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#68682 - 08/12/06 08:41 PM Hydrogen by electrolysis  
PEdoubleNIZZLE  Offline
Joined: Jun 2004
Posts: 176
McKeesport, PA, USA
I have a question about the whole hydrogen hype. I know that you can electrolyze water into Hydrogen (and oxygen). My question is how do they "bottle" the gas? They always seem to leave that part out when explaining it.

I was thinking last night that hydrogen power could be a scary thing economically. The electric company could also be the gas company (selling hydrogen as an alternative to propane or city gas), and possibly water (the by-product). Any thoughts on this? Impossible? Unreasonable? Prepare to play monopoly?

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#68683 - 08/12/06 11:22 PM Re: Hydrogen by electrolysis  
gfretwell  Offline

Joined: Jul 2004
Posts: 9,069
It takes more energy to get the hydrogen out by electrolysis than you get when you burn it back to water. If the energy was "free" (solar or something) you might be able to make a case, but why not just use the electricity to charge a battery?
Most commercial hydrogen comes from natural gas although it is a byproduct of some chemical operations. It is captured, purified and compressed.
You also have the storage and distribution problems but that is just a market issue.
Until we solve the supply problem, hydrogen is a fantasy.

Greg Fretwell

#68684 - 08/12/06 11:37 PM Re: Hydrogen by electrolysis  
NJwirenut  Offline
Joined: Sep 2001
Posts: 806
Bergen County, NJ
As far as how to capture the gases, it's just a matter of proper design of the equipment. Here is a typical laboratory device used for demonstrations:
[Linked Image]

The gas bubbles rise from the electrodes, and collect in the vertical glass tubes, where the gases can be drawn off via stopcocks. The basic design could easily be scaled up to whatever size you want.

[This message has been edited by NJwirenut (edited 08-12-2006).]

[This message has been edited by NJwirenut (edited 08-12-2006).]

#68685 - 08/13/06 12:32 AM Re: Hydrogen by electrolysis  
JoeTestingEngr  Offline
Joined: Nov 2005
Posts: 782
Chicago, Il.
We ran a number of hydrogen fuel cell busses on a single route a few years ago. The fueling point was located well away from the rest of the maintenance facility. (unlike the diesel fueling) I feel more comfortable around nuclear fuel sources than hydrogen. Maybe I'm just amplifying those little pop sounds we all heard when they put the burning splint in the H tube, in my head, scaled up to fit a bus.

#68686 - 08/13/06 01:07 AM Re: Hydrogen by electrolysis  
gfretwell  Offline

Joined: Jul 2004
Posts: 9,069
Hydrogen is not particularly dangerous and certainly not as bad as gasoline fumes or natural gas. It's pretty hard to make it hang around long enough to accumulate since it is so much lighter than air. A small vent in the roof would let it go away immediatly.

Once we get over our nuclear phobia it could become a viable fuel but you need energy to spare to make any quantity of hydrogen at a reasonable price. In a nuke plant they might even come up with a thermal cell, sort of a fuel cell running backward that outputs hydrogen.
Then we would be down to designing the transportation and distribution chain. The other big problem with hydrogen is the molecule size. A submicroscopic pore that would hold back a methane molecule is an open door to hydrogen. That is why your helium balloon seldom lasts the night (pores in a latex balloon) and helium is twice the size of hydrogen.

Greg Fretwell

#68687 - 08/13/06 03:06 AM Re: Hydrogen by electrolysis  
PEdoubleNIZZLE  Offline
Joined: Jun 2004
Posts: 176
McKeesport, PA, USA
I never really understood all the hydrogen hype. To me, the fuel cell and the fuel tank seem to be just another type of battery. I'm thinking why not just use a bunch of batteries?

Turning it into hydrogen sounds good to me if you're gonna burn it (e.g. water heater, etc.), as there would be no worry or CO poisoning and no CO2 for global warming (even though HOH is also a greenhouse gas). As far as storage for electricity, I don't see any advantage for hydrogen over a storage battery, other than maybe maintenance.
Batteries leak a charge, but the large liquid gas tanks probably leak slightly too.

Then again, I did fail high school chemistry (but I did excellent in Physics I & II), and I haven't taken it in college yet.

