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Chalmers studies shows almost air travel within 750-mile radius could be made with hydrogen-powered aircraft by 2045

New studies from Chalmers University of Technology show that almost all air travel within a 750-mile radius (1200 km) could be made with hydrogen-powered aircraft by 2045, and with a novel heat exchanger currently in development, this range could be even further.

If everything falls into place, the commercialization of hydrogen flight can go really fast now. As early as 2028, the first commercial hydrogen flights in Sweden could be in the air.

—Tomas Grönstedt, Professor at Chalmers University of Technology

For hydrogen-powered aviation, short and medium-range flights are the closest to being realized. A recently published study from Chalmers shows that hydrogen-powered flights have the potential to meet the needs of 97% of all intra-Nordic flight routes and 58% of the Nordic passenger volume by 2045.

For this study, the researchers assumed a maximum flight distance of 750 miles and the use of an existing aircraft model adapted for hydrogen power. The study, led by doctoral student Christian Svensson in Tomas Grönstedt’s research group, also showcased a new fuel tank that could hold enough fuel, was insulated enough to hold the super-cold liquid hydrogen and at the same time was lighter than today’s fossil-based fuel tank systems.

Heat exchangers are a vital part of hydrogen aviation, and they are a key part of the technological advancements taking place. To keep the fuel systems light weight, the hydrogen needs to be in liquid form. This means that the hydrogen is kept supercool in the aircraft, typically around -250 degrees Celsius. By recovering heat from the hot exhausts of the jet engines, and by cooling the engines in strategic locations they become more efficient. To transfer the heat between the supercool hydrogen and the engine, novel types of heat exchangers are needed.

To meet this challenge, researchers at Chalmers have been working for several years to develop a completely new type of heat exchanger. The technology, which is now patent pending by partner GKN Aerospace, takes advantage of hydrogen’s low storage temperature to cool engine parts, and then uses waste heat from the exhaust gases to preheat the fuel several hundred degrees before it is injected into the combustion chamber.

IMG_0963

Heat exchanger with exhaust gas preheater, developed according to the new concept.


Every degree increase in temperature reduces fuel consumption and increases range. We were able to show that short- and medium-haul aircraft equipped with the new heat exchanger could reduce their fuel consumption by almost eight percent. Considering that an aircraft engine is a mature and well-established technology, it is a very good result from a single component.

—Carlos Xisto, Associate Professor at the Division of Fluid Mechanics at Chalmers, and one of the authors of the study

The researchers also note that with more optimization, this type of heat exchanger technology in a regular Airbus A320 commercial aircraft could provide an improved range of up to 10%—the equivalent of the Gothenburg-Berlin route (approximately 450 miles).

Resources

  • Christian Svensson, Amir A.M. Oliveira, Tomas Grönstedt, Hydrogen fuel cell aircraft for the Nordic market, International Journal of Hydrogen Energy, Volume 61, 2024, Pages 650-663, doi: 10.1016/j.ijhydene.2024.02.382 (open access)

  • Alexandre Capitao Patrao, Isak Jonsson, Carlos Xisto, Anders Lundbladh, Tomas Grönstedt, Compact heat exchangers for hydrogen-fueled aero engine intercooling and recuperation, Applied Thermal Engineering, Volume 243, 2024, doi: 10.1016/j.applthermaleng.2024.122538 (open access)

Comments

Davemart

As I note elsewhere:

https://aviationweek.com/aerospace/advanced-air-mobility/h2fly-apply-lessons-learned-liquid-hydrogen-flights

' Air Liquide developed the double-walled, vacuum-insulated LH2 dewar tank installed in the cockpit area of the right-hand fuselage in the four-seat, twin-fuselage HY4. An internal heater pressurizes the LH2 in the tank, and a heat exchanger using waste heat from the fuel cell drives an evaporator that vaporizes the hydrogen for delivery to the fuel-cell cathode at 6.5 bar (94 psi) absolute pressure.

