Home hydrogen production

[cloudshipsrule]

Quote:

But is it more dangerous than having natural gas lines in your house? Or a tank of liquified propane out back?

Yes.

[fsol]

Originally Posted by Rob Lister

Gasoline is not very explosive. Hydrogen is very, very explosive.
Gasoline is well behaved (most any container will contain it). Hydrogen is the polar opposite (liquefied hydrogen requires some pretty sturdy, thick, heavy containment that you most certainly do not want to fail) .

I always thought that hydrogen was less explosive than gasoline. Do you have any data?

[Rob Lister]

Originally Posted by fsol

I always thought that hydrogen was less explosive than gasoline. Do you have any data?

Certainly...

10 44 5 67 78 546 254 0 22 5

[Slimething]

Originally Posted by Ranb

If you read my post again, it says I did not think it was MUCH MORE dangerous, not just more dangerous, there is a difference.

Oh, well, please forgive me for misconstruing your post! I'm so glad you didn't write that it was not much, much more dangerous or my counterpoint would have been correct!

Quote:

If a company is going to sell a "home energy unit" that uses compressed hydrogen gas, I think they would be liability conscience enough to engineer into the system enough safe guards to keep the home from exploding and getting sued into non-existence.

Are you willing to bet your life on it?

[Slimething]

Originally Posted by ponderingturtle

Chlorine?

No, thanks. Got plenty.

[Slimething]

Originally Posted by fsol

I always thought that hydrogen was less explosive than gasoline. Do you have any data?

The flash point of hydrogen is listed as its boiling point (20 K), so it is infinitely ignitable. The flash point of gasoline is 230 K so it does not ignite as easily.

There is subtlety here, though, as gasoline carries more energy per volume than hydrogen so, although hydrogen ignites more easily, the power of an explosion is not as potent as that of gasoline.

[tedly]

I seem to recall that part of the danger was the wide range of explosive mixtures of hydrogen and air. A quick check of Wiki gives
Lower Expl Limit Upper Expl Limit
Hydrogen 4.1 % 74.8 %
Gasoline 1.4% 7.6 %

[fsol]

Those LELs show that you need less gasoline in the air to start a fire than hydrogen though right? And I figure that as hydrogen is likely to dissipate fairly quickly and not form a pool around your feet, the wide range of explosive mixtures isn't as dangerous as it might at first seem.

So the flash point of gasoline is -43 degrees C. And Hydrogen is -253 degrees C. I can't see that that makes much difference to me if I live in a place with an ambient temperature of about 15 degrees C say. The auto ignition temperature of hydrogen is about 500 degrees C and that of gasoline 280 degrees C. So gasoline will auto ignite more easily than hydrogen.

As far as I can tell they are both dangerous. They both require care in handling. They require different saftey techniques perhaps, but because most people are already happy and familiar with gasoline they don't think about its dangers, whereas they are not familiar with hydrogen and so consider it more dangerous.

[Ranb]

Originally Posted by Slimething

Oh, well, please forgive me for misconstruing your post! I'm so glad you didn't write that it was not much, much more dangerous or my counterpoint would have been correct!

Are you willing to bet your life on it?

Lots of "misconstruing" goes on at this forum at times. You quote my post then try to say I said something else. Want to disagree with a person's post but they make too much sense? Then just change what they said, now wasn't that easy? Much easier than being right for some people like you. Your reaction to my reply is just plain chichens--t and I tire of seeing it as much as I do on this forum.

I bet my life on technology almost everyday. The brakes on my truck work, gas detectors at work tell me the air in an enclosed space will not kill me, gamma meters tell me that I will not receive an overdose of radiation exposure, and on and on. Being technophobic is not the way to advance. Developing a pressurized hydrogen energy system may be practical someday, but it will not be through the efforts of people like you.

Ranb

[cloudshipsrule]

Quote:

They both require care in handling. They require different safety techniques perhaps, but because most people are already happy and familiar with gasoline they don't think about its dangers, whereas they are not familiar with hydrogen and so consider it more dangerous.

