Turn on, drop in: sustainable aviation fuel

‘Drop-in’ alternatives to fossil fuels are the best way of addressing the drive for ‘zero carbon’, despite much-vaunted rival new technologies, claim sustainable aviation fuel proponents. Robin Gauldie investigates

Alternative new, ‘clean’ power sources have their proponents, notably ‘green’ and ‘blue’ hydrogen and electricity. None, though, promise a solution as relatively quick and easy to adopt as sustainable aviation fuel (SAF).

Hydrogen-based technology for aviation is still in its infancy and has its critics. ‘Green’ hydrogen – the only truly ‘clean’ version – is produced by electrolysis, splitting water into hydrogen and oxygen, and requires a zero-carbon power source such as solar energy to be truly green. ‘Blue’ hydrogen, produced by splitting natural gas into hydrogen and carbon dioxide (which is then captured) is a less ideal fuel.

Electrically powered rotorcraft, drones and fixed-wing aircraft are already a reality – though still only just off the drawing board – and show some promise for emergency medical services (EMS) use. As with electric road vehicles, though, battery technology – the key to prolonged endurance – is lagging behind, partly because of its dependence on large supplies of lithium, a relatively rare element. Additionally, electrically powered aircraft need to be designed from square one, employing innovative materials and technologies. By contrast, SAF is a ‘drop-in’ solution, and recycled cooking oil – on which most second-generation biofuels are based – is in plentiful supply.

“SAF can drop straight into existing infrastructure and aircraft,” noted Andreea Moyes, Global Aviation Sustainability Director at Air bp, a major manufacturer of SAF made from used cooking oil and animal waste fat. Any aircraft certified for using the current specification of jet fuel can use SAF, she added.

In the second of a two-part series that looks at how the aerospace industry is responding to the climate emergency, Jonathan Falconer reviews the use of composite materials, smarter working…

New propulsion technologies, such as batteries, hydrogen fuel cells and hydrogen as a fuel, for aviation use are not likely to reach commercial scale production until well into the 2030s, according to Robbie Bourke, Partner, Transportation and Services, Climate and Sustainability at Oliver Wyman, a global management consultancy.

“It will take several more decades for the current fleet of fossil fuel-propelled aircraft to be replaced fully by new planes with low-carbon technology. That means SAF – a gallon of which can emit up to 80% less carbon dioxide than conventional jet fuel – will be needed through much of this century for use in older aircraft,” he stated.

Total Energies, which in 2021 started production of sustainable aviation fuels in France, claims its SAF can be used directly in fixed-wing and rotorcraft engines and without any modification to storage and distribution infrastructure.

As yet, for the mainstream civil aviation industry, talk of SAF may be little more than a load of hot air.

“SAF is essential to commercial aviation’s journey to net zero,” said Boeing Chief Sustainability Officer Chris Raymond. “By the late 2030s, we estimate more than 40,000 non-hydrogen commercial jets will be in service. Emissions from these aircraft will need to be mitigated with SAF. Aviation must focus on developing and scaling SAF,” Raymond added.

Yet Boeing Chief Executive Officer Dave Calhoun acknowledges that SAF makes up less than 1% of worldwide fuel consumption and trades at more than twice the price of conventional jet fuel.

However, conventional fuels are currently heavily subsidized and there is mounting pressure on governments to stop subsidizing airlines with tax breaks on fuel. The more extreme wing of the global environmental movement, exemplified by Swedish activist Greta Thunberg, would like the world to give up flying altogether.

The EMS / search and rescue (SAR) sector, though, has an advantage in public relations terms over the broader aviation sector. Environmentalists may vent their spleen at politicians jumping in and out of helicopters, financiers heading to Davos by private jet, and package holidaymakers loading into flights to mass tourism destinations like Orlando, Cancun or the Costa del Sol. Aviation is a big, soft target for eco-activists, ignoring the fact that the broader aviation industry accounts for as little as 2% of global CO2

emissions, according to the International Energy Agency. It’s less easy to point the finger of blame at essential life-saving services such as air ambulances, SAR operators or aerial firefighting. Could that be leveraged into preferential treatment for those sectors?

Further, when fully adopted, SAF could free aviation from the unpredictable peaks and troughs of conventional fuel prices, which have for decades been vulnerable to conflicts and political upheaval in oil-rich regions. That is another incentive for governments to offer tax incentives to companies that embrace sustainable fuels. President Joe Biden’s Inflation Reduction Act, enacted in 2022, raises the existing $1 blender’s tax credit for SAF by up to 75 cents per gallon on a sliding scale linked to the level of emissions per gallon versus conventional jet fuel.

The Biden administration has also put biofuels, made from a range of feedstocks, at the forefront of its ambitious target of producing three billion gallons of biofuel-based SAF by the end of the decade.

In 2022, the UK government launched its Advanced Fuels Fund, awarding £165 million in grant funding to five British companies with the aim of having at least five commercial-scale SAF plants under construction by 2025.

Critics of biofuels – many of them advocates of rival ‘clean and green’ power sources for aviation, such as hydrogen, so-called ‘e-fuels’ (which fuse hydrogen with carbon) and, of course, electricity – allege that biofuels produce almost as much pollution as the fossil fuels they could replace. The Aviation Environment Federation, an environmental non-governmental organization, claims that SAFs produce as much CO2 as conventional aviation fuels.

Such allegations are naturally contested by fuel manufacturers.

Finnish company Neste, another leader in the field, claims its patented renewable SAF, made from sustainably sourced renewable waste and residue raw materials such as used cooking oil and animal fat waste, reduces greenhouse gas emissions by up to 80% over the fuel’s life cycle, compared with using conventional jet fuel.