Evaporator control is identified as one of the technical achievements of the Heaven program. “The storage system needs an evaporator because the hydrogen in a liquid state has to go into the gaseous state. What we learned is this evaporator has to be controlled very exactly,” Kallo says.

“That is done by evaporating enough hydrogen, which then is directly used, and we control the pressure at the fuel cell. Including the energy that goes into the evaporator–which is mainly from the heat of the fuel cell–that pressure control has to be done extremely precisely so that we have a very stable pressure at the fuel cell,” he says. “The simplicity of the controller was astonishingly good.”

Control of the evaporator, pressure and fuel-cell power output was sufficiently fast and precise to eliminate the need to use a buffer battery to handle power transients. “We expected this, but we could show that during the 3-hr. cruise flight we did not need the battery,” Kallo says. '

Pretty darn spiffy, and a bonus, that control seems so simple and near automatic.

Davemart

The link I have referenced of course refers to the far lower temperature fuel cells.
The article above is looking to use combustion engines.

It is not clear in these early days at what size and range engines become preferable to fuel cells.

We do know that if efforts to develop high temperature fuel cells pan out, then that shifts the size and range considerably upward.

Using low temperature PEMS for a small size VTOL plane, Joby have already exceeded 500 miles.

Davemart

For those looking for an in-depth study of liquid hydrogen in aircraft, here you go:

https://www.sciencedirect.com/science/article/pii/S0360319923065631

All way more challenging than SAF, which simply relies on unspecified amounts of farmland, water etc, in the interests of jetting off whenever folk fancy to ski on the snow which ain't there anymore.
But then they fancy Direct Air Capture to solve that one.
I believe the Tooth Fairy is solidly in favour of that.

For combusting hydrogen, the very high temperature is the biggest issue.
Here is work on suitable materials:

https://www.mining.com/new-aluminum-nickel-superalloy-offers-promise-for-100-hydrogen-combustion-engines/

Tough to do, as is apparent, although the link may overstate the problem somewhat, as there are hydrogen combustion jet engines demonstrated already, but I don't know what their durability etc is.

And here is a link to what is happening here in the UK, where Zero Avia and Rolls Royce are based:

https://hydrogeninaviation.co.uk/wp-content/uploads/2024/03/Launching-Hydrogen-Powered-Aviation-Report.pdf

All immensely challenging, clearly.
Not as challenging as trying to live on a fried planet in the interests of catching international flights whenever you fancy, in my view.

And SAF, or rather the dangled hope for SAF with zero plans to actually produce the stuff economically at any decisive rate operating as a fig leaf, does not help.

Davemart

On SAF, from my link:

https://www.sciencedirect.com/science/article/pii/S0360319923065631

2. Future aviation mix

' SAF is a fuel manufactured from sustainable feedstock and has comparable properties to kerosene requiring only minimal modification in the aircraft/engine (in contrast to hydrogen). It has the potential to reduce lifecycle CO2 emission by up to 70 % depending on the feedstock [29] whereas hydrogen offers carbon-free emission at the cost of significant aircraft system adaptions. The EU has set targets to use up to 5 % SAF blend by 2030, 32 % by 2040 and 63 % by 2050 [30]. The current main feedstock of SAF includes oil from the biological origin and agriculture residue. A forecast shows that due to the complex supply chain, the feedstock supply capacity will be limited to only 20 % of what would be required to power the 2040 global aircraft fleet [31]. Synthetically produced hydrocarbon fuels (called Power to liquid SAF or synfuel), with carbon captured from the air and renewably produced hydrogen (H2) as feedstocks, have the potential to meet aviation demand [31].'

Note that not only are the reductions in CO2 limited even where it is used, and other emissions notably NOx remain, but it supplies other than synthetically produced hydrocarbons are only a small proportion of total potential demand.

And that does not take account of the aim of the aircraft industry to massively increase the size of the fleet!

