Hydrogen Production for running gas engines / Chemistry / Forums

Forums

4hv.org :: Forums :: Chemistry

« Previous topic | Next topic »

Hydrogen Production for running gas engines

1 2 3 4 next

Move Thread

LAN_403

Vaxian

Wed Apr 11 2007, 11:03AM

Registered Member #635 Joined: Tue Apr 10 2007, 01:56AM
Location:
Posts: 85

I have been gearing up for another go at an electrolosys.

The problem I had before is the electrodes made a muck of corrosion after a short period. I have found a way around this by using Stainless electrodes.

Also the reaction is very slow.

I understand that adding Potassium Hydroxide to the water will speed up the reaction. The problem is where do you get Potash? And how much do you add?

Any experienced persons willing to throw me some tips would be appreciated.

Also tried the Lye /Aluminum reaction with limited results.

Chris

Wed Apr 11 2007, 01:24PM

Registered Member #8 Joined: Thu Feb 02 2006, 04:34AM
Location: Harlowton, MT, United States
Posts: 214

Electrolysis is a very inefficient and slow means of generating hydrogen, but really any known means of hydrogen production are. How big of an engine is this? Remember that 1hp = 746W, so with piston engines being on the order of 20% efficient and electrolysis itself being inefficient you need upwards of half a megawatt of electricity to keep up with a car engine of appreciable power. You can figure the electrolysis/run time ratio is then very low with only 10kW or whatever you have available. Hydrogen is the least compact of all proposed fuels to store as well; you won't be able to run an engine for very long even off a high pressure cylinder or liquid hydrogen dewar. The best means of storage are metal hydrides, especially sodium or lithium borohydride.

The problem I had before is the electrodes made a muck of corrosion after a short period. I have found a way around this by using Stainless electrodes.

Use graphite electrodes for a variety of electrolytes (I have found sulfuric acid errodes them though).

I understand that adding Potassium Hydroxide to the water will speed up the reaction. The problem is where do you get Potash?

Potassium hydroxide is not potash. Potash is potassium carbonate and/or chloride. You can buy sodium or potassium hydroxide or make them with an amalgam cell or membrane cell. Just add enough until you get the desired current.

In any case for serious hydrogen production (though still puny compared to possible demand) you probably need to use steam cracking of natural gas.

Vaxian

Wed Apr 11 2007, 02:37PM

Registered Member #635 Joined: Tue Apr 10 2007, 01:56AM
Location:
Posts: 85

This is a horizontal shaft 5 HP briggs & stratton. I have run it on a variety of fuels. Natural Gas, Propane, Hydrogen

You have struck upon the dilemna of why Hydrogen isn't fueling more cars.
The American Hydrogen Society in Pheonix has a car and a truck.
Vancouver, BC and Chicago had 2 busses each which ran on hydrogen fuel cells, not sure if they are still in service.

You can buy kits to convert a car, the problem still remains.
The only viable method seems to be solar Hydrogen but still SLOW.

Thanks

uzzors2k

Wed Apr 11 2007, 03:10PM

Registered Member #95 Joined: Thu Feb 09 2006, 04:57PM
Location: Norway
Posts: 1308

Solar powered hydrogen electrolysis would take years to fill a tank with current technology. Sodium/potassium hydroxide is found in common lye and drain cleaner, just look for it on the label. (NaOH or KOH) Unlike salt, NaOH will be recreated when split. Na + H2O = NaOH + H, meaning you can fill it once with NaOH and then just keep adding water. (Theoretically) Run your cell at lower voltages, but at high currents. To achieve this use a good amount of electrolyte to allow for the current flow, and place the cells close to each other. Given the right conditions and enough power electrolysis doesn't need to be slow.

hydropowercar.com

Pete

Wed Apr 11 2007, 04:48PM

Registered Member #106 Joined: Thu Feb 09 2006, 09:39PM
Location: Portland, OR and Istanbul, Turkey
Posts: 47

If you have a bit of funds, as in around 20 to 30 dollars, I may suggest Muriatic acid and Zinc flashing.

Muriatic acid is a low grade hydrochloric acid that you can buy by the gallon from a few hardware stores around town. Now it's been a while since I've bought any, around 8 years, so maybe there might be problems today.

