What processes manufacture hydrogen and is it energetically worthwhile?

Join the discussion
Registration is free. Start your own thread to ask a follow-up.
Sign up Log in
21 replies · 17K views
deckart
Messages
106
Reaction score
4
What is/are the process(es) to manufacture hydrogen? The reason I ask is I'm curious as to the amount of energy required to get and store hydrogen. And, if the process itself makes it an energy source worth the expense of manufacturing.
 
Engineering news on Phys.org

Discussion

The vast majority of hydrogen made today is done by steam reforming of natural gas.
 
I believe there are certain bacteria that manufacture hydrogen. Can't really see that steam reforming and hydrolising water are sustainable.
 
One would have to do a cost comparison of different energy sources.

There are applications for which hydrogen is essentially! One process is ammonia production, which can also be used as a fuel - the ammonia is cracked to form N2 and 3H2.

Steam reforming of natural gas is the most practical process given the large (but not inexhaustible) supply currently. Hydrogen is then purified and stored as a compressed gas or cryogenically. So to evaluate the cost, one must know the cost of natural gas being converted to hydrogen, the cost of the energy used to do the convertion, and the energy required to compress and store the gas. Cryogenic storage also requires that energy be removed from the hydrogen.

Converting the hydrogen to ammonia should also be considered.

At some point, hydrogen may be the most available fuel - once natural gas is depleted. So other processes are being investigated, but one must determine the processes which can produce hydrogen in millions of kgs, or millions of cubic meters.

A world in which transportation has a significant role in the economy requires a transportable (and storable) fuel.
 
Go to the DOE hydrogen website and they have all kinds of facts and figures. Production, storage, and usage are three different beasts.

Basically, hydrogen production is an economics problem, storage is a technological problem, and usage is somewhere in between. We know how to produce H2, we just can't do it cheaply enough to compete with fossil fuels or without using them in the first place. Storing it (in a non-Hindenburg fashion) is something that really hasn't been figured out from a technology standpoint so we can't really begin to consider economics. We know how to use it, in a fuel cell for example, but they need to be improved both technologically and economically.
 
Astronuc said:
Steam reforming of natural gas is the most practical process given the large (but not inexhaustible) supply currently.
But how large is large? If we start powering all of our cars from natural gas, I'm not sure "large" will be very large for very long.

Also, doesn't steam rerforming, then burning create exactly the same pollutants that straight burning the methane does? If so, it doesn't really fit the goal of the "hydrogen economy".

I think the end-game of the hydrogen economy is going to have to be water->hydrogen-> water and the energy source is going to have to come from somewhere else (the hydrogen won't be an energy source, just a carrier).
 
russ_watters said:
I think the end-game of the hydrogen economy is going to have to be water->hydrogen-> water and the energy source is going to have to come from somewhere else (the hydrogen won't be an energy source, just a carrier).
Well after all, fossil fuels are nothing more than solar energy stored in chemical form.

So one could produce hydrogen from solar power - PV or solar dynamic. Essentially an endless supply of energy for the next few billion years!
 
Astronuc said:
Well after all, fossil fuels are nothing more than solar energy stored in chemical form.
What we need is something that is renewable on human timescales.
So one could produce hydrogen from solar power - PV or solar dynamic. Essentially an endless supply of energy for the next few billion years!
Certainly, but I'm not sure the economics of that will ever work. My money's on nuclear.
 
There is a plant going up in Nevada, or at least it should be by now, that is designed to crack methane using concentrated solar, ultimately yielding hydrogen, I think oxygen, and ultra-pure carbon as marketable products. So there are carbon dioxide emission free processes coming along for methane as a hydrogen supply. Next, if we can tap the vast reserves of methane trapped in ocean clathrates, supplies could last for 500 years or more. Presently, the best well to wheels efficiency [for autos] is found in the methane -> hydrogen -> fuel cell -> electric motor fuel chain.
https://www.physicsforums.com/showthread.php?t=29373
 
Last edited:
Ivan Seeking said:
There is a plant going up in Nevada, or at least it should be by now, that is designed to crack methane using concentrated solar, ultimately yielding hydrogen, I think oxygen, and ultra-pure carbon as marketable products. So there are carbon dioxide emission free processes coming along for methane as a hydrogen supply. Next, if we can tap the vast reserves of methane trapped in ocean clathrates, supplies could last for 500 years or more. Presently, the best well to wheels efficiency [for autos] is found in the methane -> hydrogen -> fuel cell -> electric motor fuel chain.
https://www.physicsforums.com/showthread.php?t=29373

Well there is Fischer-Tropsch synthesis which takes CO2 + H2 --> light alkanes and alkenes -> heavier alkanes and alkenes.

