Leeham News and Analysis
There's more to real news than a news release.
Leeham News and Analysis
- Bjorn’s Corner: Air Transport’s route to 2050. Part 5. January 17, 2025
- What’s the future of the Boeing 787-8? January 16, 2025
- FAA understaffing affects air operations oversight; NTSB falls short, too January 13, 2025
- Bjorn’s Corner: Air Transport’s route to 2050. Part 4. January 10, 2025
- The market is ready for a 787F. But is Boeing? January 9, 2025
Bjorn’s Corner: Air Transport’s route to 2050. Part 4.
By Bjorn Fehrm
January 10, 2025, ©. Leeham News: We do a Corner series about the state of developments to replace or improve hydrocarbon propulsion concepts for Air Transport. We try to understand why the development has been slow.
We listed the different projects in the second Corner of the series that have come as far as flying a functional model or prototype. In Part 3, we went through some of the causes of the slow growth. It was a mix of inexperienced startup managments, all wanting to be the new Elon Musk but lacking elementary knowledge in the aeronautical field, to what is the real hard part of an alternative propulsion concept.
Many startups developed new electric motors for eAirplane or eVTOL use, a relatively straightforward development when the real hard part is the batteries. We described how batteries differ significantly from fuel as an energy source in Part 3.
Now, we add a market aspect that is poorly understood by most players.
Figure 1. The Pipistrel Velis Electro trainer. Source: Pipistrel.
Aeronautical battery market
In Part 3, we described how batteries are a very troublesome energy source, as these weigh a lot once they are at the system level, wear if used to more than 60%-70% of capacity, and don’t like fast charging or discharging. Their cost is also way higher than all players have assumed. Here’s why.
A very important aspect that is poorly understood by the players is the difference in market dynamics of battery markets that consume large quantities, like the car market, and the small quantities of the aeronautical market of today and tomorrow.
The batteries in our handheld devices, such as phones, computers, tools, and electric vehicles, are made up of cells that are serial and parallel connected to get the needed Voltage and Current capacity. A laptop or tool battery could have four to six cells connected, while an electric car battery has up to 10,000 cells connected to get the instantaneous and long-term power needed.
A challenging production
These cells require a very sophisticated production process as the electric capacity comes from electrodes living very close to each other, separated by a thin electrolyte separator. Any fault in the separator where the electrodes touch each other causes the cell to start a thermal runaway.
Figure 1. Cross section of a lithium-ion cylindrical cell[. Source: batteryuniversity.com
In the 10 years of debate since 2015 about battery-electric aircraft or hybrids, optimists have constantly cried out that new chemistries have been developed that now increase the capacity by X%.
What these persons ignore is the very long and costly process of taking a chemistry from the lab to reliable and economical production at scale. It can take up to five years.
For a battery player to do this, it must see a sizeable market for its new cells. There is a lot about the battery cell market that the eAircraft or eVTOL startups need to understand, or there can be major hiccups late in their programs.
A minuscule market
Too often, the marketing materials and even investor prospects from these startups take data for battery capacity and cost from the e-car market and project it on the aeronautical case. This is making a multi-dimensional fault:
- As we have described several times, aeronautical cells need higher C-rates than car cells. For aircraft cells, the double, and for eVTOLs, we talk about four to five times the C-rate. It requires cells that have a different design from the car cells.
- These cells are, therefore, not part of the gigantic production volumes and, thus, low costs of car cells. The annual production of cells for the car industry was 2024 around 800,000,000 kWh (you measure cell production in capacity as there are different form factors where the cells have different capacities).
- The annual production of cells for the aeronautical industry during 2024 can be estimated as less than 1,000 kWh or less than 0.0001% of the car industry.
The problem is that this difference in production volumes will not change anytime soon. The industry with the highest ambitions for yearly production of battery electric aircraft is the eVTOL industry.
Joby described in its Reinvent investor presentation 2021 that it would produce 350 eVTOLs per year during 2025. It now expects to reach a production volume of one eVTOL per month by the end of 2025. With a 100kWh battery system per eVTOL, we will need 1,200kWh for Joby during 2026 if the rate is realized.
On the aircraft side, we have serial production of the Pipistrel Velis with a 25kWh battery system. The production rate is around 25 aircraft per year, which equals 625kWh needed annually. The next aircraft with a yearly need of around 1,000kWh will be the Beta Technologies CX300, presumably for 2026.
So we talk about a market of 0.0001% of the car industry, with cells with a different build-up and, therefore, with a different production. There is no way these cells’ prices can be compared with the car industry’s prices.
The reality is even harsher than the different costs for the cells. With minuscule volumes continuously moved to the right, the aero industry faces disinterest and, thus, disinvestment from the cell industry as its internal business plans are continually adjusted to the right and down.
For an eAircraft or eVTOL player, it’s imperative to plan their battery side so the venture is immune from battery cell providers who decide to stop the project with their special high-capacity cell. Otherwise, the project’s battery modules must be redesigned, affecting the battery system and, in turn, the module and aircraft certification.
When there is no longer a supply of cells for the aircraft’s battery modules, a project’s final years of development or the start of production can become a nightmare for the startup or its customers. Redesigning and re-certifying the battery modules can be a major disruptor for projects using that extra-capacity, special cell.
Prudent players, therefore, opt for lower-capacity cells with a secured alternative market. Thus, they will be available when the eAircraft or eVTOL is in production and later when customers need battery module replacements during operational use.
I suspect that the quality control and approval requirements of the aircraft industry will also both drive up cost and significantly delay the availability of the latest cell chemistries.
