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Mazda RX-8 Hydrogen RE in Cold Weather Testing in Hokkaido, Japan

Mazda RX-8 Hydrogen RE during cold weather testing. Click to enlarge.

Mazda Motor Corporation is joining forces with the Hokkaido Regional Development Bureau (HRDB) to test the cold weather performance of its Mazda RX-8 Hydrogen RE (earlier post). The tests are scheduled to run from 19 to 23 February 2007.

Employing a dual-fuel system, the Mazda RX-8 Hydrogen RE can run on either high-pressure hydrogen gas or gasoline, allowing the car to be driven in remote areas where hydrogen fueling stations are not readily available, easing driver concerns about running out of fuel.

Hydrogen injection in the RENESIS engine. Click to enlarge.

The RENESIS Hydrogen RE incorporates an electronically controlled hydrogen gas injector system. The system draws air from the side port during the intake cycle and uses hydrogen injectors in each of the engine’s twin rotor housings to directly inject hydrogen into the intake chambers.

For the tests involving the hydrogen rotary-engine vehicle provided by Mazda, only the tires have been changed to suit the cold weather. The vehicle is otherwise identical to the model which currently available for commercial lease. Mazda began leasing the hydrogen car in February 2006. (Earlier post.)

This cold weather testing coincided with the Environment and Transport Symposium on Hydrogen Energy that is being held in Muroran city, Hokkaido Prefecture, on 21 February. Participants in the symposium had a chance to ride in the RX-8 Hydrogen RE and attend a briefing session. The HRDB is a division of Japan's Ministry of Land, Infrastructure and Transport (MLIT).

We plan to demonstrate that vehicles powered by Mazda’s unique hydrogen rotary engine are very practical even in cold regions. Since hydrogen cars with rotary engines are relatively cheap to produce and can also run on ordinary gasoline, we believe they will have an important role to play as we move closer to a hydrogen energy society.

—Akihiro Kashiwagi, Mazda’s program manager in charge of hydrogen rotary engine development
Mazda RX-8 Hydrogen RE
Engine RENESIS hydrogen rotary
Power 154 kW (206 hp) 80 kW (107 hp)
Torque 222 Nm 140 Nm
Fuel tank 61 liters (16 gallons US) 110 liters@35 Mpa (350 bar)
Range 549 km (341 miles) 100 km (62.1 miles)

The HRDB is conducting feasibility studies into the uses of hydrogen in snowy climates. These include plans to conduct various cold weather tests in and around Muroran city and neighboring Noboribetsu city. Both cities are in Hokkaido Prefecture, Japan’s northernmost island. This region produces abundant volumes of byproduct hydrogen and is therefore one of the most feasible locations in Hokkaido for a hydrogen fuel network.

The Environment and Transport Symposium on Hydrogen Energy was organized by the HRBD and the Town Level Research Committee to Utilize Hydrogen in the Muroran Area. The symposium participants represented local industry, academia and government, and met to discuss the possible uses of hydrogen in transportation.



That chart makes gasoline look pretty good by comparison.


Is it a mistake ? seeing that H2 would probably be more expense than gas, its a bit of a no-brainer !


If this is the best H2 can do in an ICE, H2 will never see the light of day. Now we wait for Roger to comment :)


It's a great car for corporate greenwashing, but for the average consumer it's no more (in fact much less) attractive than a dual fuel CNG-gasoline vehicle, that already has difficulty penetrating the mass market.


I wonder if it might reduce emissions running on a lean gas setting, with just a little bit of hydrogen injection?


Its a much cheaper way to make a zero emmssion car for a city that enforces such things. Its hard to tell how good the car realy is as they dont give h2 in kilos But then concider the sucker only goes 341 miles on 16 gallons of gas.... thats just about 21 mph there are sibs that get better then that.

Roger Pham

Thanks, Neil, for the thought.

62-mi range on H2 ain't so bad if you can fill it up at home, and Honda has been offering this technology for home H2 from reformation of NG. 110 liters of H2 at 350bars is less than 3kg, so the range of 62 mi is comparable with gasoline. Just like the BMW 7 designed for dual gasoline-H2 fuels, the ICE in these instances aren't optimized for maximum H2 efficiency. For one thing, the compression is too low for H2 if optimized for gasoline.
My suggestion is GDI (gasoline direct injection) with much higher compression ration, and ultra-lean burn which is further optimized by injecting both gasoline and a little bit of H2 to increase ignitability at ultra-lean gasoline mixture. Now, you have a real winner, in that you can increase efficiency by as much as 50%.


