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Powerpaste, a hydrogen technology for small vehicles

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Re: Powerpaste, a hydrogen technology for small vehicles

#31

Post by e12e »

NickM wrote: post #13
hannob wrote: post #11

Earlier quoted context omitted.

The problem with every hydrocarbon-based fuel is that you need the carbon. You get that from CO2. But then you need to get the CO2. Where do you get it from? From a fossil-based plant? Well, ideally you'd want to get rid of those, not exactly smart to create incentives to keep them running. The alternative is either biomass (problematic) or direct air capture (expensive and inefficient). (Some insightful discussion o…

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.

Re: Powerpaste, a hydrogen technology for small vehicles

#32

Post by airstrike »

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…

From the article, one other use case are drones, in which case even minor weight savings can be extremely valuable.

Re: Powerpaste, a hydrogen technology for small vehicles

#33

Post by jackyinger »

jonsen wrote: post #25
ksdale wrote: post #16

Earlier quoted context omitted.

Not that internal combustion engines are the model to aspire to... but they're just a metal contraption full of explosions. Being terrifying isn't necessarily a disqualifier, haha.

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 what is. I mean, come on, a piston moving up and down thousands of times per minute isn’t explosive enough for ya?

Re: Powerpaste, a hydrogen technology for small vehicles

#35

Post by CharlesW »

jonsen wrote: post #25
ksdale wrote: post #16

Earlier quoted context omitted.

Not that internal combustion engines are the model to aspire to... but they're just a metal contraption full of explosions. Being terrifying isn't necessarily a disqualifier, haha.

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.

> Full of combustions, not explosions.

It's both, no? Aren't all chemical-based explosions considered combustion?

If "explosion" means "a violent release of energy", that seems a reasonable word to describe what happens in a cylinder in about ~5 ms.

Re: Powerpaste, a hydrogen technology for small vehicles

#36

Post by blacksqr »

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.

Re: Powerpaste, a hydrogen technology for small vehicles

#37

Post by extrapickles »

NickM wrote: post #13
hannob wrote: post #11

Earlier quoted context omitted.

The problem with every hydrocarbon-based fuel is that you need the carbon. You get that from CO2. But then you need to get the CO2. Where do you get it from? From a fossil-based plant? Well, ideally you'd want to get rid of those, not exactly smart to create incentives to keep them running. The alternative is either biomass (problematic) or direct air capture (expensive and inefficient). (Some insightful discussion o…

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…

Direct air capture is inherently expensive unless you are doing it in the airstream of some industrial process that produces large amounts of CO2, and even then its still somewhat expensive.

Even as a waste product from separating Nitrogen, Oxygen and Argon from the air, its still expensive (retail its ~$1/lb of liquid CO2).

Re: Powerpaste, a hydrogen technology for small vehicles

#38

Post by jonsen »

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…

> ...trying to burn it as quickly as possible...

No, the speed of burn in an internal combustion engine is not explosive:

“Knocking (also knock, detonation, spark knock, pinging or pinking) in spark ignition internal combustion engines occurs when combustion of some of the air/fuel mixture in the cylinder does not result from propagation of the flame front ignited by the spark plug, but one or more pockets of air/fuel mixture explode outside the envelope of the normal combustion front.” - WP on engine knocking, which is undesirable and may damage the engine.

Re: Powerpaste, a hydrogen technology for small vehicles

#39

Post by jonsen »

CharlesW wrote: post #35
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.

> Full of combustions , not explosions. It's both, no? Aren't all chemical-based explosions considered combustion? If "explosion" means "a violent release of energy", that seems a reasonable word to describe what happens in a cylinder in about ~5 ms.

Explosion is a faster speed of burn than what an internal combustion engine is designed for.
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