The general idea is that you grossly overbuild your renewable energy production (solar and wind mostly) and during the middle of the day when the grid is fully saturated and all of the storage systems are filled up you dump the excess energy into carbon sequestration. This is why people are so angry at NEM 3.0, it's cutting the excess energy production we need as a prerequisite for saving the environment off at the knees.
Or you build solar and wind plants specifically for carbon sequestration. Then you don't have to worry about coordinating with the needs of the grid. You don't even need the plants to be on the grid. That frees you up to put them places where there is plenty of wind or solar but no infrastructure transporting electricity which would otherwise by useless for solar and wind currently.
Compressed CO2 is still a lower energy state than the hydrocarbons, so you can get net energy out.
You couldn't end up with the same hydrocarbon that you started with, of course - that would violate the laws of thermodynamics.
So you need to build the structures to keep 20km³ of liquefied CO2 each year (liquefying also takes energy).
The first is that it could use intermittent renewable energy. Solar PV during the day is already cheaper than coal. Just run CO2 removal when renewables generate surplus.
The second is that coal plants are heat engines. Most of the energy released burning coal is rejected as heat. CO2 removal might in theory be made more efficient than this. So it might not be quite as bad as it appears at first glance.
That being said I still doubt this technology could make a dent in the problem without massively cheap energy. It would require either solar panels that are as cheap as vinyl siding or something like practical high yield fusion.
I haven't seen anyone address how we will pay for carbon capture. By the time we start doing real capture, the CO2 produced should be low so carbon tax will be low.
The theory being that power would be essentially free most of the time because there would be a surplus. But then wouldn't people just use more? It's only "free" until people come up with other uses for inconsistently available large amounts of power, at which point you have to outbid them.
But also, that's crazy. You have the chance to offer the world cheap renewable energy and you're going to not? What kind of misanthropic policy is that?
One option would be taxing energy. The carbon tax would be small by that time. That would also keep the price higher.
I had idea for retroactive carbon tax, making people pay for their past consumption. Those of us that are older got lots of benefit from polluting CO2, and makes sense to have us pay to remove it. The feasibility depends on the price, and how to charge lots of people who are retired.
Taxing energy, carbon or otherwise, is highly regressive. It only works if you refund the money. Otherwise people freeze to death or go broke.
Taxing non-carbon energy makes no sense because you're not trying to discourage it. You might as well just use income tax.
> I had idea for retroactive carbon tax, making people pay for their past consumption.
The records to use for this are unavailable. Nobody knows how much gasoline someone bought in 1995. It would also generally be impossible to collect; what if your contribution for 75 years of carbon emissions was meant to be $250,000 and you only have $100,000? Do we take your last dime and leave you to starve? What about people who are already dead? Do their kids have to pay?
Retroactive taxes and taxes on retirees are both going to be intensely unpopular.
Which is why people want to justify it by claiming we're going to have a lot of surplus energy to use for it. But how does that work unless the competing demand for energy is negligible, which seems implausible?
Every part of it seems like some company trying to extract government money for their inefficient solution that costs more than it would to reduce emissions by the same amount.
The results I got where that if we built a very large solar farm (500 000 km^2) operating at the efficiency of current commercial solar farms and used all its output to power DAC CO2 removal, that would be enough to remove about half as much CO2 as we currently emit each year. In effect it would be as if we had cut emissions back to 1970 levels.
Note that since the solar farm would just be used to power DAC, it would not need electrical infrastructure outside the farm itself. We just need a place where we can put in 500 000 km^2 of solar panels and a bunch of DAC facilities.
The atmosphere does a good job of distributing CO2 so the solar/DAC facility doesn't need to be near any heavy CO2 emitters either.
BTW, the output of a 500 000 km^2 solar farm per year is about equal to the total yearly energy use of humanity, which shows just how insane the amount of solar energy available is. Let's call this one Human Energy Unit (HEU).
Build two HEU's worth of solar/DAC and we are effectively carbon neutral.
Of course you wouldn't have to build these as 500 000 km^2 facilities. 500 facilities of 1000 km^2 would do, or any other combination that gives us 1 HEU total of energy that is all used for DAC.
How far could we take this?
The 5 largest subtropical deserts in the world have enough room to hold 30 HEUs worth of solar farms.
If we built all those and turned them all on at once it would take one year to remove enough CO2 to get us down to 320 ppm, which is around the levels we had in 1960. Two years would take us back to levels last seen around 1800. 6 years would get us down to pre-industrial levels.
That was all using technology that we have today. It would be a huge project, but it does not require any new science or new engineering. Just a lot of money, politics, manufacturing, and construction.
A quick Googling to find current worldwide solar panel production suggests that it would take about 90 years of current production for the panels for a 500 000 km^2 solar farm, so to build enough to just cancel out current emissions would need about 180 times the resources that currently go annually into solar panel production.
So we'd probably need to increase mining (and several other things) by about 20x if we wanted to use this approach to get enough DAC to bring emissions to net zero.
I think that's about as far as I can go. I don't know enough about the availability of various resources to figure out if the various things needed are abundant enough and accessible enough that we could increase production by 20x.
I thought, of course, of the always attractive "breakthrough" possibility, but ... in particular, fusion isn't it.* So, deployment of renewables is the obvious solution ... and, solar, in particular, has made massive strides in the past decade+.
