Estimated reading time 17 minutes, 15 seconds.
Sustainable Aviation Fuel (SAF) — if you haven’t heard of it yet, you’ll likely find it hard to ignore for much longer. Simply put, it’s a sustainably produced, drop-in jet fuel that promises drastic reductions in carbon dioxide (CO2) emissions. While the fixed-wing world has been exploring its use for over a decade — Virgin Atlantic performed the first “biofuel” test flight on a commercial aircraft back in 2008, and several hundred thousand flight hours have already been completed using SAF — the rotary-wing industry has been a lot slower to embrace it. Until now.
In March this year, Bell announced it would be using SAF to help power its fleet of demonstration aircraft, as well as all aircraft at the Bell Training Academy. In June, Safran and Airbus celebrated the first flight of a rescue helicopter (an Airbus H145) powered by SAF, with German operator ADAC Luftrettung recording the landmark. A couple of days later, Airbus then put out a call for industry members to join a rotary-wing SAF user group. The momentum is shifting.
“You don’t need to modify your aircraft, there is no difference in performance, and there aren’t long-term considerations that you need to take into consideration.”
“I think it was a work that was already in progress but it has been accelerated by [the] Covid [pandemic],” said Regis Magnac, VP of energy, leasing and global accounts at Airbus Helicopters. “I think that Covid has made a such a thunderstorm in the global industry, and you’ve seen a lot of governments saying that ‘aviation is going to restart, but we want it to restart in a different manner.’ . . . All stakeholders are challenging themselves on having a different approach to the new world, rather than just ‘copy-and-paste’ what we did before.”
SAF is one of several initiatives the industry is using to curb the level of CO2 emissions, including the use of hybrid power, fully electric power, and enhanced efficiencies through new engine and airframe designs. However, the widespread adoption of SAF could achieve significant CO2 reduction without the need for any new technology within the aircraft or engine, or for suppliers and airports to build new fuel delivery systems.
Currently, SAF is only used as a blended product, and is provided to end users ready-blended at up to a 50 percent ratio (depending on the blending agent) with standard Jet-A/A1 fuel. Confusing matters somewhat is a broad use of the terminology: SAF is generally used to refer to both the drop-in ready blended product, as well as the “neat” product, created from sustainable sources.
That blending agent — the neat SAF — can come from a variety of sources, including used cooking oil, plant oils, trash, wood waste, waste gases, sugars, purpose-grown biomass, and agricultural residues. Specialized production facilities convert these materials into the pure hydrocarbons found in jet fuel.
The level of greenhouse gas reduction a SAF provides is a complex calculation, and different types of SAF will have different sustainability or carbon index scores. However, they should all deliver a net reduction in emissions compared to traditional Jet-A/A1 fuel, as they are consuming carbon from CO2 already in Earth’s biosphere, rather than from fossil fuels contained within the ground. If the entire process used to create it (growing, harvesting, processing, refining and transporting it, as well as all the equipment needed to do these tasks) meets certain sustainability requirements, it can be called a SAF.
This sourcing element is important. Palm oil and corn grain are both biofuel sources, but they may not have good carbon footprints due to the deforestation required to create some plantations and the CO2 emissions from farming the crop. So, not everything that would be considered a biofuel is sustainable, and the biofuel name isn’t broad enough to include some of the some of the fuel sources considered sustainable enough to create SAF — such as municipal waste.
Fuels used in aircraft must be certified to the ASTM D1655 standard. Therefore, this is the standard that SAF blended with Jet-A must meet (having first met the requirements of ASTM D7566), showing it has the same qualities and characteristics as conventional jet fuel. This is what allows OEMs and fuel suppliers to adopt SAF without having to redesign or modify their aircraft, engines, or infrastructure.
To meet the D7566 standard, each SAF has to complete a strict testing process, from labs, to bench test, to flights, to ensure that it’s safe and works as well as Jet-A/A1. Following this, a body of experts from the aviation and petroleum industries will determine the correct specification for the fuel.
Regulatory agencies and industry stakeholders around the world have their own test and approval processes for SAF, and have issued guidance to allow its use once it has been blended with Jet-A/A1 fuel.
“It’s only recently that we’re starting to see rotor aircraft, engine manufacturers and HAI come to the fore and say helicopter engines may use SAF,” said Keith Sawyer, manager of alternative fuels at Avfuel Corporation. “However, until it’s in the actual operations manuals that says SAF when blended to [ASTM D]7566 and then recertified to [ASTM D]1655 is an acceptable jet fuel to be used in rotor aircraft engines — until that happens, we’re going to see modest adoption, in my view, of SAF in the rotorcraft industry, particularly in the United States.”
While it’s only recently started making rotary-wing headlines, SAF in the helicopter industry isn’t new. According to Jean-Baptiste Jarin, sustainable fuels deputy program manager at Safran Helicopter Engines, the OEM began testing SAF in its engines back in 2013 — but there was no appetite for its use in operations at the time.
“We’ve been having discussions with operators over the last year, especially in Europe and North America, who are understanding that regulations may ask our industry to use a given amount of SAF every year,” he said.
The European Commission has confirmed that the ReFuelEU Aviation initiative, for example, will gradually scale up the adoption of SAF by mandating an increasing percentage of it to be used in flight operations over the coming decades.
Across the Atlantic, California and Oregon have added SAF as an eligible credit generator in their low-carbon fuel programs, and Canada’s proposed clean fuel standard (due to begin at the end of 2022) is set to do the same. And while the Sustainable Aviation Fuel Act, introduced by Rep. Julia Brownley (D-Calif) in November 2020, is some way from being passed into law, it aims to incentivize the production of SAF and help the aviation sector to reduce its carbon footprint.
