Catalyst with Shayle Kann - A bumpy ride toward decarbonizing aviation

Episode Date: December 2, 2021

Aviation represents 2-3% of global GHG emissions. If the aviation sector were a country, its emissions would rank around 6th in the world, somewhere between Japan and Germany. If you add the additional warming impacts of aircraft contrails and estimates are that aviation contributes something like 3.5% of total anthropogenic warming. It's also another one of those notoriously tough-to-abate sectors. Jet fuel (a.k.a. kerosene) is pretty magical. It has enabled the movement of people and the globalization of high-value goods.  Sustainable aviation fuels, hydrogen, electrification, and electrofuels are all possible solutions -- but they all carry their own challenges. Dan Rutherford knows those challenges well. He's the Director of the aviation and maritime programs at the International Council on Clean Transportation.  In this episode, Shayle talks to Dan about the pros and cons of these various tech pathways. They look at how these technologies could play out in the tight economics of airlines and who will bear those costs. They also examine the pressures on the industry to decarbonize, including consumer interest enabled by emerging low-carbon-travel search features. Finally, they peer into the future at the next generation of planes. Catalyst is supported by Atmos Financial. Atmos offers FDIC-insured checking and savings accounts that only invest in climate-positive assets like renewables, green construction and regenerative agriculture. Modern banking for climate-conscious people. Get an account in minutes at joinatmos.com.

from the studios of PostScript Media and Canary Media. I'm Shail Khan, and this is Catalyst. If 2035 seems like a long time from now, I assure you it's actually, it's almost tomorrow when you think about like a fundamental technology shift for the aviation sector. Yes, it's going to be difficult to decarbonize aviation, of course. And yet, bio-based sustainable aviation fuels,

electrofuels, hydrogen-based aviation, electric aviation, there is a lot of excitement brewing around various technological pathways. But which of them can actually scale? When utilities need flexible capacity they can count on, they turn to Energy Hub. Energy Hub works with more than 170 utilities coordinating over 2.5 million devices to manage 3.4 gigawatts of flexibility built for the moments when utilities can't afford uncertainty. Energy Hub builds and operates virtual power plants that utilities actually stake their grid planning on, coordinating EVs, batteries, thermostats, and more through a single platform built for utility scale.

Predictive, verifiable, and designed to perform when it counts. Learn more at energy hub.com. I'm Shale Khan. I'm a partner at the venture capital firm Energy Impact Partners. Welcome to Catalyst. So aviation represents somewhere in the range of 2 to 3% of global greenhouse gas emissions. If it were a country, its emissions would rank around sixth in the world, somewhere between Japan and Germany. Add on the additional warming impacts of aircraft contrails, and estimates are that aviation contributes ultimately something like 3.5% of total anthropogenic warming.

It's also another one of those notoriously hard to abate sectors. It's not hard to imagine why, though. Jet fuel, aka kerosene, is pretty magical. it has enabled not just the movement of people, but the globalization of high-value goods as well. Air transport moves around half a percent of volume of world trade shipments. Side note, we'll talk about marine emissions another time. But despite half a percent of volume, it moves around 35 percent of goods as measured by economic value.

So it's incredibly valuable. Nevertheless, we need to decarbonize it. And as is true in a number of other hard-to-abate sectors, there are multiple competing pathways to decarbonize. Sustainable aviation fuels or safs, hydrogen, electrification, electrofuels or synthetic fuels are all on the menu, but they all carry their own challenges. Dan Rutherford lives those challenges. He's the director of aviation and maritime programs at the International Council on Clean Transportation, and as you'll hear, he has strong opinions about how this suite of solutions is shaping up. This is my favorite kind of thing to think about

these days, pick a big climate tech challenge, identify the pathways to decarbonize, and then figure out which, if any, have real legs. I invest based on the outcome of that logic or don't invest if the solutions aren't just there yet. But either way, these questions are usually my first stop as I try to make sense of the big swings we're looking for in the big markets that it's going to take to reach net zero. So with no further ado, here's my conversation with Dan Rutherford. Dan, welcome. Great. Thanks for having, Michelle. excited to have you here. All right, we're going to talk about all things aviation decarbonization. Let's start with the state of affairs today. So kind of walk me through aviation's contribution

