The Exchanges

Q we'll talk about electric aircraft and we'll talk about hydrogen powered aircraft and we'll see where we land at the tail end of that. Ooh, this is a lot of flight metaphors that I don't mean to be using. Um, Okay. Let's, let's start with electric aircraft. Where are we? Like what's getting developed right now? What are we seeing in the works as far as pure battery electric aviation?

A So, uh, in terms of battery electric aviation, we have about two or three companies that are really, uh, on the forefront of this, uh, and they're developing different sizes of aircraft. Uh, so the first is aviation, which is developing, uh, the Alice, uh, that's the name of their aircraft. And it's a nine seater airplane that can, that they say can travel about 850 nautical miles. Ah, without accounting for reserves. Slightly bigger than that is Hart Aerospace, which is a nineteen-seater aircraft, and they're claiming 400 kilometers, including reserves. Uh, and then at the highest level, there is Wright Electric, and they're trying to build a hundred-seater aircraft, uh, but they're, they're also developing newer battery technology, so it's unclear what kind of ranges they're expecting to see with those.

AI assessment note: “we have about two or three companies that are really, uh, on the forefront”

Q companies start with shorter range, uh, aircraft that maybe don't meet the existing duty cycles of most aircraft of that size, but there's enough of a market there for the puddle jumpers, or as you've called them, fjord jumpers, uh, to get into the market that way. And then they slowly ride the, or quickly ride the Battery energy density curve upward into longer and longer range aircraft over time?

A There is actually a significant market for that because Airlines have, in the past few decades, shut off shorter routes because these really small commuter aircraft were really uneconomical and inefficient to operate, and so the operating costs got so large that the ticket prices became unaffordable. With these smaller electric aircraft, you have a much lower operating cost, and so the economics of these shorter routes actually starts making sense again, and that is why Um, you might be able to have these small airplanes enter at much lower ranges, but as you end up, as these battery technologies improve, you can replace the battery and get longer ranges on the same airframe, which is kind of an interesting concept and something that is being suggested by, uh, hard aerospace and aviation and the like.

AI assessment note: “There is actually a significant market for that because Airlines have, in the past”

Q So to the extent that we see activity in hydrogen, uh, aircraft development, what's the balance right now between fuel cell and combustion?

A So again, because of these differences in the amount of power that can be provided by these, uh, different propulsion technologies, the fuel cell aircraft is sort of limited to short, smaller turboprop engines that can carry at most probably 60 or 70 passengers. And when you're using gaseous hydrogen, you're getting ranges of about 600 kilometers, uh, whereas if you're talking about liquid hydrogen combustion, which is on the other end of that, you can fly, like, a 168 passengers almost 200 miles, or 3400 kilometers. Like, these are significantly larger, uh, ranges that can be expected from hydrogen combustion. Just because you can Produce a lot higher power in a gas turbine engine than in a fuel cell. Um, and correspondingly, these companies are, there's different people that are working on these, uh, aircraft, right? In, on the fuel cell side, you have smaller startups that are working on that, like Zeroavia or Universal Hydrogen. Um, these are companies that are able to be viable because the capital investment required for developing a smaller aircraft of like the Is a lot less compared to the capital investment required to build an A-three-twenty sized, uh, aircraft. Now these are, on that scale, there are only Airbus and Boeing that operate. It is essentially a duopoly when you're talking about flights, uh, aircraft that can carry more than a 150 passengers.

AI assessment note: “In, on the fuel cell side, you have smaller startups that are working on that”

Q let's move on from pure electric then and talk about another zero emissions aircraft trend that we've been starting to see, which is hydrogen powered aircraft. So there's two categories here, um, that we should talk about separately. There is using hydrogen in a fuel cell to power the aircraft, and then there's combusting hydrogen directly. Can you just talk at the high level about the trade-offs between those two?

