May 1, 2020, ©. Leeham News: We now wrap the series about technologies that can help reduce air transport’s environmental footprint.
I wrote in the first article, December 13: We have lost our way in our search for a lower carbon footprint air transport system by heading down the electric lane. I will argue why it’s not the best route as it’s not the route that leads to tangible results any time soon, despite huge investments.
In 19 Corners to date, we discussed why. It’s time to summarize what we learned.
Central to the discussion has been the notion of a hype cycle, where new technologies catch the imagination of entrepreneurs that want to make a difference. Gradually you then work yourself through the fundamentals, and projects fail as reality surfaces.
The first signs of reaching the first top is with us. Zunum’s project has gone quiet, and Airbus’ E-Fan X flight test phase was canned last week. In the next months, others will follow, and it won’t be because of the COVID crisis.
The reality that surfaces is that battery technology is so far from what is needed. There’s a massive difference between the performance of a research lab cell and the energy density of an aeronautically certifiable battery system. As this dawns on projects, they fold.
I want to repeat that the best observation platform for the state of battery technology is Formula E racing. It searches ultimate battery performance with acceptable levels of safety and durability. The battery system of a Formula E race car presently weighs 70 times more than a jet fuel system of equal energy content.
And aircraft are, opposed to cars, incredibly weight sensitive. So it just doesn’t work.
95% of the 200 electric or electric hybrid projects addressing our environmental air transport problem have battery-based energy as a cornerstone. It will kill all that relies on it.
The only air transport that can function with the battery as an energy store is extreme short-haul, think below 100nm.
We also learned that electric hybrids could work, but they bring no benefits, just complexity, and unsolved problems.
What has a chance to offer a real long term change is hydrogen-fueled propulsion. But there is a lot of ground to cover before we know for sure and have a workable ecosystem.
So we shall dig where we stand and work with the low hanging fruit we discussed last week. There is a lot of potential in these technologies, and they are worth investment.
They are all included in CORSIA, the ICAO program that is the unified approach to a de-carbonized air transport system. This is the route that leads us to real progress.
While you are entirely correct in your technological assessments and the never to be resolved fundamental problems of hauling all your fuel weight all the way, I think you are misunderstanding something about the Gartner Hype Cycle.
That cycle is not just an observation about technology development, it is an _absolutely_ _necessary_ component of all new technology development. Without the initial Hype, the broad spectrum of necessary investments (in time, brainpower and money on hundreds of hare brained approaches to the problem) will never be made, meaning you never get to the Plateau of Productivity.
The Peak and the Trough are necessary and good things. At the Peak, many different groups will have invested resources in many different technological paths and the fall to the Trough is where the bad ideas get weeded out.
At the bottom of the Trough is when the best/most viable ideas are identified and strategic long term refinement occurs which leads to the Plateau.
Right now it seems the likely end state for a fully electric aircraft will be some combination of fuel cells for cruise and supercapacitors or possibly Gen 3 solid state batteries (which seem to be about 10 years out to volume manufacture) for surge power (takeoff, climb). The use of fuel cells will benefit from decreasing fuel weight throughout the mission, while the supercapacitors or Gen3 batteries will be able to be recharged quickly during ground intervals.
But we will never get to that end state without the crazy dreamers and opportunists of the Hype cycle, the pragmatic businessmen of the Fall, the dedicated engineers and true believers of the Trough.
I think Bjorn’s point is that the hype draws support and resources away from more productive options that could be pursued. That’s actually the purpose of the hype. If the technology was provable, there would be no need for hype, it would be pursued without hype as a natural next step,
As has been discussed many times here, this is not to say that research in these areas should not continue. It should, and we should continue to learn about them. But with the learning should come realistic evaluation and presentation, as Bjorn has done for us here..
There’s no harm in saying these ideas are intriguing and merit further study, but are not yet practical. No hype is needed in that case either.
This series does a good job tapering expectations for electric *airliners*, but much of the hype is actually around eVTOL and other small, short-range electric aircraft. Many of these are or will be successful from a technology point of view. There are also researchers looking at larger electric aircraft, but most of that is academic – the goal is to see what impact/usefulness electric aircraft would actually bring and how they would integrate into the current air transportation system. Admittedly, the media sometimes picks up on this research and generates some hype, but the people doing the research generally know the technology limits.
