By Cat Hofacker|June 2021
Steve Csonka will know he’s succeeded when he works himself out of his job as head of the Commercial Aviation Alternative Fuels Initiative. This coalition of U.S. government agencies, air transport companies and fuel producers hosts workshops and directs research to accelerate the production and certification of SAFs, sustainable aviation fuels made from crop residue and other sources. Csonka is among those who believe SAFs represent aviation’s best shot at achieving net-zero carbon dioxide emissions by 2050. Hurdles to this goal include the need to approve additional conversion methods, and policies that incentivize production of SAFs at the level the air transport industry will require — some 500 million tons annually by 2050, according to the Air Transport Action Group. If all goes as Csonka hopes, CAAFI (pronounced CAF-ee) “will likely be sunsetted,” he says. I called him at his Cincinnati home to discuss the road ahead. Here’s our conversation, condensed and edited.
Q: “Sustainability” can mean so many things, so define what it means in the context of sustainable aviation fuels, or SAFs.
A: In general, we’ve been operating under a premise that sustainability refers to social, economic and environmental viability, fundamentally making a concept viable for ourselves and our future generations. Within those three categories, you can also differentiate several other different approaches, like, “What does it mean to be socially sustainable?” We’re trying to make the world better for future generations from several aspects, and we really can’t make something work in one area if it doesn’t work in all of those areas. The big driver for the aviation industry since the 2006 timeframe has been addressing the greenhouse gas aspect of our emissions, or the CO2 specifically, which is our primary greenhouse gas. Prior to that, we clearly had a focus on sustainability aspects from the perspective of lowering community noise, for instance.
Q: Speaking of the community’s interests, feedstocks, or the raw materials for SAF, can’t come from deforestation, for example, or land that would otherwise have been used to grow food crops.
A: When it comes down to looking at feedstocks, we look at issues of food versus fuel, yes, but we will also look at issues of food and fuel. We’ll look at whether palm oil is acceptable because of its link to deforestation. We will also look at whether all palm is the African palm that people fear for deforestation in Southeast Asia. The bottom line is we are very much paying attention to those issues, but not from the perspective of “everything that comes from this category is bad” and “everything that comes from that category is good.” It’s not that way when you get down to the detailed level, and the aviation industry needs to look at that detailed level.
Q: Beyond the environmental benefits, SAFs also could represent economic sustainability for aviation by eliminating the reliance on crude oil.
A: Yes. We suffered through several years of extreme swings in fuel price driven by no fault of our own, but by supply shortages or cartels establishing production levels. We not only started down this path from the perspective of supply surety, but also with respect to price stability. Having more fuel sources provides some stability. I remember in one of those years where we had the worst price swing, the military was relegated to actually stopping training flights and stopping different kinds of missions because they were operating on a fixed budget from Congress, so when the price of the fuel skyrocketed and there was nobody to hand them more money, what option did they have? On the commercial side, it’s a little bit different in that those price changes go immediately into ticket prices, and then you’ll see the second-order effect of dampening travel demand. There’s a lot of attributes associated with the development of these alternative fuels that are attractive, not least of which is potentially less money being exported from our country for the production of petroleum fuel and the development of significant jobs and economic activity, from a rural development perspective.
Q: Can SAF achieve aviation’s portion of what’s becoming a global pledge to achieve net-zero emissions by 2050?
A: It’s not going to get us there alone. We still have inefficiencies with respect to operations and infrastructure, air traffic management. All of those issues need to continue to be addressed in order to get us to a net-zero kind of approach. We’ve got something like a 3% growth rate associated with carbon. We’re trying to cap that level and then start our way on a trend toward reducing that to zero. Will we get there with SAF alone? I don’t know. CAAFI has been charged with putting the fundamentals in place that’ll allow that to happen, removing the technical obstacles. It’s tough to envision a zero future when you’re growing at 3%. What I can tell you today is that we understand the fundamentals of SAF and how much it can deliver. Looking at our other options for reducing emissions: When people talk about aggressive technology, they sometimes gravitate to electrified products or hydrogen-powered products, and what we know today is that those technologies don’t work from an overall efficiency and cost perspective, nor will they likely for another two decades — at least in the large aircraft space, which is where all of our emissions come from.
Csonka later got back to me and clarified that he was referring to large cargo and passenger aircraft with ranges over 500 kilometers, which in 2018 generated 93% of aviation’s carbon dioxide emissions, according to the World Economic Forum. — CH
Q: What about electric power?
A: Today’s electric aircraft are small personal aircraft, two passengers, a couple of hundred miles. I expect to see that technology being brought into that small aircraft space, and over the next two decades, that this technology might mature to the point where we get the energy on a volume and weight basis that’s coming close to what we get out of kerosene and turbine engines. We won’t be there for quite some period of time, irrespective of the announcements that have been made. What I do know for sure is that if folks expect aviation to start on a sustainability journey today with respect to carbon, SAF is the solution. It needs to be the solution that starts today, that mitigates that long-term aggregated amount of CO2 that we’re producing, for our kids and grandkids in the future. That’s why SAF development is so important and why we’re focused on it today.