"allowing the car to be driven in remote areas where hydrogen fueling stations are not readily available"

remote areas like, just about anywhere?

Rafael Seidl

Roger -

igniting gasoline in a *globally* lean mixture does not require the use of a fancy dual fuel system and a brand-new production and distribution infrastructure. You can do it using spray-guided stratified GDI, cp. MB 272 engine and BMW's 335i vehicle. The downside is that you need an NOx store cat or SCR system to meet NOx emissions standards.

The only reason Mazda - which is part-owned by Ford - is pursuing this is because the US taxpayer is continuing to lavish funds on hydrogen R&D, because that's what the natural gas and nuclear lobbies have paid campaign contributions for. Rotary engines are hardly going to win a lot of new friends just because hydrogen is involved, even if it does improve the thermodynamics of combustion a little bit.


The horrible figures of the Hyd rotary aren't surprising.
Rotaries have a large surface area in the combustion chamber and (because of this) an extremely low thermal efficiency.

Rotaries are extremely inefficient on gasoline, and even worse on hydrogen.

And no, the slightly lowered weight of the rotary doesn't offset it's inefficiency and low BSFC.




There really is no such thing as a natural gas industry. I work for a natural gas distribution utility. We have very little in common with upstream natural gas industries. Our customers see us as the bad guys because they don't see the upstream entities.

Converting CH4 into H2 is inheriently wasteful; as I'm sure everyone here knows. The rotary engine does have some clear advantages though its thermal efficiency is relatively low. It is inheriently cheap to manufacture and rotor sections can be pancaked together. These attributes make it well suited to cogeneration applications. In many cases, a rotary engine can take the place of a large electric motor and/or coupled to an induction motor/generator for even more options.


It has nothing to do with the us. It just happens to be the case that the first place where h2 is cheaper then many other things is in fact japan. Home h2 stations are verified to be saving people moneyand lots of it. But so ar I have not seen the numbers on how many such stations have been installed.


GDI on a rotary? I'd like to see that one...


Mark, I'm interested in your comment about there being no such thing as a natural gas industry. In Sydney they run about 400 buses on natural gas. They wanted to run the whole fleet on it but the gas distributor was going to charge them huge dollars to run the extra piping to another depot. Unfortunately the proposal was canned.The distributors may not have been the bad guys but it was a disappointing result.

Natural gas makes a lot of sense for buses, way cleaner than diesel and way more efficient than running them on hydrogen or fuel cells. I have a vested interest as I commute by bicycle. Getting stuck behind a diesel bus at traffic lights is not fun.

Roger Pham

Thank you all for the feedback regarding GDI on rotary engine.

In restrospect, there is no need to use GDI on the Mazda rotary. Just use hydrogen direct injection would be sufficient, while gasoline can be port-injected like usual, thereby raising the effective compression ratio when H2 is used because the H2 is injected during the compression stroke, adding to the final compression, while gasoline is still port injected to produce a homogenous mixture to minimize NOx and PM at normal compression ratio to prevent pre-ignition.

Now then, it would be interesting to experiment hydrogen-enriched ultra-lean gasoline regimen at part-load, without the use of the throttle plate. So, multi-mode ultralean at partload for cool combustion and hence low NOx and low HC and CO due to the use of H2-assisted gasoline combustion and a two-way catalytic converter, with significantly improved engine efficiency, as much as 50% more thermal efficiency in my prediction. Provided that H2 is already available at home or at limited locations in town, this is a great way to improve engine efficiency AND to be ready for the eventual Hydrogen Economy in the future.

At high load, stoichiometric gasoline combustion without H2, and the NOx and HC and CO will be removed by the usual 3-way catalytic converter. No efficiency gain here, but assuming that high load is not often used, overall efficiency would not be greatly affected. A hybrid drive train can improve efficiency even more on top of all this.


Using a rotary for fuel economy is like using agent orange for organic farming.

