A car that runs on water?

Google Answers customer madman514-ga had been offered plans for making a car that runs on water. He thought it was maybe too good to be true, and posted a question asking whether it would really work

The basic idea is that electricity from the car battery is used to break water down into hydrogen and oxygen. The hydrogen is then burned to propel the car.


For sure, it’s not going to work. But the information is presented in such a plausible way that I can see why some people might think it will work.

There are a number of different levels at which the answer can be approached:

Physics: The law of conservation of energy tells us right away that producing hydrogen from the water is going to require at least as much energy as we gain by burning the hydrogen and thereby turning it back into water.

Disclaimers: If it is really going to work, why are there so many disclaimers on the website that offers the plans? The disclaimers, by the way, are written to sound so helpful, so sincere. They caution you to save all the parts so that you can put your car back together again in case you can’t get it to work. They caution you to use an old car that won’t cause any problems if it becomes undriveable.

Motives: If it works, why haven’t the people offering the plans already converted their own cars? The most they will admit to is that they “see no reason why it wouldn’t work”.

Money: If it works, why aren’t the people who offer the plans getting rich by converting people’s cars at a thousand dollars a time?

Human nature: The water-to-hydrogen conversion mechanism is fully-described by a US patent which is referenced on the website offering the plans, and which is also widely available on the internet. If it really produced more energy at its output than it required at its input, wouldn’t there be massive academic interest in it?

The asker priced the question at $2.50, so I didn’t write a dissertation on the conservation of energy, but I gave quite a lengthy reply because the question interested me.

I sure hope I am able to save the guy’s time, money and car!

(photo by John Evans)

One Response to “A car that runs on water?”

  1. eiffel says:

    The question has now been rated five stars, and it’s clear that the asker won’t be attempting to drive on water. Phew!