Entropy? Never heard of it.

This is wrong, or perhaps I misundertand.
Entropy is a different concept from economic viability.
The rule of non-decreasing entropy applies to closed systems.
A carbon capture system running on solar energy on Earth (note: wind energy is converted solar energy) is not a closed system from the Earth perspective - its energy arrives from outside. It can decrease entropy on Earth. Whether it's economically viable - totally different issue.
...and I don't think the Sun gets any worse from us capturing some rays.
- Also, I don't think entropy has anything to do with carbon in the atmosphere. I thought it had to do with the size of the energy packets.
- Its that using an extra step in the process (producing energy + CO2, then using energy to remove CO2) is going to increase entropy more than not producing CO2 in the first place.
  Economic viability is separate and sometimes related to things like this.
  Its irrelevant to the economy (in the short term at least) whether a process is efficient in terms of energy or resources. What is relevant is whether or not something can be done for either small sums of money, or sold for profits. More likely both in a capitalist style economy.
  Note that it does happen in some cases that using less energy/resources is more profitable, but the driving force, again in a capitalist style economy, is the profit.

I've heard there's a practical green solution to carbon capture. The units are practically maintenance free and power themselves with solar energy. This allows to deploy them on many small patches of land. The captured carbon is stored in solid organic compounds that may be used as building materials. It may sound to sci-fi to be true, but it's actually just trees.
- Babe wake up, new copypasta just dropped !
- Agree, carbon capture process is quite efficient now. I'm working on (pretty big) company doing Carbon Capture and Sequestration. The idea is to use empty oil&gaz reservoir to inject back carbon where it comes from. So there are several advantage:
  The land is already messed up by former drilling platerform. No need to shave another forest to create a facility
  No waste to handle, as the captured carbon is injected in the underground. We also study the possibility to inject other kind of waste, like domestic ones.
  Simplified process as we can keep Co2 in gaz state to inject back in former natural gaz reservoir. Not even needed to extract carbon to solodify it.
  Yes, trees are much more efficient and eco-friendly, but sometime we cannot just plant billions of trees. Whereas a CCS facility is relatively small compared to a whole forest.
  
  That seems like a disaster waiting to (re) happen, what's your thoughts on that?
  
  Now imagine if instead of playing technowizard.... your company spent that money on planting trees?
- Density of CO2 produced vs what trees capture is massively unequal. Yes trees can, but not on any tangible scale that would ever keep up with what we are doing to the planet.
  
  Yeah, agreed. Carbon capture won't save us, not trees nor otherwise. We have to slow down what we are doing to the planet.
  
  Yes, the most that carbon capture can do is temporarily slow down climate change. It turns out the only way you can stop getting carbon from outside the carbon cycle into the carbon cycle is to stop taking carbon from outside the carbon cycle and putting it into the carbon cycle.
  But the problem with oil is that it's really good, and it does a lot of stuff really well
  
  Not to mention the area needed, for the amount of trees needed. Trees also decompose, so the storage function is different, but people are quick to assume.
- Ok, but how about we do more than trees? Why are you on the internet when pre-linguistic grunting works just fine?
  
  If you can find a more efficient, less expensive way to physically sequester carbon from the atmosphere than letting forests grow, I'm sure there's a lot of awards you could win
  
  The point of my comment is that if trees wouldn't exist, they would seem like some futuristic sci-fi solution too good to be true. Just because something is shiny new tech, it isn't automatically better. Sure, just planting trees won't save us if we release all the carbon that is already captured in the form of fossil fuels, but how about we stop releasing all the carbon that is already captured in the form of fossil fuels?
- Water is the biggest limiting factor, trees need more water.