to greenhouse gas emissions and other emissions. And then let's talk a little bit about the economics of the aviation industry because I think that'll come back as we start to talk about decarbonization. Yeah, happy to. So aviation is kind of a tricky issue here. The emissions can either look really large or reasonably small, depending upon how you normalize it. But just to give you a few different figures, airlines emitted about 900 million tons of CO2 or carbon dioxide in 2019. So if aviation was considered as a country, it would be about the sixth largest emitter, so a little bit larger than Germany, somewhat smaller than Japan. you know, globally that would be about 2.4% of anthropogenic carbon dioxide, but it doesn't

account for the climate impact of copoludence. So when you burn a gallon of jet fuel at elevation, it has a larger climate impact than if you burn it, say, on the road, because you're also emitting things like nitrogen oxides and black carbon and water vapor. So if you look at the total climate impact of flying, it's about three times larger. than carbon dioxide alone. And if you put together all of the math, it would be about 3.5% of the total radiative forcing from anthropogenic emissions.

But that's on a societal level. If you look at individual flyers, it can be very different. So half of the United States doesn't fly in any given year, and about 90% of the world doesn't get on a plane in any given year. So if you are a frequent flyer, flying is a much larger part of your overall carbon footprint, generally 20% or higher. Right.

Okay. But even from the global perspective, setting aside the contribution to my personal carbon footprint, which is admittedly and embarrassingly high, at least in normal times, it's still a significant number. Like, how does that, how does the aviation's contribution to global warming compared to other modes of transportation? Like, it's up there with what, light-duty passenger vehicles, right? It's not quite that large.

If you look only at CO2, it's about 12% of the transportation inventory. But again, that's not accounting for these other pollutants. And comparing directly of cars versus planes gets tricky on a number of levels. So it's not the largest source, but it is one of the fastest growing sources. And by some accounts, overall emissions could triple by mid-century. unless additional action is taken to reduce the pollution. All right. So we're going to talk about that additional action,

and that'll be most of our conversation. But before we do, let's talk about just the state of the aviation industry and the airline industry. How are they doing as businesses these days? Are they well positioned? I mean, one of the things that we've seen in a lot of other sectors is like booming, growing businesses that have a lot of profits can spend a lot of money on decarbonization.

Why is it that Stripe and Shopify and, Microsoft are the ones buying all the carbon removal credits. It's because they can afford to. So what is the situation with airlines these days? Well, the airlines are really regrouping right now after the COVID-19 traffic downturn. So something that's been really fascinating is just over the past two years, how the overall posture of the airlines has changed relative to climate change. So if we go back to late 2019, there was a bunch of energy around this issue.

You'll recall that Greta Thunberg went by Catamaran to the UN General Assembly meeting. I was actually in Montreal in October of 2019, and Greta led a demonstration of 500,000 Canadians in the streets of Montreal, literally walked right past the front of the UN agency that regulates aviation emissions. And at that time, there was kind of a feeling like there was going to be a sea change on, you know, aviation and climate change. And then COVID hit. And the business models went crazy. A lot of airlines were literally on the brink of bankruptcy last year. And so climate change sort of slipped to the background.

And now it's roaring back as traffic has recovered. and the economic conditions of airlines have improved. So it's a really interesting time right now. We are starting to see the airlines come out with more net zero commitments looking out. We're also starting to see some really interesting short and midterm commitments, either on emission reductions or for the use of sustainable aviation fuels, for example. Airbus is looking very seriously at hydrogen fuel designs. which is something that we're researching at the moment.

And we're seeing a number of startups, especially in the electric aircraft space, that are starting to develop products. So it's quite interesting. And I would say there's a larger diversity of action right now than I've ever seen. The big question that's maybe hanging over all of this is the cost, because we've all become really used to the idea of catching really cheap flights

whenever we want. and the question of kind of who pays for all of this is something that has yet to been resolved. Right. Okay. So that's a good segue. I want to talk about each of the different kind of proposed alternatives proposed ways to decarbonize aviation while still flying.

There's the, I can't remember what you probably know this better than me. There's a Swedish word for fligscomb. Flecks cum. Fleck shaming. Yeah, that's right. Okay. So setting aside fleekskum as the solution, assuming we're all going to continue flying around the world. There's a few different pathways that I think have emerged as kind of the leading contenders.