A Yeah, so when you're talking about fuel cells, these These are more efficient than when you're combusting hydrogen. You're using, sort of, uh, chemistry to convert that hydrogen into water and, uh, get electricity out of it. The other advantage of using fuel cells is that it is, uh, it is really zero emission. Like the only emission is water vapor, which yes, uh, is a greenhouse gas and can cause warming, but at the sort of altitudes that these aircraft would operate at, uh, that is less of a concern. When you're combusting hydrogen, however, you get water vapor, but you also get, uh, nitrous oxides, the NOx emissions, uh, from the combustion process itself. So there is, um, so it isn't necessarily zero emission. But on the flip side, when you have a gas turbine that is powered by hydrogen, that can provide a lot higher power than a fuel cell can. Um, fuel cells right now are in the range of 203 hundred kilowatts, um, whereas when you're talking about the power required to Run a single-aisle aircraft, like the A-three-twenty, we're talking in the megawatts, in tens of megawatts, 20, 30 megawatts, uh, required for that to generate the thrust to be able to fly that aircraft. So fuel cells are significantly smaller in terms of power output than, um, combustion, and that's really where the, uh, the advantage of hydrogen combustion lies.

AI assessment note: “So fuel cells are significantly smaller in terms of power output than, um, combustion”

Q So overall, what, you know, what impact do you think that electric aviation has Might have on the overall aviation market, on emissions from aviation, like how big a deal are we talking about here potentially, and when?

A So this is, this is a bit of a bummer in this whole story is, uh, these electric aircraft in the end don't actually end up playing a significant role in terms of the global aviation market. We're talking about, uh, close to like .1% of the global aviation traffic can be serviced by these aircraft. Now that's in terms of sort of passenger kilometers. Now if you're talking about Actual departures. That's more in the range of two to five percent of total departures that can be addressed by these electric aircraft. And sort of that difference in, uh, passenger kilometers and departures is because You, when you have these really short flights, you, you have them serviced multiple times in a day. So that's more departures, but a fewer, fewer passenger kilometers. So it does, it does end up having a greater impact in the departure space than in the overall aviation space. Um, but there are other technologies that can, uh, address a little more of the traffic question.

AI assessment note: “electric aircraft in the end don't actually end up playing a significant role”

Q here, and I guess as an addendum to that question, for fuel cell powered aircraft, given that you're saying that that the best fit for those are sort of in the smaller range, that's where there may be actually some competition between, you know, the sort of higher end of the Electric aircraft and the lower end of the hydrogen aircraft potentially serving some of the same use cases, right?

A Yeah, that's exactly right. And, uh, to get to, for electric aircraft to get to sort of the fuel cell ranges, you do need those batteries to get better. So for the time being, those fuel cell aircraft will operate in a space that is free of competition from the electric aircraft. Uh, but these fuel cell aircraft are Sort of closer to market than the liquid hydrogen combustion aircraft, but are slightly further away than, uh, the electric aircraft. So for example, for electric aircraft, I said, 20, 26 is about when you'd expect commercial deliveries of those aircraft. For fuel cell aircraft, you could probably expect them 20, 28, 20 30. That's because these fuel cell technologies and sort of the gaseous compressed Gaseous hydrogen storage has been proven in automotives with those fuel cell aircraft, like the, sorry, fuel cell cars, like the Toyota Mirai. When you're talking about hydrogen combustion, that is a completely new technology. Like, no such engine exists and flies currently, so it requires a lot more development, ah, to get that to market. And those aircraft are likely only to show up in the market in about twenty-thirty-five, and that's the goal that Airbus has, ah, set for itself. And when you're talking about that timeline from now to twenty-thirty-five, That gives them about three or four years to develop and mature the technologies. It gets, gives them about two o…

AI assessment note: “Yeah, that's exactly right. And, uh, to get to, for electric aircraft”

Q impact of aviation. As I understand it, there's actually a fairly significant portion of the aviation impact on global warming that comes from contrails, uh, as opposed to from greenhouse gas emissions directly from aircraft. How do you think about that in the context of the development of, of fuel switching of new aircraft? Is there a completely other category of things that we need to do to mitigate contrails?