Q: SAFs are still hydrocarbon fuels that emit roughly the same amount of carbon as conventional fossil fuels when burned by jet engines, so where is the carbon reduction coming from?
A: What we’re producing is a synthetic jet fuel, starting from a source different than petroleum crude being pulled out of the ground. The benefit is coming from the fact that when I fly an airplane and burn this fuel, I’m not having to reach into the ground and pull hydrocarbon molecules out of the ground and use those to produce a fuel that produces CO2 that winds up in our biosphere. Instead, we’re reaching into nature and pulling those hydrocarbons out. Plants take CO2 molecules out of the air and put them into the form of a hydrocarbon precursor. We take those hydrocarbon precursors and turn them into jet fuel. So if I look at the full lifecycle of a recycled carbon versus pulling them out of the ground, I’m getting somewhere between 60% and 80% reduction in the total lifecycle addition of carbon to our atmosphere. It’s not a 1-to-1 ratio because there’s often carbon generated to harvest and transport the crops that were the feedstock for that fuel, convert the feedstock to fuel, and carbon generated by transporting that fuel to the airport, for instance. Nature hands us those hydrocarbon precursors in a couple of primary forms: first in fats and oils, secondly in starches and sugars, and thirdly in the lignocellulose itself, the body material that makes up plants and trees. A fourth general category that we’re becoming more and more attuned to are the hydrogen and carbon resources that come from circular economy kinds of concepts: using the emissions that come off another process or using municipal solid waste or food waste that comes from our food production on a daily basis, or sludges that come out of water treatment facilities.
Q: Carbon isn’t the only thing coming out of the tailpipe. How promising are SAFs for reducing some of aviation’s other contributions to atmospheric warming, such as nitrogen oxides and contrails?
A: Jet fuel is a series of hydrocarbons, carbon chains with hydrogen attached to them. Hydrocarbons are a great source of energy because they like to burn. If they burned in pure oxygen, they would produce CO2 and water. Since we burn them in air, we also get some nitrogen oxides, or NOx [pronounced nox] and some other things coming up. Within that family of hydrocarbons we have four families of molecules: paraffins, normal paraffins, cycloparaffins and aromatics content. Each of those families of molecules is different and there are several thousand variations of those molecules across that full range of fuels. The aromatic content, double-ringed carbon structures, don’t burn real well. They’re responsible for the production of particulate matter, and some other potentially hazardous air pollutants. Those are very odd molecules to start with, and they don’t burn well as opposed to the other three structures that burn pretty well. Most of the synthetic fuels that are being produced today are more of the paraffinic variety. They burn really clean because they’re these long chains and they break up really nicely. So we don’t get much in the way of hazardous air pollutants or particulate matter precursors. We don’t get a reduction in the production of NOx, which is a temperature-driven phenomenon more than anything. So in order to continue to get NOx reductions in our industry, we’ll need to continue to refine combustion technology. Some of those other attributes associated with pollutants do get improved through the introduction of these synthetic fuels, and even going forward, our aromatics might not be the double-bonded structures that don’t burn very well. We can envision a future where we have fully formulated 100% synthetic fuels that will burn more cleanly, give us the energy density that we need, freeze point, all the other attributes that are in the fuel spec. We’re still in early stages, but the future continues to look bright to resolve the issues that we have with these fuels.
Q: The ASTM International standards body has only approved most SAFs to be blended 50-50 with conventional fuel. What’s the path to approving 100% SAF?
A: The idea with SAFs being drop-in fuels is that there’s no required modifications anywhere, either in the aircraft themselves, fuel distribution infrastructure, airports. We’re trying to keep the concept of SAF and the concept of sustainability from burdening society more broadly. Today the industry has approved seven different manufacturing approaches, or pathways, to produce blending components for SAF. Each of those pathways individually doesn’t produce that whole family of molecules found in jet fuel; the molecules are identical to what I find in jet fuel, but it’s not the full suite of molecules. So ASTM established blending requirements to make sure that we don’t deviate outside of the distribution of fuel molecules that we know and love and put a max blending limitation to make sure that we don’t have an excursion of the overall fuel properties in a direction that we don’t particularly appreciate. However, two of those pathways have a close approximation of the full suite of molecules. Pathway six, for instance, if you look at the details of that on a molecular basis, it really is a fully formulated jet fuel. We put in a 50% blending limitation on it because of our conservatism. We weren’t ready yet to jump to higher max usage levels or full synthetics. But there’s already been flights flown on that fuel in a 100% drop-in format during test flights — which are exempted from the 50-50 blend limit — so that pathway could go to 100% fairly quickly. We could see another approach we could take to our existing pathways and perhaps blend them together and produce something that looks more like a fully formulated fuel.
