From time to time I stumble into these people (i.e. websites, blogs, and comments) that honestly believe that you can make cars that run on water, and that the main reason why we don’t have water cars is because of the oil industry.

Supposedly, the idea is that you run the water through electrolysis, producing hydrogen and oxygen, and the burn the two together, giving off energy. This energy is allowed to power the car, and the only exhaust is water. Sounds like a good, clean, energy-efficient system, right?

Except that violates the fundamental laws of nature. You can’t get more energy out of an engine than you put into it. And water happens to be one of the least energy-rich materials on earth. That’s why we have oceans of water just floating around, doing nothing; and which is also why we use it to put out fires.

Of course, the counter-argument is that you can, in fact, electrolyze water into hydrogen and oxygen. And you can, in fact, burn these two together, giving energy. But it still is a closed system – water goes in, water goes out – and you can’t create energy in between with anything less than the complete annihilation of matter¹, which involves anti-matter anyway².

And, yes, fuel cells run on hydrogen, which can be made from water, but in that case you should have cars running on hydrogen, not water. As soon as you put water as a source material, you’ve got a closed system again, and the total amount of energy that can be even theoretically extracted is 0 joule.

So there.

I’m just writing this to set the record straight.

Now if anyone dares to comment on this article, saying that I’m wrong, I’ll taunt you and poke you with a sharp stick.

¹⁾ Which means you end up with less water anyway. Thermodynamic laws are intact.

²⁾ Finding, containing and utilizing antimatter for energy would be a cool thing. But dangerous. Not likely to be done in vehicles anytime this century.