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Powerpaste, a hydrogen technology for small vehicles

fraunhofer.de

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Re: Powerpaste, a hydrogen technology for small vehicles

#41

Post by danans »

e12e wrote: post #31
NickM wrote: post #13

Earlier quoted context omitted.

or direct air capture (expensive and inefficient) The big question in my mind is whether direct air capture is inherently expensive and inefficient...or if this is just a chicken/egg problem where we haven't invested time and money in making it cheaper because it's expensive, and it's expensive because we haven't invested time and money in making it cheaper. I don't know enough about physics and chemistry to answer t…

> The big question in my mind is whether direct air capture is inherently expensive Have a look at a tree... I suppose it's possible that billon years of evolution has ended on a local optimum for low energy input (direct sunlight), and we might revolutionize it with high energy (eg: high voltage electricity, fusion etc) - but I doubt it.

> low energy input (direct sunlight)

Direct sunlight is actually quite powerful, around 1kW/m^2 at sea level.

Although I'd guess most trees aren't particularly efficient at absorbing CO2 vs the energy they consume, which makes sense, since they only have to be as efficient as necessary to survive.

Re: Powerpaste, a hydrogen technology for small vehicles

#42

Post by tom_mellior »

frankus wrote: post #29

I'm trying and failing to come up with a use case where this is more practical than a rechargeable (and/or swappable) battery in a scooter. Refueling something like this would be faster than recharging, but if "quick recharge" is part of your requirements then it's straightforward to make a scooter battery swappable and maybe even standardized across brands. Power outlets are ubiquitous, and these things just don't u…

Based on the article and some guesses, potential advantages to swappable batteries might be: weight (as you mention); cheaper/more environmentally friendly materials; lower risk of spontaneous combustion; less dangerous stuff leaking out when the unit is breached.

Re: Powerpaste, a hydrogen technology for small vehicles

#43

Post by andrewflnr »

Nasrudith wrote: post #10
hannob wrote: post #5

Earlier quoted context omitted.

Ammonia is currently considered as one of the more promising options for future shipping fuels. There are a number of projects planning to create green ammonia at scale, e.g. this: https://asianrehub.com/ Ammonia is already made from hydrogen today, making that green is pretty straightforward, you just need enough clean electricity. Just get the hydrogen from electrolysis, the ammonia synthesis process itself is well…

Why not just use a closed loop hydrocarbon from electricity system as a shipping fuel if you have excess power and a need for transit? The main theoretical point of hydrogen is very high specific energy per mass but it is essentially purest acidic gas and a pain. Bonding it to something else mitigates it so why 3 H per N instead of 4 H per C? Both are toxic gases at this point leaving ammonia's main advantage in the…

According to Wikipedia, CH4 is actually non-toxic (which is what I'd expect for something so ubiquitous in biological systems).

Re: Powerpaste, a hydrogen technology for small vehicles

#44

Post by lovemenot »

frankus wrote: post #29

I'm trying and failing to come up with a use case where this is more practical than a rechargeable (and/or swappable) battery in a scooter. Refueling something like this would be faster than recharging, but if "quick recharge" is part of your requirements then it's straightforward to make a scooter battery swappable and maybe even standardized across brands. Power outlets are ubiquitous, and these things just don't u…

What is a scooter? A skateboard with a handle or a small motor bike? I suspect Fraunhofer is talking about the latter, and you the former.

Re: Powerpaste, a hydrogen technology for small vehicles

#45

Post by kevin_thibedeau »

blacksqr wrote: post #36
zhengyi13 wrote: post #12

In '99, while working at a solar hydrogen startup as a recent grad, I was exposed to a fellow who proposed to transport H in the form of H2O, and his solution for cracking it was to make purple ping pong balls filled w/ Na. He'd deliver a hopper of Na ping pong balls, and a machine filled with water. Feed balls into the machine, which would then use a ram to split the balls underwater, and siphon off the resulting H2…

Reminds me of my undergraduate days in the 1980's, when the chemistry majors' idea of fun was stealing chunks of sodium from a lab and throwing them off a bridge into a nearby river. Boom.