A So contrail avoidance is, uh, of paramount importance as well, because they say that current research suggests that the impact, the non CO two impacts, which includes these contrail formation can be twice as much as the impact from CO two alone. And so trying to avoid these non-CO₂ impacts is super important. The good thing about, uh, using synthetic aviation fuels is that automatically addresses some of that contrail impact because the contrails form because of incomplete combustion, because of sort of aromatic compounds that are in jet fuel. When you're creating pure synthetic aviation fuel, You don't have that aromatic compounds, and so the contrail formation reduces automatically. With hydrogen, it is, the jury's still out. These engines don't really exist, so you can't really tell whether those contrail formation is going to be higher because one of the outputs is water vapor, or whether it's going to be lower because there is no soot that is formed when you combust hydrogen. So that's kind of a very active area of research and kind of a question that Airbus is trying to answer by putting a hydrogen Combustion engine on a A-E-A-D and testing both engines in the same environmental conditions and comparing emissions. In electricity, that's the best part is you don't have any emissions at all. You don't have, uh, you don't have even the water vapor. It is just electricity tha…

AI assessment note: “using synthetic aviation fuels is that automatically addresses some of that contrail impact”

Q 19 seater, obviously from a hundred seater. Are those ranges in line with what you would expect to see for an aircraft of that size based on how we use those types of aircraft today? Or is that, you know, uh, is it less than how we typically use them today? Obviously also depends on The routes, the recharge times, all this kind of stuff, but just orient us there.

A Yeah, so we're actually, so we recently did a study on these electric aircraft, and we found that those ranges were a little on the optimistic side of what can be expected. With current battery technology, and including sort of the standard reserves that are required for flights, you would, you Probably get about a 150 kilometers out of the nine seater aircraft, which is a lot less, um, that's close to a hundred miles, at which point if you can, you should just drive. So it is, um, quite short and really only useful for things like island hopping or places where basically geography becomes a limiting factor in terms of trains or cars. Ah, so, think of, thinking of Norway, for example, where fjords, ah, cut into the way of roads, and so, driving is not possible, and you really do have to take those really short hop flights. In general, these are much shorter than what current aircraft of that size would be able to do. They often can go much further in the, uh, thousand kilometer range. Uh, so that's about 60, uh, miles, sorry, 600 miles.

AI assessment note: “In general, these are much shorter than what current aircraft of that size would be”

Q Got it. And what about from an infrastructure perspective? How difficult is it? Obviously you need charging infrastructure at the airport. Maybe you need more power to the airport. I don't know. Like what, what, how, how big a challenge is that relative to the challenge of just like Making an airplane and getting it certified.

A So I don't really think that the charging infrastructure is that much of a problem. Yes, it is a bit of an investment from the airport side. You would have to start bringing in pretty high capacity chargers for these aircraft. These aircraft require batteries on the size of 700 kilowatt hours. That's about 10 times the size of the current sort of Tesla standard. And so For that, you do require big chargers and, uh, higher megawatt as a kilowatt hour or megawatt chargers, but that's not necessarily like a technological barrier, more of just a money thing. And, uh, and I think the economics of the electric aircraft and sort of the energy efficiency gains that you see when you use, uh, electricity instead of, uh, regular jet fuel for these aircraft would, uh, Justify that investment, and I don't really think that's going to be a significant Uh, problem. And the other thing is, if you do start getting these charges in airports, there are other parts of the ground operations that can be electrified. So, for example, like an aircraft right now, when it's taxiing, is using its massive aircraft engine at very low throttle to really move this aircraft on the ground. It's, it's extremely inefficient. Um, so, for example, that could be turned into an electric Tow truck that moves the aircraft around the airport, gets it to the runway, and then you can spool up the engine and get ready for…

AI assessment note: “I don't really think that the charging infrastructure is that much of a problem.”