Yeah, it's different. I think the machine on the left is an infinite energy machine. Those will never work.
The machine on the right is a carbon capture machine which does work. But not well enough. Are fast enough to solve any of the problems that we have.
I'm fine with playing around with a carbon capture machine and seeing if we can improve it, but I would never want to rely solely on it.
I want to try a thousand solutions to the global warming problem. Including societal and government changes. Cuz you know otherwise we all die.
- I mean, we already have carbon sequestration machines that are even self replicating, and require minimal, if any maitenance....
  Trees and algae.
- Most pollution comes from shipping, agriculture, and other large industries. Poor countries/people cannot contribute because they are barely getting by as is. Even if the entire middle class in wealthy countries magically switched to electric/public/bicycling, started recycling, stopped watering grass, etc. it would make no noticeable difference.
  The idea that social changes at individual level can help with pollution comes directly from propaganda pushed by cunts who are actually killing our planet for profit. Fuck them. Don't spread their lies.
  
  I don't. When I say social change I'm more talking about like social thinking that individuals are the problem. Sorry if that was not clear.

Just checked the numbers, for those interested.
A gas power plant produces around. 200-300kWh per tonne of CO2.
Capture costs 300-900kWh per tonne captured.
So this is basically non viable using fossil fuel as the power. If you aren't, then storage of that power is likely a lot better.
It's also worth noting that it is still CO2 gas. Long term containment of a gas is far harder than a liquid or solid.
- Who says you power that thing with fossil fuels? The real way to do that is via giant nuclear reactors or reactor complexes.
  Fission power can be made cheaper per MW by just making the reactors bigger. Economies of scale, the square cube law and all that. The problem with doing this in the commercial power sector is that line losses kill you on distribution. There just aren't enough customers within a reasonable distance to make monster 10 GW or 100 GW reactors viable, regardless of how cheap they might make energy.
  But DACC is one of the few applications this might not be a problem for. Just build your monster reactors right next door to your monster DACC plants.
  
  But then the power generated by those reactors is better used to power things that burn fossil fuel in a less efficient way or to simply replace the fossil fuel powered electricity generators...
  Quebec transports its electricity over more than a thousand kilometers, surely distance from nuclear reactors isn't an issue if you build the infrastructure around it.
  
  There are 3 use cases I've seen.
  Making fossil fuel power stations "clean".
  CO2 recovery for long term storage.
  CO2 for industrial use.
  It's no good for the first, due to energy consumption. This is the main use I've seen it talked up for, as something that can be retrofitted to power plants.
  It's poor for the second, since the result is a gas (hard to store long term). We would want it as a solid or liquid product, which this doesn't do.
  The last has limited requirements. We only need so much CO2.
  The only large scale use case I can see for this is as part of a carbon capture system. Capture and then react to solidify the carbon. However, plants are already extremely good at this, and can do it directly from atmospheric air, using sunlight.
  
  Solar and Wind are cheaper than nuclear now. The main problem is it's not sunny and/or windy every day. A carbon capture system doesn't need to be running 24/7 though.
  If we build way more wind/solar than we use then the excess can dumped into things like this.
  Sorry but the economics of nuclear just doesn't work for everything.
  
  Good luck building enough capacity in nuclear power to do that. Nuclear plants tend to be a lot more expensive and take a lot longer to build than anticipated.
  
  Yes, it works as a "plan B" (along with many other things).
  Don't loose hope. We can still win. Keep pushing for producing less CO2.
- It's also way easier to just stop digging up coal instead of inefficiently trying to get the exhaust from burning it partially back underground.
- You would presumably capture the carbon using excess solar and wind power, which is also the cheapest power there is, sometimes going negative
  Is your capture number including the cost of liquifying the CO2 for storage?
  
  We already have solar powered carbon sequestration systems, that require almost no maintenance over a period of a couple of hundred of years of operational life...
  Trees.
- If you want to capture the CO2 from fossil fuel, it feels like it'd be easier to filter it out before dumping it in the atmosphere in the first place (apart from the obvious option of just not using fossil fuel)
  
  It would, but it takes more energy that gets produced total. You're spending 300wKh to make 220kWh of electricity.
- So power it with solar/wind?
  
  You could just replace the power plant with solar/wind and it would be cheaper
- Co2 is liquified before storage.
  
