Airlines are anticipating the need to de-carbonise, driven by legislation or by customer pressure, but there is not yet any emission-free aircraft solution that is practical and cost-effective to adopt. Other solutions are either too heavy, like batteries and automotive industry fuel cells, or too expensive and inefficient, like sustainable aviation fuel. It is important to get a low enough CASM (Cost per Available Seat Mile) to allow operators to switch to a sustainable solution without having to dramatically increase ticket prices.
Bob and I met at a company called magniX, who develop high specific power electric motors. magniX quickly identified aerospace as a major market for their technology but at the time, most of the customers were working on battery electric solutions for de-carbonizing air travel. We were personally involved in 3 aircraft platforms (that have flown) that used our motors. Whilst we are super proud of what we achieved and overcoming the technical hurdles to fly those planes, it became clear that batteries were never going to be the solution to de-carbonising a significant portion of air travel. We went on to work at a few different sustainable aviation companies, and slowly became convinced that hydrogen would be the only technology that would have a chance of achieving the goal of sustainable aviation. There is a lot of public discourse on what is the best technology to solve this high-stakes problem, but instead of arguing about what can and can't work, we decided it would be best to dive into the technology and give our best go at what we think has the best chance.
Our propulsion system is quite straightforward—we carry liquid hydrogen in a composite, vacuum insulated storage tank. We boil off the hydrogen and feed it into the fuel cell. We take air from outside the plane to supply the fuel cell with oxygen. Hydrogen and oxygen react in the fuel cell and produce electricity, with water vapor being the only by-product. The electricity then powers a lightweight electric motor that spins a propeller.
Unlike most other fuel cell systems, we use the oxygen supply air to cool the fuel cell as well — removing the need for large, heavy and draggy external heat exchangers. This is achieved through our choice of fuel cell membrane with a much higher operating temperature (180 C). We remove the weight of the heat exchangers but also reduce the weight of the propulsion system as we don’t need to overcome the extra drag created by the radiators. All of this combines to reduce the fuel cell system weight by about 40%, which equates to a doubling of our payload capacity and, therefore, half the CASM, when compared to a conventional PEM fuel cell system.
In addition to our tech, we are also approaching the market differently. We think that a 50-seat aircraft is the optimum size for an aircraft with our hydrogen electric propulsion. This is different from conventional turbofan technology where the optimum size appears to be about 200 seats. All of our competitors are working towards a family of aircraft going upwards of 200 seats (Airbus are only focusing on larger aircraft) but we think there are diminishing returns from building larger hydrogen electric aircraft. Instead, we are honing in on a 50-seat design, optimized for hydrogen electric and designed with automotive manufacture methods in mind. There could be a market demand for up to 50,000 aircraft within the next 25 years, driven by more efficient, point-to-point routes. Most other aircraft programs deliver around 1,000 units, which generally doesn't warrant a large amount of automation, and keeps unit costs high.
Hydrogen fuel cells are not new, but we think the need to de-carbonise, the reduction in renewable energy costs, and the improvement in component technologies such as motors, power electronics, batteries etc. make today the best time to pursue this solution to sustainable air travel. We would love to hear from any of you who have worked in aerospace, sustainable aviation fuel (the biggest alternative to hydrogen) and the hydrogen industry. We would also like to hear from people who fly often, and airlines, to learn how important a switch to a sustainable solution is to you. Looking forward to reading all the comments!
I fly between Helsinki and London often enough. On that route, the aircraft is typically either an A320 or an A350.
The size of jet planes is dictated by fuel cost. Fuel is expensive. Large planes expend it more efficiently. But they are also loud and pollute. So people don't like them too close to where they live. When you use fuel by the thousands of liters per flight, it starts to add up in terms of cost. It's also why private jets are only for rich people. They burn hundreds of liters of expensive fuel per flight. Add to that the maintenance and staffing and you are looking at eye watering amounts per flight.
Hydrogen is of course not cheap currently but it might drop in price substantially as renewable energy gets cheaper. At that point a few smaller planes might be cost competitive with a larger jet fueled plane. But still, there are lots of logistical challenges related to getting large quantities of hydrogen to fuel planes. I doubt it will be very economical or practical any time soon.
My pet theory is actually that most short haul flight will shift to small, autonomous, electrical planes. They'll wipe out three of the largest cost factors in aviation: fuel, staffing, and maintenance cost (much less complex mechanical systems). They'll fly point to point rather than hub to hub; or at least tiny airport close to your origin to tiny airport close to your destination. If you want to fly further, you can just chain a few hops. It will work like an uber pretty much.
Inter continental flight is a different challenge. At least short term it's not feasible to do that with battery electric. Synthetic fuels and hydrogen look promising for that. But I wouldn't discount electric for that either long term. If battery breakthroughs keep on happening and we get some fancy solid state batteries delivering 2000 watt per kg or so, that whole game changes as well.
* Short-haul flights, which often compete with cars and trains. Those could be plausibly served by electric VTOLs. If the claims about noise levels are true, the terminal does not need to be much larger than a city block.
* Medium-haul flights, like discussed here. The aircraft need to be much faster than the VTOLs proposed so far. Conventional runways seem to be necessary for efficiency, but they could be shorter than today.
* Long-haul flights that need big planes and long runways.
Airports that need runways are problematic, because the economic value they provide is low. There are often other more valuable uses for the land. In big and even not-so-big cities, airports tend to move away from the city over time.
For example, Helsinki recently closed the Malmi general aviation airport, which was conveniently located ~10 km from the city center. The area surrounding the former airport is now being developed as a medium-density residential area for 25k people. The runways were not long enough for current regional aircraft, and the facilities and the transit connections could not handle a meaningful number of passengers. As the alternate use as a residential area was worth billions, the airport could no longer be justified.
Instead, a huge problem with aviation is making flights between smaller cities viable. If the OP's planes get any lower operational costs or can profitably scale into fewer passengers, his company will have plenty of success.
Atlanta for example is a huge busy airport but also serves a lot of regional connections. I have flow in on a 757 and transferred to a much smaller regional jet to hop to a smaller city or town.
We worked on an electric compressor motor for a fuel cell vehicle project once and it took more than one kilowatt (maybe 2 or 3 I don't recall) to run the compressor. An EV can do highway driving at a few KW so that seemed really inefficient. Aircraft run at higher continuous power so maybe it makes more sense, but I still wonder.
Can you comment on why not go down e.g., to a 10-passenger like the Pilatus (that lands on a 3000' runway)? It seems like the smaller planes straddle the private/commercial line, while a 50-passenger plane commits you to airline buyers. (i.e., even if not optimal for hydrogen electric, would a smaller-capacity target market be more commercially viable and diversify the risk of long-term development?)
Good luck decarbonizing aviation!
If your marketing strategy is to frontally target one of the big 2, be prepared to suffer and be in a world of pain. From the stories I've heard, Boeing tends to take that very personally and will do anything in their power to see you fail. And although I have not directly heard similar stories from Airbus, it's possibly safe to assume that they are also not choirboys..
Nevertheless, cool approach. Good luck to you.
Also outside the union scope clauses. It's a good place to start.
I'm close to two regional airports so 99% of my flying is a small jet to a hub and back again, and it's definitely the worst part of the trip.
> What do you do with the resultant H2O
I can't imagine why an aircraft would ever want to carry its own oxygen supply, and capture the byproduct. Oxygen is heavy. Are you thinking of a spacecraft?
More specifically, hydrogen has an atomic weight of 1, whereas oxygen has an atomic weight of 16. For producing H20, that means you would have to carry 8x your hydrogen's weight in oxygen, if you don't use atmospheric oxygen.