Hydrogen-Electric Caravan Proposed


Textron has teamed up with California-based ZeroAvia to develop a hydrogen-electric powered Caravan. The companies want to get an STC for the design, which will carry hydrogen in a wing tank to run ZeroAvia’s ZA600 powertrain in place of the PT6 that powers standard Caravans. The two companies said in a joint release that carrying the hydrogen under-wing leaves the fuselage free for its normal passenger and cargo load. Performance projections were not included in the release but the duo hopes to have the plane in service by 2025.

“The famous Cessna Grand Caravan is on track to be one the first airframes operating commercial services—both cargo and passenger—with hydrogen-electric, zero-emission engines,” said ZeroAvia CEO Val Miftakhov. “We applaud the visionary leadership of Textron Aviation in joining us to help transform a much-loved mainstay of sub-regional aviation into a symbol of sustainable transformation in aviation.”

Russ Niles
Russ Niles is Editor-in-Chief of AVweb. He has been a pilot for 30 years and joined AVweb 22 years ago. He and his wife Marni live in southern British Columbia where they also operate a small winery.

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  1. 2 issues I see here. Ten knots already went away with the cargo pod, how much more speed is lost with those huge tanks hanging on the wing struts. With that extra loss of speed I can’t see this configuration maintaining flight into known icing certification. Laws of aerodynamics mean additional power will not mean very much increase in cruise speed. And getting ice on those tanks just greatly increases the drag created on an airplane that normally does not handle ice very well.

    • More weight, more drag, and then adding an even less energy-dense power source than even batteries. This must be either a joke or the acme of delusional pseudo-science.

      • Energy density of rechargeable Li-Ion batteries is 2.1 MJ/L. Gas is 36 MJ/L. Hydrogen is 5.8 MJ/L … better density than batteries. Also, not affected by cold temps, fast recharge. Fuel cells will power electric motors that are more efficient than gas. All of it is an improvement over batteries. Our arrow can go 600 miles in any direction on 504 lbs of gas. Batteries that could do likewise would weigh far more than the Arrow while h2 despite the limitations you describe could provide 600+ Still, I agree that presently nothing packs the punch of a gallon of gas. This electric stuff gets annoying. Whether cars or planes, batteries fall far short of replacing gas.

        • Compressed H2 will continually lose pressure so I’m not so sure that volumetrically it has that high of energy density. Liquid H2 completely negates the “green aspect” so you might as well just use a real liquid fuel.

    • Re.: Icing on those thanks…

      Studies I’ve been involved in show that the icing build up on the blunt leading surface of the underwing tank will be pretty benign. The build up will increase the slenderness ratio, improving drag, albeit with some increase in weight. Its the skinny little wings and tail items that have the most trouble with ice build up, drag, and destruction of airflow.

      • With respect, my comments on icing are based on actual experience flying the airplane for 6 years, in some of the nastiest icing conditions the plane could handle. Caravans are well known for having plenty of unprotected surfaces that can accumulate all kinds of nasty looking shapes. The drag produced by them can easily overwhelm the available power of the engine to maintain flight. The forward surface of the cargo pod is a perfect example, even though there is some protection on it.

  2. @Matt W. – Well, I *suppose* that still leaves all the warmer parts of the world for it to work in…?

    It strikes me that ‘bolting-on’ a H2 FC drive-train will never really work and the fact that no-one is even talking about a a ground-up H2FC aircraft suggests that this is just another ‘tinkering with H2’ pipe-dream that a few individuals will get rich over due to the almost required government interest – and tax-payers money – that will be lavished on it.

    We really need to come up with a ‘fuel’ (if that’s what’s needed) that carries renewable electrical (?) energy in a highly portable form and which does not involve wasting 50 to 70% of the original energy used to make it (as H2 does). This would, in my opinion, be a much more worthy ambition for all the time, energy, talent and money going into H2-based systems that have had billions squandered on them over the last 50 years to very little practical effect.

    • True about warm weather but how did that work with American Eagle’s ATR planes. No US passenger airline flies them any more.

