In the wake of the COP26 Climate conference Aviation Week editors talk to leaders of FlyZero, a UK government-backed Aerospace Technology Institute project targeting zero-carbon emission commercial aviation by 2030. 

Aviation Week’s Guy Norris and Graham Warwick take a deeper dive into what FlyZero is all about with project director Chris Gear and chief propulsion engineer Simon Webb.

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Rush transcript:

Guy Norris:

Welcome to Aviation Week's Check 6 Podcast. I'm Guy Norris, senior editor, and joining me and my colleague Graham Warwick, who's the executive editor for technology, we have two very special guests with us to discuss the UK's FlyZero project. For those of you that maybe don't know, this is actually a project led by the Aerospace Technology Institute, or ATI, and it's backed by the UK government. And it's basically a project that is targeting zero carbon emission commercial air travel by the end of the decade which is no mean feat. So I'm delighted to introduce Chris Gear, who's the project director, and Simon Webb, who's chief engineer for propulsion for this project. So, gents, thanks again for joining us. Great to see you. And if you wouldn't mind perhaps just kicking us off by explaining what the basis of this project is, I know you must be very practiced at that now, but please go ahead.

Chris Gear:

Thank you very much Guy. So I'm Chris Gear, the project director. And part of what FlyZero's objective is or vision set by the government was to look at zero carbon emission aircraft, and what does that mean? And also to look at what is the possibility of flying such a vehicle across the Atlantic because obviously we want to inspire the public that this is something that is possible in aviation. Now, FlyZero sits, as you say, under the Aerospace Technology Institute and is backed by the UK government, but the UK government also backs something called Jet Zero. And Jet Zero is a project being run by the UK government that has two streams. One of it is around introduction of sustainable aviation fuel into airlines and into OEM equipment, and they're very much focused on how can they implement that in the short period.

Chris Gear:

The other section is really looking at zero carbon solutions, and what does that mean, whether it means fuel cells and battery powered aircraft, or does it mean gas turbine burning different types of fuels. So our study has really looked at all those different modeling aspects of commercial aircraft. So we're not looking at small vehicles of ranges of less than 500 miles and carrying maybe up to 10 people. We are physically looking at a regional, a narrow body, and maybe something called the next middle size aircraft to say what is achievable in those aircraft if you could apply new technologies that would allow you to get to a zero carbon emission aircraft. So let me ask Simon to talk about some of those fuels. So Simon, would you like to discuss that?

Simon Webb:

Yes. Thanks. So in the team we've got nearly 100 people assembled from a range of companies, including Airbus, Rolls Royce, GKN. And we've got people seconded in. Around two thirds seconded in about one third are independents as well. One of the first pieces of work we've gotten done is looked at the fundamental assessment for a zero carbon emission. So that's at the tailpipe - zero CO2 coming out of the aircraft at point of use. We've published a primary fuel paper, the first publication of the FlyZero team it's available on the ATI website now if people would like to go and learn more. But to give a quick summary of that, we've looked at the different range of zero carbon emission fuels or energy sources. We've looked at hydrogen, at batteries, at ammonia as options, and compared them back to kerosene and SAF as well.

Simon Webb:

A quick summary of that is batteries we think certainly have their place for smaller aircraft, shorter range aircraft, EV tool type applications, but we are pushing up to longer range, bigger aircraft here because we want to be able to have maximum impact in the future on CO2 emissions. And that also coincidentally goes with market revenue in terms of closing a business case as well in the future. So we looked at ammonia. Ammonia is an option, but doesn't have as good energy density as hydrogen, and there's potential challenges around the formation of NOx oxides, for example, because is nitrogen in that fuel as well. And you probably need a cracking system on board to make hydrogen because of the combustion properties of ammonia as well. So we've arrived at looking at hydrogen. We considered gaseous hydrogen. Hydrogen is very good from an energy density point of view, but is very large per unit energy, so has a volumetric problem.

