Weird Water Chemistry

Recently, Honda announced the Clarity, a fuel cell based vehicle that is advertised as a clean car which only emits H₂O. The fuel, of course, is hydrogen. Now the concept is not new and fuel cell cars have been around for a while, but Honda’s decision to make 200 of them and releasing them to the public is a first step into understanding how well they might work in the real world. There are plenty of obstacles to overcome and so it should be an interesting trial. Of course, there’s a reason (actually quite a lot of them) why hydrogen fuel cell cars haven’t taken off yet, and it has nothing to do with conspiracy theories between the auto and oil companies.

1. Very few hydrogen filling stations
2. No large sources of hydrogen until you reach Jupiter. You either make it from hydrocarbon fuels like natural gas (which negates the zero CO₂ emissions claim) or by electrolysis. And if the electricity isn’t coming from a renewable source, then what exactly are you gaining? (OK, you should still be producing less NOx, CO, and hydrocarbon emissions. That’s a good thing)
3. No one likes the idea of driving around with a 5000 psi hydrogen tank sitting next to them. That is why so many researchers are feverishly looking for materials that can store hydrogen safely at low pressures with good volumetric efficiencies.
4. Price?

However this post is not about cars that produce H₂O emissions, it is about cars that claim to use H₂O as the fuel. The most recent announcement has come from Genepax, which claims to have just such a car. According to Genepax, their car converts water into hydrogen which is then utilized by a fuel cell (along with air) to produce water and electricity. Now think about this. They are taking water, mixing in a little air, and using that to produce water and energy. I would hope that this would set off BS detectors for anyone who is at all familiar with science. Are they converting matter into energy, or what? What is their secret? They pass the water through a special top secret membrane that converts the water into hydrogen. (The reports actually say hydrogen and oxygen, but I doubt they mean oxygen gas as it would just recombine with the hydrogen at the fuel cell electrode with no production of electricity.) Not surprisingly, Genepax is tight-lipped about this membrane, but indications are that it is similar to a metal hydride. Adding water to a metal hydride produces H₂ and a metal oxide. Of course, this means the hydride is the fuel, not the water. Genepax does grudgingly admit that the membrane will have to be periodically replaced (although they do not mention how often that will be needed). Basically it would be like an automaker saying “We have built a car that runs on air only. All you need is a tank full of a liquid hydrocarbon catalyst to make it work.”

The idea of running a car on water instead of a hydrocarbon fuel has been around for a long time, despite the obvious problem with the laws of thermodynamics. But as the price of gasoline has continued to rise, these reports of water-based fuels have dramatically increased. Try googling the term “HHO,” which is the term generally used by the “water-as-fuel” supporters to represent the “improved” form of water. There are several variations on this concept. In one version, HHO is actually supposed to be a high energy form of water, apparently containing H-H bonds. I’m sure the spectroscopists would be very excited to work with this molecule. In the most common variation, however, HHO is a fancy way of saying “a 2:1 molar ratio of H₂ and O₂ gases,” basically the standard product of electrolysis, otherwise known as Brown’s gas. In this incarnation, water is electrolyzed into H₂ and O₂ and this mixture is added to the gasoline/air mix in the engine. The extra energy from H₂ combustion results in better fuel economy. Of course, you have to provide at least as much energy to split the water as you get back, but that doesn’t seem to bother the “scientists” working on these projects. As is typical in these situations, there is just enough truth in there to keep these ideas from dying. Automakers have long known that adding H₂ to an engine allows you to run the engine leaner, which can help gas mileage somewhat in certain circumstances (although your emissions may no longer meet EPA requirements). The best way of producing H2 is not by an electrolysis device in your car, but by reforming a small amount of gasoline to make H₂ and CO. We'll see if the auto companies can get this concept to work.