This is not actually the case. Hydrogen IS more dangerous than plain old gasoline for some of the reasons already mentioned. Engineering systems to contain and 'move around' hydrogen is more difficult, which doesn't help either.

Hydrogen can leak out of a system undetected, where-as gasoline is, well, wet, and can be smelled and seen. Hydrogen is odorless and colorless. We'll call that invisible.

Because if it's properties, Hydrogen is considered to be one of the most dangerous gases in use in industry today. I'm in an industry that uses a lot of it (Nuclear). We work with it on, practically, a daily basis, so we'd be the ones to start becoming complacent. However, that is not the case. When it comes to working with hydrogen, whether it's refilling certain tanks from a tanker truck or swapping over to new banks of tanks when one bank is low we ALL take it very seriously.

Not three weeks ago our safety topic of the day centered around a very large hydrogen explosion story.

It's easy to look at petroleum, natural gas, hydrogen, etc and think "Heck, they're all explosive. They're pretty much equally dangerous." Well, it's just not the case. Hydrogen has properties which make it MORE dangerous than any of the gases discussed in this thread, and that has nothing to do with the public’s unfamiliarity with it.

[Slimething]

Originally Posted by Ranb

You quote my post then try to say I said something else.

No, I didn't. I merely derided your sloppy writing which just begged to be misconstrued. If you don't want to be misunderstood, use more exact languagle. Simple, yes?

Quote:

Want to disagree with a person's post but they make too much sense?

Your post did not make too much sense. That's why I challenged you on it. To say that hydrogen is no more dangerous than most other gases is just plain wrong. To take me to task because you put the word "much" behind "more" is just plain ludicrous. If you were faced with a leaky hydrogen tank would you use the same or more care than if you were faced with a leaky helium or nitrogen tank? Be truthful.

Quote:

Your reaction to my reply is just plain chichens--t and I tire of seeing it as much as I do on this forum.

What is chichens--t? Don't like the forum? Easy solution.

I bet my life on technology almost everyday. The brakes on my truck work, gas detectors at work tell me the air in an enclosed space will not kill me, gamma meters tell me that I will not receive an overdose of radiation exposure, and on and on. Being technophobic is not the way to advance. Developing a pressurized hydrogen energy system may be practical someday, but it will not be through the efforts of people like you.[/quote]

Oh, where do I start? I'm overjoyed that you're happy with technology. I really am. Perhaps you should do some research into how and why those technological marvels you rely on were developed and what their shortcomings are. You mention gas meters. Which gases will they detect and how? Which ones will they NOT detect and why? What if you come in contact with an alpha or beta emitter instead of a gamma emitter?

I'm not a Luddite, far from it. I also trust technology but I want it designed right and to do its job within its design. Energy systems using hydrogen are already in place but they are not placed in homes and there's a good reason for that. Mainly because hydrogen is more dangerous than other gases.

I didn't mean to insult you or make you look bad but writing that hydrogen is no worse than other gases in an uncontrolled situation is irresponsible. I believe that most of the frequenters of this forum are more intelligent than to take what you wrote and run with it but we do have the odd moron reading these posts and you have to admit that type of person would blow themselves up pretty good messing with hydrogen.

[Ranb]

I started off with “I do not think hydrogen in a tank all by itself is much more dangerous than other gases.” You claimed I said “You don't think hydrogen is more dangerous than nitrogen?” then “To say that hydrogen is no more dangerous than most other gases is just plain wrong.” I never claimed hydrogen gas was not more dangerous than other gases.

Why can’t you just disagree instead of making things up? I do not mind being wrong, but do you have to stoop to insults instead of mere corrections? I am well aware of the limitations of the equipment I use; you do not need to assume I am not. I also know that as new technology is developed, we need to learn how to use it responsibly. There should be no reason we can not develop a safe system for using hydrogen in the home or for driving.

It used to be that hot water heaters were a danger to home owners. Instead of banning them, people developed a safe water heater for use in the home. There should be no reason a safe hydrogen powered system can not be developed.

