Mazda's Dual-Fuel Roadster


Strolling around the Tokyo Motor Show, visitors can hardly avoid the huge array of green-engine technologies on display. From a hybrid gasoline-electric version of Toyota's (TM) Lexus to Honda's (HMC) concept fuel-cell vehicles, just about every up-and-coming environmental angle is covered. One of the most eye-catching is Mazda's RX-8 Hydrogen RE sports coupe, a new version of the popular rotary-engine-powered four-seater that burns either hydrogen or gasoline -- at the touch of a button.

The thinking behind the dual-fuel 210-horsepower roadster, which Mazda will lease in Japan beginning in spring 2006, is straightforward. Burning hydrogen is cleaner than gasoline but not as practical, given the lack of infrastructure capable of delivering hydrogen to customers. By developing an engine that switches to gasoline once the hydrogen tank runs dry -- currently at around 100-km (about 62 miles) -- drivers can use hydrogen without having to worry about where the next fuel station is.

PRICEY LEASE. Mazda also believes that the technology has an edge over fuel cells, which generate electricity from a chemical reaction between hydrogen and oxygen. While fuel cells produce no harmful emissions, auto execs say it will take the technology years, if not decades, to become commercially viable.

Hiroshima-based Mazda says it may be more effective to simply burn hydrogen in its rotary engines, although it won't necessarily be a cheap option. Mazda hasn't revealed how much it will charge to lease the RX-8 other than to say initially it will be less than $10,000 a month.

Still, in a sign that it means business, Mazda also unveiled a concept version of its Premacy minivan at the Motor Show. The Premacy Hydrogen RE Hybrid combines the dual-fuel engine used in the RX8 Hydrogen RE with an electric motor, powered by a pack of batteries.

On the floor of the Tokyo show, BusinessWeek Tokyo Correspondent Ian Rowley spoke with Akihiro Kashiwagi, the Mazda manager charged with leading development of environmentally friendly technologies. Here are edited excerpts of their conversation:

Why did you choose to use the RX-8 for Mazda's first step into hydrogen-gasoline engines?

A long time ago, we tested using hydrogen with a reciprocal engine, but we had some difficulties, especially with backfiring. With rotary engines, this isn't the case. And the RX8 has a rotary engine, so it made sense for us to utilize hydrogen in the RX8.

What's the performance like when driving in hydrogen mode?

The power output in the case of hydrogen isn't as much as with gasoline. In hydrogen mode, the engine provides around 60% of the power of gasoline. But the RX8 has more than 200 horse power, so even at 60%, it's still very practical.

Can that 60% be improved?

In the past, we have developed purely hydrogen-powered rotary engines -- not the dual-fuel type -- and it was easier for us to get a higher power output than with the dual-fuel system. But it's possible to shrink that gap.

Do you have to stop the car to switch from gasoline to hydrogen and vice versa?

In principle, you don't have to stop the car. But as far as the RX8 version is concerned, you can switch from hydrogen to gasoline while driving, but going from gasoline to hydrogen you have to reduce your speed to zero and switch while the vehicle is idling. We want to avoid customers having to switch between the two many times. The idea is that they use hydrogen until it runs out.

Do you think the dual-fuel technology will be a hit with customers?

Compared to fuel cells, of course, our technology is much more practical, so there's [certainly interest]. On the other hand, local governments [which will likely be the first lease customers] see the RX8 as a sports car, and they have trouble with the concept of leasing a sports car for a government fleet.

How long will it take to make the dual-fuel technologies available at an affordable price?

It depends on the production volume and how much growth we can get. To achieve drastic cost reduction, maybe you would need volumes to be 10,000 units per month. But that depends a lot on infrastructure, and we're not an infrastructure developer.

Right now, the Japanese government and energy companies are working together, and there are about 15 hydrogen stations. How quickly that number will increase will depend on many factors, from future [oil] prices to the state of the global environment. Depending on those factors, the infrastructure situation could change a great deal.

If the infrastructure develops, would you be willing to share the technology with other auto companies?

Many manufacturers come to use and ask us to offer this technology, but it's a difficult question, and I can't give you an answer on that. The rotary engine is Mazda's icon, so to grant a license to other manufacturers would be a big issue for us.

What about Ford (F), which owns a 33% stake in Mazda?

Ford is testing a hydrogen-reciprocal engine with large trucks -- five or six liters -- or a school-bus-type of vehicle. That's a different direction from Mazda's.

Mazda is also showing a gasoline-electric-hydrogen version of the Premacy minivan at the Tokyo Motor Show, based on similar technology. When will that be launched?

We'll begin leasing the RX8 next year, and after that we'll develop the Premacy version. I expect it will take three or four years.

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