  And how do you plan to keep it liquefied, on a large scale, for 100s of years? It's currently done using pressure vessels amd chillers, that require maintenance etc.

the picture on the right isn't demonstrating an engine. They simply use renewable energy to power the fans that suck in the air.
Doesn't change the fact that industrial carbon capture is a scam, and most of that captured CO2 is later released back into the environment to help extract oil from old wells.
https://www.aogr.com/magazine/sneak-peek-preview/carbon-capture-boosting-oil-recovery

That small red bulb counteracts the entropy argument because you bring energy (and quite a lot of I recall) into the system.
Would be a sad day if we no longer could reduce entropy locally under the invest of energy.
- Would be a sad day if we no longer could reduce entropy locally under the invest of energy.
  I don't think there'd be anyone left alive to be sad in that case...
  
  That's sad
- The wider issue is you have to generate that energy, and you have to be able to capture more carbon than that generation released.
  As I understand it doesn't at all. This is why it's seen as analagous to a perpetual motion machine, it's an endless chain of power plants capturing each others carbon to no end.
  You could use solar of course, but then why generate anything with fossil fuels just to capture the carbon with solar? Just use solar.
  
  Because we still need to bring CO2 levels down even if we stop burning fossil fuel.
  And then we'll probably need to burn fossil fuel to keep them at the right level, since we are in a capitalistic society and we're never going to be able to shutdown the CO2 collectors if they are ever built.
- What I mean by entropy is that we burn fossil fuels (low entropy) and release CO2 into the atmosphere (high entropy), so it takes a lot more energy and effort to remove CO2 than simply not burning fossil fuels.
  Clearly laws of physics work against us when we try to remove a relatively low concentration gas from a planet-wide system.
  
  Next time you write a scientific publication, /s, make sure to have it reviewed by at least 2 Nobel Prize ! 😋
  (thanks for the explanation ... it was not clear at all)

The problem isn't a missing technology. it's our political and economic system.
I'm all for advancing tech but nothing is going to work until we fix our behavior. We use fossil fuels because they're profitable and allow or growth-at-all-cost economy. There's nothing for which they're the only option. Only a few things for which they're the best option; the power grid and transit aren't on that list.

There are plenty of arguments to be made against direct air capture, but entropy isn't one of them. Nobody ever claimed this is some kind of perpetuum mobile.
- This is a joke.
  While physically possible DAC is a waste of money and energy compared to effective measures such as constructing solar farms, batteries and power lines. Even hydrolysis may look attractive.
  
  At the latest after decarbonization of the power grid (yes I am laughing as I write this), we will want to remove CO2 from the air which was emitted 50 years ago. Also I would like to point out that the IPCC scenarios about reducing global warming already include carbon capture. Plans to remove CO2 from energy production till 2035 already only work under the premise that we actively start removing CO2 from the atmosphere simultaneously.
  
  That’s right. We should only do one thing, and that’s to switch away from fossil fuels. It won’t be a problem that we will still have all that CO2 warming the atmosphere and acidifying the oceans, we really shouldn’t bother trying to make that tech any better, it has clearly no use.
  You fucking armchair Reddit-ass commenter.

Even if we went to zero emissions soon, we'd still want to decrease CO2 over time to reverse the effects of climate change. Capturing co2 is always going to be much more energy intensive than not emitting it in the first place, but sometimes you don't have another choice.
- Or you know, we could plant trees…the original carbon capture device.
  
  Yeah, but then you need to cut them down and burry them so that decomposition doesn't release the co2 again. And it takes a lot of land, which can be prohibitive on the scale we'll need.
  Another interesting option is fertilizing parts of the ocean for algie to grow. Cody'sLab has an interesting video on a possible way to do that with intentionally crashing astroids into the ocean. https://youtu.be/z7u_IqzkJzE https://youtu.be/2zQb_OitsaY/?t=13m40s
  All of these, plus mechanical direct air carbon capture are methods of carbon capture. The right answer will likely be some mix of all of them.
  
  yup, turns out burning coal is us literally releasing carbon that was already captured and stored ages ago.
  