And:

' With regards to cost, synfuel requires 22 % more hydrogen and 45 % more electricity than direct hydrogen usage [9]. Due to a more complex and less efficient production process of SAF and a carbon tax imposed on kerosene, hydrogen is expected to reach a cost-competitive point by the early 2030s [9]. Hence, hydrogen could be a long-term solution from economic and emissions perspectives, excluding the effect of contrail'

So a really decisive use of SAF would need more hydrogen than simply using the hydrogen straight!

None of this in my view is remotely credible as other than a delaying tactic by the aircraft industry, nor for those who portray themselves as some sort of free market fundamentalists, with, ' well, that is capitalism', not according to Adam Smith, for whom correct regulation was fundamental to working capitalism, to avoid the substitution of rentier behaviour for productive investment ( check out the rise in property prices since the 'system was saved' back in 2008, so that somewhere to live has become unaffordable for young people) and, germane in this case, 'trades conspiring together against the public interest'

That is exactly what is happening with the aircraft industry and airlines, with their plans to greatly expand the current, obsolete from build, aircraft fleet, in wanton disregard of the titanic environmental costs.

SAF is a fig leaf for this, and a remarkably transparent one.

Hydrogen can work, but not anytime soon.

So don't fly so much. at any rate long distance, and pay the real costs for doing so.


Roger Brown

One significant problem with any practical system of transport using hydrogen as an energy carrier is the cost of producing and transporting hydrogen. One way to get a relatively high capacity factor for your electrolyzers is to locate the H2 production plant at a site with good solar and wind resources which are dedicated solely to producing H2. However, in that case you need to transport the H2 to the site of use. LOHC seems to be the best option but involves parasitic energy loss. Liquefying the H2 involves another loss and a big one (>30%: https://www.energy.gov/eere/fuelcells/liquid-hydrogen-delivery). If getting to the 750 mile flight range requires liquid hydrogen it will be an economically difficult proposition.

Variant003

This seems like a perfect case to hybridize the turbine. I'd like to see if the new megawatt motors being designed for aircraft could be integrated between the ducted fan and the turbine engine?

Bonus! Since the turbine is being designed for H2 then power for the electric motors can then come from fuel cells.

Davemart

Much of Europe has extensive plans in place and are building a hydrogen pipe network.

Here is Germany:

https://balkangreenenergynews.com/germany-unveils-nationwide-hydrogen-pipeline-network-plan/

' The transmission grid is scheduled to be built by 2032. Retrofitted fossil gas pipelines are planned to make up 60%, which considerably lowers costs. The cabinet is preparing a law to accelerate the process, similar to the construction of liquefied gas terminals after Russia invaded Ukraine.

Demand for hydrogen in Germany is seen at between 95 TWh and 130 TWh in 2030, but the transmission network is envisaged to have an exit capacity of 270 TWh per year. Habeck said the country would cover 30% to 50% of demand with domestic production in the long run.'

If hydrogen is got working for planes, then spurs to airports with the backbone in place as soon as volumes needed there justify it will surely be built.

It would still need compressing, and that is lossy, but zero emissions including NOx are the prize.

SJC

Joby just set a distance record.

https://aviationweek.com/aerospace/advanced-air-mobility/joby-beats-range-target-hydrogen-electric-air-taxi-demonstrator?utm_source=Electric+VTOL+News&utm_campaign=2ab5569d38-eVTOL+eNews%2C+Sept+29%2C+2017_COPY_01&utm_medium=email&utm_term=0_5d82db6e49-2ab5569d38-50801281

Davemart

Hi SJC

Yeah, I was pretty excited by that, and all the bits seem to be coming together for hydrogen powered flight.

I had a good dig around to find out what is going on here:

https://www.greencarcongress.com/2024/07/20240713-joby.html

Unfortunately whilst the plane bits, and the hydrogen tanks etc seem all good, right at the end by the last post in this long thread, I came across an analysis of the assumptions Joby are using for their VTOL venture, which includes gems such as assuming 10,000 cycles for very high density batteries, which not only have high transient loads for take off and landings, unlike car batteries, but are to be routinely fast charged!