“It seems likely…” What is that analysis based on? Megawatt-scale fuel cells with weight, volume, and reliability suitable for commercial aviation are probably as far out as suitable batteries, and there’s little real work ongoing in that area, far less than for batteries. Similar story for supercapacitors. When/if substantial investments in those technologies occur, they’ll go through their own hype cycle and we’ll see what, if anything flushes out in the end, decades hence. If said fuel cells were to run on H2, then all the problems of flying with large quantities of cryogenic liquid or extremely high pressure gas come into play. If those are solved, the airplane is much better off flying with existing or optimized gas turbines on H2.
There will be different markets for electric aircraft, from quadcopters for express package delivery on to electric quad or 2×4 engine small electric helos to take you from the airport to the business area, on to bigger island hopping fuel cell driven aircrafts. Note the first combustion gasoline engines were for cars and trucks, similar for heavy fuel diesel engines both were developped further in size and supercharging for aircrafts.
Now you have the Toyota Mirai fuel cell car and Mercedes Volvo Trucks just decided to cooperate on fuel cells as they discovered battery packs will be heavy and expensive for their power needs.
So 5-10 years after they are in serial production of fuel cell trucks of around 450-600hp someone will further develop them for aircrafts.
Maybe we will see new Mercedes aircraft engines again DBXXX-E competing in the electrical aircraft racing circuit.
Thank you Bjorn for a great series of articles.And what a time for them! Atmospheric CO2 has dropped like a stone for all the wrong reasons and the whole of the airline industry is on its knees.Survival will be all any company involved in the business is concerned with frankly.And with oil at $15 a barrel of course the great persuader -profit is absent too.
As I suggested in one of the earlier articles I can only see Boeing ( and not in the near future) producing a new single aisle that breaks the mound regarding wing and engine efficiencies.If for no better reason than the fact they will have to if they are to ‘stay in the game’.
If that happens then as always in a duopoly Airbus will be forced to follow.
Interesting, the current (and hopefully not for long) CEO of Boeing says its not structure that will be the next LEAP (pun intended) but production process.
I think it has to be both or you just wind up with a match for the A220.
Clearly GTF can be improved and with more advanced materials still has an upside.
But we also need a structure that carries its weight not just the limp along.
When a 737MAX can be as efficient as a newer (though not new) A320NEO, you have not advanced structures to any significant degree.
A new wing gets you the A220 and that is it.
The B737 is competitive on a fuel burn per seat basis with the A320 because it is lighter. It is lighter because B737 seats are 2.5cm narrower and because the 737 can’t carry LD3-45 unit load devices (containers). The MAX has slightly widened seats but I note Spirit Airlines were able to push seat width on their A320 to 18.5 inches. Traditionally NG climbed faster to cruise than CEOs but the new engines on the NEOs have eliminated that disadvantage. The A320’s supercritical wing probably make it more efficient on long flights. Obviously for Ryan air doing 45 minute flights from Dublin to London seat width and containerised handling isn’t necessary because they don’t handle much luggage anyway. I would hope labour laws come in to spare the luggage handlers knees.
The Boeing Truss wing concept looks good to me. Decarbonisation isn’t going away and with technical improvements being caned the flight shame people might come back out.
Lighter? That is mumbo.
Last time OEW numbers were published 738NG and A320 were a wash.
The MAX has gained more weight than the NEO.
Lower thrust engines are a result of lesser obstacle clearance requirements. That 60ties grandfathering that makes no difference, you know!
Lower max thrust ( as required via One Engine Out performance ) gives a slight advantage for the same cruise thrust required. ( 738NG and A320 used to take about the same fuel, longer range advantage to A320.)
After survival and recovery, which will take 3 years according to Boeing (make that 6 then) the priority of the airline and airliner manufacturing industry must be to make sure this never ever happens again. Institutions and individual that failed or placed ideology above public health (WHO, certain Governments and institutions within) must be thoroughly investigated and either terminated, cut-off and isolated or reformed. This must never happen again, zero tolerance and people and interests that get in the way of that must be brought into the open. It is time for recrimination.
For airlines it means new contact free check in procedures must be developed. Facilities for testing for infections and obtaining infection free clearance must be developed and airports must put in place facilities for test stations if and when virus or antigen tests become available during pandemics. Legal policies must be in place to stop people from travelling with cold or flu like symptoms and incorporating insurance costs for their quarantine into tickets should this become necessary. Fines for those knowingly travelling with undeclared diseases must be in place. Hotels must also have procedures for dealing with quarantined people.
When people board an aircraft make them keep a medical mask on until they sit down and as they check in make them sanitise their hands by watching them. Then tell them to sanitise every time they get up. That must become the norm.
Plans for dealing with Pandemics must be developed and in place at each airline, airport and immigration border that can be implemented rapidly.
