Toyota Mirai Explained By Engineering Explained – Video

FEB 25 2015 BY MARK KANE 24

Toyota Mirai

Toyota Mirai

Here is one of the better explanation of how hydrogen fuel cell cars work, prepared by Engineering Explained.

It begins with a fuel cell stack and chemical reaction and then moves to the package implemented in the Toyota Mirai.

In fact, FCVs look just like BEVs, except for the additional electricity generator, which uses hydrogen and oxygen.

“How do hydrogen cars work? What are hydrogen fuel cells? How do hydrogen fuel cells work? How does the Toyota Mirai work? This video looks at how hydrogen (H2) can be used to power a vehicle. An onboard storage tanke send the hydrogen to the fuel cell stack, where the electrons are separated from the hydrogen via a platinum catalyst, and the energy is then used to propel the car. The electrons return to the fuel cell where they then combine with positively charged hydrogen atoms and oxygen atoms to form H2O, and the reaction is complete. The water then flows out the exhaust pipe, with no harmful emissions.”

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24 Comments on "Toyota Mirai Explained By Engineering Explained – Video"

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That actually is a pretty good and simple explanation. A couple of my questions, which is beyond the scope of the video, would be:

1) Is platinum fowling in the catalyst an issue? If so, what is done to address this?

1a) Follow on: If high hydrogen purity is the answer, what is done to ensure high hydrogen purity when it is produced? I can tell you that achieving purity in the natural gas pipeline (apart from the required amounts of sulfur) is very difficult.

2) How would the chemical equation look when considering that your oxygen source is really air that is roughly 3 parts Nitrogen to 1 part Oxygen? To be more exact, the portion of the equation where air comes into play should look like this: (3.77)N2 + O2.

I’m not entirely convinced there won’t be any NOx emissions.

Sounds like the Worst Solution Ever.

Here is a comparison of BEVs to FCVs:

When someone starts to buy into the H2 idea; I just sent them he link so they know the truth. You may want to do the same; saves a lot of writing.

“I’m not entirely convinced there won’t be any NOx emissions.”
Nope : Nox emissions (NO and NO2) are the result of a reaction between N2 and O2, as you say. BUT, this reaction can occur only in high pressure and high temperature (~1400°C).
That’s the reason why you have a lot more nox emission in diesel engine than gazoline ones.
In FC, pressure is near atmospheric pressure, and temperature doesn’t exceed 100°C …


I’ll be happy to see these finally hit the market so we can see how they do. It has been annoying to put up with the FUD for years. Put up or shut up, Toyota.

No this is just the opening salvo of a long campaign attempting to demonstrate the viability of the FCV.

The mirai currently has performance that’s slightly better than a prius, and that’s with that big ‘ol FC stack in the middle. To improve performance, we have to increase the voltage, which requires inscreasing the size of the stack (and radiators to keep the stack cool) don’t we? Anyone else think that this isn’t going to end well?

Toyota Management should have figured that out now. The longer this embarrassment continues to be on the market, the lower our opinion of Toyota Management Falls.

The Volt provides a better, cleaner, cheaper stop-gap solution till the world is driving 200-300 mile EV’s.

This is never going mainstream.

It’s the new Edsel.

Since you say that the end result of the protons and electrons mixing after recovering the electrical energy in the motor is “H2”, and the incoming supply from the tank is “H2”, why not just send the H2 to back to the supply tank? That way you’d only need a pint bottle of H2 since according to your explanation, You get the same amount of H2 back after the motor has used the electricity as you started out with.

That way we’d never run out of “H2”, and the car would go 100,000 miles on 1 pint of hydrgoen.

That is, if your explanation is to be believed. Has a bit of a problem with the Conservation of Energy.

Yeah, that annoyed me too, Bill. The truth is, the electrons and protons do NOT recombine to create H2 on the other side of the Fuel Cell. They skip that step and combine straight with the Oxygen to create H2O. The whole point of a fuel cell is that H2O is a lower energy state than H2 and O2. That extra energy is precisely what pushes/pulls the electrons through the external circuit.

Yes, you can build an electric car which uses a hydrogen fueled fuel cell to power the electric motors. Just as you can build an electric car which uses a coal fueled steam engine to power the electric motors.

But in both cases it’s crazy (and very wasteful of resources) to to try to mass produce cars powered that way!

Creating and transporting hydrogen is so wasteful it is not even funny.

Oh wait wouldn’t be a better idea to charge a battery oh that’s right that would be a Volt or Leaf or Tesla or …

What the heck are Toyota doing ?
Hydrogen is NOT the answer.

The only place I’ve heard where H2 makes sense to me is powering a home. If someone produces a low cost, long life, solar cells that takes water in and puts out H2 (skipping the electric step), it could be a big winner. The H2 can be stored and used with the houses NG supply or sent to a fuel cell to provide electricity. Removing a lot of the electronics (including batteries) associated with a solar panel system for a home.
To power a car, it’s a dumb idea.

I think I’d rather just use a fuel cell that runs on natural gas since I have a line already piped to my house. Or possibly just get a generator that runs on natural gas. Depends on which is more efficient, and what the payback would be for a fuel cell.

Thanks for the post and the explanation. Nice job.

To me this just seems like a mistake (to take on this production of FCVs in the first place). They’re too complex and the production and transportation of hydrogen will continue to rely on fossil fuels. The infrastructure required is astronomical. I just don’t see this as a viable solution. However, the fossil fuel industry has a HUGE interest in getting something like this to mainstream market. Will be interesting to see what happens.

How much water do FCV’s put out? It’s 5 degrees here in Michigan. I don’t think its a good idea to put a lot of water on the roads. Maybe the amount is so small it’s negligible, I just haven’t heard the #’s.

I doubt that will be an issue any time soon. There are no hydrogen station to fuel them.

There will be in NY, and it gets cold there too.

An interesting question is how the water actually leave the car at these temperatures. Does it still come out of a tailpipe as steam? Will it be liquid that simply drips on to the roadway? Or will it be a liquid suspended in the air?

I suspect that NY would counter too much water/ice by simply dropping more salt. I can’t imagine that it would be hard – we already run salt trucks nearly constantly during the winter.

Since the thing is only 50% efficient, I’d assume some of the heat would be enough to vaporized the effluent.

the amount of water produced by an FCV is quite the same as the production of a gasoline car (gasoline engine produce CO2 and water).

I wonder how much oxygen gets sucked out of the air for FCV is it more or less than for an ICE? Just wondering. If it is similar then while not adding to the pollution problem from the tailpipe side it is still degrading the quality and quantity of breathable air.