  Aren't there better plants? I remember reading that some forms of algae are way more efficient or something like that.

Yes but no. The two actual uses of carbon capture is to remove the co2 from the air before it would happen naturally and the other is making fuel sustainable for retro or novelty vehicles. You dont have to stop selling gas cars if all the fuel they use is made with carbon capture. This makes the fuel more expensive but more sustainable. Once you have driven a 911 or skyline you will understand why someone would want to drive a gas car ;) Also, technically you are going from a higher energy fuel to lower energy so as long as you can do something with the co2 it abides by thermodynamics but the problems arise when you consider real world losses.
TLDR: carbon capture is a technology we should use after we stopped polluting to fix the earth.
- TLDR: carbon capture is a technology we should use after we stopped polluting to fix the earth.
  Yeah, it would just give people a blank check to use more fossil fuels. It is kinda like a diabetic person who acquired the disease later in life, and still not adjusting their lifestyle because drugs mitigate the effects anyhow. And the person will keep eating unhealthy food or not exercising.
- Pointless. The gas should be used for things that actually need it like airlines.
  
  Trains go choo choo. But yeah that as well. On long haul flights that cant be avoided that is an excellent use for carbon capture fuel.
- Specifically it's not trying to be an over unity machine. Energy is spent pushing air through the filter medium; energy is spent moving the filter to the CO2 extractor; energy is spent heating the filter (or whatever the extraction system is); energy is spent compressing or freezing CO2 for storage

The point is to use a low carbon power source to power it.
- Yes that’s the point but why take the extra steps. Use the low carbon energy directly and stop using the high carbon sources.
  
  The argument is that there exist some use cases where we do not have a viable low carbon energy source yet (things like heavy farming equipment or aircraft), and one can effectively counteract the emissions of these things until we do develop one. Or alternatively, by the time that we eliminate all the high carbon energy, the heating effect already present may be well beyond what we desire the climate to be like, and returning it to a prior state would require not just not emitting carbon, but removing some of what is already there.
  
  I think the ideal argument is both. Have a grid that's (at least vast majority) green, and work towards using said green energy to recapture some CO2
  
  I think the intention is that the switch is not going to be immediate, and so there will be a stretch of time where some places use renewable sources of energy and some places still use non-renewables. There's nothing you can do if your neighbor doesn't switch, other than to try to capture their carbon output
  
  This guy gets it
  
  Renewable energy has many parts. I have listed the 5 most important here.
  As you can see, renewable biomass and hydropower are also part of renewable energy. That is because they have the advantage of being both power-sources and energy-storages. That means people will continue to use biomass and combust it in the long term.

Carbon capture is problematic. If I remember the area required to reduce C02 would be the size of Georgia and the air intake would be pulling in hurricane force winds. The numbers could be off but it would be a massive project that would require to be built by probably CO2 dumping infrastructure like factories.
Personally I'd say it would be better to colonize the Pacific Ocean so algae goes in deep ocean to be a carbon sink
- I've heard that's why the carbon capture is best done directly out of the machinery that creates the carbon dioxide.

Just wait until they figure out how much carbon is captured by planting a tree.
- Until the tree dies and rots or burns
  Specifically replanting all the forests we cut down during the age of sail is just capturing the carbon that was released when those sailing ships rotted
  If we wanted to keep the carbon captured which we captured with plants, we would have to store those plants where they are safe from rot or burn them in a (not yet invented) carbon capturing furnace
  
  It's not just ships. Before and after ships forests were/are cleared for farming. Net carbon sequestration of almost any forest is likely to be better than cropland and pasture - more so the old forests with well developed fungi and worms and stuff that fix and recycle some of it, not so much the timber forestry but i sustect theyre better than farms still.
  Steel ships did not really even slow deforestation much - globally. Though you could argue that the sail ships enabled Europeans to bring all their various shit to the Americas - so it is maybe linked to the farming thing.
  https://ourworldindata.org/world-lost-one-third-forests . FYI This graph is a bit misleading because time is warped on the vertical.
  We also drained and dried out wetlands and bogs which are quite good at trapping a high amount of rotting material, also to make farmland. I'm not sure if that is counted in those stats - that is possibly more of a European overpopulation thing than a global one anyway.
  I dont see how it will stop unles people start eating less, or more efficiently (I guess swap a lot of cow for cereals).
  I don't think monocultures + fertilizer + pesticides is going to be all that sustainable at keeping high yields in the long run - but we shall see about that I guess. Gene techlogy does seem to create some advances.
  
