Recently there has been a lot of buzz about water powered cars in the media. Understandably, it is difficult for people to make up their minds about such reports of grand technical achievements as to whether the claims are true or not, despite the common sense dictating against believing in such claims. After all such things must involve complicated technology which is not for everyone to understand. But the problem with many claims of such kind, and certainly with this particular one, is that they are in direct conflict with basic physics and chemistry. You do not need to go into details of the technology involved. The basic laws of physics and simple facts from chemistry categorically deny the possibility of using water as a fuel. Anyone who can recall their high school science correctly can refute this idea.
The reason this car cannot work is simply the law of conservation of energy, the most basic idea of physics that energy cannot be created, or destroyed, but can only change forms. You never create energy, only use some stored form of energy by converting it to your desired form (energy of motion, in case of car). This is also known to engineers as the first law of thermodynamics.
So let us look at the claim of the inventors about how this water kit works. It is a well-known fact that energy is released when you combine hydrogen and oxygen to make water. It is this energy that they claim to be using to run the car. But the problem is that you need a supply of hydrogen to make this work. The inventors claim to use water itself to get this supply of hydrogen. This is where they go absolutely head on against the law of conservation of energy.
Suppose you have a process in which some energy is released. Say some substances A change to substances B and energy is released. A simple consequence of the conservation of energy is that if you run the process backwards, tuning B back to A, you will have to supply exactly the same amount of energy. For if it were not the case, and say you needed less energy to go backwards, you could repeat the cyclic process of going from A to B and then B to A repeatedly, at each turn saving some extra energy. This way you could produce as much energy as you like. But this is against the law that you cannot create energy.
Therefore, the conclusion is that you need to supply exactly the same amount of energy to turn B back to A, as you would obtain by turning A to B. This fact is sometime stated as perpetual motion machines are impossible.
According to the inventors, the kit works by breaking water, a molecule consisting of two hydrogen and one oxygen atoms, into its parts, namely hydrogen and oxygen. When you combine thus obtained hydrogen back with oxygen to make water, energy is released which is used to run the car. Sounds simple. But the trouble is that you need to provide energy to break up the water molecule in the first place. Further, as stated above, according to the law of conservation of energy you need to provide exactly the same amount of energy to break up the water molecule as you would get when recombining hydrogen with oxygen.
This is not just a conclusion based on theory but a routinely tested fact of chemistry. So whatever energy you get out of this device, has to come from somewhere in the first place, and not from water itself. Water is not the fuel or source of energy.
The inventors claim that the water molecule is broken down using the electrical current from the battery. This process is well known and is called electrolysis. A battery has some fixed stored amount of energy which it can release as electrical power through a current. So by breaking the water molecule and then combining it back, you are just channeling this battery power to the car. When this source battery will die out, the car will stop working. As a matter of fact you will be better off connecting the battery directly to car's motors as each additional step that you introduce wastes quite a bit of energy.
The two processes involved, electrolysis of water and recombination, in this supposed generation of energy from water are well known in chemistry and can be found in class X chemistry book. So you may wonder why no one thought of using these for power generation. The reason is simple. They knew it is impossible.
There is really no way around it. It is based on the basic fact of conservation of energy and the fact of chemistry that energy is required to split a water molecule into hydrogen and oxygen. Then how do the hydrocarbon fuels work? The difference is that the chemical reaction involved in burning those release energy which is used to run the cars. When we run out of this fuel we replace with more supplies of the fuel that are available in nature. In other words the nature has stored supply of energy in hydrocarbons which we use. In the case of this car, it is the burning of hydrogen with oxygen which releases the energy. So the counter part of the fuel in this case is really free hydrogen and not water. We do not have a source of free hydrogen available here. In the case of hydrocarbons, we do not regenerate the by-products of hydrocarbon burning into the original fuel again. It is quite possible to do so. For example, one can make methane out of the final products of its burning i.e., water and carbon dioxide. Ever wonder why we don’t do this? Because it will cost more energy to do this than we will get back when burning again. If we could really do that without providing external power, it would constitute perpetual motion. These people are doing exactly this with water and hydrogen, regenerating the fuel, from by-product, which is water in this case, without any external source of energy.
Now then what about the hydrogen fuel cells? Don't they work, you may ask, on similar principles? Well they do work by using the recombination of hydrogen with oxygen to make water. However they have some external supply of hydrogen available as a fuel. That is why they are called hydrogen fuel cells. They do not generate hydrogen internally as they go using the self-generated energy.
So as long as we believe in the law of conservation of energy, and the basic chemistry of hydrogen burning, we can safely assume that this idea is completely bogus. Water can never be used as a fuel source either to run cars or generate electricity. Any such claims, no matter where they come from are wrong.
One also hears of opinions that may be the laws of thermodynamics are being violated. After all new discoveries are made in science every day. However, one has to keep in mind different realms of discoveries. Einstein’s theory of relativity did not change applicability of Newton’s mechanics for everyday speeds where it is tested and works perfectly fine for last four hundred years. Similarly, no new discovery will change the applicability of laws of thermodynamics to the chemistry of water molecules, where they are tested on a daily basis thousands of times in chemistry labs around the world.
Interestingly, this idea of using water as a fuel, though completely fraudulent at the most elementary level, is not new. Entrepreneurs in California have claimed in the past to have used water as a fuel for cars and taken some scientifically challenged investors, who did not have the good sense to trust a real engineer, to cleaners. Of course, the idea was shown to be fraudulent pretty soon and the same investors then ended up suing them for the invested money.