Sustainable air travel is an elusive goal. Zero-emission electric aircraft have begun to emerge, but only at a small scale and for short distances. Bio-based sustainable aviation fuel offers the potential for more rapid scale-up because it can be blended with conventional jet fuel for use in existing aircraft and fueling infrastructure. Until recently, sustainable aviation fuel was only available in limited quantities, but new supplies may soon change that.

The Slow Pace of Sustainable Aviation Fuel Uptake

Sustainable aviation fuel (SAF)  stakeholders have experimented with many different kinds of bio-based sources since the early 2000s, including algae, food waste, and agricultural and forest waste, along with cultivated energy crops including oilseeds and grasses as well as corn and soy.

But progress is moving at a snail’s pace. United Airlines, for example, became the first major airline to test sustainable aviation fuel back in 2009 and since then has explored various bio-based sources including algae. The company says it has invested in the “future production” of more than 5 billion gallons of sustainable aviation fuel, but achieving that scale is a long-term goal.

In the meantime, United advises that “production remains very limited,” and very expensive as well, and the airline is not alone. Sustainable aviation fuel accounted for less than 0.15 percent of the total fuel used among 77 leading airlines last year, according to a survey from the European organization Transport & Environment.

Corn, soy oil, and other cultivated crops accounted for more than 30 percent of this fuel used among the airlines T&E surveyed, indicating that agriculture-related carbon emissions could offset much of the gains from using bio-based resources. In addition, 100 percent bio-based fuel is not a complete solution. Also called “neat” SAF, 100 percent bio-based sustainable aviation fuel is not certified for use on its own. Instead, it is blended with conventional jet fuel, making it all the more important to keep agricultural supply chain emissions down to a minimum.

The Electrofuels Solution

Electrofuels are an alternative solution that is gaining ground. Sometimes called solar fuels or e-fuels, electrofuels are synthetic hydrocarbon fuels produced by deploying electricity — ideally from solar power or other renewable resources — to separate green hydrogen gas from water. The hydrogen is then combined with captured carbon to create new fuels that are chemically identical to fossil-sourced fuels, meaning they can be used on their own on a drop-in basis instead of blending with conventional jet fuels.

Read the full article about sustainable aviation fuel by Tina Casey at Triple Pundit.