When you drop the zinc flashing, and I mean not much, into the muriatic acid it will react fast. I can fill a 3 foot party balloon on about 20 to 30 seconds. The problem is that you do get water vapor and that water vapor carries a small amount of acid with it. So please be careful.

But so far this has been my most favorite and memorable method for getting loads of hydrogen gas.

Pete

Conundrum

Wed Apr 11 2007, 06:33PM

Registered Member #96 Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4059

Also, potassium chlorise is 33% or so of Losalt (tm) so this should help.

-A

Eric

Wed Apr 11 2007, 06:59PM

Registered Member #69 Joined: Thu Feb 09 2006, 07:42AM
Location:
Posts: 116

I have found that aluminum foil and drain cleaner (lye) works great/fast although once the reaction gets going it runs very hot and some steam is generated. If you can get the zinc, Pete's idea is good. IIRC 2 gallons is only $4.70 at Home Depot here in so cal. It's a bit contaminated but gets the job done at ~29% concentration. Whatever method you use it would be best to dry it before use.

stop4stuff

Wed Apr 11 2007, 09:33PM

Registered Member #64 Joined: Thu Feb 09 2006, 06:25AM
Location: Southampton, UK
Posts: 68

Go careful if you try the alu/lye route things can get damn hot... & if you do, be sure to capture the electrons given off (alu air cell)

From what i found out in the past, 316 stainless is the stuff to go for if you're using sodium hydroxide (lye or caustic soda)

Something that may be of interest re electrolysers

Vaxian

Wed Apr 11 2007, 10:45PM

Registered Member #635 Joined: Tue Apr 10 2007, 01:56AM
Location:
Posts: 85

Thanks for all the tips.

I have done the Lye / Aluminum reaction before. Filled a couple balloons, kids had fun, big kids had fun blowing them up - BOOM!

I figure a large pressure cooker would make a great vessel but 99% of them are Aluminum!!! Have been looking for a large Stainless Pr. cooker for a long time.

Chris

Thu Apr 12 2007, 12:06AM

Registered Member #8 Joined: Thu Feb 02 2006, 04:34AM
Location: Harlowton, MT, United States
Posts: 214

If you have a bit of funds, as in around 20 to 30 dollars, I may suggest Muriatic acid and Zinc flashing.

That, or any other metal/acid or metal/base production is tens to hundreds of times more expensive than electrolysis of water, which is several times again more expensive than steam reforming, if you use store-bought ingredients. If you're making your own chemicals from salt or something just for that, it would just be way more complicated with more losses and more time. In short, chemicals like HCl or NaOH, as well as zinc or aluminum, are far too valuable to be used for the mundane role of hydrogen production. Since recycling those reagents will involve difficult fused salt electrolysis (to regenerate the reactive metals) and either hydrogen itself (for direct HCl production in an HCl furnace, again relatively difficult) or membrane cell electrolysis with fractional crystallization (for NaOH), clearly it is only practical to just use a simple aqueous electrolysis to make the hydrogen in the first place.

As another possibility for the ambitious, I suspect if you used the core from a catalytic converter (the ceramic honeycomb stuff with platinum in it) at around 850C, and fed with steam from a high pressure boiler (150psi, not very hard at all to achieve), someone with fairly basic tools could perform steam reforming of natural gas for hydrogen. A similar reaction could be carried out with air such as from an ordinary compressor under the same conditions, but with a lower hydrogen to CO production ratio.

The byproduct gases carbon monoxide and carbon dioxide must be removed of course. It might be possible to use a thin sheet of somewhat permeable material as a membrane to separate the hydrogen, then simply burn the carbon monoxide as it comes out yielding only relatively inert CO2. A hydrogenation reaction yielding either methanol or acetic acid with excess H2 could also be used as a means to eliminate carbon monoxide, and if you wanted to be inkeeping with the idea of hydrogen as a clean fuel with no greenhouse emissions this would probably be the only reasonable method.

1 2 3 4 next

Moderator(s): Chris Russell, Noelle, Alex, Tesladownunder, Dave Marshall, Dave Billington, Bjørn, Steve Conner, Wolfram, Kizmo, Mads Barnkob