Mazda hasn’t ignored the possibility of a hydrogen economy, but it’s taken a quite different path than other automakers with its hydrogen test vehicles, like the Premacy Hydrogen RE Hybrid. Instead of using costly fuel cells, it’s focused its hydrogen efforts around a rotary internal combustion engine fueled with hydrogen.
The Japanese automaker introduced a RX-8 Hydrogen RE—simply powered by the so-called Renesis rotary engine, adapted for hydrogen—back in 2003. Then in 2007 Mazda announced a new hydrogen-hybrid version of its Premacy, a vehicle known in the U.S. as the Mazda5.
Mazda continues with its RX-8 project—most recently with the delivery of vehicles to the Norwegian partnership HyNor—but the automaker is looking ahead to the Premacy H2 RE as a more advanced evolution of its hydrogen technology, with improved performance, practicality, and driving range.
While the hydrogen RX-8 is sluggish on hydrogen, with the engine making about half of its normal horsepower rating with hydrogen, the new Premacy Hydrogen RE Hybrid that TheCarConnection.com recently drove can accelerate to 60 mph in around ten seconds and reach a top speed of more than 100 mph.
As in the hydrogen RX-8, the on-board RENESIS rotary engine can burn either gasoline or hydrogen—in hydrogen mode, it emits only water vapor, but because petro also goes in there, tasting tailpipe contents is unadvisable. The rotary engine is virtually the same, design-wise as what goes into the 2010 Mazda RX-8 sports car, with slightly revised lubrication. Its design is naturally well suited for hydrogen, Mazda says. However in the Premacy, the rotary doesn’t directly move the vehicle; it instead powers a generator that charges a small lithium-ion battery pack and helps power a 110-kW electric motor.
The Premacy H2 RE does have a plug to give you enough juice to limp home if needed, but this is neither a plug-in EV or a range-extended EV; the lithium-ion battery pack doesn’t have much range—an engineer said that it could creep at low range for a couple of miles—so the rotary engine is an almost ever-present companion.
Turn on the ignition in the Premacy, and the first steps are a lot like in a Toyota Prius. Engage Drive and step gently into the throttle pedal and the H2 RE moves quietly ahead quietly in electric mode only; go into the gas a little bit more and the rotary engine starts up and winds up to 2,000 rpm or so; but stomp the right pedal and the rotary sound takes over all the other electric-powertrain sounds, revving to 6,000 rpm or more to keep the battery charge up and power flowing to the motor. When going on and off the throttle for quick bursts of power, the revs slightly lag the delivery of power from the electric motor, giving it a sound and sensation somewhat like the motorboating drone of a small car with a CVT transmission—even though the engine isn’t connected in any way.
The H2RE’s powertrain responsiveness is much like that of slightly underpowered EVs. Just off a standing start, or at 5 or 10 mph, the H2RE feels super-responsive, as peak torque is available right away in an electric motor. By 30 mph and up to the 45 mph or so we reached a couple of times in a five-mile loop, the minivan was responsive but no longer felt downright quick.