Thanks to the new ASTM annex, D7566-11, the 2% of global carbon dioxide emissions that is contributed by passenger jets will be reduced. Standards for testing the “second generation” of biofuels, derived from inedible plants, tallows (animal fats) and organic waste, have been approved to power commercial planes. ASTM has approved testing standards for a 50/50 blend of traditional jet fuel and sustainable aviation biofuels, known as hydroprocessed esters and fatty acids (HEFA). The announcement, along with detailed rules for refiners to adhere to, was published on ASTM’s website on July 1.

The annex extends ASTM D7566, which encompasses aviation turbine fuels that are a mixture of conventional and synthetic elements, to allow for the use of the HEFA fuels. D7566 was implemented in 2009 with the flexibility to incorporate future synthetic fuels derived from feedstocks. Prior to the annex, the only approved fuel under D7566 was from biomass, natural gas and coal produced using UOP’s Fischer-Tropsch process, which changes a carbon monoxide–hydrogen mixture into liquid hydrocarbons to result in a petroleum substitute. D7566 includes standard tests to certify the quality and performance traits of the fuel. The approval process relies on at least 11 performance features, including energy density, freezing point, flash point, thermal stability, volatility, sulfur and nitrogen dioxide levels, and other traits to determine whether the fuel is appropriate for aviation use. The tests ensure that the blended jet fuel is indistinguishable from conventional jet fuel, and that the fuel works with all aircraft with no alterations necessary.

Relative to D7566, the new annex incorporates the same criteria, plus two additional tests, one for existent gum and one for fatty acid methyl esters. Both requirements safeguard against possible impurities and trace metals that may result from problems with processing or feedstocks. Trace metals are definitely an area of concern, confirmed Stanford Seto, chairman of ASTM’s Subcommittee D02.J0 on Aviation Fuels. “Plants absorb anything in the soil near them,” he explained. “When these oils are produced, they have to be analyzed for trace metals down into the tens of ppb.” Current ASTM methods for detecting metals in aviation fuel employ inductively coupled plasma atomic emission spectrometry (ICP-AES) and graphite furnace atomic absorption spectrometry. One method utilized is UOP389, which was developed primarily to find trace results in the tens of ppb, but the technique uses chemicals that are detrimental to the environment, including sulfuric acid. ASTM is currently searching for a replacement method. “We will take one of the ASTM methods [D7111, which uses ICP-AES and currently detects at the 100 ppb range] and generate a significant round-robin to determine the precision in the 10 ppb range for the metals that are of interest to us,” Mr. Seto told IBO.

Driving the demand for aviation biofuels are cost and regulation. The EU has stipulated that transportation fuels must contain 10% biofuel by 2020. The European Commission has teamed up with Airbus, key airlines and European biofuel producers to form the Biofuel Flightpath initiative to try to increase the annual supply of biofuels to two million tons in 2020. Next year, the EU will begin to enforce the Emissions Trading Scheme, a cap on carbon dioxide emissions. If carriers surpass the limits, they must purchase permits.

Other concerns for airlines are volatile fuel prices and uneven supplies. The International Energy Agency predicts that in 2012, aviation fuel demand will hit 7.6 million barrels per day, an 11.7% increase from 2007. The International Air Transport Association has vowed to use 10% biofuels by 2017. Virgin America wants to be running on that same percentage three years later. “All this works only if the fuel can be produced at a price competitive with current petroleum fuels,” Mr. Seto said.

The infrastructure to supply biofuels, however, is not in place yet. “Now that the HEFA type of biofuel is approved, investors should be more willing to invest funds for scale-up of the feedstock and production infrastructure,” said Mark Rumizen, aviation fuels specialist at the Federal Aviation Administration and a member of the Commercial Aviation Alternative Fuels Initiative, which was instrumental in facilitating the annex. “This will result in increased supply of D7566 fuels and increased usage.” Biofuel is expensive now—it cost more than $70 per gallon to produce biofuel for US armed forces for assessment last year—but proponents say that costs will lower as higher volumes are produced. On July 15, Lufthansa started six-month trial flights using a biofuel blend composed of camelina, jatropha and tallows to power one engine on its planes. It is the first airline to make regular commercial flights using biofuel.

Companies are investing in the biofuels revolution. By providing the fuel for Lufthansa’s test flights, Neste Oil became the first company to contribute biofuel for regular commercial flights. Great Plains Oil & Exploration—The Camelina Company and Accelergy have joined forces to develop a completely synthetic camelina-based jet fuel. The Sustainable Aviation Fuel Users Group, which counts Honeywell associate UOP and Boeing as members, has been established to facilitate the second generation of biofuels. In September, KLM Royal Dutch Airlines will initiate flights using fuels produced by Dynamic Fuels derived from nonfood-grade fats, oils and greases from a Tyson Foods facility. Honeywell UOP expects to produce 5 million to 10 million gallons of Green Jet Fuel next year.

Airlines, plane makers and fuel suppliers must decide which blend is most suitable. Camelina is being touted as a viable choice because it can be grown alongside other crops or on minimal terrain. More than 500,000 gallons of camelina-derived fuel have been produced. Sustainable Oils said that it is the only sustainable feedstock used extensively and commercially. Jatropha can also be produced in large quantities. SG Biofuels said that the amount produced is expected to increase through breeding and biotechnology advancements. Algae has received approval under the annex and has generated interest because of its low carbon footprint, but there are not ample amounts of algae currently available for use.

Only time will dictate what is next for biofuels. It is safe to assume that D7566-11 will help define the road to authorization for other renewable sources. ASTM is working on annexes for other “blend materials that are generally paraffinic in composition but that also contain aromatics,” Mr. Seto said. He added that ASTM is focusing on methods that convert alcohol into jet fuel and that depend on fermentation. Several firms are working on technologies that produce fuels directly from fermentation. “The future production volumes of HEFA and other future D7566 fuels will be influenced by many factors that are difficult to predict,” Mr. Rumizen told IBO. “We hope that innovations in fieldstock yield and production methods will spur the increased availability of those fuels.” For now, the airline industry has taken one step closer to prevalent production of fuels better suited to the environment.