Through provisions included in ASTM D7566, up to 50 percent renewable synthetic fuel components, referred to as hydroprocessed esters and fatty acids (HEFA), can be mixed with the more conventional kerosene-type jet fuel (including Jet A and Jet A-1) used in most of today's commercial aircraft. The renewable fuel components are identical to hydrocarbons found in kerosone-based jet fuel, but come from oil-containing feedstocks such as algae, camelina and jatropha, or from animal fats called tallow. Best of all, the sustainable aviation fuel is compatible with all commercial and military aircraft with no modifications required.
[Source: ASTM International | Image: Andres Rueda – C.C. License 2.0]
Renewable fuels can now be blended with conventional commercial and military jet (or gas turbine) fuel through requirements in the newly issued edition of ASTM D7566-11, Specification for Aviation Turbine Fuel Containing Synthesized Hydrocarbons. The revised standard was approved July 1, 2011.
Through the new provisions included in ASTM D7566, up to 50 percent bioderived synthetic blending components can be added to conventional jet fuel. These renewable fuel components, called hydroprocessed esters and fatty acids (HEFA), are identical to hydrocarbons found in jet fuel, but come from vegetable oil-containing feedstocks such as algae, camelina or jatropha, or from animal fats called tallow. The standard already has criteria for fuel produced from coal, natural gas or biomass using Fischer-Tropsch synthesis.
Subcommittee D02.J0 on Aviation Fuels in ASTM International Committee D02 on Petroleum Products and Lubricants, which consists of more than 2,000 members representing 66 countries, revised the D7566 standard. Mark Rumizen, who helped lead the work to revise the specification, heads the certification-qualification group for the Commercial Aviation Alternative Fuels Initiative (CAAFI)®, a coalition that seeks to enhance sustainability for aviation by promoting the use of alternative jet fuels.
A Collaborative Effort
"The revision of D7566 reflects an industry cooperative effort to accomplish this task," says Rumizen. "Because of the great emphasis on safety when you're dealing with aviation fuel, the passage of this ballot required a collaborative and cooperative effort between the members of the aviation fuels community." Representatives from companies across the fuel supply chain plus HEFA fuel producers, aircraft and engine manufacturers, and regulatory agencies were involved in the specification development and revision.
Rob Midgley, technology manager, aviation fuels, for Shell Aviation, Cheshire, Great Britain, and a D02 member, notes, "The approval of HEFA as a blending component in jet fuel builds on the great efforts expended by ASTM on approving Fischer-Tropsch components in 2009 and shows that, as a consensus group, ASTM can make great strides whilst maintaining the safety levels demanded by the aviation sector."
Aviation fuel producers, distributors, airport fuel farms and airlines in the global aviation community will use the standard to verify fuel quality and performance by testing to the D7566 specification requirements. With this new edition, D7566 includes new, specific requirements for the bioderived synthetic fuel component such as thermal stability, distillation control and trace material amounts.
After blending with conventional jet fuel, new lubricity, distillation and composition requirements in D7566 must also be met. As a result, the blended jet fuel used in the airplane is essentially identical to conventional jet fuel and does not differ in performance or operability, notes Rumizen.
"The Air Transport Association of America and America's airlines commend ASTM for this critical and significant step, which brings the airline industry one step closer to meeting our environmental goals of widespread production of cleaner, alternative fuels while enhancing energy supply security and competitiveness," said John Heimlich, ATA vice president and chief economist, Washington, D.C.
A View Forward
The revised specification references numerous other ASTM standards, including tests that measure various properties of fuel. D7566 fuels also meet the requirements of ASTM D1655, Specification for Aviation Turbine Fuels, which has been used by the aviation community for decades for the quality control and distribution of conventional aviation turbine fuel. This allows these new D7566 fuels to be seamlessly integrated into the distribution infrastructure and onto certificated aircraft as D1655 fuels.
"The revisions to D7566 are significant in also helping better to define the path to approval for other renewable blend components; components in which the aviation industry is already showing interest to help support the demand for sustainable growth," Midgley said.
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