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Nitrogen electroreduction with almost 100% current-to-ammonia efficiency (2022)

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Re: Nitrogen electroreduction with almost 100% current-to-ammonia efficiency (2022)

#171

Post by pfdietz »

cornholio wrote: post #164
pfdietz wrote: post #142

Earlier quoted context omitted.

Where did you conclude it was somewhat better than using electricity for electrolysis?

I took the author's claim of 100% electrolytic efficiency at face value and contrasted with typical water electrolysis efficiencies, followed by a Haber-Bosch step. This method of direct electroreduction should not confused with the Laser-induced method discussed elsewhere in the thread, which has abysmal numbers.

The 100% efficiency is faradaic efficiency, not energy efficiency, I believe.

Re: Nitrogen electroreduction with almost 100% current-to-ammonia efficiency (2022)

#172

Post by ForgedEngine »

lazide wrote: post #79
TheSpiceIsLife wrote: post #58

Earlier quoted context omitted.

Diesel is none of those things. I have extinguished a fire with diesel.

Diesel is definitely flammable. I works great as an accelerant. It isn’t as easily flammable as gas, and doesn’t have easily autoignitable vapor like gas. I’m guessing you dumped a lot of it on something without a lot of thermal mass? If you did the same on a bonfire, you’d have a different story.

Diesel's flash point is above ambient temperature (unless you live in the Sahara). It has a lower autoignition point than gasoline, which is one of the reasons it's preferred in compression ignition engines.

Re: Nitrogen electroreduction with almost 100% current-to-ammonia efficiency (2022)

#173

Post by lazide »

ForgedEngine wrote: post #170
lazide wrote: post #162

Earlier quoted context omitted.

Your point is? Gasoline fumes don’t typically auto-ignite either. And that is all flash point is about.

No, autoignition and flash point are two completely different things.

Ah, thanks for the correction.

Anhydrous ammonia’s ‘flash point’ (producing flammable/explosive vapors) is well below room temperature at STP? It boils at -28F. That’s why it is so commonly used for refrigeration.

It does have a specific LEL and UEL that makes it less dangerous than gasoline. It also has a much higher auto ignition temp.

Yeah, anhydrous ammonia is less dangerous than gasoline (1 instead of 4) on the fire diamond due to it being less easy to ignite.

But flash point doesn’t help you here?

electrical sparks or open flame can still definitely do it. And have, multiple times.

Some pretty amazing clips in industrial accident videos from it, actually. My favorite part is when the chunk of roof almost makes it to the highway.

[https://youtu.be/QWCiqoLb-VU?si=ZEsBDFVTQkHSpkRS]

Re: Nitrogen electroreduction with almost 100% current-to-ammonia efficiency (2022)

#174

Post by lazide »

ForgedEngine wrote: post #172
lazide wrote: post #79

Earlier quoted context omitted.

Diesel is definitely flammable. I works great as an accelerant. It isn’t as easily flammable as gas, and doesn’t have easily autoignitable vapor like gas. I’m guessing you dumped a lot of it on something without a lot of thermal mass? If you did the same on a bonfire, you’d have a different story.

Diesel's flash point is above ambient temperature (unless you live in the Sahara). It has a lower autoignition point than gasoline, which is one of the reasons it's preferred in compression ignition engines.

I’m not sure what you’re trying to say here?

If you dump gasoline on a fire, it will go ‘fwoomp’ and try to climb back into whatever container you poured it out of. If it succeeds, that container may even explode. Which is bad, and why people die or get terrible burns from pouring gasoline on fires.

If you pour diesel on a fire, the fire will get bigger and none of those things will happen. Unless, apparently, like the poster above, you pour so much on it so fast it drowns it before the diesel can get up to temp. Apparently. I’ve personally never tried that.

Diesel is basically cooking oil in many ways, and you can do the same thing with cooking oil too if you want.

This is well known by every redneck I’ve ever met, and I’ve personally done it numerous times.

P.S. also, putting gasoline on cold fuel in warm climates makes a pretty cool fireball due to said flashpoint. Just, you know, don’t light it from close up. Cold climates? No problem.

Re: Nitrogen electroreduction with almost 100% current-to-ammonia efficiency (2022)

#175

Post by ForgedEngine »

lazide wrote: post #173
ForgedEngine wrote: post #170

Earlier quoted context omitted.

No, autoignition and flash point are two completely different things.

Ah, thanks for the correction. Anhydrous ammonia’s ‘flash point’ (producing flammable/explosive vapors) is well below room temperature at STP? It boils at -28F. That’s why it is so commonly used for refrigeration. It does have a specific LEL and UEL that makes it less dangerous than gasoline. It also has a much higher auto ignition temp. Yeah, anhydrous ammonia is less dangerous than gasoline (1 instead of 4) on the…

Flash point and boiling points are different. The flashpoint of ammonia is 270F. Below this temperature at 1 atm, ammonia will not catch fire no matter what.