Q: Describe the pros and cons of governments incentivizing SAF production through means such as tax credits versus mandating that airlines blend a certain percentage of SAF into every flight.
A: Let me start off with this premise, because you’ll get some pushback from purists who want to count on fundamentals of free-market economics: What I offer to those entities is that there is still room for policy in the world, even if you’re a purist with respect to free-market economics, when the free market doesn’t have a feedback mechanism that allows for societal involvement in the decision process. At least from an American perspective, that’s the purpose of having policy, right? Policy provides some shifts in direction with respect to the free-market economy in a bunch of ways that we refer to as carrots and sticks: enticements or mandatory policy. The different mechanisms that are being used today or that some policymakers are considering are things like subsidies through the Renewable Fuel Standard tax treatment, whereby the IRS will give producers a reduced amount of tax that they have to pay on their profitability. On the other side, governments can say you’ve got to blend a certain amount of this low-carbon fuel with every gallon of jet fuel that’s produced. That is less conducive to the way in America that we think about free-market economics and how you can incentivize an industry. But blending mandates can be effective, especially with respect to sending a market signal to new producers, right? New producers say, “Hey, there’s a guaranteed market for me.” My only input is that a mandate is sort of a blunt instrument that goes against some of the free-market economics. You need to be careful with whether there are long-term effects from forcing certain commercial kinds of activity and perhaps putting the power in the hands of the producers in the near term, instead of having a more balanced approach between the producer and the buyer of the fuel.
Q: Are industry commitments through the United Nations’ International Civil Aviation Organization sufficient, or should governments mandate that the aviation industry must achieve certain milestones?
A: I don’t see any single solitary mechanism really delivering the change that is needed at the end of the day, not just for aviation, for everyone. I think in general — and I can say this with all seriousness and a lot of sincerity — society hasn’t yet come to grips with what limiting warming between 1.5 or 2.5 degrees Celsius actually means with respect to the level of investments required, the level of curtailment of human activity. We understand the goal and the need to get there, but the plans aren’t all in place to actually do that or what some of those plans might mean with respect to the level of societal investments required, the need to modify human activity, including our use of various goods, and services. All I can say is that CAAFI has been working on the fundamentals that are our primary driver for allowing this to happen. We’ll see how it plays out at the end of the day, but some more comprehensive agreed-to policy worldwide is probably necessary. CORSIA isn’t going to get us there.
About 200 countries pledged to cap emissions from international flights at 2019 levels through the 2016 ICAO agreement CORSIA, short for Carbon Offsetting and Reduction Scheme for International Aviation. Airlines of participating countries will voluntarily purchase carbon offsets between 2021 and 2027, at which time CORSIA becomes mandatory for all countries. — CH
All of the governments of the world haven’t signed up to that yet just like they haven’t all signed onto the Paris Agreement. As we continue to build societal consensus, I think that will continue to change. The ICAO activities generally around aviation sustainability are consensus driven, and so when you have a consensus decision, it might not be as strong as you might expect because some countries aren’t as progressive as others. What I can point people toward is accept this as the first stage of where we’re going with respect to CORSIA. You can also go back and look at time over the last four decades and see what has happened with respect to those tailpipe emissions. We have had ratcheting stringency for four decades, and we’ve lived up to those increased stringencies and continue to improve environmental attributes for all of aviation: prospective noise, tailpipe emissions. Same thing is going to happen with respect to greenhouse gas requirements. So is aviation going to be able to advance and respond? Yes, we are, just like we always have. It is an attribute of societal existence that’s unequaled from the perspective of the safe and efficient, timely transport of goods and services, and the importance associated with making societies connect and providing a lifeline to island nations and all of these other aspects. Aviation is an important aspect. We need to continue to make it more sustainable, and that’s what we’re all focused on.
Q: Net-zero doesn’t necessarily mean zero carbon dioxide emissions, so what comes next after the 2050 goal to achieve zero carbon or zero emissions?
A: I do believe that we might someday have 30 pathways, or we might even have something that’s a little bit better than that, a compositionally based specification that says: “Producers, you can make these synthetic molecules any way you want out of any feedstock that you want, as long as I wind up with this set of characteristics.” We’ll see how that plays out over the next couple of years. Another concept that’s also out in that 10- to 20- to 30-year timeframe is making fully synthetic fuels, starting with hydrogen and carbon only: cracking the water or using it from other sources, capturing CO2 , and then recombining those into jet fuel. That’s out in our multigenerational product plan. And those fuels by definition are designed to be zero-carbon fuels produced from renewable power. Those by definition will be zero-carbon index fuels or potentially even negative-carbon index fuels. And so you can see, with a series of SAF solutions, that you wind up with pretty deep success on achieving carbon reductions in the industry. It just remains to be seen how all the elements continue to mature, how they come together, how technology continues to play out.