The Hydrogen dream | 49 comments (49 topical, 0 editorial, 0 hidden)

Re: The Hydrogen dream (none / 0)

And finally, whenever I reflect upon hydrogen I'm always somewhat baffled on why molecules like ammonia (heavier) or methanol (heavier and less hazardous) aren't preferred as energy carriers.

Because the only emission is water dontcherknow! </snark>

Peak oil is not an energy crisis. It is a liquid fuel crisis.

by Starvid on Wed Jan 25th, 2012 at 11:36:33 AM EST

Re: The Hydrogen dream (none / 0)

Methanol would burn cleanly, not so much ammonia. If you synthesize alcohols from atmospheric CO2, the process is carbon-neutral.

We had a claim earlier that dimethyl ether should be a candidate for an energy carrier.

tens of millions of people stand to see their lives ruined because the bureaucrats at the ECB don't understand introductory economics -- Dean Baker

by Migeru (migeru at eurotrib dot com) on Wed Jan 25th, 2012 at 11:47:01 AM EST
[ Parent ]

Re: The Hydrogen dream (none / 0)

It's not a matter of burning (hideously inefficient for all but heating applications) but about fuel cells. Apparently it's really hard to build a good ammonia fuel cell.

_{It is rightly acknowledged that people of faith have no monopoly of virtue
- Queen Elizabeth II}

by eurogreen on Wed Jan 25th, 2012 at 11:54:07 AM EST
[ Parent ]

Re: The Hydrogen dream (none / 0)

Presumably an ammonia cell would produce nitrous oxide?

tens of millions of people stand to see their lives ruined because the bureaucrats at the ECB don't understand introductory economics -- Dean Baker

by Migeru (migeru at eurotrib dot com) on Wed Jan 25th, 2012 at 12:26:57 PM EST
[ Parent ]

Re: The Hydrogen dream (none / 1)

Research seems to be ongoing, but it seems that direct ammonia fuel cells may be high temperature. I came across a description of a "moderate" temperature approach, where that implies ~500C, with ammonia cracked to H2 and N2, used in an alkaline fuel cell, which has good rejection of unprocessed traces of ammonia, with the exhaust gas burned to heat the cracker.

I've been accused of being a Marxist, yet while Harpo's my favourite, it's Groucho I'm always quoting. Odd, that.

by BruceMcF (agila61 at netscape dot net) on Fri Jan 27th, 2012 at 07:21:57 PM EST
[ Parent ]

Re: The Hydrogen dream (none / 0)

Also, note from this source that ammonia can be a reducing agent for 2*NOx->N2+O2 with a proper catalyst, with some base metal catalysts working in the 450C to 800C range. Since an ammonia fuel cell would obviously have an ongoing supply of ammonia for that reducing reaction, it seems like good NOx control ought to be possible for the combustion of the exhaust hydrogen to drive the cracker.

The temperature for the base metal catalyst seems to support the 2*NH3->N2+3*H2 cracking approach I noted above for an alkaline fuel cell that works well in the 500C range ~ the gas over the catalyst would already by in the right temperature range.

A lot of this is that hydrogen fuel cells have been pursued for quite a long while, and the push to develop the technologies for ammonia as an easier to control and manage hydrogen carrier seems to be substantially more recent.

I've been accused of being a Marxist, yet while Harpo's my favourite, it's Groucho I'm always quoting. Odd, that.

by BruceMcF (agila61 at netscape dot net) on Sun Jan 29th, 2012 at 12:14:51 AM EST
[ Parent ]

Re: The Hydrogen dream (4.00 / 2)

Ammonia <-> Hydrogen+Nitrogen storage has been studied in detail and is considered practical but unproven on a large scale. Avoiding mixing with air has many advantages too (avoid contamination of the air and of the cells) and NH3 and N2 +H2 take up roughly the same volume*pressure allowing the same storage to be used for charged and discharged fuels (you can store H2 and N2 mixed together safely at room temp, they only burn with a catalyst or high temps).

by njh on Wed Jan 25th, 2012 at 12:52:02 PM EST
[ Parent ]

Re: The Hydrogen dream (none / 1)

DME I do believe in, as an energy vector for heavy vehicles. It can be used in slightly modified diesel engines, and be made out of everything from coal to black liquor.

Peak oil is not an energy crisis. It is a liquid fuel crisis.

by Starvid on Thu Jan 26th, 2012 at 03:18:07 AM EST
[ Parent ]

Re: The Hydrogen dream (none / 0)

Er... if the process emits CO2 where is it coming from?

luis_de_sousa@mastodon.social

by Luis de Sousa (luis[dot]de[dot]sousa[at]protonmail[dot]ch) on Wed Jan 25th, 2012 at 12:04:02 PM EST
[ Parent ]

Re: The Hydrogen dream (none / 0)

Which process?

tens of millions of people stand to see their lives ruined because the bureaucrats at the ECB don't understand introductory economics -- Dean Baker

by Migeru (migeru at eurotrib dot com) on Wed Jan 25th, 2012 at 12:26:04 PM EST
[ Parent ]

Re: The Hydrogen dream (none / 0)

The process. The whole pipeline to use H2/CH4/NH3. You start with electricity and end up with work, if CO2 is coming out then it must enter the process at some point, n'est pas?

luis_de_sousa@mastodon.social

by Luis de Sousa (luis[dot]de[dot]sousa[at]protonmail[dot]ch) on Wed Jan 25th, 2012 at 12:47:42 PM EST
[ Parent ]

Re: The Hydrogen dream (none / 0)

Sorry, I'm lost. Where in your diary is that pipeline? What is the (unique?) process?

There are many hydrogen fuel cell technologies, depending on the electrolytes used. I don't think many involve "a pipeline to use H2/CH4/NH3".

tens of millions of people stand to see their lives ruined because the bureaucrats at the ECB don't understand introductory economics -- Dean Baker

by Migeru (migeru at eurotrib dot com) on Wed Jan 25th, 2012 at 12:51:44 PM EST
[ Parent ]

Re: The Hydrogen dream (none / 0)

Given that H2 is only an ineffective gaseous energy store at present, whether or not there is CO2 depends on how the power is produced. Such an inefficient energy store makes it more difficult to accomplish tasks on any given renewable energy budget and more likely that non-renewable energy is required as an energy source.

I've been accused of being a Marxist, yet while Harpo's my favourite, it's Groucho I'm always quoting. Odd, that.

by BruceMcF (agila61 at netscape dot net) on Wed Jan 25th, 2012 at 10:27:17 PM EST
[ Parent ]

The Hydrogen dream | 49 comments (49 topical, 0 editorial, 0 hidden)

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