[robinson]

Home made system, hydrogen from solar, Wired story. http://www.wired.com/wired/archive/15.03/play.html?pg=9

Information on safety, with obvious link to main site explaining everything.
http://www.siei.org/hydrogensafety.html

[Slimething]

Originally Posted by Ranb

I started off with “I do not think hydrogen in a tank all by itself is much more dangerous than other gases.” You claimed I said “You don't think hydrogen is more dangerous than nitrogen?” then “To say that hydrogen is no more dangerous than most other gases is just plain wrong.” I never claimed hydrogen gas was not more dangerous than other gases.

What you really wrote:

Quote:

I do not think hydrogen in a tank all by itself is much more dangerous than other gases. When was the last time you heard of oxy-acetylene welding units blowing up?

I was reading in the book Skunk Works about Ben Rich's attempts to build a hydrogen fueling and handling station for a hydrogen powered jet. He also had the same concerns that are voiced here. He found that rupturing and igniting a pressurized hydrogen tank did not result in much of an explosion, he had to have a mix of oxygen and hydrogen to make it really nasty.

Diverting surplus solar electricity sounds like a good way to store hydrogen and oxygen in separate tanks. The US Navy makes oxygen (using DC power from the reactor plant) for their subs this way; they let the hydrogen vent overboard.

Ranb

I interpreted the parts that I bolded to indicate a bit too much nonchalance at the dangers of compressed hydrogen. I apologize if I misconstrued your post but, frankly, I can't think of anyone who would take your first sentence at face value as it's so banal that it's not worth posting.

Quote:

Why can’t you just disagree instead of making things up? I do not mind being wrong, but do you have to stoop to insults instead of mere corrections?

I don't see that I made anything up. Nor did I throw any insults your way. Yes, I was snide at times but that's why America has fallen in love with me.

[robinson]

Originally Posted by Rob Lister

Gasoline is not very explosive. Hydrogen is very, very explosive.

Neither gasoline nor hydrogen will explode. This is a pervasive myth. You can set off a spark inside a container full of either one, and nothing will happen. No burning, no explosion.



















Now if you mix them with air, that is another story.

[Macoy]

Originally Posted by robinson

Neither gasoline nor hydrogen will explode. This is a pervasive myth. You can set off a spark inside a container full of either one, and nothing will happen. No burning, no explosion.

in fact, my dad, clad in only a deep-sea diver's suit, was able to argon-weld a leaking valve inside a hydrogen-filled pressure vessel with complete confidence, knowing that the incoming pressure from the hydrogen generator was greater than that exiting from between his legs.

[Ranb]

Originally Posted by Slimething

I interpreted the parts that I bolded to indicate a bit too much nonchalance at the dangers of compressed hydrogen.....I don't see that I made anything up. Nor did I throw any insults your way. Yes, I was snide at times but that's why America has fallen in love with me.

I am not nonchalant when dealing with compressed hydrogen; I used to add it to reactor coolant for chemistry control and followed the required ventilation, atmosphere sampling and non-sparking tool requirements. But I have to admit I gave the ammonium hydroxide much more respect.

Count me as one of the Americans who has not fallen in love with you dear.


Ranb

[Pidge]

Originally Posted by robinson

Information on safety, with obvious link to main site explaining everything.
http://www.siei.org/hydrogensafety.html

Thanks Robinson, that's the site I was after!

And I retract my statement about running the Fuel Cell backwards - I blame faulty memory

[Slimething]

Originally Posted by Ranb

I am not nonchalant when dealing with compressed hydrogen; I used to add it to reactor coolant for chemistry control and followed the required ventilation, atmosphere sampling and non-sparking tool requirements. But I have to admit I gave the ammonium hydroxide much more respect.

I'm glad you know what you're doing and that you keep your wits about you. Looks like you have quite a dangerous job so you the alternative would not be pleasant.

Quote:

Count me as one of the Americans who has not fallen in love with you dear.

Ah, don't beat yourself up too much over it. Give yourself time and I'm sure you'll come around.

[robinson]

Originally Posted by briandunning

I was reading an article that described the basic process of electrolysis, with an anode and a cathode in water - hydrogen bubbling off of one, oxygen bubbling off the other (in fact my son has a toy rocket that's hydrogen powered that works this way) - but the article concluded saying that this simple process does not practically scale up to home hydrogen production.