I had a high school science teacher who was demonstrating controlled burning of sodium and potassium one day by slicing of pieces from a large sample. Being covered in oil, the main chunk got away from him and dropped into the lab sink which was unfortunately wet from previous cleaning. A vigorous reaction ensued :)

Re: Powerpaste, a hydrogen technology for small vehicles

#46

Post by Piezoid »

zhengyi13 wrote: post #12

In '99, while working at a solar hydrogen startup as a recent grad, I was exposed to a fellow who proposed to transport H in the form of H2O, and his solution for cracking it was to make purple ping pong balls filled w/ Na. He'd deliver a hopper of Na ping pong balls, and a machine filled with water. Feed balls into the machine, which would then use a ram to split the balls underwater, and siphon off the resulting H2…

In fact, only half of the hydrogen originates from the POWERPASTE; the rest comes from the added water.

Indeed, it seems it's an hybrid of your fellow's tech, using magnesium both as a substrate for H2 and as a reducing agent for water: Mg + 2H2O -> Mg(OH)2(aq) + H2(g)

Less explosive than Na, hopefully :)

Re: Powerpaste, a hydrogen technology for small vehicles

#47

Post by AtlasBarfed »

- small vehicles aren't taken far (otherwise it's exhausting), so easily achievable 50-100 mile ranges are just fine

- small vehicles will have small, quickly, easily, cheaply rechargeable batteries, likely easily recharged from even plain old wall sockets

- LFP batteries will probably get good/cheap/dense enough to handle almost all 50-100 mile small vehicle ranges, its doubtful a hydrogen engine will get cheap enough soon enough

- and again, LFP and EV/battery tech is in the mainline of economies of scale, buildout, production, and cost cutting, and will be for a decade more. This stuff will need to compete at a price point 50% lower or less than today's.

- and it still has the sourcing problems. green hydrogen still smacks of the "clean coal" whitewash with a different label

Re: Powerpaste, a hydrogen technology for small vehicles

#48

Post by AtlasBarfed »

tom_mellior wrote: post #42
frankus wrote: post #29

I'm trying and failing to come up with a use case where this is more practical than a rechargeable (and/or swappable) battery in a scooter. Refueling something like this would be faster than recharging, but if "quick recharge" is part of your requirements then it's straightforward to make a scooter battery swappable and maybe even standardized across brands. Power outlets are ubiquitous, and these things just don't u…

Based on the article and some guesses, potential advantages to swappable batteries might be: weight (as you mention); cheaper/more environmentally friendly materials; lower risk of spontaneous combustion; less dangerous stuff leaking out when the unit is breached.

LFP is as safe as it comes, and the density is hitting sweet spot for scooeter distances.

Re: Powerpaste, a hydrogen technology for small vehicles

#49

Post by coryrc »

tomas789 wrote: post #8

Solving hydrogen storage has great implications. Hydrogen has high gravimetric energy density (1 kWh worth of H2 is light) but very low volumetric density (1 kWh takes up a large volume). Easy solutions are compressed hydrogen (H2 is a small molecule and easily escapes even through a material, steel embrittlement and energy for compression are big issues), cryogenic cooling (energy intensive and cryocoolers have sign…

You don't need hydrogen, you need electrons. I prefer to store my electrons directly in atomic element 3, so I can fill it directly with electrons and get them back out, at much higher efficiencies than this process.

Re: Powerpaste, a hydrogen technology for small vehicles

#50

Post by Obi_Juan_Kenobi »

jackyinger wrote: post #33
jonsen wrote: post #25

Earlier quoted context omitted.

Full of combustions , not explosions. “The speed of the reaction is what distinguishes an explosive reaction from an ordinary combustion reaction.” - Wikipedia on explosion. “An internal combustion engine nominally operates on a controlled rapid burn.” - WP on combustion.

Internal combustion engines do in fact attempt to burn fuel and oxidizer at maximum stoichiometric efficiency, and they also are trying to burn it as quickly as possible to capture all of the heat rather than exhausting a partially burnt mixture and wasting fuel. Effective explosives have the exact same chemical goals and nearly the same thermodynamic goals. If that isn’t a carefully controlled explosion I don’t know…

Engines combustion is designed to occur as a propagating flame front in the cylinder initiated by the spark plug. Great efforts are made to ensure that this is precisely what happens.

The alternative is a detonation, i.e. engine knocking. This causes a spike in cylinder pressure and will quickly destroy an engine. It is for this reason that engines are absolutely not trying to burn fuel as quickly as possible.

This is a difference of detonation vs. deflagration. Whether you consider both of these to be forms of explosions is a semantic issue.

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