Posted February 12, 2010

Jet fuel is the most highly specified transportation fuel, but the airline industry has long recognized that a small amount of cross-contamination is unavoidable in a shared fuel system. Nevertheless, if biodiesel wants to achieve status as a pipeline fuel, it will be allowed to contribute only trace amounts of methyl esters in pipelines where different fuels cross. "I'm confident that we can get biodiesel in the pipeline system and that we can be successful," said Steve Anderson, Air BP fuels advisor.

Biodiesel qualifies as an advanced biofuel under the U.S. EPA's final rule for the revised renewable fuels standard (RFS2). As its use grows in volume, status as a pipeline fuel will have to be achieved to improve margins and entice buyers. RFS2 will require "obligated parties" to use a certain amount of biodiesel, so while jet engine makers have finally approved 5 parts per million methyl ester contamination in aviation fuel, some companies are lobbying for approval of 100 ppm.

Biodiesel is already moved through pipelines in Europe, and the European Union currently allows up to 5 ppm in its EN 590 spec for jet fuel. But there has been concern over the potential for cross-contamination there. "We'll have problems at airports-I can guarantee-if we don't get this approval [before fatty acid methyl ester (FAME) is shipped through U.S. pipelines]," Anderson said. "We were close to shutting down Heathrow airport and you can imagine the amount of press that would have gotten."

A memo from the Joint Inspection Group, a British organization committed to encouraging the "safe and cost effective best practices for aviation equipment and aviation fuel quality control and handling," reported in June 2008 that the "proactive" testing of jet fuel coming from multiproduct pipelines for biodiesel carryover revealed a problem in the fuel supply to Birmingham airport in the United Kingdom.

"As a result, a number of tanks at Kingsbury supply terminal and Birmingham airport were quarantined," JIG reported. "Once it was confirmed that the level of FAME in product was above the current 5ppm limit (concentrations up to 20ppm were measured in samples), concerned companies advised the affected airports to cease fuelling. This caused only a minor disruption to fuelling activities at Birmingham airport thanks to the availability of unaffected product from a different supply route."

Despite contamination problems, oil companies that purchase FAME in the future will want to use the efficiencies of their pipeline assets to move volume, as this infrastructure is responsible for the efficiency of the American fuel distribution system. "This is a big deal," said Rob Woodford, member of the ASTM Board who works for the Explorer Pipeline Co. "Pipelines offer up to a 20 cent per gallon advantage over trucks, and would save $50 million for biodiesel producers if 1 billion gallons is transported on pipelines."
The testing project involving FAME in jet engines (needed to precede the 100 ppm approval), however, has been a complicated, complex, multi-year episode involving millions of dollars, and a wide of variety of companies and organizations including, Boeing, Rolls-Royce, Green Earth Fuels, Exxon and the Kansas City Soybean Commission.

One of the big questions that this monolithic investigation poses-"Does FAME cause engine deposits to form?" Deposit formation leads to increased maintenance and downtime and can be very destructive to engine components. "Many OEMS lease the engines to the airlines," Woodford said. "If an engine comes off the wing for maintenance, then the OEM is losing out. So they want to keep the engine on the wing for as long as possible."

Woodford said that various fuels are often "interfaced" in pipeline transport following certain cycles. Jet fuel is often the first in the cycle, followed by diesel and fuel oil and then "cleaned up" by gasoline. This process ensures that jet fuel receives the least amount of cross-contamination "I'd like to have a dedicated system for jet fuel, unfortunately that's never going to happen," Woodford said.

Biodiesel would be interfaced in a similar way to diesel fuel, and the perfect combination of instruments and procedures are being developed to properly stage FAME in pipelines. One of the problems, however, with controlling cross-contamination is the lack of suitable and widely available test methods to measure low-level FAME content. "I need a quick test method so I can test FAME, then we can develop procedures and test methods to stage that material in the pipeline," Woodford said. "We know FAME trails back, it likes to stick to the pipe, so I need bench-top equipment that can tell me how much FAME I have in a distillate sample."

In continuing efforts to complete the approval of 100 ppm FAME in jet fuel, Anderson advised attendees at the 2010 National Biodiesel Conference & Expo in Grapevine, Texas, that "If you want to see biodiesel take a foothold, you need to contact the OEMS and tell them that we need approval of 100 ppm FAME in jet fuel."