Bjorn’s Corner: The challenges of hydrogen. Part 31. Wrap-up: Where we stand

By Bjorn Fehrm

April 2, 2021, ©. Leeham News: It’s time to wrap up our series on the hydrogen airliner alternative for Sustainable Commercial Aviation.

We review the status for sustainable aviation as of today, then look at the future next week.

Figure 1. The first certified electric aircraft, the Pipistrel Velis Electro. Source: Pipistrel.

Sustainable aviation

The increasing awareness we have a climate problem causes by greenhouse gases drove an increased awareness of how civil air transport was contributing to the problem. Though the contribution was not large it was increasing and highly visible in the debate about what to do.

In 2017 I started looking into electric aircraft as a fix to the problem as it holds promise for cars. I wrote my first Corner about it in June 2017. Having done the sums before hitting the keys, I was a skeptic. It just didn’t work, even with optimistic assumptions around the parameters for the aircraft and its batteries.

I was pretty much alone in this skepticism; hundreds of “experts” chimed in on the battery-electric revolution for airliners at the time.

The battery era

Three months later, Wright Electric and Easyjet announced it would field a 180 seat electric aircraft by 2027, flying routes like London to Paris on battery power. A flood of new companies proposing battery aircraft then followed, one more fantastic than the other.

Battery technology would advance so fast that the 70 times weight deficit against Jet fuel would soon be no problem.

Today, my assumption for battery kWh/hr for a certified battery system is halved, and I still have to see a system that achieves this. The only battery-based aircraft that reached certification to date is the two-seat trainer from Slovenian Pipistrel, Velis Electro Figure 1, and this stays within 20 minutes of the airport.

The hybrid era

After the initial battery craze came the hybrid era. The upstarts engineers had done their sums and realized that “batteries might work for cars, but it doesn’t for aircraft.” But a hybrid like the Toyota Prius must work, it would give fantastic new opportunities for propulsion with small electric fans all over the aircraft.

Now you have a carbon fuel burning aircraft that is more complex and heavier than the plane that it replaces, and if you do your sums carefully, you find that there are no fuel efficiency gains and, therefore, no environmental gains.

Yes, you can prove a single figure improvement on paper and PowerPoint, but experience says this vanishes once you fly the finished airplane in the big wind-tunnel (the one outside).

Of the many electric-hybrid aircraft projects announced from 2018, I can’t think of one that has flown and shown any progress towards the promised fuel savings.

The hydrogen twist

It started with Airbus leaving the high profile hybrid E-fan-X project it started with Rolls-Royce. Then the June 2020 announcement where the French state announced it invests in hydrogen research and expects Airbus will deliver a hydrogen airliner by 2035.

In three years, we go from batteries to hybrid and then to hydrogen. The driver is the increasing climate problems and the realization air transport can’t escape the public eye by converting to sustainable fuels. There won’t be enough of it for the 25,000 planes flying each day, the feedstock will compete with food production.

After changing course two times, is hydrogen now the route in addition to sustainable fuels? And why isn’t sustainable fuels a better path altogether?

This is the subject of next week’s Corner.

33 Comments on “Bjorn’s Corner: The challenges of hydrogen. Part 31. Wrap-up: Where we stand

  1. Thanks for your series. Maybe one of the best source of info on the subject right now.

      • Harbor Air has an electric Beaver in the works for short hops out of Vancouver as well as Otter and Twin Otter versions.

        Extremely limited sub set of a unique application.

        • I don’t grasp how even short flights work in a service like Harbour Air’s.

          Do they have to plug airplane in during their short turn time?

          Of course their trial will play well with pandering politicians, especially Victoria BC city council which has at least some significant sentiment toward around-harbour residents complaining about noise and risk of collisions airplane-airplane and airplane-boat. (It is a busy harbour, with a radio version of TalkyTooter for voluntary separation.)

  2. I have only one comment. If you can make Hydrogen economically (Which I doubt) and CO2 can be taken out from the Air (Economically), then I think it would be better to continue with a liquid hydrocarbon fuel made from water (hydrogen) and Air (CO2). There are several known industrial scale processes already used, some by Germany during WW2 and South Africa. Then the current world distribution network and current Aircraft configuration could still be used. The savings on the distribution system would make it more economical than converting to Hydrogen.