  3. Wonderful. Now tell us how you make, compress and/or liquify the hydrogen. I hope not steam reforming natural gas, which produces CO2 in the process.
    Yet another stupid boondoggle. All of aviation isn’t exactly low hanging fruit for CO2 reduction (around 2 to 3% of human caused CO2 emissions). That’s if you are silly enough to believe, without any definitive evidence, that CO2 emissions from human activity are a problem.
    We are in an interglacial. What we think of as “normal” climate has only been around for 11,000 years in the current interglacial. Enjoy the warmth, the ice will be back soon enough and then things will get grim.
    Realise also that most academic “scientists” who tell you all this is a problem would make good livings as used car salesmen.
    Best way to handle hydrogen as a fuel is to store it attached to nanoscale backbones of carbon atoms. Stores at room temperature, dense and easy to handle. I’m going to call it Avgas and Jet A1.

    • The sound you hear is me clapping and applauding your comment and my morning laughter. Strong work, Mike B. very strong work!
      Another argument for stored solar energy in those nanoscale carbon backbones is that its energy density is much higher than electrical energy storage devices. Based on my experience walking in a forest on a summer day, that solar energy conversion to stored nanoscale carbon backbones conserves thermodynamic energy too, which we release in the winter to heat our camp and roast marshmallows.

  4. One average wide-body burns approximately 30,000 gallons of Jet juice per day or enough to power 600 flight hours per day of Caravan flight. Why not power the bigs with a tiny reactor. The technology already exists. Pollution problem solved, range problems solved, weight issues solved, post crash fire problems solved……..and while we are at it let’s power the electrical grid with tiny reactors………..

    • I’m assuming you’re being sarcastic, but I know at one point in the past, there was actually serious consideration of nuclear-powered aircraft.

  5. If there is any way replace our existing fleet and to stop burning fossil fuels in the process, then it’s going to require new power plants and air frames. Correct?

    Here we have Textron Cessna, one of the few companies on the planet with the ability to actually get new planes through the process and onto the market, deciding to use the STC route in order to avoid certification hassles. One could easily argue that Textron’s true competence is no longer design and manufacturing but dealing with government. IMO, that’s just the plain truth.

    Couldn’t they just as well have written a press release that the entire certification process is what really needs innovation and upgrading?

    • THAT would require the bureaucracy we know as the FAA and — above it — DOT — to be both competant and proactive at supporting aviation at the upper management levels, Eric. Heck … we can’t get half of ’em to even go to work; they’re still hiding in their basements so don’t get your hopes up. Don’t believe me … look at MOSAIC and drone rules …

      • So why argue over practicality and science when the real issue is bureaucratic intransigence? Let’s turn lemons into lemonade. Instead of everyone concentrating on why none of the planes will ever physically work, why not point out how the current crop of piston engines is proof the FAA won’t ever let these things fly? It was how many years from when the Starship was certified to death until composites were commercially viable?

        That’s how you scare off investors and maybe get some change at the same time.

        • I don’t find the hate talk toward the FAA to be very convincing. AN STC (Supplemental Type Certificate) still must go through the same type of certification review as a TC (Type Certificate). The difference being your starting with a platform that is proven so that would be easier for obvious reasons.

  6. The true problem trying to be solved is how to store enough energy to power an aircraft for a reasonable amount of time within the weight and space constraints allowed for each specific aircraft design. The current solution is to combust a liquid fuel to convert it from chemical energy directly into thermal and mechanical energy. It also happens to be one of the easier methods, but it has its own drawbacks.

    What I think a lot of people overlook is that a proposed alternate solution doesn’t have to be the final solution. It’s an iterative process to discover what works and what doesn’t, and sometimes one proposed solution can lead to something entirely different that may be the breakthrough that was needed for something better. History is filled with experiments that lead to something entirely unexpected, but you’ll never know unless you try.

    That’s how I see this and all other alternate propulsion systems being proposed: an experiment to try something different, because if you always do the same thing, you’ll never learn something new.

    • “Build a better mousetrap, and the world will beat a path to your door.”–Ralph Waldo Emerson

      It’s been years since the basic mousetrap was invented–and despite all of the attempts–it hasn’t been improved upon.

