Multi Fuel Internal Combustion Electromechanical Batteries – Got That?

Internal combustion rotary engine battery

Internal combustion rotary engine battery

Still not sure electric power is the wave of the future? Here's a way to keep yourself squarely on the fence, batteries powered by gasoline. Set your coffee down and think about that one. When I saw this story the other day I wasn't sure what the breakthrough was. Clarian Labs designed this small rotary engine/generator, but except for size, why is it different than rotary engines we've seen before in Mazda cars or motorcycles like the Hercules or Suzuki RE5?

The difference is there's no output driveshaft. The rotary piston does not mechanically drive any external transmission, instead, the piston rotates around the components that make up the generator itself. The only output of this engine is electricity. Electricity stored in capacitors starts the engine rotating, like a starter normally would, then the gasoline or other fuel takes over. The capacitors can also be used as a power booster if needed, but all of the rotating mechanical energy is used to generate electricity to run electric motors or whatever else you want. Think about this, there are no external storage batteries, generators, flywheels, alternators, fan belts, pulleys or gears to bolt on and take up space. Even the starter is internal.

Another interesting difference between this unit and a normal rotary engine is extra pistons operate asynchronously. In other words, you can add more rotary pistons to scale up for more power but they are not connected to any common crankshaft so each piston can operate independently, at a different speed or not at all, depending on the requirements for power or efficiency with all of this controlled by the Energy Management System (EMS).

The rotary engine/generator/battery can run on many different fuels from gasoline to propane, natural gas, ethanol, methanol or hydrogen. It's an electric battery you can refill at the gas pump.

Clarian originally designed this for the Department of Defense for their humanoid robot program so it was fairly small, but it can be scaled down or up very easily. They say a typical unit would be about the size of a standard car battery.

You have to think about this for a bit to really get it and after you do, it seems like a pretty neat setup. You can use a small one to power electronics or a bigger one to run an electric vehicle. It would seem to shrink the actual power unit necessary in most applications but it would be an interesting and complex calculation to know if it was any more efficient. I'm still thinking about this one but it's definitely worth a look.

Link: Clarian Labs pdf datasheet via Wired

Previously on The Kneeslider: Free Piston Engine which also directly produces electricity from mechanical motion

Of course, we might end up with this: Video below


  1. Bob says

    So… let me get this straight….

    It has none of the pollution abatement benefits of electric because it’s fueled by liquid fuels with the same exhaust pollution…
    Yet while it’s burning gasoline (or whatever) it’ll give you the performance of a golf cart because of its electric output….

    I think their model might need a little refinement.

    • Paul Crowe - "The Kneeslider" says

      Electric power could give a vehicle using this generator huge performance, the problem up to this point with electric vehicles and high performance is it uses the battery up too fast and limits range before a lengthy recharge is necessary, but if you can gas up for more electricity you can use all of the power the electric motor can deliver. I actually hadn’t thought about this until just now. That’s a pretty cool feature.

      • says

        Hey Paul–
        I understand the device’s ability to use commonly found liquid fuels to extend the range of an electric vehicle.

        But why are we discussing electric vehicles? Because they’re cooler/more exciting than our IC motorcycles? No- it’s because electric vehicles offer a potential alternative as we move forward into a more carbon constrained/peak oil landscape.

        And in that senario, if you’re pouring expensive/carbon-laden liquid fuels into an electric output device– what have you accomplished? Same fuel, same emmisions – but now just converted to electricty and then routed to power the wheels.

        Their model is just another generator, albet a fancy one.. but would you purchase a electric motorcycle and then put a gas powered generator in place of the batteries? No… that would be ludicrous. If we’re using the same fuels, I (and I’d bet a 6-pack most everyone else too) will stick with an IC engine every single time.

        • spectator says

          dear bob, I don’t believe that our dependency on petroleum is really that bad, or that human released carbon is having any negative effects or our planet. I mean, did you see the snow in the northeast this winter??? global warming; my ass.

      • Jimmy says

        WOW a truly great idea. Now use magnetic drive to eliminate or inhance the fossil fuel drive and we have the source to get us to when batteries and regenerative charging can eliminate the fossil fuel altogether. The dreamers here just don’t get that we need a stepping stone to get to where battery technology can take over. A fossil fueled gen-set like this is the answer.

        • says

          Stepping stone? If this was, it would be one that stepped backwards!

          IC engines have about a 30% efficiency level- so for every 100 BTU’s you put in, you’ll get about 30 BTU’s of energy back–

          Electric motors have about 80% effiency- so for every 100 you’ll get 80 back–

          Now if you combine them- you’ll put in gasoline, the IC motor converts it to electricity (but you’ll lose 70% of your energy to friction) now instead of sending that 30% of remaining energy to the wheels as would a typical ICE setup, this system then converts it to electricty and sends it to an elec motor to lose ANOTHER 20% of the energy before it’s transmitted to the wheels….