  Decomp still sequesters carbon... where do you think all the oil came from, to begin with?
- What is this tree technology you speak of

Where are we putting all this CO2?
- Old oil wells, preferably in high limestone areas
- To The One Place That Hasn't Been Corrupted By Capitalism... SPACE...
- Synthetic fuels for air planes and rockets
  
  That would put it right back into the atmosphere, though it would reduce the amount of fossil fuels used
  Perhaps do this once levels are back to pre industrial and the excess is in oil wells
  Perhaps we should convert all the excess to fuel and pump it into oil wells so any successor civilisations can fuck up their climate like we have
- Your beer/soda glass.
  Once we get this tech shrunk down to the size of Nitrogen generators it's going to revolutionize the industry.
  
  I very much prefer CO2 in my drinks, some other carbon captures get you CO and I've heard that's not as good as a drink carbonator

What is the name of the contraption on the left? Looks like a perperpetual motion machine but I'd like to learn more about it.
- It's sometimes called an overbalanced wheel, an early perpetual motion device. The idea is that there's more weights on the right side than the left side, so the wheel will turn clockwise. The weights are on rods that fall to the right as the wheel turns, so there's always going to be more weights on the right. So the wheel turns forever. Free power woohoo!
  The reality is that the balls on the left are further away from the axle. Futher from the axle = greater torque. Surprise surprise it all cancels out and the wheel eventually comes to rest.

That's essentially how many gases are made from mixtures, like notrogen or oxygen. Showing this as something new tells a lot about author's uderstanding. Carbon capture is not about making entirely new tech, it's optimization, and that's where startups suck at everything except for getting and then wasting cash.
- I don't question the working principles of DAC, or as you mention separating gasses. It's just that burning fossil fuels for energy would make no sense if you had to use most, if not all of that energy on DAC. And if you want to use low-carbon energy to power carbon capture, why not use it directly to replace fossil fuels? It seems to me that to reduce net emissions it's most efficient not to emit it in the first place.
  
  Because stationary energy generation is the easiest thing to decarbonize, while other sources are much more difficult. Also some carbon sources are so disperse to practically track down. You going to hunt down every person using a diesel generator in Subsaharan Africa, go to their rural villages, and take their generator from them? Maybe, or it might be easier to just set up one big nuclear powered DACC plant. Then you don't have to deal with the practical and political nightmare of hunting down millions of low intensity carbon sources among the poorest people on the planet. Just let the poor village keep its diesel generator til they're ready to switch to solar. You don't have to go in and start taking stuff from poor people. There are lots of examples of this, low intensity sources that add up in aggregate but would be a political nightmare to try and stop. DACC shines for this.
  
  That's why you power the thing with renewables. We have to switch to green energy; that's a given. But the point of DAC is we've already so thoroughly fucked up the environment that we have to also go further and start cleaning up our mess. Just switching to all solar power generation and electric cars would eventually work, but it would take hundreds of years at least for atmospheric CO2 to go back to normal.

Cant you just feed the CO2 from the nearest coal power plant?
- And? You want to spend even more energy on capturing it from air first?

I really think we can capitalism our way out of a capitalism caused climate crisis who's with me and rex tillerson

AI will develop a reaction to turn atmospheric CO2 into electricity and oxygen and then we’ll have nothing to worry about in our future except for the constant threat of combustion.
- We already have that technology it just sucks. Look up plant microbial fuel cells
- We have such technology already, it's just too expensive