“We decided to be proactive for our community and support them in understanding not only the regulations, incentives, penalties and so on, but also in facilitating the deployment of SAF within their fleets,” said Jarin.
ADAC is the most high-profile example of this. Safran’s discussions with the operator regarding SAF began in April, and the first flight took place just seven weeks later.
With the 40 percent blend used for the flight — using a blending agent produced by TotalEnergies at its refinery in Normandy from used cooking oil — the ADAC fleet could achieve a 33 percent reduction in CO2 emissions. With more than 3.3 million kilometers flown each year, that equates to a reduction of around 6,000 tones of CO2.
“Safran was very proactive in the SAF supply [to ADAC],” said Jarin. “We do not manufacture SAF — but we understand well how it’s manufactured, how it’s certified, how it’s produced, and then distributed.”
The flight, said Jarin, helped promote that SAF is available as an option for helicopter operators, and showed “Safran’s willingness to be active in the decarbonization roadmap.”
The next step, he said, would be to show the medium-term benefits of flying with SAF over the next few years.
“We want to show the industry that flying daily with SAF is good for the operations, and might be good for the maintenance and local emissions,” he said. “We see some potential to reduce not only the CO2, but also some local pollutants. As such, we will run several tests with different SAFs in the coming months.”
While ADAC used a 40 percent SAF blend for the flight, Safran’s engines are certified to be used with SAF at a blend of up to 50 percent. The longer-term third step for Safran is to certify its engines to run with up to 100 percent SAF. Hand in hand with this, the OEM is working with operators, universities and energy manufacturers to develop an “e-fuel” roadmap.
Synthetic e-fuel, also known as power-to-liquid kerosene, is created by using a “green” form of electricity (wind, hydro, solar or nuclear) to split water into hydrogen and oxygen. The hydrogen is then combined with carbon dioxide captured from the atmosphere to form a hydrocarbon with zero net greenhouse gas emissions. Work to develop this technology continues.
Understandably, industry members have a lot of questions about SAF now that it has appeared on the horizon.
“What they are asking Safran is, basically, is it safe to operate SAF up to 50 percent?” said Jarin. “The answer is ‘Yes, as long as it is certified as ASTM D1655.’ Does it have any impact on my engine maintenance? The answer is ‘No’ — and the only impact we could see would be positives.”
To help demystify the topic, Airbus Helicopters is organizing a webinar to be held in mid-July in which SAF experts will explain how the sustainability of a fuel is calculated, how it’s regulated, and the official paperwork available to demonstrate your carbon reduction if you use the fuel.
“I’m very excited at the idea of decarbonizing our industry,” said Airbus’s Magnac. “Airbus has been working on those [SAF-related] topics for a few years, but now there’s a focus and we wanted to amplify it.”
Neat SAF can emit up to 80 percent less carbon than Jet-A/A1, he said. So, a blend of 50 percent would still provide an immediate 40 percent reduction in emissions.
“Today, all Airbus made products are certified to run with a blend of Jet-A1 and SAF fuel, and the blend cannot exceed 50 percent of SAF. So, why do we wait? Let’s do it.”
Cost and distribution appear to be the major issues — at least for the time being. Currently, SAF can be anywhere from twice to four times the cost of Jet-A/A1. However, there may be government incentives available to help lower the cost, and the production of SAF is expected to become cheaper over time, to the point where it may even compete with conventional fuels as costs are lowered.
“We have seen the price gap narrow, and many things are going to drive that, but I don’t think it’s much more than availability, demand and volume,” Doug May, VP of flight at Bell, told Vertical. “The volume of SAF that’s available today isn’t at the level of Jet-A, so the producers will be helped and gain efficiencies as the demand and the volume increase, and so we’ll see that price differential continue to narrow.”
Bell’s decision to use SAF for its training and demo fleets was driven by parent company Textron’s wider push towards “doing the right things for the environment,” he added.
“I think you’ll find a number of companies like Textron who are very much interested in sustainability and will incorporate SAF as a viable means to directly impact the carbon footprint for their aircraft, and because it is a drop-in replacement it is a good and viable means by which to reduce your carbon footprint,” said May.
He said Bell was seeing a lot of interest in the new fuel source, and that the OEM was working to get the word out and help people understand that SAF is a ready replacement for Jet-A/A1.
“You don’t need to modify your aircraft, there is no difference in performance, and there aren’t long-term considerations that you need to take into consideration,” said May.
In terms of what operators can do to help enhance the availability of SAF — and incorporate it into their operations — the general advice from fuel suppliers is to tell your FBO, airport, and fuel supplier that you want it, and commit to purchasing it if it becomes available. You could also contact your local, state, and federal government representatives to register your interest in SAF.
“The reason California is an attractive market for SAF is there are significant incentives available today and in the future,” said Sawyer. “We anticipate similar state incentives to become available in Oregon and Washington states . . . and that’s a very important element.”
Magnac said Airbus’s SAF user group aims to pull the various industry stakeholders together to help drive change. “You have people that are trying and starting to produce [SAF], the network of distribution is not there in the middle, and then you have customers that would like to use it, but don’t find it,” he said. “We want to find out what operators need, collectively, and how can we support that, collectively, to make it available faster, to have the price go into a reasonable zone, to have appropriate technical feedback if we need, [and] to have the energy providers liaising with the end users in the same effort.”
Despite a slow start, the helicopter industry appears well set to make up for lost time in adopting SAF and reducing its carbon footprint. If aviation is to be sustainable in the long term, it must surely attempt to do so.