That video took place in an engine room, so any combination of heat, flame, or spark is possible.

Re: Nitrogen electroreduction with almost 100% current-to-ammonia efficiency (2022)

#176

Post by lazide »

ForgedEngine wrote: post #175
lazide wrote: post #173

Earlier quoted context omitted.

Ah, thanks for the correction. Anhydrous ammonia’s ‘flash point’ (producing flammable/explosive vapors) is well below room temperature at STP? It boils at -28F. That’s why it is so commonly used for refrigeration. It does have a specific LEL and UEL that makes it less dangerous than gasoline. It also has a much higher auto ignition temp. Yeah, anhydrous ammonia is less dangerous than gasoline (1 instead of 4) on the…

Flash point and boiling points are different. The flashpoint of ammonia is 270F. Below this temperature at 1 atm, ammonia will not catch fire no matter what. That video took place in an engine room, so any combination of heat, flame, or spark is possible.

“Flash point is the temperature a liquid (usually a petroleum product) will form a vapour in the air near its surface that will “flash,” or briefly ignite, on exposure to an open flame”

If ammonia is boiling (and producing a fog) of concentrated vapor which then burns/explodes in exposure to an open flame, which it will definitely do at even OF, that is an entirely academic point no?

It still has the same effect.

Re: Nitrogen electroreduction with almost 100% current-to-ammonia efficiency (2022)

#177

Post by lazide »

lazide wrote: post #81
CuriousCosmic wrote: post #70

Earlier quoted context omitted.

Well... there's hydrazine (N2H4) which is the stuff they use as monopropellant rocket fuel. It burns even without the presence of oxygen and it's even more toxic and explosive than ammonia. It's the reason the capture crews for returning spacecrafts wear hazmat suits. However hydrazine is liquid at room temperature and it can be converted to hydrazone (also being considered for fuel cells) which is solid at room temp…

If there is anything that would make ammonia seem warm and cuddly, it is indeed hydrazine! Urea maybe? It’s almost non toxic and is 2x ammonia + a carbon monoxide molecule. though not sure how efficient it would be to extract energy from. Speaking of ‘extra nitrogen’s are generally bad’, a callout to the azides! https://en.m.wikipedia.org/wiki/Azide https://en.m.wikipedia.org/wiki/Lead(II)_azide

P.S. Found a sweet Hydrazine youtube video, and figured I needed to add it. [https://youtu.be/V3HuKQvRBUE?si=wTuEwvKJQkidKZAp]

Re: Nitrogen electroreduction with almost 100% current-to-ammonia efficiency (2022)

#178

Post by amluto »

sfink wrote: post #169
amluto wrote: post #167

Earlier quoted context omitted.

That’s not the same thing, though — your dad forgot the oxygen! A balloon full of approximately pure hydrogen makes a nice fireball but doesn’t really explode — the same group that made the exploding balloon I watched also did one of those. The stoichiometric premixed balloon is only 2/3 H2 by volume, so it releases 1/3 less energy, but it’s a whole different experience when the energy is released essentially all at…

> That’s not the same thing, though — your dad forgot the oxygen! Oh, I'm quite aware. The other fun game we played was with his acetylene welding torch and balloons. It has separately controlled tanks of acetylene and oxygen. Acetylene only = nice big fireball. Acetylene + oxygen = no fireball at all, instead a very loud boom + a bit of a shockwave.

A quick search for higher heating values suggests that acetylene and hydrogen gasses have fairly similar HHV per mole of oxidizer. (H2 needs 1/2 equivalent or O2; acetylene needs 5/2 equivalents, so H2 wins by a bit.)

But H2 takes up most of the space in the balloon, and acetylene is nice and compact, so considerably more total energy should be available with acetylene!

I don’t know whether oxyacetylene will detonate nicely, though, or whether a balloon-sized oxyacetylene mix will merely combust subsonically.

Re: Nitrogen electroreduction with almost 100% current-to-ammonia efficiency (2022)

#179

Post by colechristensen »

applied_heat wrote: post #163
gofhwgwidi wrote: post #117

Earlier quoted context omitted.

Aluminum

Do aluminum factories shut down daily due to fluctuating prices or are they located in areas with cheap and plentiful reliable electricity supply?

Sometimes they’re built next to hydroelectric dams and use the entire power output of the dam. Usually with long term power contracts that are more about constant load than consuming excess peaks (having a larger base load is more of an old school energy efficiency benefit, having users for variable loads is the future)

They don’t shut down entirely because the aluminum has to stay molten at a thousand degrees, but they can scale the energy usage significantly, this is becoming more of an interest in the last decade.

https://www.greentechmedia.com/amp/article/german-firm-turns...

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