          Multiple conversions mean more energy used in the process, before being transmitted to the wheels. So you’d end up with a machine that get’s less miles to the gallon than the standard IC engine…

          Once again- why are we talking about electric vehicles? To increase the amount of gas we use, or decrease the amount of gas we use? This system would increase the amount of gas needed to go the same distance.

          • Jay says

            Bob, I think you are missing the point of how this could be used in RE-EV.

            Also, your math is making ICE vehicles way too efficient. Yes, the combustion engine in a typical ICE is 30%, but then there is transmission/differential losses on top of that. So, you are not getting 30% to the wheels.

            An electric motor with 80% efficiency is pretty bad. I worked on an electric Xprize car and we typically used our motor (including motor driver losses) within the 86-94% efficiency range.

            There is no claimed efficiency for this new generator, so we have no idea if they perform better than a typical 30%. Since it is smaller/lighter, has no drive-shaft/etc, I would hope that this generator is more efficient at generating electricity than at 30%.

            Where this technology would be very cool would be if it was used to replace the ICE engine inside a vehicle like the Volt. Right now, the Volt has an ICE engine and a generator to extend the range, whereas this system combines the ICE engine and generator into a single part. This would be less weight and most likely higher efficiency due to reduced part numbers/cost.

            Since batteries are not yet ready for supplying 400-500 mile trips on a single charge, having an ICE range extension option which is lighter and more efficient will make range-extended electric vehicles more efficient (i.e. a longer electric range). I believe this is the stepping stone that Jimmy was describing.

          • FREEMAN says

            @ Jay:

            Clarian Labs claims 5kW output on a 125cc modified Sachs KM3 Wankel and that the whole thing, including fuel, weighed approximately 22 lbs.

            I find the whole design interesting. It begs the question: why did we not have such a thing sooner? It makes sense to combine the engine and generator into one unit. I’m not sure I believe all the claims Clarian Labs makes, but it’ll be great to see technology like this in the future. And as always, hopefully it’ll actually be affordable and work as advertised.

  2. Paul says

    They must have seen those commercials for electric cars, in which all the household appliances have gas motors. I’m still looking for the link to the good European one.

    The most logical use I can see would be portable oxygen concentrators.

  3. Boog says

    I can see a lot of uses for this gadget.

    I recently had the opportunity to use one of the small Honda inverter generators to power some portable 2-way radio equipment in an outdoor setting. It was amazing to have a 1K generator the size of an ordinary gas can sitting under the table and still be able to carry on a normal voice level conversation with another person on the other side of the table with the generator running!

    This device could be built into the equipment we were powering with the external generator. Imagine a 1000 Watt generator you could throw into a briefcase!The only drawback, of course, is it WILL give off carbon monoxide, etc. like all IC engines, so operating indoors or within an enclosed space with human beings present might be hazardous to your health. In addition, I was wondering about the noise output. If it cannot be sufficiently quiet, well…nevertheless, a great idea! I would be interested in a pocket-sized generator, even if I couldn’t use it indoors!

  4. baconpocket says

    if colin chapman were designing generators…

    reduce the number of components and simplify to meet the needs of what you are designing, i love it

    efficiency is the big question, but i would bet it’s at least lower weight/output power. that’s a big deal when you start thinking about putting these in moving vehicles.

  5. ooli says

    it’s just the logical evolution/streamlining of the hybrid drivetrain. not bad. very interesting. but still a half-step towards full electric (assuming that’s the goal) i like it.

  6. BoxerFanatic says

    I have long thought about the benefits of a rotary engine powering a generator.

    It didn’t occur to me to make the rotary engine INTO a generator… but it looks interesting.

    Batteries are the big, huge, 900lb stumbling block for electric drive, not electric motors.

    The Clarian report mentions that even with 30% efficiency, an ICE engine produces much more energy than a battery possibly can. And efficiency is improved merely by running an engine at an efficiently implemented steady-state, instead of throttling from 900-9000+ rpms, and trying to make the engine efficient over that whole range.

    Paul Lamar, a rotary researcher and engineer has ideas on how to increase efficiency well above 30%, with turbine compounding, supercharging, and stratified burn with direct fuel injection allowing leaner mixtures and less unburned hydrocarbons in the exhaust.

    I can only imagine the POWER EFFICIENCY gains by combining these technologies. As in claiming far more of the kinetic energy output, from the chemically stored energy in the fuel. Using the fuel that works more efficiently should be the goal.

