Flying the friendly skies on green fuel

By Lucy Stitzer June 15, 2022 | 10 MIN READ

Soil and Crop Management

The Dirt

Sustainability in aviation sets the flight plan for today and tomorrow. Governments around the world have challenged the airline industry to convert to completely sustainable fuel by 2050. But what is Sustainable Aviation Fuel (SAF)? Where is it going to come from? What does SAF mean for our food and agriculture system? We look at this complex issue fueling the aviation industry and what it means for you.

Sustainable Agriculture

Flying the friendly skies on green fuel

What is Sustainable Aviation Fuel? Where is it going to come from? And what does it mean for our food and agriculture system? We look at this complex issue fueling the aviation industry and what it means for you.

Soil and Crop Management

By Lucy Stitzer June 15, 2022 | 10 MIN READ

The Dirt

Sustainability in aviation sets the flight plan for today and tomorrow. Governments around the world have challenged the airline industry to convert to completely sustainable fuel by 2050. But what is Sustainable Aviation Fuel (SAF)? Where is it going to come from? What does SAF mean for our food and agriculture system? We look at this complex issue fueling the aviation industry and what it means for you.

You put your household garbage in the trash. Just imagine that within a few years, that garbage will no longer just sit in a landfill; instead, it will be used to power the jet to take you on a business trip to London or on vacation to Tahiti. Or consider that the used cooking oil to make your french fries from McDonald’s will be collected, refined, and turned into Jet A fuel, the fuel all jet and turbine airplanes use.

And as you drive through America’s heartland, you see farmers in tractors planting soybean seeds, some of which will be used to fuel the airline industry.

Why is SAF so important in the drive for sustainability?

Commercial and transportation aircraft today use a lot of fossil fuels. A lot of fossil fuels.

Every single day, the U.S. Federal Aviation Administration deals with more than 45,000 flights involving 5,400 aircraft and 2.9 million people. That’s more than 16 million flights annually, 10 million of them on scheduled airline flights. The airlines handle 12 million pounds of our supply chain each day as well. On a global scale, the numbers are even more impressive – 500 million passengers, riding in aircraft that can consume as much as a gallon of fuel every second. It sounds inefficient, but really because of the passenger load, a large plane like a 747 gets 100 miles per gallon per person.

In 2022, there were 28 million flights, most likely the amount will increase back to the pre-covid number of 40 million flights. A seat on a flight between New York and London emits about 1/10th of one’s annual emissions, around 1.65 tonnes of carbon dioxide. According to The Nature Conservancy, the average person in the U.S. emits about 16 tons.

“The average level of consumption for a new car is approximately 35 miles to the gallon, which means that in order to burn 18,000 gallons of fuel, which would be used in a single flight between New York and Europe, a car would have to travel more than a half-million miles.”

Simple Flying Editorial Team, May 9, 2021

Now, can you imagine flying through the sky and not adding any CO2 to the atmosphere? That could happen. Sustainable aviation fuel (SAF), also known as synthetic fuel or synfuel, is touted as the solution to the aviation industry’s contribution to reducing greenhouse gas (GHG) emissions and ultimately holding back climate change.

A Big, Hairy Audacious Goal: The SAF Challenge

The Sustainable Aviation Grand Challenge led by The Department of Energy, The United States Department of Transportation, and the U.S. Department of Agriculture is encouraging enough production of SAF to:

  • Achieve a minimum of 50% reduction of GHG compared to aviation fuel
  • Supply at least 3 billion gallons of SAF by 2030
  • Replace all petroleum-based jet fuel, about 60 billion gallons a year, by 2050.

By using alternative feedstocks, SAF can reduce emissions between 40% to 80%.

The purpose is not only to reduce environmental impact but also to support energy independence, create jobs in agriculture, forestry, infrastructure, research and development and other areas where America already exceeds at production’

The global airline and transport aviation industry uses about 60 billion gallons of fuel per year. Pre-covid, 98 billion gallons were burned a year while transporting people and products around the globe. To replace just 10% at today’s usage would mean we need 6 billion gallons of SAF, globally. Where are we now?

The International Air Transport Association (IATA) is a trade association for 290 transportation and passenger carriers across 120 countries and represents 82% of total air traffic. In 2021, IATA estimated that the SAF industry made about 26 million gallons. This equates to…less than 1% of total global volume.