Almost like magic, ain't it? ;-)

Maybe Archer are a bit more sensible, but to me it looks as though electric VTOLs, at any rate from Joby, are not in any way on the cards.

Hydrogen flight is a wholly different matter, so the test by Joby was interesting in that regard.

Planes yep, VTOL nope, for me from the info to hand.

Roger Brown

"It would still need compressing, and that is lossy"

According to this article not just compression but liquefaction.

Davemart

Roger:

Yep, I meant liquefaction, but somehow typed compression!

They are looking to liquid hydrogen for trucking too, and building out the filling networks, so the tech should be pushed on by that.

China, for instance, has developed a 100kg liquid hydrogen fuel tank, and Daimler two 44kg stainless steel tanks, each one with an inner and outer tube

https://www.daimlertruck.com/en/newsroom/pressrelease/fuel-cell-technology-daimler-truck-builds-first-mercedes-benz-genh2-truck-customer-trial-fleet-52552943

Dunno if the Daimler version would need further weight optimisation for planes, perhaps using aluminum instead of steel, as in the Joby, until we can manage to do composite tanks.

sd

"almost all air travel within a 750-mile radius (1200 km) could be made with hydrogen-powered aircraft by 2045" Is this a joke? Joby just did about 500 miles in 2024. I would expect that battery electric aircraft will be able to this by 2035 and maybe sooner at a much lower cost and much less hassle than dealing with hydrogen

Davemart

@sd

That was for a VTOL designed as an air taxi

With normal take off and landing HyFlight and Zero Avia etc are showing with much the same tanks etc even in modified bodies of aircraft designed for jet fuel that short to medium flight using liquid hydrogen for 40-80pax is doable

Roger Pham

Roger Brown stated: "One significant problem...transport using hydrogen as an energy carrier is the cost of producing and transporting hydrogen."

Reply: One company in China is able to price green H2 from renewable-energy electricity at the cost of $4.89 per kg at the pump, which is cost comparable with diesel fuel on per BTU basis in China's market.
H2 can be transported in existing Natural gas piping system at equivalent rate (kW-mile) as natural gas. The cost of H2 transportation in pipelines costs 1/8 the transmission cost of electricity on kW-mile basis. So, H2 can be produced near the Solar and Wind farms and transported via pipelines to end-users thousands of miles away for much lower transportation cost than the use of high-voltage power lines.

Eventually, H2 will be the LEAST EXPENSIVE renewable-energy fuel in comparison to all other options. In aviation, LH2 can transport twice the payload weight per mile in comparison to jet fuel per BTU basis. The use of LH2 in future aviation will be certain and a no-brainer.

Davemart

Roger Pham said:

' H2 can be transported in existing Natural gas piping system at equivalent rate (kW-mile) as natural gas. '

References?
This is not the case so far as I am aware:

https://www.mdpi.com/2673-5628/1/4/13

' In line with that, a 342 km, 36″ natural gas pipeline was used in this study to simulate some technical implications of delivering the same amount of energy with different blends of natural gas and hydrogen, and with 100% hydrogen. Preliminary findings from the study confirmed that a three-fold increase in volumetric flow rate would be required of hydrogen to deliver an equivalent amount of energy as natural gas. ' (abstract)

It might be possible to up the pressure somewhat to increase flow rate, but that would surely take purpose built hydrogen pipelines.

However, most natural gas is used primarily for space heating, and better insulation, heat pumps, solar etc can surely reduce how much energy we need pumped about, so around a third of the pipeline capacity is perhaps not a bad fit.

As needed, some of the backbone is to be in purpose built hydrogen from the get-go piping.

The alternative, of trying to substitute electric everywhere, would entail the complete write off of the massive investment in NG pipelines for a start.

Davemart

@sd

Using batteries the Joby has a 155 mile range.
Using liquid hydrogen 523 miles.

So you are positing a very large increase in battery energy density and none at all using liquid hydrogen

Perhaps from around 300kw/kg now to around the 800kw/kg usually reckoned needed for some decent range, excluding issues of high drain on takeoff and landing, fast charge etc


That is to enable a range possible right now with liquid hydrogen, whatever other hassles it may have.