NJ & gfret - so, if they make H by electrolysis, do they use the setup NJ shows and hook it to some type of compressor?

the chemistry ignorant,

#68688 - 08/13/06 07:21 AM Re: Hydrogen by electrolysis  
Alan Belson  Offline
Joined: Mar 2005
Posts: 1,803
Mayenne N. France
I hate to be pessimistic, but all these ideas like 'H' powered cars, wind farms, solar power, bio-fuels, tidal barrages, nuclear power and the like are dead ends.
If we don't stop our profligate use of energy, our civilisation, like all those before it, is finished. Period.

I give it another 100 years, maximum.


Wood work but can't!

#68689 - 08/13/06 01:25 PM Re: Hydrogen by electrolysis  
gfretwell  Offline

Joined: Jul 2004
Posts: 9,069
Yes they do need to compress the gas and in most schemes it ends up having to be cooled to a liquid to get the energy density needed for long range travel.
I agree hydrogen is just a battery but it is in effect instantly rechargable.
BTW the thing nobody talks about are the oxides of nitrogen you get when you burn hydrogen in air. That is still simply a function of heat and nitrogen which is about 80% of air. You will still need pollution controls on your car.

Greg Fretwell

#68690 - 08/13/06 02:29 PM Re: Hydrogen by electrolysis  
Jps1006  Offline
Joined: Jan 2004
Posts: 615
Northern IL
I think the answer is cogeneration. No gases should be burned for any process or heating without turning a turbine to generate electricity. All gas appliances (except maybe cooking) should have a mini turbine within them or the mechanical systems of homes altogether nead to be more integrated and/or thought through.

Could you imagine how much electrical energy could be created using even 10% of the natural gas we burn just in residential water heaters?

Then the grid becomes your battery. excess energy gets deposited to be withdrawn when needed.

#68691 - 08/14/06 05:02 AM Re: Hydrogen by electrolysis  
PEdoubleNIZZLE  Offline
Joined: Jun 2004
Posts: 176
McKeesport, PA, USA
I always forget that our air is 80% Nitrogen. Every time someone reminds me of that, I start to feel like I'm suffocating. You're right, I forgot about the compunds of nitrogen. Assuming you burned 1 kG of gas (or petrol if you prefer) and 1 kG of hydrogen, would you have less, more, or the same amount on Nitrogen compounds from one or the other?

I was just thinking about the instantly rechargeable part of your post. Anything not attached to the earth, if powered by battery would take hours to charge and would have to sit idle, or take a few MINUTES pumping Hydrogen into a tank.

I'm still undecided on the whole hydrogen thing as far as the grid goes. I don't want to go into nuclear because it would be too political, but if you want to discuss it privately, feel free to drop me an email.

As for being pessimistic about any type of energy, in reality, on a long enough timeline, everything drops to zero. An example:

It's dark, no power. You're trying to get your generator running. You have one candle (the kid next door borrowed your flash light last week and wore down the batteries.) You have two options:
1) Light the candle at one end. You will have a small amount of light for one hour
2) Light the candle at both ends. You can see better, but the candle will now only last a half hour. However, you can work faster because you can see.

Conclusion: With non-renewable resources, no matter how much you use or conserve, the same amount of energy will be used and the same amount of work will get done, the only thing that fluctuates is time.

As for renewable resources, they are here indefinitely. The devices we use to generate power are very reliable... but the energy they capture isn't. (for instance, a wind generator making zero volts on a windless day can be said to be reliable, as it is performing to specs. If it's not turning but is somehow making power, you probably just ripped a hole in the fabric of space-time.)

I can see hydrogen's uses in automobiles, but as far as grid power, i can only think of things such as long term storage, such as excess solar energy stored for winter when there's less sun. However, this seems very expensive and more like a last ditch effort rather than high-tech innovation. Don't get me wrong, it will technically work, but it seems more like hopeful hype. After all, there arent any batteries on the grid right now, unless you consider unspent fuel to be a battery, which it technically is)

I have seen hydrogen back up generators, and they look pretty cool. Plus from what I understand, the water coming out can be used for heating when it's cold. It might be a good option for remote places too, but it doesn't seem very feasible for grid use.

I hope this isn't too political, but why not use felons to generate some power? Every able-bodied prisoner takes shifts on some exercycles connected to generators. Parking ticket? $50 fine or an hour on an exercycle. Rob a bank? Mandatory 20 years of 8 hours a day on one. Of course, you still need fuel (food) and there will still be waste (unmentionable but you get the picture)

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