You alluded to all of them, but let's dig into each of them individually and talk about the kind of tradeoffs. So the first one is sustainable aviation fuels. And there's multiple categories within that. So why don't you walk us through kind of what are sustainable aviation fuels and then what are the big buckets underneath that umbrella? So sustainable aviation fuel is sort of a catch-all phrase. It's meant to describe drop-in alternatives to fossil jet fuel. You may hear me call it Jet A. That's kind of the baseline fuel for aviation. And so these are being generated using a variety of feedstocks. Current uptake is very, very small. It's less than 0.1% of global jet fuel use. But sustainable aviation fuels have a lot of merits in that they're meant to be drop-in. So,

can blend them into existing supply and continue to use the same planes and the same engines that are already in surface. They're energy dense, so as sort of a liquid hydrocarbon in essence, they will allow planes to maintain their same range. So you'll be able to take a long-haul flight, for example, on a sustainable aviation fuel. And we do believe that they'll be less polluting not just on a CO2 basis, but those other cop pollutants I mentioned, sort of NOx and contrails and whatnot. We think sustainable aviation fuels can reduce those climate impacts as well. So that's the good news. The limitations are supply is very low. Cost remains really high. So the figure you often hear quoted is three to four times the cost of conventional jet fuel

or Jet A today. Can you put that in like dollars per gallon or dollars per kilogram terms? Yeah. I'm used to thinking about this in euros per liter, believe it or not. So let me think dollars. I mean, fossil jet field today in the U.S. is a little more than $2 per gallon. So when you're talking about a three to four multiple, it would be like $6 to $8 per gallon. In terms of the buckets, I'd say that there are four main ones.

and I'm going to introduce them a little bit out of order here. But the first are what we call waste, fats, oils, or greases. So these would be things like used cooking oil or beef tallow or yellow grease. You know, waste that can easily be converted into a jet fuel and have good life cycle emissions. So we do think that once you account for all of the energy used to produce them and also things like land use impacts. We expect that these fuels can reduce emissions by 40 to 50% on a lifecycle basis.

Those are the cheapest and the most available today, but the supply is relatively limited. So we think overall maybe about 2% of overall jet fuel use could be met by diverting these waste fogs from existing uses to aircraft. So that's one bucket. Second bucket are what we call advanced biofuels. So those would be things like cellulosic fuels or municipal solid wastes. And there's even some technology that can convert exhaust gases from steel plants into first an alcohol and then a jet fuel.

This is like Lans of Tech. Exactly. Yeah. So those are more expensive. the technology is kind of emerging, but the potential supply is much, much larger if you can kind of get through the, you can get over the hurdle of developing the technology and making the capital investments. Those fuels can provide even larger reductions, something on the order of like an 80% reduction in life cycle greenhouse gases. So that's bucket two.

Sorry, I'm picturing this like, we're like going up a scale here where from easiest, most available, and cheapest, relatively speaking, to now sort of stage two you're describing as more available, larger potential supply, larger greenhouse gas impact, but more expensive. Exactly. And that's why I'll go to three, which are electrofuels or synthetic fuels. And that is the basic idea is that you capture carbon from some source, either directly from the air or from a point source like a like a like a landfill. And then you generate hydrogen from renewable electricity, either wind or solar, plus an electrolyzer. And then you synthesize a jet fuel out of that. So that's a variety of names, e-fuels, sin fuels, e-carosine. That is an emerging technology.

We just, actually, there was a plant that opened up in Germany recently that, that is now producing e-fuels for the first time. Huge potential supply, also quite expensive. So the cost figure that they released was five euros per liter, which is roughly 10 times the cost of jet fuel in Europe today. So that's bucket three, a little bit more long-term, larger potential reductions up to like 99% reductions, essentially a near-zero fuel.

And essentially limitless supply, right? I mean, in theory, right? If you're using direct air capture to get your CO2, we've got plenty of CO2 in the atmosphere, unfortunately. And if hydrogen is your other input, we can produce basically as much hydrogen as we want by just using renewable electricity and water. So supply is not your constraint. Cost is your constraint.

Exactly. There are some complications near term, though, because obviously there are limits on the supply of, well, both direct air capture carbon and renewable electricity today. and you want to make sure that you don't take like a solar or wind power that's currently being used to charge EVs and then diverted to planes and in the process prolong the useful life of a coal power plant, for example. That would be net negative in terms of emissions. So yes, long-term supply could be nearly unlimited. We just want to make sure we don't push too hard too fast on it.

