[HN Gopher] Chemists discover new way to harness energy from amm...
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Chemists discover new way to harness energy from ammonia
Author : theduder99
Score : 38 points
Date : 2021-11-13 13:14 UTC (9 hours ago)
(HTM) web link (phys.org)
(TXT) w3m dump (phys.org)
| gus_massa wrote:
| In case you are wondering, the molecule at the top is 2-Pyrroline
| https://en.wikipedia.org/wiki/Pyrroline and as far as I can see
| it's totally unrelated to the reaction discussed in the article.
| xhkkffbf wrote:
| Exactly. I was wondering what was going on because I remember
| enough chemistry to know that ammonia is not a ring. I would
| have been less confused if I was totally clueless.
|
| As the Pope said, a little knowledge is a dangerous thing.
| gus_massa wrote:
| In the graphical abstract and the figure of the research
| paper, they have the molecules that are actually involved
| https://www.nature.com/articles/s41557-021-00797-w
|
| In the graphical abstract, the two ruthenium atoms are in the
| center, and the ammonia makes a temporary bound on top of
| them. They are surrounded by two organic molecules.
| throwaway743 wrote:
| Excuse my ignorance, but could this possibly lead to an energy
| source powered by animal waste/urine?
| xyzzy21 wrote:
| Ammonia is like hydrogen - not a fuel source but merely a fuel
| storage medium.
|
| Further we used to common use ammonia for refrigeration before
| Freon became a thing - the reason we don't use it for that except
| in very limited large scale applications, is that it's SUPER
| POISONOUS and prone to leaking and killing.
|
| So pushing ammonia is another example of solving one problem but
| creating 5-10 more problems which our society ALREADY KNOWS WILL
| HAPPEN - because we've been there before and abandoned it for
| safety, economic and environmental reasons. It's willful
| ignorance of history and science.
| p1mrx wrote:
| If ammonia is safe enough for agricultural use, then it may
| also be sensible for other large-scale applications, like
| powering ships and industrial processes.
|
| You definitely wouldn't want it in your car though.
| jabl wrote:
| If we're gonna have an energy economy based on nitrogen fuels,
| I'd vote for the even spiffier hydrazine. What could possibly
| go wrong?
| lambdatronics wrote:
| From the abstract[0]: they have a promising catalyst that could
| be used for a "direct ammonia fuel cell" operating at room
| temperature. It involves ruthenium, which is an expensive rare
| earth element.
|
| For context, it's possible to 'crack' ammonia into hydrogen and
| nitrogen & feed that to a PEM fuel cell, but this requires extra
| equipment, high temperatures, and consumes some of the output
| energy. Solid oxide fuel cells can also run directly on ammonia,
| but that's b/c they operate at high temperature [650 C].[1] Solid
| acid fuel cells can turn ammonia into hydrogen at 250 C -- but
| this is still extra equipment & consumes energy.[2] Ammonia can
| also be burned in modified gas turbines, which IMO would be a
| great way to quickly displace natural gas in peaker plants, to
| enable higher renewables penetration w/o relying on fossil fuels
| to take up the slack.
|
| Ammonia is a better hydrogen carrier than liquid or compressed
| hydrogen because storage is easier due to high energy density.
| The round-trip energy efficiency could also be higher.[3] It's
| less flammable, but more toxic. For more, see [4]. It sounds like
| the real enabling technology would be direct fuel cells and
| direct electrosynthesis (reverse fuel cells) to get higher
| efficiency.
|
| [0] https://www.nature.com/articles/s41557-021-00797-w
|
| [1] https://www.ammoniaenergy.org/articles/ammonia-for-fuel-
| cell...
|
| [2] https://news.northwestern.edu/stories/2020/11/ammonia-to-
| gre...
|
| [3] https://www.ammoniaenergy.org/articles/round-trip-
| efficiency...
|
| [4]https://www.intechopen.com/chapters/40233
| mojomark wrote:
| Good, thoughtful, comment, but the statement that ammonia is
| more "energy dense than H2 is innacurate and misleading.
| Ammonia has very slightly higher Volumetric Energy desnity than
| H2, but it has an extremely lower Gravimetric (mass) energy
| density.[1] The difference has significant implications for the
| intended application.
|
| 1. https://commons.wikimedia.org/wiki/File:Energy_density.svg
| R0b0t1 wrote:
| I think this is an interesting development for smaller
| generating needs, maybe even personal, but:
|
| > Ammonia can also be burned in modified gas turbines, which
| IMO would be a great way to quickly displace natural gas in
| peaker plants, to enable higher renewables penetration w/o
| relying on fossil fuels to take up the slack.
|
| Nukes can operate as peaker plants. The feedback from the
| control rods is nearly instantaneous. It's just in some markets
| they must telegraph their moves and get approval, which can
| take ~4 hours or more.
|
| I bring up nukes because _how are we going to make the
| ammonia?_ Nitrogen fixing reactions take loads of power. You
| could get it from nukes until we figure out higher capacity
| solar collection, but I don 't know of anything else that would
| work well.
| bryanlarsen wrote:
| > "One of the next challenges I would like to think about is how
| to generate ammonia from water, instead of hydrogen gas,"
| Trenerry says. "The dream is to put in water, air and sunlight to
| create a fuel."
|
| Producing ammonia from water is a lot easier than producing it
| from natural gas the way it's currently done now. The drawback is
| that it requires a _lot_ more energy. There are 6 steps in the
| process here: https://en.wikipedia.org/wiki/Ammonia_production
|
| If you use water & electricity & air as the feedstock, it's a 2
| step process:
|
| 1: electrolysize water to produce H2 2: Haber-Bosch 3 H2 + N2 - 2
| NH3
|
| (In practice step 1 is multiple steps of purification and adding
| electrolytes)
|
| In many situations, it's cheaper to convert hydrogen to ammonia,
| transport the ammonia, then convert back than it is to transport
| hydrogen.
|
| That's exactly what Korean steelmakers are doing to source green
| hydrogen: https://www.kedglobal.com/newsView/ked202107160003
| neltnerb wrote:
| Being able to use ammonia as a fuel to produce electricity is
| really neat to me because an ammonia fuel cell uses a liquid
| fuel, unlike a hydrogen fuel cell, and so is far more energy
| dense (including storage cylinder weight).
|
| It might be a better way to handle energy storage than
| batteries, honestly, if we didn't make the ammonia from fossil
| fuels...
| robthebrew wrote:
| "If the reaction were housed in a fuel cell where ammonia and
| ruthenium react at an electrode surface, it could cleanly produce
| electricity without the need for a catalytic converter." If the
| ruthenium is not a catalytic converter, then what is it? A god
| particle?
| gus_massa wrote:
| I agree, it's confusing/misleading/wrong.
|
| Anyway, I interpret is as: "This reaction does not produce
| Nitric Oxide, so it's not necessary pass the exhaust though a
| catalytic converter like the ones that car have."
| [deleted]
| AtlasBarfed wrote:
| Maybe they mean "no Platinum"
| lambdatronics wrote:
| Phys.org reporting is not great. Most methods for using ammonia
| in fuel cells rely on high-temperature catalysts to convert
| ammonia back to hydrogen, possibly in a separate unit from the
| fuel cell or else inside the fuel cell itself, if the fuel cell
| already runs at high temperature. These folks are claiming to
| have a room-temperature catalyst that can be part of a fuel
| cell that uses ammonia directly.
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(page generated 2021-11-13 23:01 UTC)