05.23.06
Why can’t a car engine run on water?
I recently came across a mention of yet another inventor who supposedly has built a car engine that runs on water. The claim is in a video which doesn’t play on my computer, so I don’t know much for details of what he’s actually claiming. But even without watching the video, I can say with almost absolute certainty that this inventor hasn’t built a car powered by water.
I’m sure of this, even though I have no idea how this engine is supposed to work. Why? It’s a matter of applied thermodynamics.
First, imagine that the engine is in a black box. We can’t see into the black box, so it could be any possible type of engine that has been or will be invented. All we can measure is what goes in and out.
What goes in is basically just the “fuel”: room-temperature water. There might be some air with it, too. There are a couple of things that come out: The exhaust from the engine, and the power from the engine — maybe in the form of a shaft coming out of the engine that it’s turning, or something.
According to the First and Second Laws of Thermodynamics, available energy cannot be created, though it can be destroyed by turning available energy into unavailable energy. If we apply that principle to the box with the engine in it, it’s pretty clear that the sum of the available energy that goes into the box and what is in it when we start running it has to be at least as much as the sum of what comes out and what is in it when we finish.
Now, this is an “engine”, not a storage system; it’s not allowed to be running off some sort of hidden internal energy supply that’s also contained in the box. So, if the engine isn’t cheating, the amount of available energy in the box when we start will be the same as the amount when we finish. Thus, we conclude: what goes in must be at least as much as what goes out.
So, look at the available energy that’s in that exhaust. Whatever the exhaust is, it has to contain the same hydrogen and oxygen atoms that came in with the water, along with the atoms that came in with the air. It could hot steam — which has higher available energy than the water that came in. It could be some other compounds of hydrogen and oxygen and stuff in the air — and all of those have higher available energy than water and air do. It could be a cool wet fog, which has slightly higher energy than the water. It could even be ice, but even that has higher available energy than room-temperature water. The best possible case is that it could be room temperature water and air just like what came in, and have the same available energy.
That means that the available energy that comes out in the exhaust is at least as much than the available energy that goes in with the fuel and air. And there’s supposedly even more energy coming out via the power from the engine — thus, the output is claimed to be higher than the input.
This is obviously a contradiction. We just found that, by the laws of thermodynamics, we can’t have more energy coming out in the exhaust and power shaft than what came in with the fuel.
Thus, the engine is impossible.
TWAndrews said,
May 24, 2006 at 6:36 am
From the thermodynamic point of view, the an engine which produces a waste product with the same or greater energy than the fuel which went in obviously doesn’t work. However, if you step back and look at the engineering problem of getting a car to run on water, this doesn’t tell you a lot. Thermodynamics doesn’t forbid a car which uses water as its primary fuel source.
The key to this being the assumption that the water is only the primary source of energy. One can put together a pretty realisitc scenario where we get big improvements in the efficiency of turning energy into motion by having another power source in play.
One of the problems with converting fuel into motion is that the theoretically available energy based on a fuel’s chemical composition is much higher than the energy that can be productively used in a mechanical system. And as I understand, this is particularly true for the current generation of battery operated cars, as cars have grown up with, and are hence optimized for, use with internal combustion engines which typically run between 500 - 5000 rpm.
However, its possible to imagine that the inventor in this case has developed a clever new way of splitting water into hydrogen and oxygen using current from a battery. So the water goes in, is split using power from a battery stored in the car, and explosively recombined to power the car. The total energy cost is whatever energy was drawn from the battery to split the water.
So some questions about whether or not this is possible, based on the claim that 4oz. of water can drive the car for 100 miles are:
1. Is there even enough energy in the hydrogen gas produced from 4oz. of water to drive an average size car that far? Or, Is this just a total hoax?
2. If so, is it theoretically possible (i.e. using a 100% efficient method) to split 4oz. of water with an energy source which could fit in the box shown in the video (which is aprox. 2′ x 2′ x 3′)? How much energy (and hence battery weight) can be saved by using battery power to split water for fuel rather than moving the car directly? Or, Is this actually a viable method for powering a car?
3. If so, how much does this improve on the efficiency of current electrolysis methods. Or, Is this new?
As far as I can see, the questions are increasingly likely to be answered in the negative. Though I don’t know, I can imagine that there’s enough hydrogen in 4oz. of water to power a car.
I’d be rather more surprised if it was possible to gain efficiency by essentially adding a step to the chain of conversion from energy –> motion. But since each step is quite inefficient, I suppose it would be possible to replace one particularly inefficient step with two more efficient ones and realize a gain.
However, I’d be absolutely shocked if this was really a drastically more efficient way of splitting water such that it all of a sudden made sense to use spoonfuls of water to drive cars.
Isaac Ikoro said,
August 11, 2006 at 12:03 pm
I believe I can make a car that runs on water
Andrew said,
December 11, 2006 at 12:27 am
You need a self-sustaining nuclear reaction that operates on water molecules. Not impossible.
Brooks said,
January 9, 2007 at 1:54 am
Andrew: True enough. I should have specified that I was assuming that the same atoms came out as went in, so that there weren’t any nuclear reactions. I think that with current technology that’s a justified assumption, though perhaps in a few hundred years it won’t be.
Anantdeep Handa said,
June 24, 2007 at 3:27 am
A car engine working on water could be possible…the available form of water can make a car engine run…if u want to knw how…u can contact me at the given email…
Ankur walia said,
October 3, 2007 at 9:55 am
a car can run on water. the thing is that we all are thinking abt ic engine but water will not work on that principle. we have to develop a new principle. i am working on it and i am sure that i will surely do it.
Gary Landsen said,
January 28, 2008 at 6:46 pm
Of course you can run a car on water. And in many situations there is more energy coming out then what came in. For example transformers inside plugs they change 120v into 9v and works the same way around if the electricity is coming from the other side.
figaro (peter njeru) said,
April 10, 2008 at 1:42 am
very good arguments. but is what is on sale -technology kit workable? has anyone tried it out yet?
Hayath said,
May 10, 2008 at 8:07 pm
I am young graduate. Just left my job in Dubai and came back to india to work on hydrogen engines. The arguement about transformers is not so suitable because transformer steps up the voltage at the cost of reducing Power [amps] in equal proposion. So without amps work cannot be done. So however i just want to know weather those electrons in electrolysis can make wonders or not. What cavalic compound we can add for easy and high density splitting of water molecules.
Jack said,
June 9, 2008 at 3:40 pm
How many cubic inches of atmospheric pressure H2 is there in a quart of water? We run IC engines on propane. H2 is a better fuel than propane so why not. You don’t have to compress the H2 in high pressure cylinders to use the H2 — You just have to release it from the H20 and run a small gas pump to put into the same system of a converted car engine, running on propane.
mark said,
July 20, 2008 at 5:33 am
If a car can be run on water only then the worlds energy problems are solved.! However that would be perpetual energy which defies the basic principals of physics and chemistry.Chemical theory suggests that you must put as much energy into splitting water molecules as you can get by burning hydrogen.HHO conversions increase the efficiency of the engines fuel and does not produce any net energy once consideration of the load on the engines alternator is accounted.If I am wrong pleeeease tell me.I want to be wrong!