A Winnipeg inventor has developed the H2N-Gen, a hydrogen generator about the size of a DVD player that could someday sit under the hood of our cars. Through the wonders of hydrolysis, it makes hydrogen from water (requiring a distilled water refill every 80 hours or so of operation), which is then injected into the engine along with the vehicle's primary fuel. Among the claimed benefits are cleaner emissions and better fuel economy.

As far as the latter is concerned, it?s interesting to note that the first application listed is for trucks, buses, and trains - vehicles with diesel engines, of course. Compression ignition engines respond well to the pre-injection of gaseous fuels; propane being the traditional one, due to availability and performance. I would think that hydrogen might work just as well for diesels, depending on its autoignition point and rate of burn. For those with closed-loop mixture control (i.e. every gasoline-powered vehicle sold in the last 18 years), injecting hydrogen will tend to enrich the mixture not just by adding additional fuel by also by displacing some of the intake air. If the EFI system does its job, it will pull fuel out to restore the proper air/fuel ratio, which should mean that less gasoline is burned. 
But the electricity for the hydrolysis process has to come from somewhere, and if it?s from the vehicle?s relatively inefficient alternator, it will be extremely difficult to come out ahead in the mileage game. Also keep in mind the limited quantities of power available from the alternator, as some vehicles are going towards twin alternators or liquid cooling just to keep up with existing loads. It would seem like pre-generation of the hydrogen using electricity from the grid would be a better alternative, depending on energy prices in the user?s area.

The emissions angle is even more difficult to unravel. The article notes that they saw zero carbon monoxide emissions from their Grand Cherokee test vehicle, but that?s exactly what I?d expect from a new car. Unfortunately, no mention was made of measurement for oxides of nitrogen, because I believe that?s where hydrogen injection may actually cause an increase in emissions. NOx is probably the most troublesome of the three major pollutants, because it shows up during high combustion temperatures and pressures - the sort of conditions favored for increased economy. Hydrogen tends to burn very hot, and therefore NOx emissions have been said to be a problem when using the gas as a primary fuel. But as a co-injected fuel, it?s extremely difficult to say what effect it may have, and may very well vary from vehicle to vehicle and depending on the amount used. Where it might prove very beneficial is during cold start conditions, since hydrogen will have no vaporization problems even under the coldest conditions (what the water supply inside the module does is another matter entirely).


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