Right. And also, I mean, long-term supply, if we're talking about, about getting up to the volumes of kerosene that are consumed today, I mean, the amount of direct air capture or the amount of renewable electricity, the amount of hydrogen production that you would need is like monumental. It's very, very large. I don't recall the exact figure, but it's on the order of all renewable energy potential, sorry, all renewable energy generated in the world today. It's something on that order of magnitude. So it's quite large. That's bucket three. bucket four is actually I'm reversing myself now. This is actually the cheapest possible fuel,

but the one that is most problematic in terms of potential emissions. And these are crop-based biofuels. So it is possible to use soy or corn or worst-case scenario palm as a feedstock to generate sustainable aviation fuels. that is generally considered a rather bad idea just because any time that you create a fuel that competes with food, you open up the possibility that you indirectly trigger deforestation in the tropics. And as a result, you can actually produce sustainable aviation fuels

that on a life cycle basis emit more carbon dioxide than the base jet fuel. So that's kind of my fourth bucket of, of I hope we don't go there. And there are some policies that, unfortunately, could push us in that direction if we adopt them. Virtual power plants are becoming a reliable way for utilities to manage capacity. But enrolling devices is just the start. What really matters is confidence,

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delivering 3.4 gigawatts of flexible capacity. See what that looks like at energy hub.com. All right, so there's a couple other categories we're going to talk about, but just within this world of sustainable aviation fuels, these four buckets that you've described. I mean, what's your, there's activity going on in all four, as far as I can tell. There are commitments being made,

there are plants being built. I think it seems like the big question is the ones that are cheaper at some point we hit a ceiling on available supply, the ones that are more expensive, we got to drive the costs down. Are you optimistic that we will kind of bridge this gap somehow and land the plane, so to speak, so that we could scale up sustainable aviation fuels using some combination of those four pathways, or I guess the first three, since the fourth

sounds problematic. No, I think sustainable aviation fuels are going to be a pretty sizable part of the puzzle of how we decarbonize aviation. In addition to kind of the overall cost, like the cost increment for the advanced fuels being higher, the costs are actually different. So if you look at crop-based biofuels in particular, and then also these waste, fat soils and greases, most of the cost for fuel production is actually an operational cost. You're paying for the feedstock. In contrast, for advanced biofuels and especially power to liquids, most of the cost is a capital cost. So it's an upfront investment

cost to build a facility. And then once you have, you know, when solar plant and you've got your direct air capture going, the cost of running that is actually relatively low. So there's a, there's a, there's a jump in the magnitude of the cost, and then there's also a shift in when you have to pay for it. The good news is that we're starting to get a variety of proposals for how you would generate the revenue needed for these investments. Certainly, Europe is looking into basically just mandating the use of the fuel. But there's also the potential to start to tax jet fuel properly, which is something that we've been lagging on. And then some, you know, a little more complex incentives like contracts for difference, where you collect

revenue from something like a cap and trade system, and then you use that to subsidize the cost of producing these new facilities. So I think we'll get there. It's, It's really about making the economics work. And currently, I mean, the big barriers are that, one, jet fuel is too cheap. And then two, you know, the airlines themselves are sort of, it's a very competitive industry with very low margins. So clearly you'll need some sort of regulation in order to, you know, I guess heard the cats towards the airlines. making the proper investments in the fuels. All right.

We'll come back to what the airlines are saying they're going to do in a little bit. But let's finish off with the different pathways to decarbonization. So the big bucket, sustainable aviation fuel is what we just talked about. But you at the beginning also alluded to two other pathways that are receiving a fair amount of hype and attention, certainly in the world that I inhabit in the venture capital universe, which is hydrogen aviation and electric aviation. So let's talk about each of those. So hydrogen, you know, Airbus is probably.

the biggest kind of public player that's making big commitments there. What's your take on where hydrogen fits in here? So you're correct. So Airbus is currently investigating three potential designs that they think could be brought into service by 2035. That would be powered by hydrogen. And if 2035 seems like like a long time from now, I assure you it's actually, it's almost tomorrow when you think about like a fundamental technology shift for for the aviation sector. And they're like clean sheet single aisle jets. Like they're talking about big stuff. Close.

Yeah. There's this really funny phrase that I'm just getting used to saying is evolutionary hydrogen designs. Because I mean, this is a fundamental technology shift going from the jet A that these planes have always operated on onto this liquid hydrogen fuel. Two of those three designs that Airbus is looking into are what they call evolutionary design. So you basically maintain the existing either turboprop or narrow-body aircraft fuselage.