      Today, there are a lot of people trying to build “aviation mousetraps” (alternatives to liquid combustibles)–but so far, nothing beats the tried and true ones. Like the classic mousetrap–liquid combustibles WORK, they are relatively CHEAP–they are ENERGY DENSE, and well-suited to their mission.

      Perhaps one has to be “of a certain age” to recall Rube Goldberg–his fanciful cartoons employed difficult “solutions” to simple perceived problems. Rube Goldberg seems to be alive and well, and trying to work in the aviation industry.

      • Everyone knew a heavier-than-air vehicle could never be built. And everyone knew a 250kt+ helicopter wasn’t possible. Yet many attempts were still made (and failed) at constructing such things, until eventually a solution was found.

        Just because there doesn’t currently exist a solution that is cheaper and more efficient than a gasoline-powered ICE aviation powerplant, doesn’t mean that one doesn’t exist. But there will be many failures along the way.

        • Well said, Gary. Amazing how many commenters here—aviation lovers!—seem to love nothing more than to naysay against innovators. Like you said, just because a given product or idea isn’t the be-all and end-all, doesn’t mean it’s not a worthwhile iteration.

          • If Textron spent time trying to figure out how to build airplanes more productively so as to bring down the cost, we’d all be better off and maybe be flying new(er) airplanes. This “green” stuff is sucking manpower and dollars out of any such effort.

  7. As I have commented in other threads the impasse for electric airplanes is not the motor but the battery.

    As I have also opined HFC would work, so IF we are going to be forced off safe and proven IC technology this is likely the best pathway.

    Electric motors are superior in many (maybe even most) ways to IC but batteries cannot work in aviation due to weight and the realities of the periodic table dictating rules of electrical potential.

  8. The other point in favor of this is here we have a genuine aviation company proposing a genuine aviation product. Not some paper startup making a paper airplane.

  9. Compressed hydrogen/fuel cell cars seems to stay at the initial level of non acceptance mostly due to lack of infrastructure, stations to refuel. I think the other drawback is expensive fuel cell technology. If I’m not mistaken, compressed hydrogen stored in well designed carbon fiber tanks have sufficient capacity for range with little weight issues. Perhaps the lighter weight of fuel cells powering a light weight electric motor allows configuring tanks for sufficient range without weight penalties. Initial prototypes of a fc/e-plane Textron/Cessna/ZeroAvia as proof of concept is no small undertaking. It will be interesting if they succeed.

  10. You can probably make this work but there are many problems with hydrogen with one of the main problems being economics with the cost of hydrogen and the fuel cells. I think that the answer for this application will be battery electric but it will not be a conversion of an existing aircraft. Eviation’s Alice just made its first flight with existing lithium ion battery technology. I believe that we will have commercially available lithium sodium batteries within the next 5 years that will have about 3 times the energy density of the current lithium ion batteries. This will make battery electric flight practical for short haul flights up to at least 750 miles but the aircraft will need to be more aerodynamically efficient than a Caravan. Yes, i realize that I will be mocked by some of the more ignorant people commenting on this article.

  11. I’m not mocking you but I disagree.

    Do my degrees from Rutgers College, my doctorate from Rutgers Medical School, or my post doctorate training at Yale University School of Medicine make me ignorant?

    Or maybe its my time working for and teaching at Stanford with the Palo Alto Medical Clinic?

    Or my multiple leadership and teaching positions at higher academic medical institutions and hospitals?

    Not everyone who disagrees with you is ignorant.

    Or my 36 years

    • William, I was also privileged to be able to go to a good school. I have an undergraduate in physics and 3 graduate degrees in engineering included a doctorate in mechanical engineering all from MIT. I also cross registered and took a few classes from Harvard Business School but I was not that impressed with Harvard. I have been involved in the start-up of 3 companies. The last was to make high tech ag equipment which use a number of electric drives to gain smoothness and efficiency. That company which takes in raw steel and puts out self-propelled machines that are transported as an oversize load now has about 250 employees. I have also been a faculty member in major university teach practical design and while I am mostly retired, I am still an advisor for students building an electric race car fo the FormulaSAE Electric student competition. For about 2 1/2 years but ending last year, I was a consultant on a joint NASA/DARPA project to design a high performance axial flux electric motor. The project was mostly an exercise in designing and using multi-disciplinary software for design but as I had some background in motors, I was the one to come up with practical concepts. The object was to design a 10 KW motor that weighed less than a Kg (~6 hp/lb). I never asked what the motor was supposed to be used for but I would guess that it was aerial drones.

