On January 14, Boeing announced its conclusion that green diesel, a renewable fuel already used in ground transportation, is a potentially significant new source of biofuel for aviation. This potential game-changer in the quest for sustainable advanced jet fuels could create a sizable new market for existing biofuel production facilities, and push the airline industry to make progress towards carbon reduction goals. Boeing has set a goal of achieving 1 percent biofuels by 2020.
Green diesel represents an important, practical climate solution because it is already available, it’s a fuel with lower carbon intensity than petroleum, and it’s cheaper than other potential aviation biofuels.
Boeing, the Federal Aviation Administration (FAA), engine manufacturers, green diesel producers and others are working together to document the suitability of green diesel for use as part of a new fuel blend, in hopes that the fuel will win approval from an international group that sets standards for the aviation industry.
Boeing's leadership has already led to a number of breakthroughs in the development of sustainable aviation fuels. Boeing pushed for 1 percent of commercial aviation fuel to be plant-derived biofuels by 2020. This week’s announcement builds upon 2011 approval for commercial airlines to fuel up with a blend of up to 50 percent biofuels, which has led to a number of successful biofueled commercial passenger flights.
Aviation depends completely on liquid fuels, in contrast with ground transportation, for which a range of alternative energy sources is available. Renewable wind and solar power, or even hydrogen, can play an increasing role in ground transportation; but both technical and safety concerns rule out both as aviation fuel options for the foreseeable future. For this reason, it makes sense to prioritize biofuels for aviation and employ alternatives for ground transportation. The aviation industry has an advantage in that its fueling infrastructure is centralized, with 95 percent of commercial air traffic fueling concentrated at just 1,700 airports throughout the world.
Green diesel is chemically different from biodiesel, and is created through a process involving pressure and hydrogen that is unrelated to the biodiesel process. Boeing researchers, including Dr. James Kinder, performed analysis that found green diesel, which is made from oils and fats, to be chemically similar to today's aviation biofuel. If approved, the fuel would be blended directly with petroleum jet fuel.
"Green diesel approval would be a major breakthrough in the availability of competitively priced, sustainable aviation fuel," said Kinder, a Technical Fellow in Boeing Commercial Airplanes Propulsion Systems Division. "We are collaborating with our industry partners and the aviation community to move this innovative solution forward and reduce the industry's reliance on fossil fuel."
Carbon intensity for green diesel produced from waste oils, such as tallow, is about 1/3 that of fossil fuel diesel. Concerns have been raised that, depending upon the source of oils, some green diesels might actually have a higher carbon intensity than petroleum. The sustainability of these new fuels is being monitored both at an industry level and by NGOs. Boeing and the 27 airlines in the Sustainable Aviation Fuel Users Group are committed to developing biofuel that is produced sustainably, without adverse impact to greenhouse gas emissions, local food security, soil, water, and air.
Significant green diesel production capacity (800 million gallons per year) exists today in the U.S., Europe, and Singapore, with technology in use by firms including Honeywell UOP and Neste Oil. The process of producing green diesel is less expensive than other methods for creating sustainable jet fuel. The wholesale cost – about $3 a gallon with U.S. government incentives – is competitive with petroleum jet fuel. Quickly creating a market for hundreds of millions of gallons of sustainable advanced biofuels will accelerate biofuel production.