Roger Pham

My posting just above is not restricted to rotary engine alone, but is entirely applicable to piston engines as well. But, since it is well-recognized that the low efficiency of Wankel rotary engine is due to 1) higher heat loss in the wedge-shape combustion chamber, by making combustion significantly cooler at part load due to the excess air in ultra-lean combustion mode, heat loss would be less and hence proportionally higher efficiency can be gain in comparison to the stoichiometric combustion mode.
2) Poor combustion at part-load with higher proportion of HC emission, likely also due to the wedge-shape combustion chamber resulting in poor flame propagation or excess cooling? This can also be addressed with H2-enriched gasoline combustion at part-load, as well.

I hope that somebody at Mazda would find the inspiration to experiment with what I've posted above, and then we'll see how much the Wankel rotary engine's efficiency can be improved. The beauty of the Wankel rotary engine is its compactness, light-weight, simplicity, and potentially much lower internal friction...So, if the Wankel rotary can even partially catch up with the piston engine in term of combustion efficiency...Watch out! Dual-fueled H2-Gasoline Wankel rotary may be the wave of the future...And when petroleum will run out, then run it with methane/H2 tank or just pure H2, if H2 is all you've got!


I am not sure rotary engine is lost cause. Up to today rotary was only 10% less fuel efficient compare to conventional engine, mostly due to high heat transfer in the combustion chamber. Modern ceramic coatings can significantly reduce heat transfer and wear on seals. Modern conventional ICE benefit from variable valve timing, living rotary far behind in regular cars.

However, in series hybrid or in PHEV with electromechanical continuously variable transmission rotary engine could be tuned to Atkinson cycle without need for transitional performance compromises (it will work in narrow RPM and throttle setting interval).



From what I know (which isn't much) gas utilities in Australia are mainly part of combination (electric/gas) utilities. In such relationships, the electric utility part of the company almost always dominates corporate politics because that's where the money is. So, my guess is that the big dog decided it wasn’t worth the trouble. And so they made an unattractive offer. Besides, it appears with energy markets opening for competition, utilities are probably preoccupied in positioning themselves.


Roger Pham

Agree with you, Andrey! Wankel has poor part-load efficiency, but at high-load, its efficiency is but 10% less than piston engine. The full hybrid drive train that allows the engine to run only at its higher efficiency regime will ameliorate the Wankel's lack of variable timing. Likewise, the bi-turbo setup in the Rx-7 or Rx-8 turbo can make up for the lack of variable valve timing by force-feeding the engine at high rpm, thereby allowing for more efficient port valve timing setup optimized for low-rpm efficiency.


Has anyone thought of using the earth to compress hydrogen? More precisely, what stops a company from running two cables down into the ocean 10,000 feet and supplying the cable with wind powered elecrtricity, thereby producing hydrogen from the ocean at a pressure of 4454 psi. The hydrogen would be collected at depth and piped, at a collection pressure of 4454 psi, up to a surface collection station and further into existing high pressure gas distribution infrastructures.


Rejuvenating the RE 2007 today. The RE hydrogen RENESIS talked a lot. RE has not capitalised on the CNG/gasoline fuel being used by millions of vehicles in Australasia. Hundreds of thousand of filling stations set up in Karachi, other cities of Pakistan with 160 million population. Helping millions green fuel, save costs. Why anything is not done on the CNG fuel which compliments the RE, and a market to Mazda for larger markets. It's important to research in Pakistan, China, and countries with larger CNG vehicles, and market for Mazda. City of Karachi will be pleased to test Mazda RE on CNG/gasoline on the new flyovers, signal free roads, for zero emission vehicle sporty Mazda RE cars, where every gasoline filling station has a kiosk for CNG to protect our city from pollution, and offer fuel of CNG which 40% cheaper than gasoline. Karachi city will welcome Mazda's initiative for research and introduction preview on the new flyover with Mazda green cars. Haroon Rashid Member Advisory Board - Consumer Association of Pakistan

Wow, hydrogen would only be a better choice compared to Gasoline if it were dirt cheap

the idea is to use fuel cells basically 2 platinum plates around a positivly charged membrane to produce the h2 which geuss what Comes from WATER my god man i think theve done it

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