      Anyway, I believe that we will have short-haul and commuter battery electric aircraft based both on engineering science and economics. The battery electric aircraft are projected to have a seat mile cost about 1/4 that of other propulsion techniques. That is hard to ignore. I had seen a NASA chart that concluded that you needed to have about 600 Whr/kg to be able to build a 737 sized aircraft for short-haul. We are going to get that and more. See https://lyten.com/products/batteries/ for some information on lithium sulfur batteries. Also see https://pbs.twimg.com/media/E81j2loXEAYzjo5?format=jpg&name=large for some information on uses for hydrogen and note that the authors seem to think that battery electric is more promising for short-haul flight along with light aviation.

      • Nice CV! Impressive.

        I agree that electric flight is possible, and may someday be practical, but not with batteries.

        With foreseeable technology I predict only HFC could be doable.

        With that said I don’t see the need.

  12. No one has mentioned what happens when that hydrogen powered Caravan crashes and the H2 container ruptures in the presence of fire. Remember the Hindenburg, folks? I guess that’s of little concern when applying for their STC? No wonder a new C172 costs $.5M anymore … IF you can get one. Someone I know bought one but had to FIRST allow it to be used by a flight school for a period of time.

    This whole electric airplane thing is getting a bit onerous to me. VolksCars for local urban mobility where weight and refueling time and environmental issues aren’t an issue … maybe. Airplanes, where defeating gravity is an additional major energy need … no damned way in MY lifetime. You’re insulting me, Cessna.

    WAIT !!! Isn’t this the same company that sold hundreds of Chinese made FlyCatcher LSA’s to unsuspecting victims and wound up smashing the few they had left over to sell? That’s where THIS idea belongs.

    • On “Green” hydrogen:

      • That’s a damning criticism, coming from an “alternative energy” publication! Interesting link–Thanks!

  13. If the industry wants to consider hydrogen, perhaps a return to the Hindenburg-style airships is in order? (sarcasm)

    Capable of transAtlantic flights, 79 mph top speed–twice as many crew as passengers–ON THE OTHER HAND, there IS that FAMOUS FILM OF ITS FINAL FLIGHT.

    No, Thank You–I’ll stick with wings–carbon-based liquid fuels–and internal combustion engines–nothing in the industry has had a better safety and economic record for nearly 100 years………….BUT DREAMERS CAN KEEP ON DREAMING!

  14. Agree.

    Like I was saying I don’t think its a worthwhile endeavor but if one wanted an electric aircraft only HFC is a viable power source.

  15. The younger generations are entertained by science fiction/horror/fantasy platforms like sci/fi programs, Game of Thrones, Avatar movies, all based upon nonsensical impossibilities. My regular alternative entertainment is reading the similarly fantastic and nonsensical articles in AvWeb, like this one, while being further entertained by those who try to explain and justify the contained inanity.

    • My concern is not the viability of these “alternative energy” and “wishful thinking” breathless announcements. My concern is for AvWeb.

      AvWeb has been a consistent REPORTER of aviation news–as well as outstanding COMMENT that puts things into perspective. Lately, it seems to be caught up in the morass of “breathless announcements” of “impending breakthroughs and certification” of unproven technologies–whose certification and production are “imminent.” It reminds me of the old “Mechanics Illustrated”–they always had articles on something “just around the corner.”

      One thing about it–it certainly has changed the number of comments on articles! AvWeb–suggest you split these “emerging technologies” announcements into a separate section–and return to reporting “news you can use”. By separating the “real news” from the “fanciful” press releases–you don’t damage your credibility.

  16. GREAT Engineering Explained video on hydrogen vs gasolene:


    Looks like unless you’re using H2 to power a fuel cell, you’re better off using gasolene.