By on June 7, 2012

A report in the Nikkei claims that Mazda’s rotary engine will live on as a range extender for electric vehicles using hydrogen power for the Wankel engine.

“We should be able to make the most of the rotary engine’s advantages, such as the ease of making it compact and safe,” President Takashi Yamanouchi said.

No time frame was given for the production of such a vehicle, though Just-Auto claims that it will be offered via a leasing program in 2013. Yamanouchi also has ambitious plans for Mazda, hoping to turn a 1.3 billion dollar loss into a $125.5 million profit this fiscal year.

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29 Comments on “Mazda: Rotary Will Live On As Hydrogen-Powered Range Extender For EVs...”

  • avatar

    Way to go Mazda. Here’s hoping you are able to finish the 1.6 petrol engine as well.

    • 0 avatar

      As someone once observed; “the hearse that drives you to the cemetary will have a gasoline engine in it”.

      Or maybe my sarcas-O-meter is broken?

      I dont know about the rest of the world but there is no real infrastructure for hydrogen in the US and the time table for it seems to be moving at a pace slightly slower than tectonic drift, given that, this car at best is the mazda version of a Leaf with little bit longer range (try going coat to cost in this rascal).

      • 0 avatar

        There is hydrogen infrastructure in Europe where they are a bit more open minded and who said this engine was destined for the US anyway?

      • 0 avatar

        You’re correct. Around here in California, there are fewer and fewer gasoline/diesel stations. The regulations are prohibitively expensive.

        To start again with hydrogen, and overcome the mythic, but incorrect, Hindenberg fear of a gas, will never get off the ground.

        You can’t get a permit to open a photo gallery in Los Angeles. Imagine what it will take to stock hydrogen. We’re so timid about everything that *could* go wrong, we’ll never press forward.

        A larger question is, can you make hydrogen less expensively than gasoline? It’s the same problem for ethanol. Both burn just fine, but takes more energy to create it that it produces.

      • 0 avatar


        Most hydrogen in the US is produced by steam reforming natural gas. I suspect (without researching) that total well-to-wheels CO2 output is similar, perhaps a bit better for hydrogen .. although you can employ carbon sequestration for steam reforming.

        A small hydrogen genset for EVs would make sense in some cases, especially if interface was standardized. Need to go on a 300 mile trip? No problem, just swing by a rental shop and pick up a small genset, plug in and off you go. Cheaper than renting a gas car.

  • avatar

    Now we know Rotary in RX8 and such isn’t that great on fuel economy, but how are they as a generator in constant RPM mode? I guess if its good its a cheap alternative to turbine, which is great in that type of operation, but probably too expensive…

    • 0 avatar

      Mazda claimed pretty good efficiency with its hydrogen combustion RX8, similar to the best fuel cells. Don’t recall ever seeing real-world results.

      The rotary may work better because it’s small and simple than because it’s more efficient.

  • avatar

    So basically Mazda is hinting that the rotary is over? Because we know that hydrogen will NEVER happen. Nobody who knows anything about the technology believes otherwise.

    Whatever happened to that Wave Disk Engine concept? It was basically a non-retarded rotary engine.

  • avatar

    I can see the Wankel in APU-type or co-generation applications. Wankels are very good at turning the energy in fuel into heat. In an automotive application, it’s very difficult to recover the energy in that lost heat. In a fixed application, that heat can be used for water or space heating with great effect. One could also drive a turbine off the exhaust heat and combine its mechanical output with that of the Wankel (so-called turbo-compounding which was used to great effect on US WWII bombers).

    The advantages would be relative mechanical simplicity, exceptional smoothness and the ability to run on very low octane fuels (a 13B happily runs on 70 octane fuel). Periodic maintenance might be a real issue, though.

    • 0 avatar

      I agree about turbo compounding – it may well happen in Formula One as a way to run an alternator to charge up the KERS system.

      Turbo Compound was, and maybe still is, a trademark of Wright Aeronautical and/or their subsequent owners. No US aircraft used turbo-compounding in WWII. Wright delivered the first 3350 TC in 1950, and its most iconic installation was the Lockheed Constellation airliner. Production ceased in 1958.

      Other than an abortive attempt to use a similar system on the Allison V 1710 in 1941, the Wright 3350 TC remains the only successful application ever. It reduced fuel consumption by almost 20% at cruise. Pretty clever implementation.