I'm wondering why not.

Hello Brian. The key here is the phrase "does not practically scale up". The bottom line is the issue. With the current system providing energy at low cost, what they are saying is it cost more to build the system than it does to just keep buying energy. It doesn't mean it can't be done, it means right now, if you are near a power line, gas line, or other energy distribution grid, energy is cheaper to buy than to harvest from the sun.

Originally Posted by briandunning

I can easily envision a system with a solar panel and your home water supply, charging a battery to run a compressor, and constantly bubbling off hydrogen. A few valves and sensors and you've got what appears to me to be a complete package.

Of course. In fact, this system is used in multiple countries, using multiple methods of generating and storing energy from the sun. It is also used on Space Stations. It isn't even new, the first system I know of was built thirty years ago, and is still working just fine, running during the day using electricity directly from the solar cells, as well as generating hydrogen which is stored for night time use. Some systems use a fuel cell at night, others just run a generator burning hydrogen as fuel. Either way, hydrogen is used as a storage medium for solar energy. Fears about massive explosions from stored hydrogen are the result of ignorance.

Originally Posted by briandunning

What am I missing? Why wouldn't this work?

What is missing, is the economic factors, which either paint hydrogen as expensive, dangerous, or not ready for prime time. The expensive part is valid if you are, again, located close to an existing energy grid. But like all those solar powered lights on road signs, far from a power line, it is cheaper to use solar, if you are not close to a grid. And using hydrogen made from water, using solar as the energy source, is the cheapest way to store large amounts of solar energy.

Hydrogen is a safe, reliable energy storage medium, which is used to store solar energy, every day, in locations where solar energy is the only source of power. Or where someone values free, reliable energy, more than they do the amount of money the system cost up front. While spending $50,000 to make your home solar powered isn't practical, it certainly is doable.

Hydrogen, in either liquid form or pressurized gas, in nothing new or mysterious. It is used all the time, in mass quantities, all over the world. Making it, storing it, or transporting it, all of these are well understood.

Building a system to store hydrogen from solar power, isn't hard, it is expensive.

Same goes for using solar power to make hydrogen to run your car. While BMW has been doing this for thirty years or more, nobody is claiming it is practical.

Very cool however. If they offer me one to drive, I'm going to have to accept.

[cloudshipsrule]

Ranb wrote:

Quote:

I used to add it to reactor coolant for chemistry control and followed the required ventilation, atmosphere sampling and non-sparking tool requirements.

I know of no plant where a chemist would add hydrogen to the RCS. This is usually done automatically via the VCT and a bank of H supplying overpressure for O scavenging of the RCS. Where did you work that you added hydrogen yourself, if you don't mind me asking? What was the atmosphere sampling for?

[cloudshipsrule]

Quote:

Fears about massive explosions from stored hydrogen are the result of ignorance.

With proper engineering the inherent dangers of hydrogen can be mitigated, without it that statement is completely false.

Additionally, given the gist of some of the previous posts concerning the dangers of hydrogen, the above statement is rather pompous.

[fsol]

My experience of working with hydrogen, pretty much on a daily basis over 3 years, leads me to believe that the danger is overstated. I have swapped in and out hydrogen bottles, used it as a fuel and generated it via steam reforming of LPG and methane. This while sitting next to my rig in the lab. I had leaks from my rig, because when you are running a rig at 7-800 degrees C, without welding it is difficult to rule them out. None of the leaks caused any problems in the way of fire or explosion. It didn't self ignite, despite being right next to a very hot chunk of metal when it leaked.

Now we took all the precautions with hydrogen that you would expect. An, extraction system for ventilation, the hydrogen was stored outside (along with all the bottled gas, including "safe" gases like nitrogen) the combustible gas sensors were hooked up to trip the power to the lab in the case of a leak, and normally closed solenoids would then cut off the flow of gas into the lab.

So, no nonchalance here either. I just think the relative dangers of hydrogen when compared to gas or gasoline are overstated. A look through ScienceDirect seems to bear that out.

----

International Journal of Hydrogen Energy
Volume 17, Issue 10, October 1992, Pages 807-815

A comparison of H2, CH4 and C3H8 fuel leakage in residential settings
M. R. Swain and M. N. Swain
Department of Mechanical Engineering, University of Miami, Coral Gables, FL 33124, U.S.A.
Received 19 May 1992. Available online 11 August 2003.

They determine that the LEL is the important parameter, out of the three gases only propane reached the higher limit, and then only small amounts were too rich to burn. For low flow rates, low enough to form a homgenous fuel air mixture, propane forms a combustible mixture before hydrogen and methane takes longer than either. For high flow rates, high enough to form concentration gradients, then propane forms a combustible mixture before methane, and hydrogen takes longer than either.

They got those results by experimentally measuring the properties of leaks and sticking the data into a CFD simulation.

----

Journal of Loss Prevention in the Process Industries
Volume 19, Issue 6, November 2006, Pages 719-723


Safety distances for hydrogen filling stations
A.J.C.M. Matthijsen, a, and E.S. Kooia
aRIVM Centre for External Safety, P.O. Box 1, 3720 BA Bilthoven, The Netherlands
Received 8 February 2006; revised 19 May 2006; accepted 30 May 2006. Available online 30 June 2006.

In which they conclude that

Quote:

In comparison with other transport ‘fuels’, safety distances in the Netherlands for gasoline (20–25 m), CNG and hydrogen (10–15 m) are of the same order of magnitude. Safety distances for LPG are larger: 15 m for the dispenser, 25 m for the underground buffer, and, depending on annual sales, 45–110 m for the filling point on the LPG tank trailer (Government Gazette, 2004). The capacity of a hydrogen filling station does not appear to have a large influence on the safety distance. For this reason a filling station for gasoline can also be equipped with a filling unit for hydrogen without increasing the external safety distances.

----

International Journal of Hydrogen Energy
Volume 3, Issue 2, 1978, Pages 157-176

Is hydrogen a safe fuel?*1, , *2
J. Hord
Cryogenics Division, Institute for Basic Standards, National Bureau of Standards, Boulder, Colorado 80302, U.S.A.
Received 9 February 1978. Available online 11 August 2003.

I'll give you the abstract as the summary is over a page long.

Quote:

The safety aspects of hydrogen are systematically examined and compared with those of methane and gasoline. Physical and chemical property data for all three fuels are compiled and used to provide a basis for comparing their various safety features. Each fuel is examined to evaluate its fire hazard, fire damage, explosive hazard and explosive damage characteristics. The fire characteristics of hydrogen, methane and gasoline, while different, do not largely favor the preferred use of any one of the three fuels; however, the threat of fuel-air explosions in confined spaces is greatest for hydrogen. Safety criteria for the storage of liquid hydrogen, liquefied natural gas (LNG) and gasoline are compiled and presented. Gasoline is believed to be the easiest and perhaps the safest fuel to store because of its lower volatility and narrower flammable and detonable limits. It is concluded that all three fuels can be safely stored and used; however, the comparative safety and level of risk for each fuel will vary from one application to another. Generalized safety comparisons are made herein but detailed safety analyses will be required to establish the relative safety of different fuels for each specific fuel application and stipulated accident. The technical data supplied in this paper will provide much of the framework for such analyses.

Bolding mine

----

I am not convinced of some kind of "ultra danger" that exists around hydrogen when compared to other fuels.

[robinson]

I love this guy in New Jersey.

http://www.csmonitor.com/2007/0315/p12s01-sten.html

Faced with the fact he runs his modern house (with all the luxuries), as well as his car, on 100% FREE energy, with zero pollution, the naysayers have only two things to say. It is expensive, and it is ... well ... not practical.

heh

And for $500,000, I think that "not practical" thing is valid.

Maybe somebody is claiming the storage tanks are some huge danger, and they left that out.

But it got me thinking about the "not practical" part. Hmmm...

