Energy Matters Forums

[KenL]

I am toying with the idea of using excess solar power to generate and storing Hydrogen gas for cooking purposes.
My Idea is to build a gasometer storage system using an old septic tank in the ground filled with water and placing a open ended tank with the open end down and letting it sink until its full of water before sealing off the outlet pipe valve
Using electrolysis to separate the hydrogen and oxygen in water and pumping off the hydrogen into the gasometer. This will make the open ended tank start to float. The generated Oxygen will be vented to the atmosphere as a waste gas.
The amount of generated Hydrogen stored would be limited by having a hall effect limit switch activated by the height of the open ended tank floating out of the water to shut off the power to the electrolysis unit and the gas pump using solid state relays so no sparks to ignite the hydrogen.
I am anticipating that the pressure of the gas would only be 2 or 3 Psi and this is adequate to feed a modified gas burner with a catalytic ignition system.
Problems I foresee might be the need to deoxygenate the water for the gasometer and seal the surface with an oil base product to prevent any ingress of oxygen into the floatation water thus transferring it into the hydrogen storage space

Comments and ideas for and against would be all welcome

Regards
Ken L

[davidg]

Using electrolysis to separate the hydrogen and oxygen in water and pumping off the hydrogen into the gasometer. This will make the open ended tank start to float. The generated Oxygen will be vented to the atmosphere as a waste gas.

Does it actually have to pumped off? the fact the tank is sealed by water like an upside down heavy bucket, maybe you could simply take it striaght off the top of the tank so to speak.

You could use biogas as well if you tap into, "crap", then using both, one to run the hot water and the other the stove or soomething along those lines

[Smurf1976]

The gasometer you've described is just that, a scaled down version of an actual gasometer. So it's a very well tested concept that's been around since at least the mid-1800's if not earlier.

The only real concern I'd have is with the hydrogen itself. It's a very "leaky" gas by its' nature and hard to contain. It's not like natural gas (methane), LPG (propane / butane) or even the old town gas (a mixture of mostly carbon monoxide, methane and a bit of hydrogen). Pure hydrogen is far harder to contain, it has a real tendency to simply leak through solid steel etc so that's a problem.

You'd also want to be very confident that there is no chance of ending up with a combustible mixture inside the gasometer. Gasometers at the old gas works didn't blow up, since in normal circumstances they didn't have enough oxygen inside to form a combustible mixture. Suffice to say that you need to be careful to avoid this circumstance, otherwise you've just built yourself a nice little bomb just waiting for static electricity or something else to set it off.

I'm not saying it's a dud idea, just thought I should point out some potential safety concerns that you need to address.

[KenL]

Does it actually have to pumped off? the fact the tank is sealed by water like an upside down heavy bucket, maybe you could simply take it straight off the top of the tank so to speak.

The need for a gas pump is that the pressure of the gas inside the gasometer would be higher than the pressure in the catchment tank of the electrolysis unit and without the pump with its non return valve system the pressure flowing back from the gasometer would displace the water around the electrode generating the hydrogen. The pump would be switched on as needed by a floating magnet inside the catchment tank by a hall effect module on the outside and thereby controlling the level of water around the electrode.

You'd also want to be very confident that there is no chance of ending up with a combustible mixture inside the gasometer. Gasometers at the old gas works didn't blow up, since in normal circumstances they didn't have enough oxygen inside to form a combustible mixture. Suffice to say that you need to be careful to avoid this circumstance, otherwise you've just built yourself a nice little bomb just waiting for static electricity or something else to set it off.

I'm not saying it's a dud idea, just thought I should point out some potential safety concerns that you need to address.

I am aware that unlike other flammable gas/oxygen mixtures, Hydrogen/Oxygen mixtures can explode and has a very low critical ratio with no upper limit to this ratio where as for example petrol/air mixture has to be at a critical ratio to burn to much of either inhibits ignition. This is why the mixture of petrol and air is important for the efficient running of as car engine.
The use of a pump and gasometer means that the gasometer can be remote from critical structures with the gas inlet to the gasometer would be below the water seal level.
The permeability loss of hydrogen in the gasometer has to be accounted for and should not be significant.
I thank you all for your input as it adds to the list of possible problems to be considered

[Gordon-Loomberah]

What do you plan to use as electrodes for your electrolysis?
A while ago I was thinking about using excess PV energy to produce Oxygen for my aquaponics system, and off-gassing the H2, but never did find suitable electrodes, and shelved the idea. Platinum or Palladium would be ideal, but are hideously expensive, and metal like stainless steel gradually dissolves, not something I want happening in my AP water. I did email a place that sells electrodes for electro-plating, but never had a response.
I'm not interested in the H2 ATM, I'd rather do my cooking with PV powered induction, microwave, oven etc, than have to worry about the safety and containment issues with Hydrogen. Electrolysis isn't very efficient, so producing H2 to burn isn't really an efficient use of PV power, although that doesn't really matter if you have an excess that can't be used in other ways. However, if affordable fuel cells ever become available, then I'd be seriously investigating H2 storage, as another form of storage in parallel with the LiFePO4 battery and pumped stored hydro.

[Tracker]

...... and metal like stainless steel gradually dissolves, not something I want happening in my AP water. ......... if affordable fuel cells ever become available, then I'd be seriously investigating H2 storage, as another form of storage in parallel with the LiFePO4 battery and pumped stored hydro.

Can't you do it separately and bubble the gas/gasses into the pond..??? Would it matter if you did both as so much will bubble out anyway.. would hydrogen disolve and cause a problem..?
Hydrogen not a safety issue out in the open..

I do see devices said to be used in cars.. modular devices for boosting the engine power (on eBay)

I once had a serious bucket of hundreds of Cichlids to take to the pet shop.. too lazy to make many trips..
Used an O2 bottle and an airstone, thinking the O2 would be better.. the fish freaked out, seriously..
I had to change back to the air pump...
..
.

[Gordon-Loomberah]

H2 has minimal solubility in water compared with O2, but there is twice as much of it, and I wouldn't really want to turn it into a spa bath, or have the fish speaking at really high pitch if they breathed some in

The ebay devices sound like a scam. The energy required to do the electrolysis is likely more than the gain in engine power.

Used an O2 bottle and an airstone, thinking the O2 would be better.. the fish freaked out, seriously..

Too much O2 for the number of fish/volume of water? O2 is bad news for humans too, if they get too much of it for any length of time.

[Windy]

There was a good artical on just this thing a few years ago in I think Mother earth magazine. I have still it. The person used electrolysis and stored it in a gas state and then used a fuel cell to convert to electricity. I think in a gas state the leakage is small. It was using a fiberglass tank. Storing oxygen would probaly be more dangerous. Alas I am at work for another week. I will see if I can find the artical for you. I wonder what the legalities are in Australia.