As the price of fuel increases, more and more people are draw to consider novel sources of energy for homes, workplaces and even cars. A common fringe theory is the idea that water can somehow be used as a source of fuel. Some suggest that gasoline-powered generators, cars and other vehicles could be powered solely by water. There are even kits and adaptors on sale that purport to convert gasoline engines to run on water.
Could we all run our cars on water? It's an exciting thought. No more dependence on gasoline, no more queuing at the gas station, no more air pollution: just safe, clean energy. Unfortunately, the reality is a little different — at least for now.
In the most abstract theoretical sense, it is indeed possible to convert water into usable fuel. That much is true. Water, as any high-school chemistry student can tell you, consists of hydrogen and oxygen: H2O. Using a process called electrolysis, it's possible to break the chemical bonds between the hydrogen and oxygen molecules. The hydrogen gas can then be burned, driving an engine; the sole byproduct of this process is pure water. It's also possible to modify a gasoline engine to run on this fuel: either hydrogen alone or "water gas," consisting of a mixture of hydrogen and oxygen.
The issue isn't really one of possibility, however — it's one of efficiency. At present, it's simply not terribly efficient to split water up into hydrogen and oxygen. The amount of electricity required to break the bonds between the hydrogen and oxygen molecules and convert water into fuel is prodigious, far outweighing the energy that could possibly be produced by burning the resulting hydrogen.
This fact does not prevent certain unscrupulous merchants from selling kits online that are advertised as converting your car or other vehicle to run on water. Some of them work, up to a point; you will have to expend large amounts of electricity to make them function, meaning that you don't save any energy. Others simply do nothing, consisting of a few yards of tubing and other cheap materials that can't really convert water into hydrogen or anything else.
In order to support sales of their products, the manufacturers play up suggestions that there is some kind of conspiracy bent on suppressing water-fuel technology. This conspiracy, they argue, wants to maintain the grip of conventional fuels and prevent people from adopting new and alternative technologies. Those who attempt to prevent the sale of fraudulent car conversion kits are branded as "pseudoskeptics" and deemed to be in league with the supposed conspiracy. According to those with a vested interest in selling conversion kits, we could all be riding around in water-fueled cars right now — we're just being prevented from doing so by the evil forces of Big Oil.
Perhaps one day, technology will move on sufficiently to make hydrogen-fueled cars the smart, efficient choice that their proponents claim. It really will be possible to run your generator on hydrogen or drive to work on a gallon of tap-water. For now, though, water-fueled engines are the stuff of science fiction, not of fact.