Presumably there are fast growing plants (perhaps phtyoplankton or phyto-bacteria) which also takes CO2 + H2 and produces cellulose or sugar or other compounds of C, H and O.

It would also help to increase fuel efficiency or otherwise reduce wasteful use of hydrocarbons.

Using solar energy, which isn't necessarily stored, and which is always available somewhere on the earth, makes the most sense. :-p :approve: :biggrin:
 
Isn't there one way where you can frezze oxygen to it's liguid(or soild)state and wait tell starts vaporize and that gass that starts to varproize is hydrogen?Or is that helium?
 
Sorry I ment air.I'll edit that
Can a mod edit that for me for some reason it let me edit it
 
scott1 said:
Sorry I ment air.I'll edit that
Can a mod edit that for me for some reason it let me edit it

Sure, one could probably extract hydrogen from air using some type of advanced freezing/controlled thawing, but could you imagine the costs!
Also, I suppose one could even design a centrifuge that would separate the various densities of air-gases. But again, imagine the costs-vs-the volume of hydrogen obtained.
 
Air is mainly O2 and N2 - no H.

We can get hydrogen from H2O because it has [an H] hydrogen as part of the molecule.

Natural gas - Methane - is CH4, which is why we look to methane as a source of hydrogen.
 
Last edited:
pallidin said:
Sure, one could probably extract hydrogen from air using some type of advanced freezing/controlled thawing, but could you imagine the costs!
Also, I suppose one could even design a centrifuge that would separate the various densities of air-gases. But again, imagine the costs-vs-the volume of hydrogen obtained.
Air has been liquified for about 100 years. Primarily it was done for the oxygen, however, it other gases were collected as well.

Interesting history at - http://www.boc.com/aboutus/history/index.asp (click on History on right to get decade index)

Even as the Brins were developing their chemical process for separating oxygen from air in the 1880s, others were working on a method involving liquefaction. In 1895, two scientists, Dr William Hampson in Britain and Dr Carl Linde of Germany, took out British patents for producing liquid air.

The method essentially involved cooling air repeatedly in a huge refrigerator until it became liquid, at which point nitrogen gas evaporated and rose through a column to leave oxygen-rich liquid at the bottom.

Linde's process - which offered an oxygen purity of around 97 per cent, far better than that of the barium oxide process - went on to triumph in the patents race with Hampson.

Brin's Oxygen Co had already entered into an agreement with Dr Hampson. The next step was to negotiate an agreement to use the Linde patents, too. Eventually an agreement was reached and the company also acquired plants built to produce oxygen through the Linde process.

BOC is one of the largest companies producing industrial gas. Others are Linde (formerly part of Union Carbide) and Air Liquide.

Lecture by Heike Kamerlingh Onnes -
nobelprize.org/physics/laureates/1913/onnes-lecture.pdf

From Linde Engineering - the history of air liquefaction -
http://www.linde-process-engineerin..._seperation_plants/air_separation_history.php

As Ivan Seeking mentioned, air is primarily N2 and O2 - ~78% and 21%, respectively. The hydrogen in the air is in the form of water vapor, which is removed in the initial stages of compression of the air before it is cooled, because water freezes at 273 K.

Ultimately, once fossil fuels are depleted, hydrogen will be produced mainly from dissociation of water (H2O). Hydrogen production in a nuclear power plant is one consideration, as well as from solar power.
 
Last edited by a moderator:
I checked about the ligufiing air way of getting hydrogen.It was hellium not hydorgen.It's very uneffecient to get hellium that way since there's very little hellium in air.
 
Helium is extracted from natural gas. The helium comes from alpha decay of trans-plumbic elements - U, Th, Ra, Rn, Po, At and Bi.

The US Navy had a program to obtain He from the natural gas industry, primarily for their blimps and dirigibles.
 
Small scale production

What's the best way to produce hydrogen on a small scale? Taking into mind I don't want to be working with dangerous currents and have no access to any kind of concentrated acid. What's the best kind of readily available power supply to use for electrolysis? Also, isn't there something u can do with NaOH? thanks
 
russ_watters said:
...My money's on nuclear.
Exactly. And H2 for autos is the way to go. How much H2 could we produce per year from water electrolysis with one 500 megawatt generator?
 
Check out the following web site: http://www.renewableenergyaccess.com

Thanks,

Gordan
 
Last edited by a moderator: