[beheada]

So I've recently been quite impressed with a DvD made by Roy McAlister about converting internal combustion engines to run on Hydrogen. I've got my engine converted, I've got my electrolyzer set up off a solar panel I bought at a hardware store, but the only thing holding me back is figuring a way to store the hydrogen and deliver it at the correct PSI. In the DvD, he doesn't explain this part too well, but he says the tank he's using (a small green tank) is rated to 3500 psi (which seems insane). Aside from that, the video states the psi for the engine only has to be 2-5 psi which is LESS than atmospheric pressure~?

So my questions are:

1) Do I need some type of compressor for storing this hydrogen and what is the proper PSI for storage? I understand it may be application dependent, but right now this is only running a 3.5 HP lawnmower engine hooked up to an alternator.

2) If 5 psi is less than atmospheric (14.7), could tubing be fit from the HDPE container I'm currently storing the gas in, straight to the injection port with a regulator and a needle valve?

Just some stuff that's been troubling me with this project that I can't seem to get any good answers out of my professors on. If anyone can help that'd be great. Most of the storage devices they sell online for hydrogen are hundreds and hundreds of dollars which I don't have.

Thanks

[billnotgatez]

I was going to suggest a metal hydride system, but I do not think that would be cheap.
http://en.wikipedia.org/wiki/Hydrogen_storage#Metal_hydrides
http://www.switch2hydrogen.com/h2new.htm

Not knowing about this CD I would venture a guess that it is 5 PSI not 5 PSIA.
You can get a regulator like they uses on helium tanks to control the output from a tank.
You might chat with your friends that do scuba diving.
 

[resonance]

One can make lightweight high pressure vessels with graphite thread and epoxies. It would require a machine that can wind onto an inert inner shell, like the rubber bands in a golfball due on that little inner ball. You glue the winding together with epoxy forming a multilayered laminate. This would contain extreme hydrogen pressure but could lead to potential safety problems, especially during fill cycles and accidents. 

The best way would be lsolid state to remove the need for high pressure vessels. It would be sort of a rechargeable battery that gives off hydrogen gas instead of electrons. One  swaps the module, with a fresh one, with recharging occurring safely in a factory. LiH has some potential. A better strategy would be something that requires a little electricity to work. A battery gets it going and then it runs off the alternator. This would be an added safety feature.

[Dude]

I believe that the first thing you need to do is to calculate how much H2 you are actually generating from the solar cell you have.  Most solar cells are very inefficient at water electrolysis and can't generate enough energy to even run a light vehicle let alone generate enough excess H2 to require pressurized storage.  Running a heavy internal combustion engine on hydrogen is difficult (spark timing, power transfer, etc.) as BMW has been working on this for many years.  Fuel cells are much lighter and have about the same or slightly higher efficiency and generally weigh less.  Alternatively, skipping the use of water altogether and directly using the electrical energy is how most solar powered cars run. 

What was required to convert the engine to run on hydrogen?

[beheada]

Although solar cells are VERY inefficient at converting water into hydrogen and oxygen, they happen to be FREE once installed (hence why I'm using it). The hydrogen is simply a means of saving the energy. The conversion of a 3.5 HP lawnmower engine was easy.

Simply remove the throttle body/carberator on the side of the engine and the fuel tank. Hook up a small 1/16 I.D. piece of steel tubing into the port where the carberator used to be (directly inserting hydrogen into the intake valve). The hydrogen is fed through a needle valve regulated to 5 psi max and at 2psi idle and directly into the port.

Spark plug timing is NOT required. You MAY change the spark plug timing (if you have the know-how) to ignite when the piston is at top-dead center in order to achieve greatest efficiency. But as I don't know how to do this, I've left it alone. The only way I've gotten the engine to run so far (since I haven't figured out a way to pressurize the hydrogen, nor found out what type of tank is suitable: someone told me you could use an old scuba tank up to a certain PSI...) is by hooking up a bunch of 2-liter bottles in parallel. Yet, this doesn't last very long and it doesn't use up all of the H2 in the 2-liters.

