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Powerpaste, a hydrogen technology for small vehicles

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Re: Powerpaste, a hydrogen technology for small vehicles

#81

Post by ncmncm »

danans wrote: post #79
ncmncm wrote: post #64

Earlier quoted context omitted.

2% efficient, at best. 1000J in, 20J worth of wood and leaves out. Burning it, you get back only a fraction of that, with much of it carried away in the smoke.

That sounds about right. It takes a whole lot of energy to reverse entropy at the margins. Then again life exists basically at the margins of the massive energy output of the sun. But still, I'm not holding out that any such human created sunlight to chemical energy storage process is going to best the 20% conversion efficiency of solar panels * 95% round trip efficiency of modern batteries any time soon. I know ther…

I here predict that there will not be any producers of fuel from atmospheric CO2.

The prices of extracted petroleum and CH4 will plummet as carbon taxes increase and demand decreases, until only the absolute cheapest extractors remain, and those products will be used only where the carbon tax can be afforded: mainly aircraft, and then only until the much more cost-effective LH2-powered airframes ground them. (Those will be fueled with LH2 generated on the spot at airports using regional solar.)

Solar-powered CO2 capture projects will bid for carbon tax credits. Only the cheapest processes will win bids, so will not produce fuel. Probably they will blow it underground, in places where the ground is porous, and let it react with rocks down there. Turning it into fuel and selling it will not qualify as reclaiming, because the carbon doesn't stay claimed.

Re: Powerpaste, a hydrogen technology for small vehicles

#82

Post by corty »

diggernet wrote: post #80
kaliszad wrote: post #59

Earlier quoted context omitted.

Ammonia is quite ok. You can smell it :-) You can put it into water, where it is quite stable. We know how to handle it at industrial scale because of fertilizers.

Yes, you can smell it, when drastically diluted in water (which, as you say, is stable) such as for a household cleaner. But in a concentrated form such as that required for use as fuel, if you smell it, it will kill you. Quickly.

Also, water-free Ammonia is gaseous at room temperature, you have to transport it in pressurized containers. Should one of those rupture, all the Ammonia will boil off, creating a nice cloud of fun for all involved. Neutralizing it works by spraying acetic or hydrochloric acid, which is not quite as bad, but still quite ugly.

Re: Powerpaste, a hydrogen technology for small vehicles

#84

Post by gspr »

adrian_b wrote: post #78
imtringued wrote: post #76

Earlier quoted context omitted.

Are you seriously suggesting we should waste our renewables and nuclear to capture CO2 from the atmosphere and then turn that stuff back into hydrocarbon fuels only to turn 80% of it to waste heat? Seriously, man. There is no future where this is going to happen. We are not going to replace waste primary energy generated by fossil fuels by wasting our low carbon energy. We are going to reduce the amount of waste ener…

You are right that the main disadvantage of storing energy in hydrocarbons is the low efficiency of the complete cycle, which is indeed around 20% today. It is likely that the efficiency can be improved a lot but it is improbable that the efficiency of the complete cycle could reach much above 50% any time soon. So you are right, for the best efficiency rechargeable batteries are the best. Nevertheless, there are man…

> It is likely that the efficiency can be improved a lot

What makes you think that? I thought internal combustion engine efficiency is widely believed to have hit its reasonable limits?

Re: Powerpaste, a hydrogen technology for small vehicles

#85

Post by s0rce »

kaliszad wrote: post #57
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…

Well, I don't think hydrogen is the answer for all these reasons. It seems, that sodium (Na) can under certain conditions (very thin film, e.g. when applied to a surface with great speed of 10s of m/s) react directly with water and produce stable electric current. That is not so hard to do, e.g. hard disks, regular turbines etc. pretty much would provide such conditions :-) The patents for such use in Lockheed-Martin…

Doesn't most of what you said also apply to magnesium? Seems like we'll never run out (2.5% of earth's crust), there are well established methods to refine it and you just react the hydride with water to generate hydrogen.

