Truckers in the U.S. and Canada are using on-the-go hydrogen generation to cut fuel costs by 10% and as a by-product, pollution is also reduced substantially, with particulate emissions (the black smoke seen from some diesel engines) by up to half.
The hydrogen is generated by a small, bolt-on system that generates hydrogen by electrolysis, which uses electricity from the truck's alternator to strip hydrogen from distilled water. The hydrogen is injected into the fuel-air mix and produces more efficient burning fuel.
At current fuel prices, the system pays for itself quickly, and the only "fuel" needed is distilled water, which is much cheaper than diesel fuel.