another good question, (I'm not trying to be difficult or a smart a**, really interested) what's the efficiency of the system? I mean, hydrogen is the best I've heard of so far, it works in current type engines, and the exhaust gas is steam. The problem is that it takes more energy to produce the electicity to electrolize the water into hydrogen and oxygen, than is saved by not using gasoline, and you have to consider the pollutants caused by the elecrical generation process. Wind is not abundant enough, and there will always be calm days, the sun doesn't always shine, and now we are talking coal, gas, or nuclear power. Compressed air is intrigueing, but I wonder about the actual economy, and efficiency of it. I hope they have actually found something workable.