, Flying the friendly skies on green fuelEven so, the industry seems optimistic and IATA states that airlines have about 3 billion in forward purchase agreements and at least 45 airlines now have experience with SAF. Markets and Markets projects SAF revenue to go from $219 million in 2021 to $15,716 million by 2030, at a very aggressive growth rate of 60.8% during the forecast period. But not every country can afford, or desires (think OPEC countries), to fill their planes with SAF. As shown in the chart, Europe, followed by the U.S., lead in creating the SAF demand.

Ideals and reality don’t always align – at least, not at first. As laudable as the purpose behind the SAF Challenge may be, several practical matters still require further attention.

For example, matters of reliability – and safety – need to be clarified, if only to reassure the flying public that the shift to SAF won’t endanger anyone. Consider the special composition of today’s jet fuel – Jet A — and remember that it didn’t come into being without a reason.

What is Jet A?

Jet A is the fuel that all airplanes use. All jet fuel must have good performance and be able to operate in all conditions. It is a particular mixture of gasoline and kerosene derived from the classic barrel of oil. It also contains a complicated combination of over two thousand chemicals and additives.

Of course, when you are flying at 25,000+ feet over the ground, or even 1,000 feet, you want to make sure the aviation fuel has just the perfect combination to fuel the flight. Jet and turbine engines are delicate machines that have been refined for eight decades. They won’t run on just any fuel formula. It must be clean enough so it won’t clog the engines, have a low freezing point for cold temperatures such as -65 F up in the Earth’s troposphere, contain an anti-icing additive, and high octane for fuel-efficiency.

What is the source of SAF’s Wonder Fuel?

It is called feedstock. And it can come from almost anywhere. There are three different generations of feedstocks available. The first generation is ready to go and the second and third will need better technology both to create SAF as well as to scale.

, Flying the friendly skies on green fuel

Some of these sources are incredibly hard to believe they could be burned as Jet A. A garbage bag full of old clothes? Yes, jet fuel and diesel can be made from household garbage. This amazing technology combines a gasification process and is converted into synthetic gas. This ‘syngas’ is then upgraded to a transportation fuel using a well-known technology developed in the 1920s called Fischer-Tropsch. Besides municipal waste, this technology is what converts agricultural residues and small woody crops.

But we have a long way to go before the technology can scale up to all the material in landfills. Right now, the focus is on dry biomass. The USDA  and the U.S. Department of Energy created a Billion-Ton Report that states that one billion tons of biomass can be collected sustainably each year to produce 50-60 billion gallons of low-carbon biofuels. Some of which will be used for the aviation industry. An added benefit to using dry biomass is the added revenue for farmers. It can increase income in rural America and support farming communities.


But The Sustainable Aviation Grand Challenge reignites the long-term debate about how we use our agricultural products. Should our enormous productive capacity be channeled to feeding people…or machines? Do our environmental concerns trump our obligation to feed a hungry world?

Can we do both?

Sustainability also applies to food security, not just environmental protection. Will crops used as a feedstock interfere with feeding animals and people? Because there is such a variety of feedstocks, the reliance will not be on just one. Having said that, right now, the technology available to scale is mostly in favor of oils from soybeans, canola, palm, as well as other agricultural residues.

, Flying the friendly skies on green fuel

Turbulence ahead: Sustainability Requirements

The glidepath to the SAF Challenge won’t be without headwinds and turbulence, either. It’s all about the life cycle analysis, meaning that the fuel must be sustainable over its entire lifecycle. Reducing emissions is the sustainability option that receives the most attention, but other considerations are legal, social, environmental, and managed planning.

For instance, especially in the developing world, is the feedstock made with paid labor? Does it interfere with their food? What about the environmental considerations?

Regarding plant feedstock, it is not enough just to say that the plant takes CO2 out of the atmosphere and the airplane puts it back while burning the fuel. That alone would be carbon neutral. But there is the fuel made to plant and harvest the crop, as well as transport and refine it into SAF. And, while plastic feedstock from landfills sounds very exciting, the fossil fuels to make the plastic contributes to more GHGs in the lifecycle than biomass’s carbon-neutral lifecycle.

, Flying the friendly skies on green fuelEven so, compared to drilling, refining, and transporting oil, depending on the feedstock, SAF can save between 40% to 80% in emissions.

