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Engineers find neat way to turn waste carbon dioxide into useful material

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Re: Engineers find neat way to turn waste carbon dioxide into useful material

#71

Post by swiley »

namibj wrote: post #57
gpm wrote: post #24

Slightly offtopic, what's the easiest way to scrub CO2 from air (e.g. in a house) without using up consumable materials? Some form of pressure swing absorption?

Not really without consumables, unfortunately. But it's easy and costs about 50-200$ per human and month when you just buy the required substance, granular CaOH treated with 1~2 NaOH (by pouring a concentrated solution of it over the CaOH), from Alibaba once a year. That stuff is e.g. used for re-breathers in anesthesia. CAS 8006-28-8 is the "magic" word/number. The potential alternative, which would not use consumab…

Now you have caustic soda laying around and potentially being aerosolized, I’m not sure that’s an improvement.

Re: Engineers find neat way to turn waste carbon dioxide into useful material

#72

Post by swiley »

adrianN wrote: post #53
gpm wrote: post #24

Slightly offtopic, what's the easiest way to scrub CO2 from air (e.g. in a house) without using up consumable materials? Some form of pressure swing absorption?

Get a large amount of calcium hydroxide in a watery slurry. That absorbs CO2 to form calcium carbonate. Take the carbonate outside and heat it up sufficiently to form calcium oxide and carbon dioxide. Add water to go back to calcium hydroxide.

Be careful with alkali metal hydroxides! They tend to be caustic and mixing them with water is exothermic (it can boil if you do it fast enough.) They will also react with aluminum, potentially violently and can ruin glass.

Re: Engineers find neat way to turn waste carbon dioxide into useful material

#73

Post by swiley »

gpm wrote: post #48
marcosdumay wrote: post #46

Earlier quoted context omitted.

If you are concerned about indoor CO2 concentration, the answer is to ventilate the place. No reasonable amount of plants will keep a house stable. If it's just really curiosity, well, people have been scrubbing CO2 since space travel is a thing. Wikipedia was completely unhelpful to me, but I remember there is a mineral with high CO2 selectivity that you can simply push the air though it.

98% curiosity, 2% lack of faith in our long term ability to keep CO2 levels down to healthy levels (1000ppm is enough that we can detect minor negative effects... I have to wonder if really minor ones exist even at 400 ppm). Wikipedia was similarly not useful for me. Scuba divers and the like apparently use a one-time-use non-regenerative mineral that absorbs CO2. The space station has something that regenerates but…

I know older spacecraft didn’t have a regenerative material, this is the first I’ve heard about the space station.

You’d have to reduce the CO2 pretty far (I’m betting reducing to CO like in TFA isn’t what you’re looking for.) I think a lot of people underestimate how much energy this takes.

Re: Engineers find neat way to turn waste carbon dioxide into useful material

#74

Post by gpm »

swiley wrote: post #73
gpm wrote: post #48

Earlier quoted context omitted.

98% curiosity, 2% lack of faith in our long term ability to keep CO2 levels down to healthy levels (1000ppm is enough that we can detect minor negative effects... I have to wonder if really minor ones exist even at 400 ppm). Wikipedia was similarly not useful for me. Scuba divers and the like apparently use a one-time-use non-regenerative mineral that absorbs CO2. The space station has something that regenerates but…

I know older spacecraft didn’t have a regenerative material, this is the first I’ve heard about the space station. You’d have to reduce the CO2 pretty far (I’m betting reducing to CO like in TFA isn’t what you’re looking for.) I think a lot of people underestimate how much energy this takes.

Re ISS, I've been clicking around on this a bit more, and

> While cabin air processing, one carbon dioxide removal bed is in the process of regeneration. Regeneration is accomplished using pressure/thermal swing methodology. First, the two-stage pump removes the free air from the adsorbent bed and returns it to the cabin, reducing oxygen ullage. Then Kapton heaters integrated within the adsorbent bed raise the zeolite temperature, and space vacuum creates a low, partial pressure driving the carbon dioxide gas overboard. Daylight and continuous day power cycle is overlapped with the operating cycle. In the daylight power cycle, the carbon dioxide adsorbent bed heaters are only allowed to be powered on during the day portion of the cycle

> [...]

> The CDRA continuously removes 6 person-equivalents of CO, when operating with both C02 removal beds (dual beds) functioning.

https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/200502...

Converting CO2 into CO would be rather counterproductive (absent a reliable and efficient mechanism to remove CO), I suspect an efficient setup will involve "mechanical" filtration not chemical reactions.

Re: Engineers find neat way to turn waste carbon dioxide into useful material

#75

Post by gpm »

gpm wrote: post #74
swiley wrote: post #73

Earlier quoted context omitted.

I know older spacecraft didn’t have a regenerative material, this is the first I’ve heard about the space station. You’d have to reduce the CO2 pretty far (I’m betting reducing to CO like in TFA isn’t what you’re looking for.) I think a lot of people underestimate how much energy this takes.

Re ISS, I've been clicking around on this a bit more, and > While cabin air processing, one carbon dioxide removal bed is in the process of regeneration. Regeneration is accomplished using pressure/thermal swing methodology. First, the two-stage pump removes the free air from the adsorbent bed and returns it to the cabin, reducing oxygen ullage. Then Kapton heaters integrated within the adsorbent bed raise the zeolit…

Ah, and this paper contains an incredible amount of details, and zeolite 13x and 5a is really cheap on Alibaba, I'm going to have to try this

https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/199700...