Simon Webb:

When it's gaseous you can look to address that by putting it under high pressure. The problem then is you need to wrap a heavy, thick pressure vessel around that and that offsets the weight advantage. So then the solution we've moved towards is liquid hydrogen, that helps the volume geometric challenge to some degree, there is still a challenge that we're looking to address at aircraft level as to where we put the tanks, where we position them, the center of gravity effect that can have, and the insulation challenge because as I'm sure you're aware liquid hydrogen, it's only liquid at very low temperatures. We're talking about going down to 20 Kelvin, approximately minus 253 degrees C. That is a big challenge in terms of having refueling at the airport storage of the fuel and then the onboard cryogenic tank and the fuel delivery system and the equipment that goes with the types of pumps and valves, some of which the technology is there in the space industry, for example, but aviation has quite different requirements in terms of its life, the reuse or the weight of it, the cost of it.

Simon Webb:

So there's new technology needs to be developed specific for aviation now. And that's part of the challenge that we're here for is to identify those technologies and bring out roadmaps and elicit the interest and investment and support to develop those technologies for the future.

Guy Norris:

Can I just ask the, obviously the target by the end of the decade, is this realistically aimed at a vehicle per se, or are we talking about really laying out the milestones towards that for industry to follow by the end of the decade? How should we interpret that end of the decade statement?

Chris Gear:

I mean, it was a vision it by the government of what they'd like us to achieve, which would be to, I would describe it as an experimental aircraft to validate that you can fly this type of system and fly it before the end of the decade as a challenge, similar to maybe what you would argue when the US was going to the moon. Kennedy sent a very of challenge, and that is what our government has set us. I do believe you could make a vehicle and fly an experimental vehicle and validate these arguments. And some of the work we've done has really shown that a liquid hydrogen aircraft, because liquid hydrogen is so much lighted than kerosene. You can basically count to the weight penalty for carrying the tanks and everything because of the weight of the fuel. It's very easy to develop an aircraft that could fly across the Atlantic on a liquid hydrogen solution. And so we do see that as a real possibility.

Guy Norris:

So really as far as end game from this perspective would be something like for want of a better word, an X-plane type of demonstrator, which would be able to show from the whole life cycle really as well, or just the technology application in an aircraft itself.

Chris Gear:

I think what we'd really like it to be is an aircraft that the technology we're putting into it could actually be implemented into a commercial aircraft platform. So to make sure that it has a commercial viability at the end of the day. And so that is one of the key aspects of what we're looking at. So the technology teams have been looking at the specifications needed for the components to allow them to meet an aerospace commercial application. And it's one of our challenges.

Graham Warwick:

So was this an independent look at the fuel choices, because obviously the British industry's one of its largest customers, while Airbus has pretty much made it quite clear that they want to go liquid hydrogen and they want to go liquid hydrogen by 2035. So were you really able to take an independent look or because of the links between the UK industry and the OEMs, were you just trying to validate what your biggest customer had said already.

Chris Gear:

No, our object was absolutely we were going to do an independent view on behalf of the UK government and the Aerospace Technology Institute of what are the right answers, because actually one of the big issues here is how do you join up and accelerate whatever you find is the right solution, because you have lots of industry working to different scenarios. And so we are taking completely independent. What do the options look like? And so whilst we've been looking at the technology, we've also been looking at the economics and the cost of the different fuels and also the infrastructure that you need to have in place to make these fuels that doesn't exist at the moment to be honest with you. So there is a lot of things we've looked at completely independent from what Airbus and Boeing and to some extent Roll Royce have been doing, but the team is made up of people from Airbus and Roll Royce and Boeing.

Chris Gear:

So we've got the expertise that we need in the team to help us make true real judgment based on aerospace knowledge. So yes, we've come out with an answer which is correlating to whatever is saying, but you must remember our objective was not net zero. It was zero carbon emission out the tailpipe. So actually your answer gets driven by that question. The key thing we had was whether it's liquid or gaseous hydrogen, or ammonia. And we realized when looking at ammonia, it's so toxic that it was, and it's a lot heavier as well. So it doesn't fit an aircraft scenario. And it's really the energy level in the liquid hydrogen drives the overall answer to be honest with you, it's so much higher and lighter than the SAF and the kerosene. It just works out that it is the right solution for aerospace, but it does then leave you with lots of technical questions to solve, including how do you operate such an aircraft in an airport and how do you create the fuel at the airport. And so it's not an easy answer. It's a hard answer.