    I am less impressed by increasing fuel efficiency over distance by replacing some internal combustion power output with inefficient batteries that are inefficiently charged from inefficient transmission lines from a power plant somewhere, and combining that with lowering power outputs with smaller engines… and calling that advancement. That is just being satisfied with less power, and more complication for the same or less net result, and deferring to other wasteful or inefficient tech, rather than improving real energy in to energy out efficiency.

    Chemical fuel is a primary energy source. Electricity is a transition state of moving energy. This system acknowledges that.

  7. oldtimer says

    From Clarion Labs pdf datasheet:

    As well, the flat rotor surfaces found in a rotary engine are ideally suited for low-friction ceramic seals (vs. steel piston rings in a traditional piston-driven engine).

    Seeing as how I’m knee deep in the restoration of a 75 Hercules, and knowing that the seal material available in 75 was the biggest weakness of the Wankel engine……….Gotta go….gotta make some calls…

  8. says

    I think this is a really novel idea that truly needs to be nurtured. While I see a lot of potential in certain applications, my experience with Rotary engines in cars is that they have always been a bit more fuel thirsty than traditional piston designs.

  9. Scotduke says

    Very interesting, not sure how fuel efficient any rotary engine can be though. Does this have a total loss oil system?

  10. Greg the Giant says

    Until they develop a small nuclear reactor of this scale, this design doesn’t solve anything. You’re still burning hydrocarbons. Electricity doesn’t come from a current bush. Solar and wind power, unless huge efficiency gains are discovered or developed, will be hard pressed meet the demand for electricity to power all the electric vehicles they envision much less our homes and businesses. Hydroelectric power is clean renewable energy but I don’t see any new dams under construction in this country. Hydrocarbons are the fuel our entire economy is based on and the byproducts are so intertwined into everything we do, most don’t even realize it. We’ve regulated ourselves into a corner on the opposite side from the exit.

    All that aside…very cool little generator !!

  11. Davidw says

    Cool idea but wankel cycle engines have never been as fuel efficient as an otto cycle engine.

  12. rohorn says

    A generator/KERS system has the potential to blow away either a battery or internal combustion engine powered racer. I could care less about carbon emissions – electric power offers amazing control potential. And constant speed engines offer amazing power and efficiency potential.

    Do any/all of the above Negative Sorts (Is the term “Negas” too…?) have any imagination at all to see the potential in anything new? Yeah, cafe racers and street trackers forever (barf).

    In the mean time, thanks for publishing this sort of info – this brings me here. Whether or not that it a good thing is entirely your opinion.

    • Paul Crowe - "The Kneeslider" says

      “A generator/KERS system has the potential to blow away either a battery or internal combustion engine powered racer. I could care less about carbon emissions – electric power offers amazing control potential.”

      Exactly! The comments here about how this isn’t a solution because it still uses hydrocarbon fuels assume the only reason anyone would consider electric vehicles in the first place is to get off of oil, since the commenter has that view, they assume everyone else does, too. In reality, many folks who look at electric power think it’s an excellent high performance option. Whether it’s “green” or not isn’t a factor.

  13. spectator says

    here’s a riddle: why would you want this to power a generator for a car, or motorcycle, over, I don’t know, a small, direct injection turbocharged diesel engine?

    don’t call me a Negas call me a NO-GAS!

    Find a way to get 80-90% efficiency from an ICE and i will be on board with you 100% of the way. This is a funny invention, but junk, and totally unhelpful to transportation

  14. ken says

    I like the possibilities. Just think you could have 3 of these stacked in a bike frame.
    with one running for low speed/around town.all 3 burning for HIGH SPEED.
    If this rotary could run on bio even better.

  15. Paulinator says

    This technology surfaced about 6 or 7 years ago, as a butane powered, PC board-mounted micro-generator for hand-held devices and lap-tops. The Wankel format was appropriate based on scaleability and physical layout. Battery improvements and the TSA eliminated any market potential, however:

    …`No sir…my lap-top won`t fire-up and I`m not sure if its fuel, spark or compression..(five minutes later)…can I pull my pants up now?`

    This current variant is slick, but it should be wrapped around a more efficient ICE.

  16. Todd says

    I think I’ll get one of these to go with my pocket nuclear generator. Somehow this is immensely more cool.


  17. K Lee says

    What all of the proponents of all electric vehicles never seem to mention is where is all this electricity coming from? In the US almost 70% of our power comes from coal and natural gas fired power plants, that certainly is carbon neutral! Batter powered electric vehicles are not necessarily the great answer everyone thinks they are.

    • Travis says

      Yes coal plants release co2 but they release significantly less kW than the gas engine in your moms yugo.

  18. mattg says

    Good for mechs maybe:) : Unlike a motor driving a hydrostatic pump which can fail or be taken out with a single round you could distributing power accross a personel battlefield system.

