Physics Van 3-site Navigational Menu

Physics Van Navigational Menu

Q & A: water as fuel?

Learn more physics!

Most recent answer: 10/22/2007
I was surfing the net when i came across this very interesting site. It deals with a car being able to run on water. Please look it over and tell me what you think. Is it possible?
- Steven Groves (age 15)
If you have followed our site much, you know we have a tendency to worry about exceptions, uncertainties, complications, etc.  With that as background:
The 'water as fuel' idea is absolutely 100% impossible. Schemes like this are always being proposed and they always completely fail. A fuel is something which has more free energy than it would if it settled into equilibrium. As it settles down toward equilibrium, work can be extracted. One example is separate hydrogen and oxygen. As they combine  to form water, energy is released which can be extracted to do work. Water can supply energy if it is up a hill. As it flows down, a water wheel can extract work from it. Once it's down at the bottom, there's no gravitational energy left to extract. Likewise, once hydrogen and oxygen have combined to make water, there's no chemical energy left to extract.

The site proposes separating the water using electricity generated by the reaction of the previously separated water. Sorry- the work to separate always exceeds the work gotten back. This scheme is a loser.

Mike W.

(published on 10/22/2007)

Follow-up on this answer.