.1021/ef060607m S0887-0624(06)00607-4
Approval of a Fully Synthetic Fuel for Gas Turbine Engines (Pratt & Whitney)
Alternative Jet Fuels (Chevron)