For aircraft manufacturers it means new cabins and interiors. Air flow must be rearranged to bleed out air at each individual seat and draw it up into the ceiling so that it is not spread in the cabin. There it will be filtered of bacteria and viruses. Bacteriostatic materials need to be added to all materials, UVC disinfection lamps added and facilities organised for disinfecting cabins and to help flight attendants.
I think we hit the peak simply based on the economy.
RR I believe is continuing with the project, I think they feel they advance electronic systems in other areas than just Aviation (Lasers are coming on in Warships and that is an area RR has a significant presence in) .
Overall no one is spending on anything in the future other than direct results.
We already has oil surplus and zero financial incentive.
“We now wrap the series about technologies……”
I don’t think for a moment that Airbus was wasting its time and money on E-Fan X. It has a solid, practical, realisable direction. Airbus was planning the complete decarbonisation and complete elimination of any emissions, including NOX and water vapour. That is now on hold.
Superconducting motors and transmission is now practical which means lossless centralised power generation from fuel cells (potentially 75% efficient) or gas turbines with a sCO2 super critical CO2 Brayton topping cycle (potential practically 65% efficient)
Fuel Cell technology based around PEM/Platinum technology has been advancing in the automotive world. Already fuel cell cars are much cheaper to make than battery electric. The problem has been expanding a refuelling infrastructure, I think about 70 refuelling stations in Germany and 2 in Switzerland, many in California. Toyota have had the beautiful MIRAI FCEV car on the market for many years and BMW with decades of hydrogen experience have signed up a cooperation.
Bosch say they can get platinum use down below that of a standard car with a catalytic converter a 10 fold reduction has been achieved. About 10 grams per car.
The interesting thing about Toyota’s MIRAI tells us what a fuel cell aircraft would be like. It is a light hybrid with a 1.5kWHr battery, the battery is essential from a responsiveness point of view as well as adding efficiency etc. PEM fuel cells need to be well cooled hence a fair sized radiator but it also means the vehicle collects all of the water in its exhaust and rather than dump it on the road as a distraction for other drivers it has a water dump switch to release it.
Hence a fuel cell electric aircraft could completely eliminate all forms of pollution. Particulates, unburned hydrocarbons, nitrous oxides, noise, CO2 and even the release of water vapour into the upper atmosphere. The goal isn’t just energy efficiency.
All of the technology is now in place for a zero emissions flying wing able to handle multiple sources of power: Composite structures, 3D CAD, giant robots, lightweight electric motors, superconducting motors, generators and conductors, efficient production of hydrogen, compression or liquefaction as well as carbon neutral fuels.
Those who think the depression of economic activity COVID-19 has caused will be of benefit are mistaken. This will simply delay the evolution of solutions by a decade.
Peak Hype alert – based on dropping all the buzz words into a food processor
“zero emissions flying wing able to handle multiple sources of power: Composite structures, 3D CAD, giant robots, lightweight electric motors, superconducting motors, generators and conductors, efficient production of hydrogen, compression or liquefaction as well as carbon neutral fuels”…..Phew
It is a little funny, but your pooh poohing isn’t really an argument is it and nor does it acknowledge the fact that Airbus was trying to decarbonise aviation, their current CEO said that clearly was his main concern pre COVID-19.
The ‘experts’ are telling us CO2 emissions from aircraft are bad and may end human life on the planet. Children have eco-anxiety, they’re going to be mentally fixated on this fear till they’re 45. They’ll shutdown aviation completely if they can. The experts are not only telling us that CO2 emissions are bad but that emissions at high altitude are far worse. They’re also saying that water vapour at high altitude is worse than CO2 and that NOX is worse again and particulates as well.
The point is this, unless the Aviation industry can point to a plausible future hope of emissions and pollution free aviation they will go towards harsh taxes and aviation bans to shutdown the industry.
The only plausible system that can eliminate CO2, NOX, Particulates and even Water is the fuel cell.
The key technology is the high power to weight electric motors. That problem has been solved whether it be permanent magnet, cryogenic or superconducting. The latter are essential from an efficiency point of view. I think we have enough experience to say that cryogenic hydrogen can be made to work.
That leaves only the fuel cells to get right whether PEM or SOFC. I think Airbus was thinking of centralised power generation using turbines, they’ve released concepts, using combined cycle gas turbines in the interim. I believe these can be made 70% efficient since apart from the topping cycle a non condensing heat exchanger can be used to precool the air.
Particular emissions actually reduce warming.
I thought Bjorn made a plausible argument for biofuels or synthetic fuels. They offer the energy density, their weight burns off during flight, they are compatible with existing systems, and would (hopefully) meet sustainability conditions.