Sounds pretty speculative to me, rather than a slam-dunk

sd

@Davemart

Yes, it is possible to have hydrogen powered aircraft in the relatively near future that will have considerable more range than 750 miles. That is why I asked if their statement was a joke. A comment on scaling: The larger the aircraft, the easier it is to have a higher range. Also, it take less energy to make normal takeoffs and landings than to make vertical takeoffs and landings. Having said that longer range hydrogen powered flight is possible, I would ask if this is the best thing to do with whatever green hydrogen can be produced. I would suggest using it to make ammonia based fertilizer at least until that basic need is met.

On battery powered aircraft, NASA has suggested that you need about 600 kWhr/kg to make a battery powered Boeing 737 or Airbus 300 sized battery electric aircraft. (I wish I had the reference but I do not have it. However, next week I will be at the Experimental Aircraft Association show at Oshkosh, Wisconsin and will ask the NASA reps about electric flight.) Right now, the Lithium ion with MNC get about 260 kWhr/kg. Solid State Lithium Ion batteries are projected to get 400 to 450 kWhr/kg and Lithium sulfur are projected to get 600 to 800 kWhr/kg and be lower cost to manufacture. Eviation Alice is projecting 250 nm range with reserve (287 mi or 462 km) with convention lithium ion batteries so it is not much or a stretch to get 750 miles with a larger aircraft with lithium sulfur. Lyten is now shipping "A" samples of their lithium sulfur batteries so it is not all that speculative. The seat mile costs of using battery electric will be less than half that of using hydrogen so it makes economic sense to use battery electric wherever possible.

Nocreditreports

No slam dunks when air services are hugely subsidized worldwide, because they're simply uneconomic, brutally harmful, and plainly unsustainable. The operative word is "could." It must instead be "should." Talk about hydrogen powered flight as the next gee-whiz technological marvel is missing the point.

Roger Brown

Several years ago I read an article by a consortium of ammonia manufacturers speculating about the possible emergence of economically competitive green ammonia production. They felt that high capacity factor for the electrolyzers was a key economic parameter and thought that locations with very good solar and wind resource were necessary for success.

On the European Hydrogen Backbone (EHB) initiative web site (https://www.ehb.eu/) they have posted various documents including an implementation roadmap (https://www.ehb.eu/files/downloads/EHB-2023-Implementation-Roadmap-Part-1.pdf). In this roadmap they state:

"The Spanish Hydrogen Backbone collects multiple supply sources from around Spain and allows connection to North African project developments, making it one of the most promising hydrogen production locations in Europe."

They propose to transport the North African hydrogen by pipeline under the strait of Gibraltar. EHB a seems to recognize that exceptionally good renewable resource sites are a key to the production of economical green hydrogen. Once a full scale attempt to decarbonize the whole economy gets underway other actors are going to line up to demand energy from such sites. Aluminum manufacture is the most obvious since it uses lots of electricity, but there are plenty of other industrial processes using natural gas furnaces which will have to convert to electric furnaces or to electrolytic production methods. Steel and lime are two of the most obvious but there are undoubted a number of others.

In the EHB document about demand, supply, and transport of hydrogen (https://www.ehb.eu/files/downloads/EHB-Analysing-the-future-demand-supply-and-transport-of-hydrogen-June-2021-v3.pdf) they include a section on transport by ship, mentioning Australia as a promising location for the production of low cost renewable hydrogen. The fact they include this section on long distance transport indicates that they do not regard it as a slam dunk that Europe can locally produce all of the hydrogen that it needs at reasonable cost.

One interesting future possibility for high capacity factor electrolytic production of hydrogen is solar power towers. Research is going on into power towers employing falling particle (e.g. sand) receivers. Energy storage in particles is potentially cheaper than energy storage in molten salt, and higher temperature can be achieved which might allow the use of high efficiency generation cycles such as brayton cycles employing supercritical CO2 as the working fluid. With a cheap storage medium high capacity factor electrolysis becomes possible. Of course concentrated solar requires lots of direct sunlight. Deserts at relatively low latitudes are the most promising locations and Australia fits the bill nicely.

