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Waste, not watts

Sustainable aviation fuel makes significant progress

For all the attention the eVTOL movement has received, it sometimes feels like we are on the cusp of trashing our engines for electric motors and our fuel tanks for battery cells. But, at least in the near to mid-term, the power of choice won’t be watts. It’s waste.
Illustrations by Andrew Baker
Illustrations by Andrew Baker

Sustainable aviation fuels (SAF) represent a potential breakthrough in our competing desires to fly far and fast, all while lowering our carbon footprint. Traditional jet fuel offers an incredible amount of power per pound. And despite the fact that today’s turbine engines are much more efficient than those from 40 years ago, it’s clear the world is ready to move on from the environmental impact caused by conventional jet fuel. Electric propulsion, while promising, has yet to offer anywhere near what we currently enjoy in terms of range, payload, or speed, especially for turbine operators. SAF bridges the gap.

First introduced more than a decade ago, SAF has rapidly progressed into a promising replacement for petroleum-based jet fuel. It was originally dubbed biofuel, but the increasing variety of raw source materials spawned a more inclusive marketing term. Today SAF can be produced by an astounding array of organic and inorganic materials. Municipal solid waste, including product packaging, grass clippings, furniture, and bottles, has great potential because of its vast supply. Cellulose waste, such as excess wood and forestry products, has already been proven as technically viable and marketable, as has used cooking oil. Crops such as jatropha and camelina have high fat contents, making for great fuel sources, although with the typical downsides of using agricultural land for fuel production. Other processes that show potential, but aren’t yet economically viable, include algae and something called power-to-liquid. This process takes energy produced from renewable sources, water, and carbon dioxide from the air, and converts it to fuel. It’s like hitting the reverse button on the fuel burning process.

Each SAF production method has environmental advantages and disadvantages, but according to a report by the Air Transport Action Group, SAF has the potential to reduce aviation’s greenhouse gas emissions by 80 percent. With commercial aviation’s commitment to cap carbon dioxide emissions at 2020 levels, and halve emissions from 2005 levels by 2050, only SAF seems to have the current mix of easy swap-in, economics, and environmental benefits.

Commercial aviation’s push to reduce emissions is one reason SAF is starting to show up at GA airports. But are operators ready for it? “Having information available for pilots has been our major hurdle,” said Steve Malone, the executive vice president of finance and business operations at Sun Air Jets, an FBO chain and charter operator with locations at Van Nuys and Camarillo, California, that has been stocking SAF for months. Malone said uptake has been slower than anticipated, in part because pilots have many questions about the regulatory issues of introducing it to their jets.

Currently all available SAF is drop-in approved, meaning it doesn’t require any approvals, paperwork, flight planning changes, or documentation. While it is likely to change in the future, today SAF is blended with traditional jet fuel at concentrations between 10 and 50 percent, and meets the same chemical composition specifications as full petroleum-based Jet A. Sun Air Jets segregates its SAF for customer transparency, and to track how much is being sold, but it’s not a requirement. Theoretically an FBO could offer SAF without the pilot even knowing it was being dispensed.

Recently Williams announced it had tested full SAF in the FJ44 up to Flight Level 450 with good results, and it’s conceivable that 100-percent SAF will work for other engines as well. But to this point, ASTM, the organization that sets the chemical standards for jet fuel and avgas, has given expedited pathways for any blend up to 50 percent. Beyond that will take significantly more time and investment to study, certify, and distribute.

Advancing technology is only one factor needed for widespread adoption, the other is obviously demand. So far business aviation has lagged the commercial aviation sector, but that is slowly changing. Epic Fuels, Signature’s fuel supplier, has promoted more widespread adoption, especially in California. Sun Air Jets is a Signature Select location that uses Epic fuels. Maloney said the impetus for the company to offer SAF came from a desire to serve customer demand. “Especially in California you have a high awareness of the greenness of aircraft use,” he said. “So, if these folks can reduce their footprint, that’s a good story.” Critically, the company’s own corporate goals also factored into the decision. “Putting gas in the airplane and taking it flying is the most carbon-intensive thing we do, so SAF helps that.” Although Sun Air Jets has installed solar panels, changed lights to LED, and taken other steps, their charter business makes the biggest environmental impact.

Illustrations by Andrew BakerThrough Epic, Sun Air is offering a deal to help promote adoption. Although the current market rate for SAF is between 50 cents to a dollar more per gallon than traditional Jet A, an anonymous company is paying the difference as a way to gather carbon credits. Tracking the sales is critical for the relationship, one reason the supply is kept distinct from traditional Jet A.

As companies look for ways to make environmental goals, SAF demand should steadily increase. Hawthorne has added SAF to its chain of FBOs. Will Harton, director of business development, said initially SAF will be available on a per-load basis, but as demand increases, so too will supply. Like Sun Air Jets, Hawthorne decided to offer SAF both from a desire to be early into the market, and also to meet their own corporate goals. “Hawthorne corporately and our financial backers are concerned about sustainability and making sure we are a responsible corporate citizen,” he said.

Aviation organizations, government, and aircraft manufacturers are starting to coalesce around a future where SAF is a dominant fuel. A group of leaders on the House Committee on Transportation and Infrastructure, including Representatives Sam Graves, Peter DeFazio, Garret Graves, and Rick Larsen, sent a request to the Government Accountability Office asking it to address barriers to the deployment of SAF. Every jet that comes out of Gulfstream’s Savannah facility goes to the buyer with a load of SAF, as do the jets from Cessna.

As research progresses and prices continue to come down, it’s not a stretch to see the business go from 60 million gallons pumped in 2020 to more than 1 billion gallons a year by 2025, as Commercial Aviation Alternative Fuels Initiative Executive Director Steve Csonka has predicted.

There’s no doubt that the days of conventional Jet A are numbered. “We’re proud to be on the straight edge of that,” Maloney said. “This is the future.”

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Ian J. Twombly

Ian J. Twombly

Ian J. Twombly is senior content producer for AOPA Media.

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