Ask anyone who has worked with hydrogen, “How quickly did hydrogen lose its charm?” It is a monster pain in the butt to control. And of course, it is dangerous when it mixes with air. It’s bad enough in the lab. I’m not eager to fly with it at 30,000 feet.
The flame of burning hydrogen is nearly invisible in daylight and if its pure H2 there is no smoke. Not great if you want to put it out
Hydrogen has been used in the industry more than 100 years, the protocols for handle it are very well stablish.
Still does not deal with the heavy nature of the tanks which looses you range.
Gains emissions, but transfer into an aircraft?
Synthetic fuel works fine, it also is another cost as it has to be converted and your energy source to do so?
One of the gas rich gulf state has a huge plant, but they pay nothign for the gas they use to convert and sell a high quality product.
Both the gas use and the burn of clean fuel is better emissions wise but how much?
We could make a huge inroads and simply replace coal plants with gas plants. Still emissions not anything as grossly bad (and no slag piles)
The PDF says Hydrogen gas produion is 1/4 of Natural gas, that is so out of the plausible realm as to be beyond absurd.
TW, in fairness the PDF says that natural gas consumed in hydrogen production is 5% to 8% currently. It projects that a hydrogen economy would consume less that 25% of proven reserves. That was in response to the concern that reforming methane to produce hydrogen would reduce supply and drive up natural gas prices.
The PDF is meant to put forward the best case for using hydrogen. Just as Bjorn puts forth the best case for electric aircraft, it’s a useful tool to evaluate the technology.
Amory Lovins has been advocating alternative energy technologies for a very long time. I’ve attended a few of his presentations and he’s very enthusiastic & knowledgeable, and has great depth of understanding in this field. Whether or not you agree, it’s always good to listen and consider what he says.
Thanks Bjorn for the series, highlighting the many engineering obstacles to electric conversion.
Hydrogen in compressed gas form is both impractical and uneconomic as a zero carbon fuel source.
First, hydrogen is primarily made from natural gas, which releases CO2, and 45% of the energy is lost by compression and transportation. End to end efficiency of compressed hydrogen gas fuel ends up around 25-35% due to losses. The extra weight of a high pressure gas tank needs to be considered in aircraft after this. For these reasons, hydrogen powered aircraft will have a larger carbon footprint that conventionally fueled aircraft and the fuel will cost more. Existing natural gas to liquid fuel plants can make fuel for aircraft more effectively. If the carbon is captured while producing hydrogen. this in turn uses energy and needs to be compressed taking another fraction of the energy to do.
If hydrogen could be produced cheaply from intermittent renewable electricity, thermal solar or other carbon neutral power sources, then combining this with a gas to liquid process has lower losses than compression and transport of hydrogen.
This is the reason that hydrogen powered cars are not being sold, in cars the extra weight isn’t the issue, but the end to end efficiency is a killer. 25–25% vs 70-90% for batteries. Fuel cells need compressed hydrogen to work as well, and at the moment there is not enough carbon neutral energy for the grid. let alone aircraft.
Fuel cells are good for space they seem to have very limited use elsewhere.
CO2.Its easy to forget that the carbon cycle is one of the key factors for life on earth as we know it.It is mind boggling in its size.So often people see no further than – CO2 bad with no knowledge that the answer is -good.The question is simply -how much.
Of course CO2 levels have been higher in the past with no ‘unnatural ‘ intervention .65 million years ago it was so high ( and warm)that there were no ice poles.
Indeed man’s virtual deforestation of the planet has reduced the natural carbon cycle enormously.The harnessing of hydrocarbons to create energy has been the single most important advancement for our present level of technological life.
But yes we are now creating too much CO2 but that does not make the substance evil or that we have to back to the stone age and produce none.
Like so much it’s a balance.
We don’t have to burn billions of tons of coal (thus CO2)to produce energy as was the case 100 years ago.Electric cars that don’t have any gravitational issues are ( give or take) ready for full commercial rollout.So no need to burn millions of tons of oil.
Aircraft are gravitationally ‘challenged ‘ so have to use high density energy.What the industry imho needs to show is that they are doing their level best to minimise CO2 output.
That means not flying aircaft designed 60 years ago and thinking its ‘good enough’ because it isn’t.So no 737’s and 747’s even 320’s and moving designs forward in imaginative and new ways – fast.
Post covid nothing less will do.
Innovative technologies, and especially game changing technologies are rarely if ever provable without spending significant, and sometimes enormous amounts of money.
Not to de-rail the discussion, but Boeing appears to be in its present situation by only going for provable technologies. Let’s hope that other famous American companies don’t fall into the same trap. GE?