You use very similar engines, but you stretch it out, you stretch out the fuselage to allow for additional fuel storage in the rear of the plane. I'm getting a little bit ahead of myself here, but the thing to know about hydrogen is it's very energy-dense on a mass basis, but not on a volume basis. And the mass basis is great because planes are very mass-sensitive. And in order to achieve sufficient ranges, you need to have either a liquid fuel or something that's very liquid-like. Right. We'll come back to this in the context of electric aviation where this is the biggest challenge.

But it's one of the benefits that hydrogen has over batteries is that you can put a lot of it in a plane. It's not very heavy. Conversely, it's not very energy dense on a volume basis. So, you know, it generally occupies something like four to five times the volume of petroleum jet fuel. And as a result, you need to have larger storage volumes, generally in the fuselage of the plane instead of the wing. and then there is a mass associated with the storage itself. And we can dig into that if you'd like because there are really big differences between compressed hydrogen and liquid hydrogen.

But, yeah, Airbus is looking very seriously at this. They are planning to make a build-no-built decision in 2025. So they're going to review the technologies between now in 2025, decide whether or not to build these planes. And then it becomes sort of a role. rush to mature and deploy all the technology, make sure that the infrastructure is available, et cetera. So that's really an interesting development because, you know, in contrast, Boeing is more bullish on SAFs, sustainable aviation fuels. And there are, again, there are real merits

to those fuels. But if you're an manufacturer to say, you know, we're going to build, we're continuing to build our planes as they are today, and someone else is going to produce the fuel to make them zero carbon, it's a little bit of passing the buck. Whereas I think Airbus, if they can crack the hydrogen code, they're kind of taking the bowl a bit more by its horns. There is one other startup, by the way, Zero Avia, that is working even shorter term on compressed hydrogen fuel cells and regional aircraft. And they're certainly worth worth paying attention to as well. Do you think the difference between Boeing and Airbus on this?

I think this is interesting. Like you said, Boeing is sort of all in on sustainable aviation fuels. Airbus is not all in on hydrogen, but they've certainly been very public about their hydrogen ambitions. Do you think that's a function of their headquarters? Boeing is an American company. Airbus is a French company. Europe is ahead on climate policy in general, but on hydrogen in particular. Or is it a shareholder thing?

Is it just me like, what's the difference? I think it's a little bit of everything. Certainly, like concern about the climate change is higher in Europe baseline than it is here in the United States. I think that's one facet of this. Also, discussions about sort of the hydrogen economy and hydrogen infrastructure are definitely more accelerated in Europe than they are in the U.S. Generally, I think that's a good thing, but I will put maybe an asterisk around it. There is concern in the environmental community that hydrogen is basically just a Trojan horse for natural gas. And that, so I've sort of, actually, we haven't really talked about gray versus green versus blue hydrogen.

That's like a whole conversation in of itself. It's a whole other thing. Why don't we just, yeah, I take the point around that, right? like this that where how the hydrogen is produced does matter in terms of the life single emissions um nonetheless you know it's a clean hydrogen is clean hydrogen uh and if you use clean hydrogen to power a plane then then great from your perspective though so this is an alternative path to sass right you either uh drop in sustainable aviation fuel of whatever kind into a plane or you redesign a plane so that it can handle compressed hydrogen or liquid hydrogen or something like that.

So these are pretty mutually exclusive, at least for the same plane. They're mutually exclusive. They are. And again, Airbus is not saying hydrogen is the answer. They're saying we're looking at hydrogen seriously. And they think it can work for regional short haul and maybe medium hall flights. So this would be flights of 4,000 kilometers or less. That's a big chunk of the overall inventory, right? That's about about two-thirds of overall CO2 emissions from aviation occur at 4,000 kilometers or less. So it's a big chunk of the inventory. Long-haul flights, just because of the mass required to store the hydrogen, everyone expects for the foreseeable future that's going to be addressed through SAFs or, you know, at a minimum continued fossil jet fuel use. So, you know,

there's some complications here. But, I mean, I agree with you that if the hydrogen is produced in a clean manner, it does have potential advantages, not only on cost, because you don't, you're not dealing with a carbon at all. So direct air capture, for example, becomes unnecessary if you have hydrogen instead of SAFs. Some research, research, researchers also believe that hydrogen could get you larger reductions in the sort of contrail and serious impacts that we believe could be up to two-thirds of the total climate impact of flying. So there are definitely there's an underlying logic for, you know, why you might want to use hydrogen instead of SAFs for the flights that it's suitable for.