Once an aircraft is approved it is expensive and cumbersome to change core components… something that does not lend itself well to a relatively rapidly evolving technology.
Yeah, there’ll be a whole new area the FAA will have to design certification standards and maintenance standards for, and they will evolve as the industry gets more long term knowledge.
While the 787 had a host of issues with its original Battery, quality control was a huge one. Volumes were low and always will be and they were doing the form work by hand.
Hand work ins turn meant irregular quality. Boxed into a corner.
The factory was also dirty, which is lethal for an Li Ion battery.
From memory, 80 or 90% were being approved. Again from memory, I believe 60% rejectiobn rate is common.
Bottom line, the FAA had no standards and let Boeing make fake standards (or not set them) and the end result was all too close to a catastrophe.
The electric thing is Aviation’s version of the .com. We will see the cascade of shut downs.
Tech and the limits simply do not allow battery power other than some niche applications. I don’t see that changing.
Electric cars didn’t take off because they’re eco-friendly. They did because they’re freaking fast, quiet, comfortable and easy to care for. Being green was the icing on the cake.
Other than GA, electric aviation doesn’t have a similar incentive. Passengers will fly whatever is cheapest. In short-range, recreational or training GA, there’s plenty of value for an electric aircraft. But that’s an even smaller market than commercial aviation.
Electric cars took off because of incentives and perceived Green. Custom drag racers can be extremely fast, you don’t see them in any kind of longer race.
No care but extremly complex electronics.
And to keep it in perspective, I do own an battery powered lawn mower. Our old one died and my brother had been keeping me up on his ownership.
My basis was I wanted to mow the front and back in one go. This one exceeds that, almost two mowing. So for my application, it works extremely well. Love it. Snow Blowers are not up to the am mount of snow I have to move. In my Brothers case, yes, short two care driveway.
An aircraft if vastly different. The range is not there and you always carry the battery weight.
An A320/737 type would have half the range. Most networks have a combo of short flight s and longer ones. They don’t even have to gas and go, they run calcs and figure out where the best place (time available) to refuel. It can be the last stop of the day and ready to go in the first morning flight.
We just had a flight of 172 miles, 737-900 which is not remotely justified for that short a trip and pax numbers. But it flew onto other destinations.
Cars are not anywhere near the same as aircraft. Realistic range is still 250 miles and you always have to be able to charge if you hit the limit. Gas stations are everywhere so any town or stop spot will have one. And its all of 5 minutes.
Aircraft are beyond different. Hydrogen is a remote possibility though I wonder why not propane.
You still use fossil fuel to make the electricity to crack the Hydro.
Cleaner Jet fuel for now is the best answer. Cooler running engines would be a big help.
There might be a large market in cities for AAM’s replacing helo’s and quickly can pick up patients when traffic limit ambulance speed and where helo landings are hard to do due to propwash and required landing spot size requirements. Not only traffic but accidents at schools and sport events like horse jumping, motocross, speed skiing etc. where small veritport spots can be prepared in advance.
Also for airports need to make AAM’s vertiport attractive having biz passengers security checked before boarding the AAM and land close to the boarding gate.
I’ve just seenh reports of Toyota introducing “cans” of hydrogen for refueling electric cars with fuel cells, so that the can can be quickly changed rather like refueling a petroleum -fueled car – is this a technology that could be used on light aircraft, at least? what is the power density of hydrogen like, in terms of potential KWh per kilo?
raw energy: 33kWh per kg H2.
fuel cell efficiency is 40%(good) ..60%(super!)
reduce available energy accordingly.
if you push H2 through a conventional turbine things are different.
looked around: 40% seems to be an absolute top value for a stationary application.
I can certainly see the problems. On the other hand many of mans accomplishments have had impossible, insurmountable things to overcome. Color TV? who could imagine that Remember the tiny VeryVery Heavy little black and white TV”S that were too heavy for a regular person to carry. Now an old lady can carry a 6 foot diameter TV! that is about 1″ thick!! And color!
Going to the moon? Never?
Telephones that let you talk to anyone, anywhere, anytime! and affordable? (I had a friend who had a telephone 30 or 40 years ago that was in a suitcase and cost a fortune to use. Now phones have more computer capacity than the ones that took men to the moon!
I think they, man, will overcome. They have to come up with a new battery, made of different materials that weigh 1/10th or 1/100 th of todays batteries. Which they will do. It will be as unrecognizable to a man who had a 6″ black and white TV that weighed 100lbs and cost a months wages, who sees a 8foot color tv that weighs 10lbs! Etc, Etc.
Batteries are very old tech.
Combustion engines equally so, they have yet to replace the combustion engine. Sure you can talk about electric cars, but what powers them? Mostly combustion engines and a grid is not stable on solar (none at night) nor wind.
So expecting a sudden shift in an old tech is a mistake to compare it to something like the solid state devices that opened up entire frontiers. Have computers gotten faster lately?
Advances have been in solid state drives (memory) and the chip sets but processors have reached a cost limit.
So no, do not expect some kind of miracle solution. In fact, slower than they thought.
A lot of solar has been put in, using old Tesla car batteries and it works but on a pure cost basis, its a loss (or its written off and supported via tax credits ie. people who can afford it have money)
Flip is for some applications its worth it, having your house freeze up aka Texas? they never fixed the problem, the better off homeowners put in solar and increased system reserves.
Its not an easy issue and aviation has its big bear on its back in weight is always the top issue. Batteries weight a lot . It can work in cars if you can deal with the short range, but cares are not doing 500 knots. Double the speed cost 4x the power.