Davemart

Hi sd.

Your arguments appear to be predicated on an essentially fixed amount of hydrogen production being routed by some central authority to either ammonia or aircraft fuel etc

Not only does no such authority exist, but upping production for whatever use is likely to of course increase expertise and reduce all costs.

So I do not buy your essentially reductive argument.

And you mention 'projected energy densities' and so on repeatedly for batteries.
I have seem umteen projected figures for all sorts of things, which are chiefly dependent on the assumptions built into them.

I have been folllowing batteries since around 2010, when I argued with others for the introduction of the Nissan Leaf, against heavy opposition, some of which panned out since an early Nissan Leaf had all sorts of problems and some did not, as it is now perfectly clear that electified light transport is the way to go.

What did not pan out and has not for the last 15 years or so are super optimistic 'projections' of battery energy density.

It is quite clear that for the rapidly growing ( stupidly so, as it essentially ignores the massive contribution to GW) aircraft industry liquid hydrogen at least at medium range has the energy density to do something about it, whatever the other difficulties.

Batteries ain't, nor is there any substantial evidence other than faith-based 'projections' that that is about to change.

Davemart

Hi Roger Brown.

Worth a mention since they are selling about the cheapest hydrogen at the pump around, and are already making for instance for their trucks, 100kg hydrogen tanks, is China.

They are not only building pipelines to move hydrogen from renewable energy sites many hundreds of kilometers to where it is needed, but are to produce hydrogen at their PBR nuclear reactors, which cost a fraction as much and take many years less to build than in the west.

sd

@Roger Brown

I would think that the lowest cost method of making green hydrogen is to use high temperature electrolysis with nuclear power. The higher the temperature, the less electric power is required and if you can get the temperatures high enough, no electric power is required but I am not sure that we have materials that will withstand the heat. Using nuclear power to generate hydrogen has an another advantage. It is advantageous to run nuclear power plants at a constant power output. Making hydrogen when the electric demand is lower allows the plant to run at a constant output.

Roger Brown

SD,

Nuclear power would certainly give you high capacity factor on the electrolyzers without the need for energy storage, and it is siteable anywhere. I have never understood the economics of high temperature electrolysis. The temperature involved means that the heat required to produce the steam is not "waste" heat. It could be used to produce more electricity. So the question is whether it better to produce more electricity and use low temperature electrolysis or whether better produce less electricity and use high temperature electrolysis. A number of people think that the answer is door number 2, but I have not stumbled across the analysis which demonstrates it.

sd

@Davemart

You do not need to buy any of my arguments. However in the US, we have about 40% clean electric energy. Roughly 20% nuclear, 10% hydro, 10% renewable. So until we have a surplus of clean electric power and assuming the object is to reduce greenhouse gases, it makes more sense to me, at least, to use the power where it will have the largest effect on reducing greenhouse gases. If there is a temporary surplus or renewable energy in some region, it make more sense to me to use a reasonably efficient storage system such as pumped hydro or batteries.

Davemart

@Roger Brown:

At the moment vast quantities of heat produced from many processes are simply vented, including at, for instance, peaking power gas turbines, steel plant, and loads more.

Pretty much the class leaders in utilising such otherwise wasted heat are Topsoe Haldor, and their Solid oxide electrolysers can utilise it to reach very high levels of efficiency supplementing a renewable feed:

https://www.topsoe.com/our-resources/knowledge/our-products/equipment/soec

Its kinda disengenuous to look at their quoted efficiencies, but also kinda not, as the top up energy would otherwise not only be wasted, but vented directly to the atmosphere to contribute to high temperatures.

Hopefully that source of extra energy will gradually decrease, but by then renewables should be in greater supply and cheaper anyway - many years away in any case.

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