  19. Rob says

    Very cool. I like the butane powered mini generator idea too. Rotary engines get a bad rap for being inefficient, however I think this device will operate differently, no gear box or driveline. Control over engine speed will help too.

  20. Keith says

    Interesting, regardless of what they’ve done the wipers are still going to be an issure. Still it should do well on CNG, propane etc. Surprised I haven’t seen something similar with a migrating combustion chamber motor.

  21. Cameron Nicol says

    The main drawback of electric vehicles is lack of range. A simple generator for longer trips is a logical answer. Jaguar has it’s twin turbine powered generators, Chevy has it’s Volt. Short battery powered trips pollute less, period. I want a Zero but the limited range stopped me. A small removable generator would be the answer: pull out one of the batteries and plug in the generator.

  22. Adrian says

    I think we’re forgetting the most important thing: what would a tiny, air-cooled rotary sound like?

  23. Dan says

    very cool and definitely a step in the right direction, petrol generators running at constant revs charging smaller battery/capacitor packs that drive an electric traction motor are far more efficient than an exclusively ice traction motor.
    add regen braking and no idling penalties and you have a very efficient solution
    PLUS instant torque and linear power, HELL YEAH.
    why do you think trains have diesel generators and electric traction?
    also rotaries have a very high power/capacity ratio, ideal for this scenario, there’s more to efficiency than km/l.
    well done clarion labs i say

  24. Dai says

    One thing people seem to miss is, is there enough of the raw resources to create all these batteries for battery powered cars/bikes to power all the cars we will ever need. I don’t think so! No one ever talk about the resources needed to replace the ICE with electrical powered vehicles do we have them. This idea sounds more like something we will eventually end up with in the future. No one mentioned how or how little fuel is needed to to run this generator. If you can get decent performance for something like 150 mpg bingo your now in business at helping reduce our need for oil. If you can run this thing on hydrogen then you have won the lottery as the planet is two thirds water.

    • Jimmy says

      same problem as with resources for batteries, “if when” we run out of water EVERYTHING dies. Hydrogen is not the answer. At least not derived from water.

  25. bblix says

    Years ago I read about micro-power generators whereby they had quarter sized units powering laptops.

    The idea hear is sound. No longer are you bound by the current vehicle geometries. Power generation could be distributed to where it fits or for mass distribution, electric motors built into the wheels, etc.

    Efficiencies would be much better because electric power transmission losses are much smaller than mechanical transmission losses; further, surplus power could be stored (batteries, capacitors). Power generation could be micro-tuned, generating only what you need, when you need it.

  26. Jimmy says

    Thank-you Jay, put into words I could not have. Its difficult sometimes to see and hear how narrow minded the masses are. Its refreshing to read word like your’s.

  27. Mzungu says

    Its my thinking that something of this sort would be ideal for light aircraft: multiple modules for redundancy, centrally located for weight distribution, powering remote electric motors (e.g. on the wings, or where needed), high power-to-weight ratio, flexible fuel options. When pricing drops, would be a viable option, IMO.

  28. Mzungu says

    …the difficulty, tho, is that not 100% of the Hydrogen is recombined back into water – so if this were happening on a massive scale, there would be a net loss of water on the planet, necessitating the use of hydrogen from other sources to make up the difference (or some other solution…?)

  29. Jimmy says

    Rohorn, if you think that after you use the hydrogen for energy that you will get back the same amount of water used to create the hydrogen in the first place you are sadly mistaken. Just like all of the proponents of hydrogen, not really thinking it through very well.

    • rohorn says

      There are lots of practical reasons for not currently adopting hydrogen as a fuel. You haven’t mentioned any of them. Instead, you spew pathetic freshman level debate team FUD about “Running out of water and EVERYTHING DIEING”.

      I, Frankly, prefer math, chemistry, and other technical information over the pavlovian responses you have posted so far.

  30. Brian says

    Just remember the efficiency of internal combustion engines are what, 20%?
    There’s the rub.

  31. Toad says

    Nice concept…I’m still trying to figure out what a Subaru accessory sub woofer has to do with this…that’s the “black box” on the left. Great use of “borrowed” image.

    • Paul Crowe - "The Kneeslider" says

      “I’m still trying to figure out what a Subaru accessory sub woofer has to do with this…that’s the “black box” on the left”

      Size comparison, perhaps?

  32. actprime says

    This would be perfect for camping . A gasoline generator is dirty & requires gasoline, oil etc to be carried. Honda have released a butane generator in Japan but it is too big. This thing could produce 15A at 12V to charge an accumulator for an inverter to power fridge , TV etc and if it is small & less than 15lbs that would be great.

  33. Hogwash97 says

    I see the potential. We need to think of properly addapting, or refining options( long comutes vs short) I like not having to charge if there is not one availiable.