[TjW]

Originally Posted by robinson

I love this guy in New Jersey.

http://www.csmonitor.com/2007/0315/p12s01-sten.html

Faced with the fact he runs his modern house (with all the luxuries), as well as his car, on 100% FREE energy, with zero pollution, the naysayers have only two things to say. It is expensive, and it is ... well ... not practical.

heh

And for $500,000, I think that "not practical" thing is valid.

Maybe somebody is claiming the storage tanks are some huge danger, and they left that out.

But it got me thinking about the "not practical" part. Hmmm...

Half a million dollars is certainly an interesting definition of "free".

[Ranb]

Originally Posted by cloudshipsrule

I know of no plant where a chemist would add hydrogen to the RCS. This is usually done automatically via the VCT and a bank of H supplying overpressure for O scavenging of the RCS. Where did you work that you added hydrogen yourself, if you don't mind me asking? What was the atmosphere sampling for?

I was an ELT on several submarines in the US Navy. We used a bottle of hydrogen to pressurize a flask to the amount required to raise hydrogen concentration in the primary coolant system, then added it using a charging pump. Reverse threaded brass fittings and a brass wrench were used to prevent any sparking while making the connection. We were required to have recirc fans running in the engine room, and used an explosimeter to ensure we were not dumping any large amount of hydrogen into the space. I never detected any hydrogen while adding to the primary as it is a very simple procedure and I guess the only way to really screw up was to fail to close the bottle isolation valve after the disconnect.

Ranb

[Ranb]

Originally Posted by Slimething

I'm glad you know what you're doing and that you keep your wits about you. Looks like you have quite a dangerous job so you the alternative would not be pleasant.....

I was stationed on several submarines in the 80's and 90's. The radiation exposure and hydrogen were the least of my worries. I foolishly sprayed myself in the face with ammonium hydroxide while opening a bottle with my face shield up. A single little drip on the tongue was enough to eat a little crater in it. Opening a watertight door after the Captain ordered a faulty ventilation lineup resulted in a broken nose. Add in the various burns from hot pipes, bruises from working on equipment and heat rash from the oppressive heat and humidity; using hydrogen becomes routine.

Ranb

[robinson]

Originally Posted by TjW

Half a million dollars is certainly an interesting definition of "free".

Yep. Course he only spent $100,000 of his own money on the project. And he has the cool underground freon pipe system to cool the house. Still, getting it past the zoning board was the big hurdle. And the anti-hydrogen element.

They still use the Hindenburg as an example of the dangers of hydrogen.









Idiots.

[Slimething]

Originally Posted by Ranb

I foolishly sprayed myself in the face with ammonium hydroxide while opening a bottle with my face shield up. A single little drip on the tongue was enough to eat a little crater in it.

You're in good company in the foolish department. My first chemistry teacher showed us how to waft odors to our noses and not try to sniff chemicals directly. Well, who was he to tell me how to do stuff?! So, I went up to a bottle of conc ammonium hydroxide and sniffed it. Ah, the agony that ensued was a great object lesson for me to listen to people.

Everyone thinks acids are the real baddies in the lab because of horror movies. You and I have learned that bases are far worse.

[TjW]

Originally Posted by robinson

Yep. Course he only spent $100,000 of his own money on the project. And he has the cool underground freon pipe system to cool the house. Still, getting it past the zoning board was the big hurdle. And the anti-hydrogen element.

They still use the Hindenburg as an example of the dangers of hydrogen.









Idiots.

Whereas now the more enlightened among us are sure that the stored chemical energy in the hydrogen contributed not a whit to the massive fire. And the low ignition energy of hydrogen could never have been a factor in the fire starting in the first place.

[TjW]

Originally Posted by Slimething

You're in good company in the foolish department. My first chemistry teacher showed us how to waft odors to our noses and not try to sniff chemicals directly. Well, who was he to tell me how to do stuff?! So, I went up to a bottle of conc ammonium hydroxide and sniffed it. Ah, the agony that ensued was a great object lesson for me to listen to people.

Everyone thinks acids are the real baddies in the lab because of horror movies. You and I have learned that bases are far worse.

Obligatory "All your base are belong to us" reference.