Therefore, I'm looking for a way to store the hydrogen that isn't metal hydrides since they are extremely expensive. Although pressurized would be dangerous for a car, I'm not nearly mechanical enough to convert a car. Therefore, the experiments here are done for conservation of energy around my home, such as running an emergency generator off a lawnmower engine and cooking all of our food off of hydrogen. (Besides, we rarely drive our car if the weather is nice.) Ideally, I would like to find a way to keep the generator running for a longer amount of time, because the engine's exhaust (located beneath the carberator port) actually produces potable water (which would save on the water bill).

Therefore, if anyone has any suggestions, such as scuba tanks or compressor pumps, please let me know the specifics and I'll attempt them at my earliest convenience.

Thanks

[beheada]

So I've been looking into various forms of compression and found (so far) that they only sell industrial strength hydrogen compressors for storage. The most viable (and the option which McAlister uses in his DvD) tank for storage is a carbon fiber tank which is EXTREMELY expensive, almost as expensive as a new car. The compressors I've come across are only for small hydrogen stations. But, since hydrogen is technically the lightest element, wouldn't it be viable to utilize an air compressor of some sort to pressurize hydrogen to a specific (non-dangerous) pressure?

[hmx9123]

LLNL has a hydrogen-powered internal combustion engine car with a 40-gallon tank that runs around 5000psi.

http://www.llnl.gov/str/June03/Aceves.html

Also, your 2-5psi is probably psig (pounds of pressure per square inch, gauge) which is actually atmospheric + gauge.  PSIA is pounds of pressure per square inch, absolute, and is less used.

You will need high-pressure tanks if you want to store a lot of hydrogen sans metal hydrides ($$).  The technology is out there, but it is expensive.  BMW is supposed to have a hydrogen powered car in the works, actually.

[billnotgatez]

It would be good to point out that hydrogen is odorless. When it was used in the past, they would mix in another gas that had an odor. If you have a small stationary system the powers that be would probably look the other way. If you had a large enough set up or put it in a mobile application they would want it to have the odor safety feature.

[beheada]

The extremely sad part about this experiment is that the video negates to tell you that you have to invest a massive amount of money in some sort of hydrogen storage system (typically a composite compressed gas tank) which costs a ton. They actually cost so much, the referenced sites which sell them don't list the costs. For example, check out www.dynetek.com or www.lincolncomposites.com. Although they give specifics, they fail to actually give a price without request. Sadly, my hopes and optimism have been crushed.

[constant thinker]

Just as a note, we've discussed hydrogen pretty extensively. It may be worth doing a forum search.

[mikester602]

Hi beheada i also purchased the multi-fuel car dvd and couple other things from Steve Harris knowledge publications(note he is a jerk)

Well anyway i have a few ideas that might help.  I would suggest a scuba tank and a hvac refrigerant recovery unit(aka reclaimer).  Recovery units are not terribly expensive you could find a used one on ebay for 100-200 bucks. they only go to 550 max pressure depending on the type make sure you get a little newer on most older ones only go to 350. I figured 500 something psi is not bad for personal tinkering with scuba tanks.

I was going to supplement my diesel pick up on hydrogen and oxygen(two separate tanks) but i did not know how store it while driving i think you might need an end cap but im not for sure. i couldn't use it if i wanted to unless i snuck a hose thru the end cap and put the regulator on after or modified the end cap but im sure both are illegal.
If anyone has any ideas or thoughts on that please reply

I do not know how you made your electrolyzer if it separates the two gases or not.
I know how to separate them inefficiently in a wet cell but not like the dry cell in the dvd. wet cell you have the plates far apart and have a divider partially submerged underwater to keep the two separate not efficient  but it works.
Do not compress hydrogen and oxygen together boom unstable i heard even at 100psi