And so to the extent that there are pitfalls for hydrogen, it seems like the third, Three, are cost, still expensive to produce clean hydrogen, infrastructure. You got to have, you know, with SAF, you can use the existing fueling infrastructure and so on. With hydrogen, you got to build a whole new fueling infrastructure from scratch. And then this energy density by volume issue, which means you need to have big storage tanks, which can remove room on the plane for revenue, customers, cargo, whatever it might be. Right, right. I mean, there is the safety question.

By all accounts, hydrogen is not any... A lot of people think about Hindenburg, right? That's the first thing you think of when you say aviation and hydrogen. By all accounts, hydrogen itself is not more dangerous than jet fuel. It's just different. And so you're going to need to have new standards, new regulations for how to handle the fuel, how to fuel at the airport, et cetera. So, I mean, you don't want to ignore the complexity there.

But yeah, definitely those three barriers, the cost infrastructure and volume are relevant. From a design perspective, we've been, I would say, pleasantly surprised on the volume issue. Like, we're actually modeling this right now and trying to figure out sort of how much mass is needed on an aircraft in order for it to operate off hydrogen. Where would you store it? there are some interesting complexities in that currently most of the fuel on an aircraft is stored in the wing, which is located near the center of the aircraft. So as you burn it through a flight, the center of gravity of the plane doesn't change very much. But if you move to a hydrogen design and you put the fuel tank in the back of the plane,

as you burn the fuel over the course of an operation, you do have some changes in the center of gravity of the plane. plane. But based upon our initial modeling, I mean, these all look to be pretty resolvable if airbus goes this route. Okay. So sustainable aviation fuels category one, category two, hydrogen, category three, electrification, battery powered planes. What's the state of affairs there? This is where the storyline gets a little grim, I'm afraid. And it goes back to just the fact that, I mean, if you've picked up a battery recently, like if you've changed the 12, volt battery in your car, you'll recognize that batteries are just really heavy. And that's something that is not a big issue for cars, for example, but it's a huge issue for aircraft. And we actually

have to deal with it on a couple of different levels. First of all, there's the fact that the fuel itself is much, much heavier. So the battery is, you know, 40, 50 times less energy dense on a basis than the jet fuel. But the battery also stays with the plane the entire length of the operation. One of the nice things about jet fuel is as you fly, you burn it off and you get rid of that mass over the course of a flight. The battery is with you when you take off. It's with you when you land. And so there's a mass penalty of the battery throughout the entire flight. So, you know, There's a fair amount of bullishness, I think, right now about electrification. But by our analysis, you know, it's really a market for commuter flights and for flights of, you know,

300 kilometers or less for the foreseeable future just because of the underlying mass penalties of the technology. Right. So displacing like turboprops, six-seaters, three-seaters, ten-seaters, but not single-isle jets any time soon. I mean, up to 19 seats probably is reasonable. And again, you know, 300 kilometers range seems reasonable. Like, it's really complicated. Like, one thing we are modeling out right now is reserves. Like, when you, you don't land a plane empty.

You have to have a variety of reserves for safety reasons. And typically, there's a reserve for holding time over an airport. There's a reserve for diverting to another. airport if you can't land at it and then there's like on top of that just like 10% extra reserve or 5% extra reserve just getting the reserves to make a reasonably long flight for electric aircraft is super tough because you're just carrying that fuel the entire time of the trip you know I think electrification of aviation advocates would respond with the sort of trajectory of battery technology right and the fact that there is so much improvement, both on cost and on energy density that we are seeing

and in batteries today driven in part by electric vehicles, but some of which could be applied here. Do you see a pathway where that changes as batteries get better, or is there something fundamental that's just tough to overcome? No, no. I mean, the ranges will increase, but there are a number of unique kind of requirements for aircraft just in terms of, you know, in terms of cooling and packaging and certification allowances, because this is a very, very safe industry with almost zero tolerance for accidents. So, I mean, you'll definitely see incremental improvements. The question is whether those will be

significant enough to break through any of these hard constraints. I will say that. I will say that we haven't dug deep yet into things like distributed propulsion, which is a technology where instead of having a couple big engines or props, that you have a number of small props throughout the wing. And those can give you additional efficiencies. So I will never say never, but the flight physics are really punishing for electric aircraft. All right. So to put you on the spot, if you're betting, let's just say, I don't know, 2030 and 25. 40, which of these pathways has sort of done the most to decarbonize aviation? What do you think wins?