      • 0 avatar

        I remember looking at a maintenance manual for the 3350. It looked painful to work on….

      • 0 avatar

        Ah, I didn’t know that. I thought all R3350s had turbo-compounding. There was a great article in Kitplanes two years back that had some of the original engineering notebooks and the calculations about where the energy in the fuel was really going. After reading that article, I immediately thought of the Wankel. Having owned a then-new 1980 RX-7, I was well aware of its characteristics. The radiator would look right at home in front of a rat motor, it was so big. The exhaust was similarly big.

        I had one more thought about the APU idea. The engine would scale really well by adding more rotors. That could be a huge advantage…

        BTW, one of my earliest memories is standing on the tarmac at Idlewild feeling the propwash of a DC-7 which, I believe, had four R3350s. That was back in 1959 or so.

    • 0 avatar

      They are talking about hydrogen so no need to worry about the octane rating.

  • avatar

    Doesn’t make a lot of sense. Hydrogen burns more completely than gasoline in a rotary, but considering that you have friction surfaces on all sides of the combustion chamber and that you would still need oil injection to lubricate the thing (I may be wrong about that). And that means that you would still need a cat to clean up the oil burned during the combustion process.

    And if you are going to store compressed hydrogen gas, why not just use a fuel cell, which is loads more efficient? The FCX already does that very well.

    • 0 avatar
      Richard Chen

      Tank size is indeed substantial, the dual-fueled Mazda Premacy Hydrogen RE loses half its cargo space behind the second row:

  • avatar

    Never mind how efficient it is, I don’t think it will work as a range extender for EVs. Don’t you think it will be easier to find an outlet than a hydrogen filling station?

  • avatar

    My guess is that the Mazda engineers are mature enough to have done the homework on this. I will be interested to see how this turns out although I am skeptical, purely because the rotary engine is not known for its fuel efficiency. But… This is a different application and a different fuel… Interesting.

  • avatar
    Felix Hoenikker

    Turbins are the way to go for tange extenders no matter what the fuel. The big problem with turbines is turndown which makes them unacceptble as a direct replacement for the piston engine. This is not a problem for a range extender that can run at it’s optimum efficiency.

  • avatar

    Most stationary generators run on diesel. The reason being that a Diesel engine can be optimized to run very efficiently at a specific RPM. If I was putting an engine in a car for the sole purpose of generating electricity, there is no question it would be a Diesel.

  • avatar

    I believe BMW was planning on a tiny wankel range extender for the i series of electric cars.. apparently those plans (and the cars) have fallen by the wayside.

  • avatar


    I was really excited about H2 used in ICE-mode, because that would create a zero-emissions vehicle while preserving the “vrooom” factor and the driving characteristics of conventional cars. H2 can be harvested from the sea by hydrolysis of water, powered by wind turbines along shorelines. I doubt that our planet will be running out of seawater anytime soon.

    But H2 is low-density stuff. If you store it in more concentrated liquid form (LH2), as with the BMW “Hydrogen 7” experimental cars, then boil-off is an issue. This means H2 could accumulate in a closed garage by venting from the vehicle…an explosive situation. And if you don’t use your LH2 car for a week, it may simply run out of fuel by evaporation. If you store H2 as a compressed gas, then that’s OK, but the tanks required would fill up most of any boot (trunk) space if you wanted to get a reasonable range, say 250-300 miles.

    So, the problems may not only be infrastructure related. Certainly, the greater efficiency of fuel cells (H2FC) does allow a lower amount of H2 to be stored on the vehicle, but then H2FC is really just a VERY expensive version of the electric car….which we know is no fun at all: e.g., Honda Clarity. (Fuel cells are not cheap, and the car would weigh more than with H2-ICE, all else constant.)

    What we really need is for someone to invent a way to store H2 in an ultra-condensed, non-boil-off mode that can be used in ICE’s. Any takers?


  • avatar

    What a waste of R&D, just use a small 2-cylinder atkinson cycle or HCCI cycle piston engine. It takes a lot of energy to make hydrogen and the infrastructure is not here in the US, and I don’t want it to be because the oil companies would obviously have control over it.

    Stick with electric drivetrains with efficient gasoline or diesel generators.

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