Re: Powerpaste, a hydrogen technology for small vehicles

#86

Post by s0rce »

ChuckMcM wrote: post #53

Ah chemistry is pretty neat. Presumably there is a process to take the left over magnesium hydroxide and convert it back into metallic magnesium? Their explainer[1] doesn't say much about that part of the process. (note it looks like you can bake it at 332 degree C to get magnesium oxide. (can you tell I'm not a chemist?) I think it would be helpful to have the entire fuel cycle laid out somewhere. That said, the ope…

There are a few industrial processes used to convert magnesium oxide to metal, for example the Pidgeon process (https://en.wikipedia.org/wiki/Pidgeon_process) which I still remember learning about in my Materials Science undergrad in Toronto.

More info here: https://en.wikipedia.org/wiki/Magnesium

I suspect some variation of these processes could convert the spent fuel back to metal and then the hydride form or something like that.

Re: Powerpaste, a hydrogen technology for small vehicles

#87

Post by 8note »

adrian_b wrote: post #73
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…

This magnesium hydride technology certainly does not solve the hydrogen storage problem in the sense of being better than using hydrocarbons for energy storage, as the living beings have been doing for billions of years. For many applications, using magnesium hydride should be much better than using compressed or liquefied hydrogen, but it remains far worse than gasoline despite the misleading statement from the arti…

TIL you can put gas in a fuel cell. Why don't we today? That seems like a handy way to run a hybrid

Re: Powerpaste, a hydrogen technology for small vehicles

#88

Post by ChuckMcM »

s0rce wrote: post #86
ChuckMcM wrote: post #53

Ah chemistry is pretty neat. Presumably there is a process to take the left over magnesium hydroxide and convert it back into metallic magnesium? Their explainer[1] doesn't say much about that part of the process. (note it looks like you can bake it at 332 degree C to get magnesium oxide. (can you tell I'm not a chemist?) I think it would be helpful to have the entire fuel cycle laid out somewhere. That said, the ope…

There are a few industrial processes used to convert magnesium oxide to metal, for example the Pidgeon process ( https://en.wikipedia.org/wiki/Pidgeon_process ) which I still remember learning about in my Materials Science undergrad in Toronto. More info here: https://en.wikipedia.org/wiki/Magnesium I suspect some variation of these processes could convert the spent fuel back to metal and then the hydride form or som…

Thank you. That is excellent information. I wonder if anyone has looked into concentrated solar as the heat source for small batch magnesium production using that method.

Re: Powerpaste, a hydrogen technology for small vehicles

#89

Post by alexchamberlain »

s0rce wrote: post #85
kaliszad wrote: post #57

Earlier quoted context omitted.

Well, I don't think hydrogen is the answer for all these reasons. It seems, that sodium (Na) can under certain conditions (very thin film, e.g. when applied to a surface with great speed of 10s of m/s) react directly with water and produce stable electric current. That is not so hard to do, e.g. hard disks, regular turbines etc. pretty much would provide such conditions :-) The patents for such use in Lockheed-Martin…

Doesn't most of what you said also apply to magnesium? Seems like we'll never run out (2.5% of earth's crust), there are well established methods to refine it and you just react the hydride with water to generate hydrogen.

Hehe never run out. Like we never ran out of IPv4 addresses or crude oil... I think any solution needs to be cyclic.

Re: Powerpaste, a hydrogen technology for small vehicles

#90

Post by DennisP »

kaliszad wrote: post #57
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…

Well, I don't think hydrogen is the answer for all these reasons. It seems, that sodium (Na) can under certain conditions (very thin film, e.g. when applied to a surface with great speed of 10s of m/s) react directly with water and produce stable electric current. That is not so hard to do, e.g. hard disks, regular turbines etc. pretty much would provide such conditions :-) The patents for such use in Lockheed-Martin…

If we were to use sodium on such massive scale, I'm wondering what we would do with all the chlorine.
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