    • Similar points to this have been raised at various junctures in the course of this series, but no calculations have ever been presented (which is understandable: the series is about aviation, not about world energy).

      I recall one commenter (sorry, I forget his name) doing a calculation a few months ago from which transpired that more-or-less the entire global renewable energy sources presently available would be required to generate enough H2 for the aviation industry…which goes to show how much of a challenge this is.

      Multiple commenters have asked whether you get more CO2 “bang for your buck” by spending money on industrial CO2 capture — with continuation of present fuels — rather than switching to LH2, but no answer has emerged to this question. Environmental movements tend to oppose this approach because they suspect that it’s a ruse by multinationals to be able to continue “business as usual”. Unfortunately, the entire discussion around this topic is distorted by a lot of wishful thinking, wild assumption and fanaticism.

      • It should be added in the very short range nature of the possible if everything goes right is an impossible hurdle for feasible. Might as well do electric rail.

        Only the EU could come up with something like that. If Alaskans don’t like props how will the EU public take that?

        While its interesting as is Battery Air, its Lucy in the Sky with Diamonds.

      • An A320 with centre tank activated can carry 23,430 Litres of fuel. Each Litre has about 8kW.Hr of energy. Hence there is about 8MW.Hr in each 1000L or in the entire aircraft. A 100m diameter wind turbine atop a 100m tower with a 4MW rating and generating at 50% of rated capacity will provide 48MW.Hr/day. One would need 4 such wind mills to power 1 A320 fuel load if the production of cryogenic LH2 or synthetic carbon neutral PtL jet fuel was 100% efficient. In Because efficiency will be 66% at best we would need 6 such giant wind turbines. It makes sense that an 900 kmh aircraft with a 37m wing span will need 6 x 100m span wind mills operating at only 50kmh. Of course there are of shore wind resources and floating wind turbines but each carbon neutral fuelled A320 would need capital as expensive as the aircraft again in the form of renewables whether wind or solar thermochemical water splitting. There is no conspiracy of energy companies to keep this energy supressed its so expensive no conspiracy is needed. Its going to be extremely expensive energy. I do see a sort of conspiracy to hide the costs of renewable energy. While Bjorn has explained the impossibility of medium range battery powered jets there are other voices in the wilderness warning use that thorium molten salt reactors are the only solution. At the moment the Chinese are the only ones that will master this technology.

        • And that is the bottom line.

          What is the true cost of so called renewable?

          We have hidden costs for fossil fuels as well in the US (tax structure ) that needs to be corrected as well to get the right picture.

          • The Saudis and Russians would be happy to get $50/barrel. ($0.25/Litre). Most of the estimates for refined PtL fuel are between 4-6 times that price. Say $1.25/Litre. No taxes on that. Given the 2L/100km per seat mile a 6000km Paris-New York flight would consume 120 litres per pax costing about $100 more. It seems affordable. Anything that saves fuel: turbo props, electric ground taxiing will be worth it and used.

  3. Whilst these conclusions are probably correct, they are only probably correct today. Sixty years ago, Lead-Acid was the dominant movable/portable battery technology. Thirty years ago, Ni-Cad was the dominant movable/portable battery technology. Today, Li-Ion is the dominant movable/portable battery technology. There are lots of clever chemists with lots of money behind them in lots of parts of the world currently trying to displace Li-Ion. If any of them succeed, the calculations in the future about the viability of electric or hybrid airplanes may be quite different.

    • I agree, Sploddox. What I write about is the projects that all were saying they be in the market around 2025 to 2030. Batteries will improve and the limit where they are useful, which I would say today is UAMs traveling 50nm, will step by step move up.

      But we are below 100nm for some time and I, as a pilot, is always thinking about the poor Captain that has 19 passengers in his nominal 200nm battery plane where his route was 200nm and the reserves are 30 min, then he crashes.

      The weather is VERY unpredictable and NO captain wants to be left with 30min, NEVER EVER. The margins with battery power are just too small. The UAMs can go down very slowly where they stand so for these the small margins are OK, not for a plane. This is my problem with the battery plane. Captains on fuel planes pad the reserves with 100%-200% most of the time. It’s just not possible in battery planes for quite some time.

      • @ Sploddox / @Bjorn

        There are indeed *potential* battery chemistries that yield significantly higher energy densities than Li-ion batteries. However, in many cases, the chemistry involved is (highly) unstable, which would make make application (particularly in aviation) very difficult.

