What are the cons of cars with hydrogen internal combustion engines?

Question by Shannon: What are the cons of cars with hydrogen internal combustion engines?
I’ve been researching hydrogen cars for a project and I don’t understand why all the focus is being put on hydrogen fuel cell electric cars instead of hydrogen internal combustion engines. As I understand it, regular old internal combustion engines like we use in all gasoline cars can be modified to burn hydrogen instead, so it seems weird to me that people are focusing so much on fuel cells, which have flaws of their own, like the fact that they use platinum which is really expensive. So why aren’t car manufacturers just making cars with a normal internal combustion engine that burns hydrogen instead of gas? Why the fuel cells instead?

Best answer:

Answer by Tony
The internal combustion engine is horribly inefficient at converting energy, and that’s the biggest reason I’ve heard over time for doing away with it. At a rough estimate from what I can remember a gas engine has around 30% efficiency at most and going down from 18% in other cases. The processes that still use combustion on a large scale such as coal or gas power plants can get around 90% efficiency. Basically with the internal combustion engine you’re wasting energy by turning it into heat rather than a form you can use for movement. If you start researching the physics behind internal combustion engines that should give you a good lead to start branching out from.

The other aspect is safety. Hydrogen is pretty flammable to say the least, so burning it already has risks when it comes to malfunctions, but also accident safety. You also need to consider that it needs to be transported. You can’t feasibly keep it as a liquid like we do regular old gasoline. In gas form you either need a lot of space to contain it, or keep it under extremely high pressure to have a decent carrying capacity. Again, pretty big risk if you get into an accident. The fuel cell approach can avoid those problems pretty well. As for the platinum, it is used as a catalyst, but it doesn’t get used up the fuel will. It’s like using a pot to cook food. The food is basically one use, but the pot is reusable.

All in all, safety and efficiency are the big ones to delve into a bit more.

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