Graham Warwick:

Did you do a forward projection of the rate of technology development? So you identify the tanks as being a major challenge on the airplane, the tanks as being a major challenge. Did you assess the rate at which that that technology might improve? Did you have a sense as to how quickly we could get to a 30% mass fraction or something that makes it really from 15% today to something that really makes it work on an airplane? Did you get a sense of how long that might take?

Simon Webb:

That's exactly what we're doing now. So we initially did this fundamentals study and the paper covers that. It looks at where the strategic capability could get to with these various different fuels and the power trains that would go with them as well. What we're doing now is we're sizing those systems around concept aircraft, which provide good technology vehicles for us to be able to contextualize the actual real systems we might need. And then we're projecting forward as to what the technology challenges might be and taking an engineering judgment view as to how competitive we think it's realistic to assume those technologies would be at a point in time for, let's say a first generation system and then projecting opportunities maybe for us second generation system after that, to get to a more strategic capability as well.

Simon Webb:

There is a lot of uncertainty in that, and we're gathering a lot of views from people who are seconded into the team independent as experts, and we're working with a whole range of other companies, including universities, SMEs, as well as the big industrial players who conducted people into the team. And we're also running a set of peer reviews with industry experts now to get feed back as to those assumptions, the requirements we've set to allow us to size the system and for those technology assumptions we've made as part of that.

Guy Norris:

And so can you talk as a through a little bit of those scout concepts that you've come out with, and also, I suppose the second part of that is, could you envisage a point where one of those could be the ideal demonstrator, if you like at the end of the decade, could that be part of the way this works?

Simon Webb:

We looked at all the different technology options. And as part of that early on, we created a whole series of scout aircraft. As you rightly called them. There was over 20 of those initially, because we wanted to look at a whole range of different aircraft concept options, including quite radical solutions with separate few, the largest to hold fuel, blended wing body type of arrangements as well as coming down to more conventional regional type of concepts with propellers and the more conventional A320-737 narrow body type concepts, we've the run through a scoring and selection process and from a bandwidth point of view, we've converged down towards three concepts, which address three macro subset of the market. So we've got something that's targeting regional, something targeting the narrow body sector and then something pushing up towards the wide body midsize type of sector. And we're tailoring the most appropriate technologies into each of those concepts to target each market as well.

Guy Norris:

You've said you have experts from industry and academia. Have you been surprised in any way in the way that this has evolved or you really didn't have any assumptions I suppose that's the other option, isn't it?

Simon Webb:

Yeah, I think it's, I mean, personally, it's been in really interesting and a great learning exercise to be able to do this and a personal reflection on this is, I mean, obviously COVID has been horrible for the aviation industry, but as I step back and reflect on where we are now in this study activity, it had to some degree actually enable this to have cons. Some of the ethos of the collaborative working we've got now came off the back of people seeing what was possible at, for example, in the ventilator challenge, which preceded this. And I think it got people used to remote working as well. And this team is spread right across the UK. We have people in the middle of Scotland. In Northern Ireland, Chris himself is based on the Isle of Wight. It would've been very challenging to get everybody together into the same office for this study activity, but COVID has forced to get comfortable generally with working remotely, and that has been very successful. So I think it's allowed this cross UK, cross industry collaborative working to actually happen it.

Graham Warwick:

So Chris, do you think that, from what you said, it seems that one of the more aspirational outputs of FlyZero is a more unified view within British industry of where to invest for the future. Instead having the company's individually pursuing what they think the market's going to want, you will come out with a more, do you think that is forming as you as a result of what you're doing that more unified view?

