Water as Fuel?

Hydrogen generators may be fact, fiction or a little of both.

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My commute home in the evening can take up to two hours, depending on traffic. To avoid frustration, I have a favorite afternoon radio show that always keeps me smiling. On the way home the other day, the DJs were encouraging listeners to come up with something spectacular in order to earn tickets to a very hot concert that was coming to town. A young lady called in and this is what she offered.

"My husband says he'll install hydrogen generators on all your cars for free in return for the tickets."

The female DJ on the show responded, "Is that the thing that jacks up your car? That would be cool!" Amidst the laughter from the other two male DJs, the caller said, "No...it is a device that turns water into gas for your car, and will add six to seven miles per gallon." The DJs respectfully declined, saying that they could not benefit directly from giving away the tickets.

And that was it. No mention of whether there was any truth to the claim. I wondered how many listeners were intrigued by what the young lady had said, and how many shops were called the following day and asked about this miracle device? So I thought I'd do a little digging and share what I found.

Hydrogen as a Fuel

Hydrogen is the most abundant element in the universe. It has the second widest range of flammability of any gas, able to combust in air in concentrations as little as 4 percent and as great as 75 percent. Compare that to gasoline, which is only combustible in air in a much narrower range — from 1.4 percent to 7.6 percent. Hydrogen also is easily ignited, even by a small static electricity spark. It is a low-density gas, lighter than air, and contains three times the energy of gasoline by mass.

These factors make hydrogen attractive as a fuel substitute or supplement. Alone, it can be run at extremely lean ratios. As a supplement, it promotes better ignitability, a higher flame speed and reduces knock, which, in turn, allows for a leaner gas mixture to be used with higher compression ratios.

The drawback is that there is no such thing as "free" hydrogen. All naturally occurring hydrogen molecules are attached to another element. Gas and diesel fuel, for example, contain two hydrogen molecules for every carbon molecule. Water, of course, is two parts hydrogen and one part oxygen. In order to get the hydrogen, we have to separate these chemical bonds. Two methods are used to do so: reformation and electrolysis.

There are three ways hydrogen currently is being used as an automotive fuel source. Hydrogen fuel cells are arguably the most known because they produce zero emissions, with their only exhaust byproduct being water. These fuel cells combine hydrogen and oxygen in an electrochemical process, resulting in the production of electricity. This electricity is then used to power an electric motor, which in turn drives the car down the road. There are several technologies, with the Proton Exchange Membrane (PEM) being one of the more common. An individual PEM cell produces about 1.2 volts, but is most efficient when voltage levels are closer to 0.5 to 0.6 volts. The cells are wired in series to form stacks that can provide the total electrical power needed to power the car.

Another method is to use hydrogen as a replacement for gas or diesel in a conventional internal combustion engine. Ford has built such prototypes, as have a few other manufacturers. But because of the low density of hydrogen, more volume is needed to produce the same power from a given displacement versus gasoline. Supercharging is one solution to packing in that volume. Other factors also have to be considered and designed for. The low ignition requirements of hydrogen require precautions against pre-ignition, and combustion chamber designs differ from those using gasoline as the primary fuel. The hydrogen fuel source is stored on board, in either a liquid form or as a high-pressure gas.

Hydrogen also can be used to supplement gas or diesel fuel. On these systems, hydrogen is not stored, but produced on the vehicle using electrolysis to separate water molecules into their base elements: hydrogen and oxygen. In use on many commercial diesels, fuel economy has been improved up to 10 percent and tailpipe emissions have been reduced. These systems produce only very small quantities of hydrogen, usually on demand as the engine requirements warrant. It is this concept that is often advertised as "running your car on water," with the promise of fuel economy increases of 50 percent or more.

Very Little Hydrogen

Hydrogen generators offered for use on automotive gasoline engines vary in appearance and details of operation, but the basic concept is the same. Water and an electrolyte additive (typically baking soda) are poured into the "generator." This generator is really an electrolyzer and may contain more than one cell. Each cell has an anode and a cathode, and gets its power from the car's electrical system. With current flowing, water molecules are separated into hydrogen at the cathode and oxygen at the anode. This gas is then routed to the engine, usually downstream of any MAF (Mass Airflow Sensor) in the intake boot. (That's a good thing, since any hydrogen introduced in front of a hot wire MAF could easily result in a fire hazard.)

The idea is that the additional fuel source will minimize the gas used by the engine. While it is true that hydrogen is proven to be an effective supplement to conventional fuels, the factors that make it so must be taken into account, and the engine parameters modified to take advantage of these benefits. Simply adding the gas typically results in no difference in fuel economy.

These generators, even more so than their diesel cousins, produce very little hydrogen. Even assuming a 100 percent efficiency of the electrolysis process itself, these generators typically produce less than 0.002 liter of hydrogen per second — a small fraction of the total airflow of even a small 4 cylinder at a steady state cruise. The electrolysis process itself consumes a lot of energy. More energy is used by the alternator to produce the electricity needed for the process than is contributed to the engine by the hydrogen thus produced.

Adding hydrogen and oxygen downstream of the MAF should pose no problem to MAF readings, nor should it affect the operation of the oxygen sensor, because the hydrogen/oxygen gas is stoichiometric. Because both of these sensors provide the information needed by the ECM for fuel control, no shift in ECM strategy should be seen. Think about that one for a moment. The impact on fuel usage would be what?

Most of the posts I read associated with installing these generators also referenced some type of electrical device wired into the oxygen sensor circuits. Some even advocated removing the sensors from the exhaust entirely. Apparently, these techniques are aimed at "fooling" the ECM into thinking the mixture it is feeding the engine is too rich, in an attempt to force the ECM to make lean corrections to its fuel trims and cause the engine to run leaner. This will, indeed, increase fuel mileage at the expense of emissions.

There have also been reports of engine component damage as a result of hydrogen embrittlement, a chemical reaction in many materials caused by constant exposure to hydrogen that results in the material weakening, even cracking. And while the sellers of these devices claim they do not violate federal law concerning the modification or tampering of emissions components, nor impact factory warranties, remember it is still on you if you decide to install such a unit on your customer's car.

Pete Meier is an ASE CMAT, member of iATN, and full-time tech in Tampa, Fla. His experience reaches back more than 30 years, and his contributions to Motor Age reflect a wide variety of experience with almost every make and model. You can contact Meier directly at www.autoservicetech.com.