Re: Engineers find neat way to turn waste carbon dioxide into useful material

#76

Post by 08-15 »

bit_logic wrote: post #10

Every time there’s a discussion about synthetic carbon fuels, there’s the same frustrating replies. I want to reply to those with one statement: the whole point is to use excess power from solar/wind. There’s always the same replies pointing out how it’s more efficient to use the power directly in EV batteries, laws of thermodynamics, and other similar things. Those completely miss the point. Solar/wind is going expo…

The article provokes these replies by prominently making this absurdly stupid statement:

This technology could be retrofitted to coal fired power plants.

No, it can't! The power plant is run precisely when you don't have excess power to store. Conversely, you don't have concentrated CO2 when the power is available. It might work for a cement kiln, but not for a power plant.

I'm sure you know that. But the idiot who put a picture of cooling towers into the article clearly doesn't. He probably doesn't know the first law of thermodynamics, either.

Re: Engineers find neat way to turn waste carbon dioxide into useful material

#77

Post by twic »

LegitShady wrote: post #42
bit_logic wrote: post #26

Earlier quoted context omitted.

Solar produces only during the day, but wind is at any hour. And these days, the idea of massive over-provisioning is being discussed to overcome the intermittent problem since solar/wind keeps getting cheaper and cheaper. The idea is simple, how to overcome the cloudy winter day issue? Simply overbuild a lot of solar/wind so it can still provide enough on a winter day. Then during summer, shutoff the excess power ge…

>Use the excess summer power to fill up a near empty dam with desalinated water? Pumped storage hydroelectricity is the biggest form of power storage at the moment, and has efficiencies around 70-80%. The losses for desalinization (pumping through media) are ruinous compared to just pumping uphill, and storing desalinized water means you can't use it without spending potential power. There might be good reasons not t…

I think the idea here was simply to use the excess energy to stock up on potable water, which people could drink later, rather than to also use it for pumped storage.

Re: Engineers find neat way to turn waste carbon dioxide into useful material

#78

Post by twic »

08-15 wrote: post #76
bit_logic wrote: post #10

Every time there’s a discussion about synthetic carbon fuels, there’s the same frustrating replies. I want to reply to those with one statement: the whole point is to use excess power from solar/wind. There’s always the same replies pointing out how it’s more efficient to use the power directly in EV batteries, laws of thermodynamics, and other similar things. Those completely miss the point. Solar/wind is going expo…

The article provokes these replies by prominently making this absurdly stupid statement: This technology could be retrofitted to coal fired power plants. No, it can't! The power plant is run precisely when you don't have excess power to store. Conversely, you don't have concentrated CO2 when the power is available. It might work for a cement kiln, but not for a power plant. I'm sure you know that. But the idiot who p…

> The power plant is run precisely when you don't have excess power to store. Conversely, you don't have concentrated CO2 when the power is available.

Unless you have some way of buffering the CO2. Biologically, this is what CAM photosynthesis does [1], and i have a vague memory of there being an industrial equivalent. Something like dissolving the CO2 in calcium hydroxide, to make calcium carbonate, then later on sparging it with hydrogen to recover the carbon?

[1] https://en.wikipedia.org/wiki/Crassulacean_acid_metabolism

Re: Engineers find neat way to turn waste carbon dioxide into useful material

#79

Post by lykr0n »

readams wrote: post #51
perl4ever wrote: post #41

Earlier quoted context omitted.

I do not understand the concept that a property of a sum of a bunch of numbers somehow applies to those components. Whether something is net zero depends on what you are adding it to; it's not inherent in that thing. It's like, if you have a pile of blue things, then the pile is also blue. But other characteristics do not work that way. If you have a pile of things that each weigh 1 lb, then the pile does not weigh 1…

If you make a hydrocarbon by taking CO2 from the air, and you use a carbon free energy source to do it, then burning that hydrocarbon is net zero carbon. That is, if all your hydrocarbons that you burn were made this way, then the atmospheric carbon doesn't increase because of your activity. It acts just like a battery.

Exactly. It's not a solution, but it's a way to stop the problem from getting worse.

It's like moving from a variable rate credit card to a 0% loan. You still have this pile of debt you need to deal with, but you more or less stop the problem from getting any worse.

Re: Engineers find neat way to turn waste carbon dioxide into useful material

#80

Post by marcosdumay »

gpm wrote: post #75
gpm wrote: post #74

Earlier quoted context omitted.

Re ISS, I've been clicking around on this a bit more, and > While cabin air processing, one carbon dioxide removal bed is in the process of regeneration. Regeneration is accomplished using pressure/thermal swing methodology. First, the two-stage pump removes the free air from the adsorbent bed and returns it to the cabin, reducing oxygen ullage. Then Kapton heaters integrated within the adsorbent bed raise the zeolit…

Ah, and this paper contains an incredible amount of details, and zeolite 13x and 5a is really cheap on Alibaba, I'm going to have to try this https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/199700...

Just be careful during the regeneration. CO2 is toxic at high concentrations.
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