If for no other reason, consider the amount of energy that would be released if a tank with enough compressed air to propel an automobile for 50 miles were released in a collision over the course of a few hundred milliseconds.
Say the energy output is equivalent to running a 50-horsepower engine for an hour. 50 HP-hours = about 35000 watt-hours, or 250 megawatt-seconds (MJ).
A stick of dynamite produces about 2 MJ. So that tank of compressed air, if it ever ruptures, will yield the equivalent explosive power of more than 100 sticks of dynamite.
Gasoline is a safe way to store this much energy because a tankful of gas can't be oxidized rapidly enough to do much damage, at least not by accident. Same is true for hydrogen. But compressed air, where the released energy is purely mechanical, is a bit more interesting.
Never mind the extremely high thermodynamic losses associated with compressing (and expanding) that much gas. They're probably on the same order as internal-combustion efficiency, or lack thereof.
Sorry, but the physics just don't work as far as I can see. It really does smell like a scam.
Gasoline is hard to oxidize fast enough, but hydrogen is not.
The LFL/UFL (Lower/Upper flammability limit percentage - the min/max amount of fuel vs air you can have and still burn) for gasoline is 1.4/7.6 - that's a pretty narrow range. But hydrogen is 4/75, so hydrogen will burn in virtually any circumstance.
Hydrogen is, however, lighter than air, so it tends to escape upward before, or while, burning, which limits damage tremendously (except in a tunnel).
Say the energy output is equivalent to running a 50-horsepower engine for an hour. 50 HP-hours = about 35000 watt-hours, or 250 megawatt-seconds (MJ).
A stick of dynamite produces about 2 MJ. So that tank of compressed air, if it ever ruptures, will yield the equivalent explosive power of more than 100 sticks of dynamite.
Gasoline is a safe way to store this much energy because a tankful of gas can't be oxidized rapidly enough to do much damage, at least not by accident. Same is true for hydrogen. But compressed air, where the released energy is purely mechanical, is a bit more interesting.
Never mind the extremely high thermodynamic losses associated with compressing (and expanding) that much gas. They're probably on the same order as internal-combustion efficiency, or lack thereof.
Sorry, but the physics just don't work as far as I can see. It really does smell like a scam.