        – Li-ion: ~100-200 Wh/kg.
        – Li/CuCl2: ~1000 Wh/kg.
        – Li/O2: ~1500 Wh/kg.
        – Al/O2 : ~5000 Wh/kg ?

        Very detailed info, for enthusiasts:

        • These are laboratory figures however real world batteries will require TMI “Thermal Run away Inhibitors”; chemicals that are released with excessive heat or mechanical damage to spoil the reaction. Also required will be a strong cell casing able to take high pressure and a pressure relief valve to allow purging in a controlled manner. Phase change materials or microcapillaries to carry away excess heat from cell hot spots and increasingly more common microchips to measure cell voltage and also temperature at several points so that charging or discharging can be stopped. On the outside materials that stop heat causing run away in adjacent cells. Strong battery packs. A Tesla in Switzerland crashed and burned killing its owner and another in the US reignited repeatedly several times over days. Maybe battery packs need to be jetisonable.

    • True, but it take a lot of time for it to develop and its not got their yet.

      Hydrogen is a fixed entity vs battery that is still evolving.

      The question on Hydrogen is multiple of cost, tech to get it to work and what you get out of it range and power wise (prop to start with)

      How do you fit it in with so called Green Energy ? You need a base grid that has underlying base power (or some big cables to link your Solar Cells across the world)

      Or you can treat Aviation as part of the system and issue that needs to fit into a whole system and solution not an isolate.

      If you look at the move to electric cars, where does the energy come from and you have to dig mines to get the materials for the battery (as well as the car)

      No getting around that and whats the trade off?

      In the case of wind you are trading off the environment (full of wind mills) vs the possible gain. That too has an impact. Its not free lunch.

      • Hydrogen is still evolving – just not high pressure or Fuel Cells

        Try H2-O2 Combustion Internal Steam Pulse Jets Rotary Engine -generator,

        Designed to use H2-O2 as fuel it is intended to produce the H2-O2 on board the EV as part of a Flow type fuel system -it will not be compressed and will not have big tanks.

        To aid this we have a Generator Magnifier which brings about considerable reduction in Fuel use = makes the Fuel on board feasible.
        For past 2 years we have been looking at Road Transport and our intended On Road Proof of Concept — will be a LEVC e Taxi

        We are clear that there will be many applications for a stand alone generator and this includes short to medium range e-motor Propellor aircraft.

        In making contact with all manner of personal – just the same as the Auto makers – little or no reply — it seems they may well be embarrassed –if HyPulJet works – cost of initial modelling TU Berlin €250,000 — where would they spend all these £billions

      • Hydrogen generation from hydrolysis for min electrical power input is a hot reasearch field at many top universities. In the EU they are looking at running sea based windmills full steam and as soon as the grid cannot swallow all the electrical power generated the excess goes to H2 production ideally at the windmill. With the latest Vestas and GE windmills the installed power will take big step as soon they are certified and series production pick up steam.

        • >excess goes to H2 production ideally at the windmill

          Why generate the H2 at the windmill? Then you need to transport it from the windmill. There is already a cable that takes the power ashore.

          Install hydrogen batteries into the grid. They create hydrogen when there is excess power and electricity when there is shortage.

      • Why do we need a Grid — this is the 21st century – for Hydrogen it is best to produce as close to point of use as possible

        Most certainly producing hydrogen out at sea and piping that say 300 miles is rediculous – it would be easier to transmit electrons along a cable.

        The only reason that personal/homeowner H2 Energy systems are not in play, those owing the Grid and O&G would see the end of their business model …. choice people – keep doing things this way and Fry the Planet or accept that the Old system is not needed – the failure to be effective on GHG emission being because we are trying to adapt a method which does not blend

        • there is so much wrong with your statement(s).

          In Germany we have a wide distribution network for natural gas. The high pressure pipelines start in the Russian far east and the low pressure grid distribution network has a drop point at most houses ( even in rural areas )

          Where do you see a major difference to transporting H2?

          • What is wrong with Hydrogen aspect is the energy density is never going to change, its a fixed deal.

            You can refine how you store it or make it all day long.

            It still is not going to fit into an aircraft like a fossil or synthetic liquid type Kerosene fuel will.

            Batteries are still seeing major changes in density of energy.

            That takes more exotic metals and mfg though.