Right now, SAF is called a ‘drop-in’ fuel that is blended with Jet A to create up to a 50/50 ratio. It is called a ‘drop-in’ because at this maximum ratio no modifications need to be made to the engine or other components. However, most airlines and engines are currently approved to a 10% SAF mixture.

Who decides if SAF is safe to fly?

The American Society for Testing and Materials (ASTM) International makes products safer and improves international standards to make goods easier to trade around the world. As one of the largest standards-development organizations in the world, it has established the criteria for the use of SAF and is relied on by the FAA for their testing requirements.

, Flying the friendly skies on green fuel

If the SAF is deemed equivalent to conventional jet fuel, then it is certified to drop in without any regulatory approvals.  If you are curious about the technical aspects of SAF, click here for the U.S. government review of the technical pathways.

It is expensive!

And then there’s the small issue of economics. Is SAF a realistic alternative in terms of cost – or just another greater expense waiting to contribute to ever-increasing inflation?

Expect more for your airline ticket. SAF can cost up to eight times more to produce than petroleum. But it can depend on the type of ‘fuel’ being converted. As of this writing, in the United States, the average retail cost of Jet A is $7.20 a gallon and the average SAF is $8.30. An extra $1.15 or $3.15 a gallon doesn’t seem like much, but if you are filling a Boeing 737 with 6,800 gallons of fuel, it will certainly force passengers to pay more.

On the KLM website, they state that SAF is two to three times more expensive. As a result, they are advising their passengers that they are adding a few euros to their ticket prices based on the distance. The benefit is that each passenger will reduce the CO2 emissions of their flight and contribute to SAF.

Like any new technology, government incentives help reduce the cost. The Low Carbon Fuel Standard in California is incentivizing fats, oils, and grease technology. In addition, the Department of Energy has a $250 million budget allocated to technologies associated with SAF. If incentives are not enough, governments might start taxing the ‘dirtier’ fuel.

, Flying the friendly skies on green fuel

Who is ready to fly and meet The Challenge?

Everyone. The FAA, USDA, EPA, trade associations, airlines, food processors, governments and airlines around the world, and the petroleum industry. Just to highlight a few:

  • The IATA is committed to net zero emissions by 2050. The association plans on achieving Fly Net Zero with 65% SAF, 13% new electric and hydrogen technology, 3% infrastructure and operation efficiencies, and 19% offsets and carbon capture.
  • Right now, Airlines for America, another trade association for U.S. airlines, has also approved SAF, but only up to 10% of a blend with Jet A.
  • Started in 2006, the Commercial Aviation Alternative Fuels Initiative (CAAFI) is a coalition of 450 U.S. and international aviation trade representatives, energy companies, universities, and NGOs. CAAFI encourages the use of alternative jet fuels to promote ‘energy security and environmental sustainability for aviation’.
  • As stated on its site, “Clean Skies for Tomorrow” is an initiative from the World Economic Forum that provides a crucial global mechanism for top executives and public leaders to align on a transition to sustainable aviation fuels as part of a meaningful and proactive pathway for the industry to achieve carbon-neutral flying.
  • The European Landscape is participating, as well.

, Flying the friendly skies on green fuel

What is next on the flight plan?

New technologies to make SAF work well are under development, but not yet ready for prime time. For example, hydrogen is a very promising replacement for electric batteries. Airbus plans to burn hydrogen in their engines for fuel within the next 15 years. The only byproduct here is water! Here is a chart by McKinsey of new fuels and propulsion technologies.

, Flying the friendly skies on green fuel

Before there are clear skies….

This ‘audacious goal’ still must answer a few questions before taking off:

  1. Can this fuel scale to the level of millions of gallons delivered throughout the world with a new supply infrastructure to the refiners?
  2. Is there a long-term food versus fuel debate?
  3. How long before production costs are in line or cheaper than petroleum?
  4. Will SAF always need government incentives?
  5. Right now, this is a ‘drop in’ fuel of up to 50%. What happens to engines after the 50% mark? Do they have to be rebuilt? What if you have an old engine and go to fill up with more than 50% SAF? Will airports need two different fueling systems?

The Bottom Line

Changing an entire industry wholly dependent on petroleum to alternative fuels is an incredible goal. Green transportation can shift the balance of oil production from politically unstable oil-producing countries to the rest of the world, including farmers landfill operators, and food service owners. It can help reduce waste in the messy landfills, pull more carbon out of the air with additional crops, and bring much-needed income to farmers around the world. It will be interesting to see how it unfolds.