Is the Promise of Sustainable Aviation Fuel a Myth?

For all its future glories in the air, will the production of sustainable aviation fuel (SAF) have a negative impact on the ground?



May 24, 2023

DALLAS — Last summer, an assessment by the Center for Biological Diversity (CBD), it will be difficult to accomplish the White House target of meeting 100% of U.S. jet fuel demand with biofuels by 2050 due to sustainability and supply issues.

The CBD is a national, nonprofit conservation organization with more than 1.7 million members and online activists dedicated to the protection of endangered species and wild places.

According to the report, the majority of the feedstocks being evaluated for the production of sustainable aviation fuels (SAF) would have a negative impact on the environment or the climate. The report adds that the development of renewable fuels alone cannot achieve the ambitious SAF production target.

“Once you examine the data, the aviation biofuels boon looks more like a boondoggle,” said John Fleming, Ph.D., a scientist at the Center’s Climate Law Institute and the lead author of the report.

“Aviation is inarguably one of the toughest sectors to decarbonize, but that’s exactly why we need a diversified, comprehensive approach. For Biden to put all our eggs in the biofuels basket is a reckless disregard of climate reality.”

To further complicate the matter, setting a 2050 target can seem disingenuous given that airplanes last, on average, a little over 20 years and that technologies won't likely be widely available for fleet adoption until the 2040s.

The Boeing 2022 ecoDemonstrator will test 30 technologies to enhance safety and sustainability. Shown here, the 2022 ecoDemonstrator – a Boeing-owned 777-200 ER (Extended Range) — after its livery was painted in San Bernardino, Calif., in June. (Photo: Boeing)

Background on the Legislation

The Biden administration announced executive actions in the middle of the pandemic to promote the production of billions of gallons of SAF to aid in meaningful reductions in greenhouse gas emissions.

On September 8, 2021, the U.S. Department of Energy (DOE), the U.S. Department of Transportation (DOT), and the U.S. Department of Agriculture (USDA) entered into a memorandum of understanding (MOU), thus launching the government-wide SAF program.

The administration’s “Sustainable Aviation Fuel Grand Challenge” set a target of sufficient SAF to meet 100% of aviation fuel demand by 2050 by reducing the cost, enhancing the sustainability and expanding the production and use of SAF that achieves "a minimum of a 50% reduction in lifecycle greenhouse gas (GHG) compared to conventional fuel."

However, the report from the CBD concluded the US government can only hope to meet 4% to 38% of the predicted 35-billion-gallon demand in 2050. Moreover, the use of SAFs by airlines would be entirely optional.

The Inflation Reduction Act recently signed by POTUS also contains funds to strengthen SAFs.

Airbus A380 MSN001 SAF flight. Photo: Airbus

To Make Something Out of Nothing

The paper also points out that a lot of the raw materials, or feedstocks, suggested for the manufacturing of SAF are anything but sustainable, even though these biomass-based fuels are intended to cut emissions by 50% compared to traditional jet fuel.

For instance, feedstocks based on food crops produce greenhouse gas emissions comparable to those of fossil fuels and put pressure on food resources. Using animal fats, animal manure, and wood biomass, on the other hand, gives way to environmentally harmful enterprises.

Finally, though possibly sustainable, crop residues, wastewater sludge, and municipal solid waste don't produce enough biofuel to reach the intended goal.

“There’s only so much sewage sludge and crop cuttings, and most other biofuel feedstocks aren’t truly sustainable,” said Fleming.

Indeed, the lead author of the assessment is on order when stating that the US needs to set airplane emissions standards not "mired in the myth of sustainable aviation fuels" and advance electrification, or else any aviation climate goals "could vanish into thin air."

Neste's SAF is called "Neste MY Sustainable Aviation Fuel". Photo: Neste

The Ugly Truth

The sky is not the limit with SAF, however, which Bain & Co partner Jim Harris pointed out in his July 2022 op-ed for Aviation Week.

The technical and infrastructure challenges of producing alternative fuels were thoroughly examined in a recent Bain study on future aviation propulsion technologies, which also projected future economics for the large-scale production of SAF and liquid hydrogen.

Harris' conclusion is that, despite bold projections for technological and operational advances over the ensuing decades, SAF production costs and supply availability will fall short of meeting aviation needs, even with government mandates and incentives that encourage early adoption and investment.

Seasoned Captain Ben K told the Marshall Skill Academy that while it was part of the push toward sustainability, “SAF is not completely carbon neutral; there are emissions when it’s refined, and then transported to the airports. You also still need to grow plants to make it – which takes up things like water, farm space, labour costs, and so on. This is why ‘lifecycle emissions’ is a phrase that pops up a lot in SAF press releases.”

Douglas DC-8-11 N8008D takes off from Long Beach Airport, at 10:10 am, May 30, 1958. The heavy exhaust smoke is a result of water injection. Photo: Boeing Historical Archives

Bottom Line

Four billion passengers are moved by air each year, and the industry supports more than 60 million jobs worldwide. Despite an annual increase in flights, the aviation industry has invested heavily in new technology and operational methods, significantly reducing its carbon emissions, which is 2-3% of global carbon emissions (motor vehicles account for 83% of global emissions).

And, as aviation enthusiasts, we have to acknowledge that, compared to the early passenger jet models that entered service in the 1950s, today's aircraft are over 80% more fuel-efficient.

No one is saying SAF is a panacea for aviation's CO2 emissions, but I agree with Harris' assumption that, unless we are ready to cap aviation traffic, the industry will eventually need to accelerate the adoption of other technologies into its fleet, which will probably take more time to accomplish.

Lowering CO2 emissions is a battle on many fronts, and the aviation industry is leading the way. The companion Center for Biological Diversity report, Flight Path, outlines feasible solutions that include improving aircraft fuel efficiency, making operational and regulatory improvements, and achieving "ambitious advancements" toward a fully electrified aviation sector.

What's your take on the push for SAF production in the industry? Will electric flight and new codified regulations have a more predominant role in the industry's zero-emission goals? Be sure to leave your comments on our social media channels.

Featured image: Neste's SAF is called "Neste MY Sustainable Aviation Fuel". Photo: Neste