And I wonder whether the answer changes over those two timeframes. I think it would. I should caveat this. My background is actually an environmental engineering. And a lot of my research to date has been not about zero emission technologies, but about fuel efficiency and fuel efficiency improvements. And I often get critiqued as being like way too negative about SAFs, in part because there's just, there's been so much optimism about them over the past decade that has not come to fruition because of the, because of the economics and the supply constraints. So, you know, in the course of the past 10 years, fuel efficiency has been the major driver.

Like, that is what has been reducing emissions over time. We're going to pivot into the future where SAFs become more important, especially after 2025. Hydrogen could become significant after 2035. And then we'll have electric aircraft kind of in a few regional niche markets, I mean, as soon as 2025. But, I mean, I would say, you know, 2030, SAFs definitely. 2040, I would also say SAFs. 2050, it may shift to hydrogen. We'll just have to see how the economics work out.

And, you know, we've got a number of new technologies that are competing here, right? We've got direct air capture. We've got carbon capture. We've got renewable energy. And then overlaying this, there's the non-CO2 climate question, which, you know, we don't know the answer yet. All right. So we've talked about all the different fuels. dual pathways. I mean, we should also at least briefly talk about the sort of consumer-facing

stuff that you're starting to see happen. You know, Google flights now, if you search a flight, tells you the expected emissions from your trip on that flight and, you know, you could, you could make a decision based on a route or a seat that should have less emissions. There's, you know, similar things from kayak and other places like that. Do you put any stock in those efforts in terms of, you know, actually decarbonizing aviation? I mean, it gives you another pull for these new technologies. So, again, it's not end-all and be-all in and of itself. I mean, we've looked at this pretty in-depth.

And any market you look at, there's a substantial difference already today between the carbon intensity of both airlines and the flights that they operate. So in the U.S., if you have good emissions estimates, you could choose a ticket that is somewhere between 20 and 60% less carbon intensive for flights within the United States. So it is significant today. And as you start to introduce SAFs or hydrogen or electric aircraft, that's an additional lever that you could put into the model.

So I think it's really positive that Google and Kayak and others are starting to provide this data. there are definitely gaps. The data can be spotty. We need to work more on standardizing both the estimates and then also how they're displayed for the consumer. And then finally, this non-CO2 climate impact overlay is a tricky one. But I think it's definitely something to keep your eye on and something that I hope is refined and expanded as we go forward. So we've talked about Boeing and Airbus already, but we haven't really talked about the airlines in the airline industry, what is their level of commitment here, do you think, and to what?

Right. So this is changing quickly. You know, a number of first airlines, then airline groups, and now sort of the Global Trade Association, have come out in favor of net zero emissions by 2050. So that's a really high goal to hit. And just to put this in context, airlines globally first made a climate commitment back in 2009, and it was to have carbon neutral growth from 2020,

and then to reduce emissions by half in 2050 based upon a 2005 baseline. If you look what happened after that goal was announced, emissions actually increased faster in the decade after they announced the goal than in the decade before it. So that goal that was first announced had literally no impact on the emissions trajectory and very little impact on the technologies. We'll see where this recent commitment goes. What's different this time is that individual airlines are starting to announce commitments, especially for sustainable aviation fuels. So a number of groups have come out and say, look, we're going to get 10% SAF fuel supply by 2030. So that's different from where we were a decade ago, where it was kind of an industry-wide aspirational goal.

So we'll see. I mean, the dialogue has definitely shifted, but we will see, I guess, how much money the airlines will actually devote to this. For the airlines that are saying things like we'll get 10% sustainable aviation fuel by 2030, are they giving any more detail where that sustainable aviation fuel is going to come from? I mean, to your point originally, like, the lowest hanging fruit cost perspective, sustainable aviation fuel is pretty severely supply limited. So are they looking at this and seeing either more supply or seeing the cost trajectory of e-fuels coming down fast? Or like, what do they see that makes them think it's possible?

Yeah. I mean, in terms of what's being disclosed publicly, generally you'll get like an overall volume target. generally you'll get like a range of years. Like we're we've agreed over a 10-year period to purchase up to this many hundreds of millions of gallons of SAFs. And then they'll typically have like the name of the company involved. And if you're, if you know the space, you can from there kind of work out the feedstock and then ballpark the life cycle emissions from it. It's a little bit of an exercise in judgment.

