What Is It?
Mazda RX-8 Hydrogen RE Concept
What's Special About It?
The Renesis rotary engine made its debut at the 33rd Tokyo Motor Show, and two years ago, the company showed the first production version of the RX-8 here. This year, Mazda showed another application of Renesis: This one is an RX-8 that can run on either hydrogen or gasoline — with no modifications required to switch between the two.
The company says that the unconventional design of a rotary engine makes it well suited for hydrogen fueling. Direct injection, for example, works well here, as the engine's separate induction chamber protects hydrogen injector seals from exposure to unduly high temperatures. Additionally, a rotary engine offers enough space for two hydrogen injectors in each combustion chamber — necessary, says Mazda, because hydrogen's lower density compared to gasoline requires larger-than-normal injection volumes. Finally, the greater travel of a rotary engine's output shaft (270 degrees versus 180 degrees in a traditional engine) produces a stronger intake flow, which yields a more uniform hydrogen/air mixture for better combustion.
Actual output from the hydrogen-fueled Renesis is not all that impressive at this point, rating just 109 horsepower at 7,200 rpm and 89 pound-feet of torque at 5,000 rpm. Those figures go up to 207 hp and 164 lb-ft when the engine operates on gasoline.
A sizable hydrogen tank has taken up residence in the RX-8's trunk, effectively eliminating it as a useful storage space. To compensate for the additional weight, Mazda has undertaken various measures to improve aerodynamics and cut down on extraneous weight. Besides that, the company gets another check mark or two in the green column for using a water-based paint with a shorter-than-normal drying process (which reduces carbon dioxide emissions) and plant-based plastics (rather than the usual petroleum-based variety) for interior components.
Why Should You Care?
Although this is a prototype still undergoing road tests, Mazda says that the car is reliable and easy to operate with either fuel source, and suggests that its flexible, dual-fuel design would encourage hydrogen usage and promote development of a refueling infrastructure. Obviously, if such a car were to target driving enthusiasts (even those with an environmental conscience), though, the company would need to get more power out of the engine (during hydrogen use at least) to make it seem a viable option to consumers alongside the regular 238-hp RX-8 — good thing Mazda is also exploring the feasibility of an electric motor-assisted turbocharger for hydrogen-fed rotaries of the future. — Erin Riches
Mazda RX-8 Hydrogen RE Concept
What's Special About It?
The Renesis rotary engine made its debut at the 33rd Tokyo Motor Show, and two years ago, the company showed the first production version of the RX-8 here. This year, Mazda showed another application of Renesis: This one is an RX-8 that can run on either hydrogen or gasoline — with no modifications required to switch between the two.
The company says that the unconventional design of a rotary engine makes it well suited for hydrogen fueling. Direct injection, for example, works well here, as the engine's separate induction chamber protects hydrogen injector seals from exposure to unduly high temperatures. Additionally, a rotary engine offers enough space for two hydrogen injectors in each combustion chamber — necessary, says Mazda, because hydrogen's lower density compared to gasoline requires larger-than-normal injection volumes. Finally, the greater travel of a rotary engine's output shaft (270 degrees versus 180 degrees in a traditional engine) produces a stronger intake flow, which yields a more uniform hydrogen/air mixture for better combustion.
Actual output from the hydrogen-fueled Renesis is not all that impressive at this point, rating just 109 horsepower at 7,200 rpm and 89 pound-feet of torque at 5,000 rpm. Those figures go up to 207 hp and 164 lb-ft when the engine operates on gasoline.
A sizable hydrogen tank has taken up residence in the RX-8's trunk, effectively eliminating it as a useful storage space. To compensate for the additional weight, Mazda has undertaken various measures to improve aerodynamics and cut down on extraneous weight. Besides that, the company gets another check mark or two in the green column for using a water-based paint with a shorter-than-normal drying process (which reduces carbon dioxide emissions) and plant-based plastics (rather than the usual petroleum-based variety) for interior components.
Why Should You Care?
Although this is a prototype still undergoing road tests, Mazda says that the car is reliable and easy to operate with either fuel source, and suggests that its flexible, dual-fuel design would encourage hydrogen usage and promote development of a refueling infrastructure. Obviously, if such a car were to target driving enthusiasts (even those with an environmental conscience), though, the company would need to get more power out of the engine (during hydrogen use at least) to make it seem a viable option to consumers alongside the regular 238-hp RX-8 — good thing Mazda is also exploring the feasibility of an electric motor-assisted turbocharger for hydrogen-fed rotaries of the future. — Erin Riches
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