Clarian Labs, a Seattle-based tech startup that has been working on power source for the Department of Defense Humanoid Robot Program, has just pulled-out of stealth mode its rotary generator (read the patent here). A battery-sized hybrid generator solution, Clarian’s invention basically creates an electric power source that can be rapidly refueled by swapping out a fuel source pack (a host of fuels can be used in this regard including bio-fuels and hydrogen).
These fuels then in-turn power the rotary-piston motor, exactly as you’d find in any sort of Wankel-powered vehicle, except for one small detail: there’s no output shaft. Instead of mechanically driving the wheels of the vehicle, the unit uses rotational induction from the rotary-piston to create an electrical current, which would then power the electric motor of your choosing. In reality, the system isn’t that different from what is found on modern diesel locomotives (modern trains use a diesel motor as a generator which in-turn powers electric motors), except obviously more compact.
Realizing that battery technology is still a ways off from having the energy density, and perhaps more importantly the recharge time, necessary to be viable in an automotive application, Clarian’s approach is to use the benefits of existing fuels, and couple them with the advantages of electric output drives. With the energy density of hydrocarbon-based biofuels somewhere in the ballpark of 20-30 times more dense than current battery technology, there is still a considerable advantage for these fuels, even at a 30% energy conversion efficiency in modern drivetrains. Add on top of this a refuel time that’s comparable to current ICE engines, and there’s some weight to this idea of engines as generators.
What makes Clarian’s rotary generator extra unique is that the motion of the rotor assembly is not constant, and can be adjusted on the fly to produce more power, optimize fuel consumption, control vibration, and to limit peak loads. For even more adjustability and modularity, the generator can have several rotary pistons, but unlike in a car, they are not mated to a common crankshaft. This means that pistons can be activated and deactivated according to application demands, e.g. turning on an extra piston to create more power to race up a hill, or pull a heavier load.
Clarian wants us to think of its rotary generator as a “powerful self-contained electromechanical battery”, which is sort of a misnomer, since batteries store energy. However since the whole package can be self-contained, the form factor is certainly battery-sized. According to Clarian, the use of a rotary generator also means that the company’s solution has twice the power-to-weight ratio of traditional piston generators. What really tickles our fancy with this unit, is that if you ran the rotary generator off of hydrogen fuel, it would technically be race legal in any of the zer0-carbon race series currently running. Chewy, thanks for the tip Mike!