            For all of it you need a real world cost to match kerosene and then a factor to reflect that kerosene burns off and the plane looses weight (vs battery)

            Equally another factor for how much all the Hydrogen system takes away from range and layout and the cost of the systems to make it work.

            And what is the gain vs clean kerosene?

        • Yes you can install the GE Haliade 13MW or Vestas 14MW units at airports but few want these beasts close by and they are designed for off shore installations. HVAC cables and salt water is not optimal hence you need expensive HVDC converters at the windmill and ashore to convert to 400-800kV and correct phase angle for the grid. To produce LH2 at the windmill using the sea water for coolant in the power hungry H2 to LH2 process, I assume GE likes it as they can provide both the 13MW windmills, electrical motors and compressors for LH2 production and I would not be surpriced if they buy a big electrolysis manufacturer like ITM Power so they can provide a fully integrated solution. Most likely they will also provide the HVDC ashore equipment to a closed down nuclear powerplant where the grid power cables are still connected to its transformers. Siemens and Hitachi will be competing as well..

  4. Any comments on the Magnix electric retrofit of Harbour Air’s DH Beaver? Harbour Air’s typical flight is about 30 minutes one-way, which could make pure-battery electric power practical for them. News accounts have touted the very low running cost of the electric system. But I have not seen any detailed discussion of the electric Beaver’s range/endurance or useful payload in the various press accounts so far.

    • They are essentially for joy riding flights for tourists and prices to match. The ones that serve small communities with passengers and cargo will remain conventionally powered.

    • The trail on a float aircraft is smart because like the UAM it can put down in many places. The flight was done over the water because today’s battery systems with their monitoring circuits (you need to monitor EVERY CELL for the temperature of the 10-30.000 you need depending on your energy level) can stop the whole or parts of the battery system at anytime (as Pipistrel electric aircraft stopped with Norwegian Ministerial people over a sea during demo flights, the pilot and passenger survived and could swim to shore Pipstrel crash in Norway). MagNix knows this, thus the test with Harbour Air over a river.

      This is why I talk about CERTIFIED battery systems all the time, that are run at safe levels and that are safe (We’ve had the Alice and Lilium prototypes burning in unstoppable Li-Ion fires when the batteries are run above safe levels). The first test pilots and later passengers of battery based aircraft are taking risk on the level of pioneers in aviation without understanding it.

      Battery based float aircraft operating over sea lowers the risk of being killed, I will still not enter battery based aircraft until these have operated for quite some years.

      • Bjorn:

        Supposed the FAA and EASA etc will set standards for that and you will be safe.

        It will be interesting to watch, I cannot see myself being in a position where I would be in one anyway.

        Over water and a fire is no better than over land and a fire (well maybe if you can get it on the water soon enough).

        Lessons from the (Swiss?) MD-11 was that they should have ditches and not tired for the airport.

        On the flip side the 777 P&W failures don’t give me a warm and fuzzy feeling either on conventional stuff.

  5. Liquid Hydrogen: the real world.
    Here’s what happens when the liquid hydrogen tank insulating vacuum is lost:-

    ….so we must vent this overboard. At the vent, there will be powerful electrostatic effects and the Oxy-Hydrogen will ignite. The very high flame propagation rate means the flame remains attached to the aircraft ( cf Concorde ), and the multi-megawatt blowtorch cuts through aluminium like butter.
    The best mitigation for this problem is: Parachutes.

    • title is “MRI Cryostat Vacuum Lost” and what they seem to show is the energy release from the superconductive ( no longer) magnets? ( cooling medium is He anyway. )

  6. This seems to have been overlooked from 2008
    Boeing makes history with flights of Hydrogen Fuel Cell Demonstrator Airplane
    “A two-seat Dimona airplane, built by Diamond Aircraft Industries of
    Austria, was used as the airframe. With a 53.5-foot (16.3-meter)
    wingspan, it was modified by BR&TE to include a Proton Exchange
    Membrane (PEM) fuel cell/lithium-ion battery hybrid system to power an
    electric motor coupled to a conventional propeller
    It required supplemental Li battery for takeoff and climb…..

    Followed a few years later by the part scale Phantom Eye LH2 fuled high altitude drone demonstator, it could fly for 4 days at 60,000 ft
    Propulsion was by means of 2 turbocharged Ford 4 cyl engines driving propellors

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