Chris Gear:

I think one of the things we've noticed since we've been going this year that there's a lot more discussions in the UK going on about hydrogen and how it applied in the aerospace industry, which I don't think was there before we really got going. But I do generally think there are lots of components as Simon just described that sit in a hydrogen system where the knowledge bank or the skills or capability to make those things is very small in terms of the capabilities within industry. And so we've had to go outside the aerospace industry in some areas to get knowledge and understanding of cryogenics or tanks and things like that. And what I do see is the industry recognizing actually to go forward, it needs to go and get knowledge from areas which it may not have done before. And interesting enough, we had been asked by industry, can we help them point them where they could go and find some of that knowledge.

Chris Gear:

So if anything, it is made me more aware the skills and capability needed to develop some of these technologies and we need to get back to academia to help us, but also we need to get into maybe oil and gas and space to help us as well. So a lot to do really, to bring aerospace up to that capability. But I think what we can provide as a group is we understand the bits and therefore we can help assemble the spec and therefore people could actually see or could do that piece. I need this requirement. So that's a great benefit we can give back into the UK.

Graham Warwick:

So there is huge skepticism about hydrogen, and it's really not so much about can you build an airplane that runs on hydrogen? It's the sheer scale of production of hydrogen. We want the sheer amount of renewable energy. If that's going to be green hydrogen, the likely cost of that fuel if we have to have that much renewable energy, the competition with other sectors and everything like that, I mean, are you going to be able to help galvanize the investment that's going to be required?. I mean, it's, it's on such a huge scale over so many sectors for this to work. I mean, yes, if it happens, aviation can ride on the back of it, but we want it first. We need it first. I mean, do you think that FlyZero is going to be able to help drive that?

Chris Gear:

I think we can point and give people direction of where we think the right way to go is, but obviously we don't have the financial backing, as you say, that's a massive investment and it will need a lot of big industry and government to help. We're hoping that we can at least educate people on what the differences are. So if you take SAF for example, I think if you take the plant-based SAF and also the livestock-based SAF, the volumes you need to support aviation, even if you max out that you would still only have about 30% of the SAF that you need, the rest would have to come from power to liquid SAF. And the only way to produce that is to probably electrolysis at the moment. So there are other techniques, but I know electrolysis is the main one.

Chris Gear:

So you need a big electrical infrastructure when you produce that SAF, guess what the first thing you produce is? Hydrogen. So therefore you then produce the hydrogen. Then you convert it to power to liquid SAF, there's additional cost to do that. And I think people are talking about maybe the cost is eight times JA1 one today. Now clearly with the advancement of volume and economics, you'll get that down, but we see that hydrogen's still basic of what is in the power to liquid. So if you can just take the hydrogen and use that, but you still have the fundamental problem that your electrical infrastructure that you need to generate either is massive. And what we see is how do you do that? It has to be green, otherwise you're putting carbon back up in the atmosphere.

Chris Gear:

If you do go to the SAF route, you still put carbon in the atmosphere. So you're going to have to build another industry to extract the carbon out of the atmosphere. And that's called net zero, but I don't know if all those equations work in my own mind, there isn't an easy solution. But what I do see is it's almost like the old Betamax v VHS tape, one's going to win. I don't know, which so your best to do both and you need to do both now is my recommendation. I can't say any easier than that, I suppose.

Graham Warwick:

Yeah. It's very interesting. I write a lot about this stuff, and I love to see that when aerospace engineering horsepower gets applied to these problems, it's really interesting to see that you actually start to see solutions coming out. Literally in the last few days, so Embraer just did some announcements and what they're looking at is you would use hydrogen for the main part of the mission, but you might use SAF for the reserve requirement. You might never use that SAF cause you might never need the reserve requirement, but you've taken the energy problem that you face and you've divided it and you make it more manageable that way it, and that's just aerospace engineering being applied to the problem. It's fascinated to see as we tackle these things how we make progress and maybe towards solutions.

Guy Norris:

And I think beyond that, the fact that you're looking at bringing in other parts, it's a bit like battery technology being applied to eVTOLS tells us that how you're bringing in outside elements to aerospace, which is just going to push the whole initiative forward I think. Well, gents, thank you so much for your time. I think that's a wrap for this week's Check 6, which is now available for download on iTunes, Stitcher, Google play, and Spotify. Thank you again in for listening and stay safe.