But, yeah, it's, I would say, overall, the commitments that we're seeing, the volumes are definitely getting up. And the feedstocks are, by and large, pretty good. There are some questions about a few companies. And those, again, go back to this idea of using crops to generate some sustainable aviation fuel. All right. Let's finish off by talking about some fun futuristic air aviation stuff. There is plenty of excitement out there around, I guess, two categories, like areas of next generation aviation. The first would be VTOLs or specifically EVTOLs, so the flying air taxi kind of thing. Second category, supersonic aviation making its triumphant return.

So from your perspective, thinking about decarbonization, how do you think about each of those? Yeah, I mean, I think they're both really marginal plays at best. And again, EVTALs in particular are a little bit outside of my own area of expertise. But one thing to think about when you're thinking about commercial aviation is airplanes are mass transit. So it's like an air bus, right? It's a bus in the air. Whereas these EVTALs, you're talking more about two, three, four-seaters. that are being pitched, you know, as ride-sharing or air taxis.

So it's fundamentally a different market, potentially a new market. So you may have caught that United is making this investment into WISC, I think, that is an EVTAL startup to, as a way to get some of their customers to the airport in urban areas. So that's kind of its own market. I don't think it will really decarbonize the existing fleet in any meaningful way. Supersonics is a really interesting area, and there are a lot of different opinions on this. I will say kind of the basic problems, the basic economic challenges, the fact that you cannot currently operate aircraft over land in most of the, sorry, supersonics over land in most of

the world. And then this environmental concern, not only noise and ozone depletion, but now climate change, I mean, that's, that makes it really hard to see supersonic as a viable, you know, mass market for aviation. I know I've seen that like, I think boom supersonic, you know, claims they're going to be run on all sustainable aviation fuel when they, or either immediately or at some point in the future. I mean, do they end up just being similar to airlines? in like it just depends on what fuel they use basically, or is it actually there's something like more insidious about it from an environmental perspective?

Right. Well, first of all, as you've alluded to, the manufacturers don't buy the fuel for the planes. So they can say that their plane can use 100% sustainable aviation fuels. Then they sell it and, you know, what fuel is then used is really out of their control. Overall, you know, the estimate is that the aircraft, themselves will be about five to seven times as carbon intensive as comparable subsonic designs. And when you combine that with the cost premium for SAFs, it's just really hard to see a profitable

market for supersonic. So you've got five to seven times the fuel burn times three to four times the fuel cost. You know, it's hard to see the promise that they will. operate on sustainable aviation fuels really come to pass in this very competitive market against more fuel efficient planes. All right. To close out, gun to your head, what, actually remind me again, what share of, you said at the beginning, it's like half a percent currently of aviation fuel is decarbonized somehow, is sustainable aviation fuel?

Oh, it's about half of a tenth of a percent. It's about 0.05%. 0.05% today. Okay. So a decade from now, what do you think is a realistic expectation? Globally. A decade from now, 2 to 3%, I would say. And so that's one decade from now.

2050 when everybody is saying they need to get to net zero, that's three decades from now. So if we go from 0.05% to 2%, this decade, is there any pathway to go from 2% to 100% over the fall? following two decades? People have modeled this out, right? The airlines are saying something like 60 to 70 percent of mitigation in 2050 will come through aviation alternative fuels. I don't have insight into that on like a facility basis. Again, I won't say it's impossible. The economics of renewable power are, you know, are rapidly improving. And I would expect that we'll

also see breakthroughs in direct air capture and probably hydrogen as well. So, you know, I don't have a straight answer for that. It's not impossible. It's more about political will and also generating the capital needed for the investment. Dan, this is extremely illuminating for me. Thank you so much for being here. Yeah, thanks so much for having me. Dan Rutherford is the director of the Aviation and Maritime Programs at the International Council on Clean Transportation.

Catalyst is hosted by me, Shail Khan. The show is a co-production of PostScript Media and Canary Media. Find me, Canary, and PostScript on Twitter. Tag us if you want to provide feedback on this episode or if you want to suggest future topics. We always welcome your ideas. You can also find background links on topics and guests in the show notes, or you can go to Canarymedia.com. Our producers are Daniel Waldorf and Stephen Lacey, Sean Marquan, composed our theme song.

I'm Shale Khan, and this is a show. Catalyst.