Q like aviation, like the trade-off is, yeah, you don't have the weight problem that batteries present. Batteries are very heavy. On the other hand, you need a lot of space to store sufficient hydrogen to power an aircraft of any size, but particularly true for these larger aircraft. So to the, Uh, so for those who are designing these hydrogen powered aircraft, how are they dealing with the space issue?

A Yes. Uh, the space issue is significant, especially because aircraft are also constrained, um, both in mass and volume as, and if you've traveled economy on a budget airline, you know, you have to fit into ever narrowing rows of seats and have to pay for every ounce of baggage that you bring on. So that, that requirement for the fuel being extremely energy dense, both in mass and volume is extremely pronounced in aviation. Hydrogen has really high energy per unit mass, but has really low energy per unit volume. So when you're talking about hydrogen, you can either store it in compressed, uh, tanks, but really you need to get to liquid hydrogen to be able to get these longer ranges out of these aircraft to really be able to fit enough hydrogen into the aircraft. These, what ends up happening is you end up sacrificing seats. You end up sacrificing payload capacity or passenger capacity to be able to carry some of that extra hydrogen, which isn't the worst because you can, um, even when you take into account the volume requirement, uh, of liquid hydrogen, you can still service a 160 passengers traveling 3400 kilometers. That is At least, that is two-thirds of all narrow-body flights, or about a third of all, uh, commercial aviation. Liquid hydrogen aircraft can replace one-third of all passenger aviation that is flown currently, and that is a significant chunk, and that is really …

AI assessment note: “You end up sacrificing seats. You end up sacrificing payload capacity”

Q the hydrogen side to what I asked on the electric side, which is infrastructure requirement. I mean, here there's more, right? Because in the context of an electric aircraft, you really just need a charger. You've already got electrical hookup. Obviously, maybe you need to increase your power capacity, but, but that's not a total overhaul of refueling infrastructure. Uh, hydrogen would be a different story here. Am I wrong?

A No, you're absolutely right. Uh, hydrogen production, delivery, storage, refueling, all of these are challenges that will need to be addressed. Specifically, the hydrogen production and delivery is really massive, and this is where The drop in sustainable aviation fuels become more, uh, attractive because those can be produced and sort of use the infrastructure that is already in place for jet fuel. Hydrogen would require you to build, uh, completely new plants. You'd need to have, if you're using high cryogenic, uh, sorry, liquid hydrogen, you would require cryogenic storage solutions. And really the best option for all of this is to be able to produce and store that hydrogen on site. So the airport itself would have the means to produce that hydrogen and store it and then use it as quickly as possible. Um, because hydrogen storage is also expensive. Um, when you're talking about liquid hydrogen, again, you start having There is heat that will creep into the system and boil that, uh, liquid hydrogen off into gaseous hydrogen, and then you have to reliquify it. And so that cycle becomes pretty expensive and energy intensive. So in an ideal scenario, an airport is able to have all of that hydrogen produced on site and used as soon as possible. And the estimates for about, for what kind of Investment that would require, um, is on the order of sort of build all of that onsite prod…

AI assessment note: “No, you're absolutely right. Uh, hydrogen production, delivery, storage, refueling”

Q to what extent is charge time an issue? If we're trying to operate these planes for multiple runs a day is, and we're going to try to put as big a battery pack in as we can. Do we need super fast charging? Are the, you know, current batteries capable of that? Uh, is the electric load at the airport capable of that or is that just not an issue?

A So the, when you're talking about sort of megawatt class of chargers, then it doesn't end up becoming a problem because these, these aircraft can then be charged in usually in less than an hour. The other thing is when you're, when you're taking into account the reserves of, uh, uh, that are required for flight, these batteries don't get discharged all the way. They get discharged at maximum about So you have a significant amount of, uh, charge that's already left, so you, those charge times aren't necessarily going to be a problem. Again, these are, in terms of battery technology, the weight is still really the most limiting factor. Uh, charging, faster charging, uh, those are technologies that are developing and maturing much faster than the weight of the batteries are reducing.

AI assessment note: “when you're talking about sort of megawatt class of chargers, then it doesn't”