Disruptive fuel and aircraft technologies are playing a key role in the aviation industry’s contributions to achieving global sustainability targets. Experts share with Lauren Haigh how they are approaching the…

First-generation fuels – made from feedstocks derived from high-calorie conventional crops such as palm oil, maize, oilseed rape and sugar cane – raised fears that demand from fuel manufacturers could create shortages of such crops for human consumption. Over the last decade, though, those fears have been partially addressed by developments in ‘second-generation’ biofuels based on non-edible plant cellulose and even certain bacteria.

Most promising, though, at least in the short term, may be those SAFs based on recycled used cooking oil – of which almost every country in the world has a plenitude.

Biofuels like these are already beginning to make SAF a realistic option. In 2021, German operator ADAC Luftrettung first flew an Airbus H145 rescue helicopter powered by a blend of conventional JET-A1 fuel and biofuel made from used cooking oil by TotalEnergies.

Safran Helicopter Engines – which built the engine that powers ADAC’s H145 – also supports the claim that using 100% SAF offers a potential reduction in CO2 emissions of 80%. Due to ASTM fuel specifications, Safran engines are currently certified to operate on a mix of up to 50% of SAF with conventional fuel, but the goal of flying with 100% SAF came closer in February 2023, when a Safran-engined Bell 505 became the first single-engine helicopter to make a flight fuel

ed solely by 100% SAF – the first-ever single-engine helicopter to do so. The fuel used was developed jointly by Neste and Virent, a subsidiary of Marathon Petroleum Corp, which manufactures an aromatics component made from renewable plant sugars. Added to neat SAF, this eliminates the need to blend SAF with petroleum fuel.

“The SAF supplied for this test flight by Neste and Virent is a 100% drop-in replacement for petroleum-based aviation fuel, requiring no engine modifications,” stated Linda Deslatte, Vice President of Commercial Programs, Commercial Business at Bell.

However, making SAF a viable proposition for EMS and SAR companies ultimately depends on the bottom line. The price of SAF at the pump is currently significantly higher than the bill for conventional fuels.

“The hardware (engine) is not the problem,” said Siegfried Axtmann, founder and chairman of FAI Aviation Group, a Nuremberg-based global air ambulance operator. “Availability and an extremely high price for the SAF is the issue. The price at the pump is still too much, and availability will continue being an issue in the near future.”

SAF, though, is a rapidly evolving technology, according to Jonathan Wood, Vice President Commercial and Technical Management at the Renewable Aviation Business Unit at Neste. “Neste will increase its annual SAF production capability to 1.5 million tons a year by the beginning of next year,” he said.

“The key to greater acceptance and deployment of SAF is reduction in costs,” stated Moyes. “The higher cost of sustainable fuel is down to a combination of the current availability of sustainable feedstocks and the continuing development of new production technologies. As the technology matures it will become more efficient and less costly.”

“Production of SAF is limited, as the higher cost for SAF is preventing wider uptake. Air bp is working on helping to create more demand in the short term, which will lead to more production and lower costs,” she added. “In the short term, interim support from governments through policy incentives is needed.”

Wood concurred: “Governmental support in the form of mandates or incentives is crucial.” He continued: “We see encouraging developments across the globe with the UK policy proposals for an SAF mandate requiring 10% of aviation fuel to be renewable by 2030, as well as incentives to help promote SAF production plants in the UK. Whilst the EU is nearing completion of its ReFuelEU regulations, the USA has adopted incentives, and governments in the Asia-Pacific region are also working on regulatory support.”

Carlos Barrasa, Commercial and Clean Energies Director at the major Spanish energy company Cepsa, is also optimistic. “Supply and demand will set the price,” Barrasa told the Dow Jones Oil Prices Information Service in December 2022. “Right now, it’s around 2.5 times as expensive as conventional fuel. A target of between 1.5 and two times as expensive in the medium term should be within reach. I think cost won’t be the issue in the long term.”

After price per gallon, the other big issue for EMS operators is availability. From the point of view of medical evacuation and air ambulance providers, SAF needs to become as ubiquitous as conventional fuels are now, especially in smaller, remoter airfields.

There are indications that the worldwide rollout of SAF provision is gathering pace. In 2018, according to the International Energy Agency, only five airports worldwide (Bergen, Brisbane, Los Angeles, Oslo and Stockholm) had regular biofuel distribution.

“The complexities of creating supply chains and moving SAF around Europe mean it is currently out of reach for many potential customers,” said Moyes.

Air bp has supplied SAF at more than 30 locations across three continents, but producing SAF in every country and making it available at every airport ‘is neither viable nor a cost-effective solution’, she added.

Instead, Air bp favours the implementation of ‘mass balancing’ centres from which SAF can be delivered into select air transport hubs, simplifying logistics.

In May this year, Neste and Miami-based World Kinect, a global energy management company, announced an agreement under which Neste will expand the supply of its SAF to enable World Kinect to increase the number of European airports it can supply to more than 40. This would pave the way to making SAF available at more than 100 airport locations in World Kinect’s worldwide network.

“Fundamentally, SAF is a drop-in solution that can be used in existing engines and fuel infrastructure and is available to be delivered to any location, so long as the demand is there,” said Wood.

For air medical and rescue operators, converting to sustainable fuels may seem a challenge. But as SAF becomes cheaper and more widely available, it needn’t be an intimidating one. Where there’s a will, there’s a way, and it appears that among governments, suppliers and end users, the will is there.

Robin Gauldie is a former editor of Travel Trade Gazette and other travel and tourism industry titles. Now a freelance journalist specialising in travel, aviation and tourism, he writes for a variety of international consumer and business publications including International Travel & Insurance Journal, AirMed and Rescue, and Financial World.