Hydrogen engines

Hi just recently I was thinking about hydrogen powered engines in cars. I was having a discussion with my friend about it. He seems to believe that if, you get in a crash with a hydrogen powered car. It would be like setting off a mini hydrogen bomb. Frankly, I just think thats crazy :screwy: but i wanted to find out from other people if this is true or not. .

Hi just recently I was thinking about hydrogen powered engines in cars. I was having a discussion with my friend about it. He seems to believe that if, you get in a crash with a hydrogen powered car. It would be like setting off a mini hydrogen bomb. Frankly, I just think thats crazy :screwy: but i wanted to find out from other people if this is true or not. .

Its "Crazy":

When hydrogen burns it is a chemical reaction between hydrogen and oxygen resulting in water and heat. If the reaction is large and fast enough an large explosion could occur. This is a legitimate risk of hydrogen power vehicles.

A hydrogen bomb is a nuclear reaction in which a hydrogen atom (I think even the hydrogen molecule is different from above: see heavy hydrogen) is split in to two parts. In a nuclear reaction a tremendous amount of energy is given off, compared to a chemical reaction. Nuclear reaction are not simple to create/control and will not occur during a car accident.

It is crazy. Hydrogen can explode (Hindenberg). But a Hydrogen bomb is another animal. The H-bomb derives it energy by combining hydrogen atoms into new elements-like helium. This process is very difficult to achive. The velocities involved in a car crash are WAY to low. So, don't worry it won't be much worse the gasoline.

In the case of the Hindenburg you can't really blame the hydrogen, the real problem was the impregnation of the fabric. The impregnation can basicly be descibed as "rocket fuel", this also explains why the flames was visible when the Hindenburg burned (hydrogen burns with invisible flames similar to methanol).

Being in a crash with hydrogen will probably be no more dangerous than being in one with gasoline, tests have infact shown that hydrogen is safer.
Almost 50 years ago Lockheed tested what was needed to make hydrogen detonate, except with liquid oxygen and explosives the hydrogen didn't go off. So unless you are planning to have a bomb or liquid oxygen in your car you will be safe.

Also, since hydrogen is very light, fuel from a leak will disappear very quickly. Hydrogen also emits very little heat when burning so even if the fuel tank in a car is on fire, the car will probably be ok after the hydrogen has burned up.

There are of course disadvantages with hydrogen, since it's very light large tanks must for example be used. Hydrogen is also usually made by cracking it off from hydrocarbons based on crude oil so currently it isn't better for the environment than gasoline. Also, since the fuel is in gas form under normal temperatures and pressures it's difficult to handle.

Hydrogen, eh? Why not just get out the oxygen/acetylene tanks and combine those? Of course you'd have to be nuts to drive with an acetylene tank in your car.

holy crap i couldn't imagine what kind of HP you would get form oxyacetylene fuel... thats if the engine could handle it.

The valves would probably burn up, or else solid ones would be needed, and then there' d have to be a lead additive for them. The pistons would have to be made out of something very heat resistant, not to mention stupid strong because the explosion of those two gases would be nothing short of hard on an engine. forget aluminum heads, they'd probably burn up. And you'd really have to retard the timing a lot. Now I'm getting an idea. Time to put an old sitting junker to the test and blow it up.

thatll be kool! Dont be too close to it just incase tho.

Nah... fuels like hydrogen and acetylene are just beyond the scope of current metallurgy technology. Way too hot and way too violent to be contained by iron, steel, and aluminum.

Hydrogen can be used in a modified otto-engine, BMW have for example built several of that type of engine. The output of the hydrogen engine is a little lower compared to its gasoline counterpart.

Hydrogen does also burn with a temperature similar to gasoline, but its laminar flame speed is much higher. Acetylene does burn a little hotter, but just similar to nitromethane at 2400 degC. The flame speed of acetylene is however lower compared to hydrogen.

That pure oxygen increase flame speed and temperature is nothing new, it does apply to gasolien aswell.

Using pure oxygen and a fuel ther will however not much of a point using the otto engine, since a turbine with a rocket style gasgenerator will do the trick.

The main drawback with hydrogen today is the production as it's mostly made by cracking it off hydrocarbon chains. Making enough hydrogen to replace gasoline using for example solarpower isn't something that is easy done.