Mazda giving green twist to rotary engine

The squeeze is on. Automakers around the world are coming under increasing pressure to improve fuel economy and reduce emissions, even though consumers seem unwilling to sacrifice performance or pay a higher price for the technology needed to go green.

In this highly competitive horse race, there is no “silver bullet,” no single environmentally friendly solution, so manufacturers are turning to an array of alternatives that could eventually supplement, perhaps even replace, the time-tested internal combustion engine.

Mazda, the small Japanese affiliate of Ford Motor Co., is betting it has a unique weapon in its own powertrain arsenal, the Wankel, or rotary engine. Small, simple and lightweight, it was once seen as a promising substitute for the piston engine, but never lived up to its initial expectations.

But now Mazda believes the Wankel could move from a niche to mainstream source of power, and one that could be brought to market sooner and at a significantly lower cost than the fuel cell vehicles and battery cars on which other manufacturers are showering their attention —and billions in research dollars.

At a recent preview of Mazda’s 2010 product line, the maker unveiled two rotary-powered prototypes running on hydrogen, rather than gasoline. Many experts believe hydrogen could become the fuel of the future.

Most manufacturers have focused their attention on hydrogen-powered fuel cells, which feed the lightweight gas into a device called a stack, where it combines with oxygen to produce a steady flow of electric current. The resulting current is then used to power an electric motor. It’s a sophisticated and elegant technology that’s still better suited to the space program —where it was first used on the Apollo moon mission — and likely years away from commercial viability.

Mazda’s approach is to feed hydrogen, rather than gasoline, into its rotary engine, explains Akihiro Kashiwagi, head of the Hydrogen RE (short for Rotary Engine) project. It’s not quite as efficient as a fuel cell, but the technology is readily available and reasonably affordable. As with the fuel cell, the only byproduct is a misty stream of water vapor spewing from the tailpipe of a modified RX-8 the automaker allowed me to drive around the grounds of the Laguna Seca Raceway near Monterey, Calif.

The RX-8, a four-seat sports car, fires up with the touch of a button, the engine developing a curious buzz that one bystander suggests sounds a bit like “a vacuum cleaner that’s just swallowed something big.” But as it slips into gear, the car lurches forward and picks up speed.

Not a lot, however, for Mazda has had to detune the engine a bit to let it operate in dual-fuel mode. A critical advantage of using the rotary engine is that once this RX-8 has run out of hyrdrogen, it can switch to a second tank using readily available gasoline and just keep on going. The various hyrdogen-powered fuel cell vehicles being tested in Southern California as part of an elaborate experiment by other automakers and government authorities can never go more than 50 to 100 miles away from their refueling stations — unless the driver wants to be towed home.

Mazda recently introduced a second, more complex version of the Hydrogen RE system, using the Japanese version of its MX5 microvan.

This vehicle has been set up as a "series" hybrid. Unlike a Toyota Prius, whose wheels can be powered by its gasoline engine, electric motor or both, the Hydrogen RE Primacy van is powered solely by electricity. The hydrogen rotary functions only as a generator, charging up the vehicle’s battery or sending power directly to the electric motor turning its wheels.

The system is more efficient than that found in the Hydrogen RE RX-8, meaning better fuel economy and a range of about 200 miles.

At low speeds, the battery alone is used. And, says Kashiwagi, “In the future, this system could easily be converted to a plug-in hybrid,” like the planned Chevy Volt, by increasing the size of the lithium-ion battery. That would allow the vehicle to travel for 20, 30, 40 miles or more solely on electric power.

As with the Hydrogen RE RX-8, there’s a fair amount of buzzing from the Premacy. There’s also the drawback of giving up the third row of seats to make room for a big tank of hydrogen. But there’s still enough space for five passengers.

Like other hydrogen vehicles, the Mazda Hydrogen RE technology still has a bit of work to be done, but the company insists it could be ready for the retail world far sooner than fuel cells – and overcome some of the limitations of battery power, notably the lack of range.

The challenge is probably not one of using hydrogen, says Kashiwagi, but simply getting the fuel. There’s no nationwide production or distribution method and setting up one would likely be a slow and costly challenge. Nonetheless, hydrogen does have its advantages and plenty of proponents. And if Mazda is right, its technology could provide a clean alternative powertrain sooner than many other alternatives still struggling to make it to market.

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