What you're talking about is actually much more attractive, though. Sounds like a potentially great implementation / execution. And, all of this - much more rapid deployment for (electric) power generation, or, even better, as you propose, I think - seems like exactly the context in which a new "TVA" (Tennessee Valley Authority) or similar (maybe even "Apollo Project") would be the way to actually get it done with the urgency that seems warranted.
Of course, the US coffers have been so raided, it may take the kinds of "national pain" experienced around a century ago to generate the political "housecleaning" required to, well really, "right the "USS USA". As usual, it's not clear the will is there in the electorate. But, I'd say this much for sure: as old as I am now, the behavior of people older than me has disgusted me in many ways for years, and anyone younger than me should be thoroughly pissed off, I think. I don't want to veer into more of a rant - suffice it to say ... if you look at the benefits a certain generation enjoyed, then consider their voting for policies / tax breaks likely to deny such benefits to future generations (already happening, of course - take a look at college tuitions in the US, for just one example), it's a travesty.
In any case, I think another commenter raised a good point regarding the materials requirement. I'd imagine that would be "paid back" many times over very easily by the scheme overall, but don't know for sure ... I know there have been issues with having enough of the right type of sand to make high (enough) purity silicon wafers for chip manufacture ... but, my knowledge is very limited in these areas in general. If anyone has a real handle on what the materials side of this type of scheme looks like, I'd be interested...
* It was always such an attractive idea ... sounds so perfect ... until you know about neutron generation / flux and realize that something like a "tokamok", in particular, is just not likely to be economical AT ALL (the problem being that without some method to contain neutrons or method for preventing generation, you bombard your materials and end up having to replace / "decontaminate" / etc. far too quickly ... at least, based on my sense of best methods available around 10 years ago ... last time I was involved in any work even marginally related to anything in that field). In any case, even if we have or can determine ways of further reducing neutron generation or ... doing something w/ Higgs or something to deal better w/ the neutron problem, seems like it'd take more like a "miracle" than a breakthrough at this point for it to have any bearing on the climate problem on the timescale relevant.
By simple thermodynamics we can be 100%, not 99%, 100% sure, that the energetic cost of removing CO2 from the freaking atmosphere is higher than the benefit of putting it there in the first place.
A non-sustainable process that converts fuel to CO2 and then into a solid or liquid that isn't fuel could theoretically have positive efficiency, but it is by no means guaranteed to (especially when the competition is heat pumps), even if it did by a small margin it could still cost significantly more, and it implies that you're eventually going to both run out of fuel and convert it all into an enormous amount of industrial waste.
Maybe I should add that I do agree with your conclusion (that replacing the stoves makes sense). I just disagree with the argument from "basic thermodynamics" which gives you "100% confidence".
We will always, 100% of the times, expend more energy to reverse a irreversible process than we could possible extract from this irreversible process.
This statement is valid regardless of the path chosen.
Which naturally spawns the argument 'let's not reverse it, let's do CH to CO to Cx, all we have to do is find x'.
The problem is this is not valid because we burn a lot of fuel.
Even if we found x, it would not be enough to sustain our rate of carbon emissions. In 2022 the world consumed 5.8*10^12 liters of crude oil.
So it would be necessary to include y. And z. Etc until n.
Inevitably including a regeneration step Cn + H to CH + n.
Now the path looks like:
CH -> CO -> Cx -> Cy -> (...) -> Cn -> CH
Which is a closed loop, meaning net power loss. With 100% confidence.
Maybe the one who oxidizes CH pays the bill to remove the CO2 emitted. Is it even possible to put such measure worldwide? Logistics would suddenly be prohibitively expensive for all but the most valuable products per weight/volume. Globalization is addicted to fossil fuels.
Well, that is literally all we did and build and invest in the last century or so. The very power grid of the world is based on carbon fuels. We can't run our carbon removal machinery on dirty power or we would be emitting more than we could possible remove.
It becomes 100% clear the winning strategy is not removing CO2 from the atmosphere, it is replacing all machines and appliances that burn carbon. Worldwide.
Not all are possible, ofc. But a stove ayy.
One still does not imply the other. The question was about what makes sense. That's economically, socially, politically, regionally, etc. Amount of energy extracted via some processes is not the same as benefit. However, benefit is what matters. I guess this discussion isn't moving forward from here.
We can convert one in the other, at different conversion rates granted, but still.
Energy input cost is a line in every company spreadsheet, it can block or allow companies to succeed. Today this line is kept artificially low because we base our economies on a very exothermic open loop CH to CO. Closing this loop is not an option because basic thermodynamics, which is the very logic behind carbon removal.
We have to stop entering this path as much as possible.
Also: "The Bhadla Solar Park has faced some challenges due to its location and scale. One of the main challenges has been dust accumulation on the solar panels, which reduces their efficiency and output. The park is also located in an arid region that experiences frequent dust storms and sandstorms."
Obviously the goal is to move as much stuff off of GHG emissions, but we've done a lot of damage to the atmosphere. If you look at a CO2 graph in the atmosphere over 40,000 years our GHG emissions are basically a vertical line:
And discovering this factoid didn't lead you to realize how insane the whole idea is?
> Just a lot of money, politics, manufacturing, and construction.
Oh yes. Surely just a matter of that. I understand you're more interested in getting ballpark numbers than actually solving this problem though, so thanks for sharing.
For reference, cities currently cover 3 500 000 km^2 of the earth. Also, solar density is still improving, and other sources of energy exist.
Funny enough, this was done in the SF novel “The Hail Mary Project”, and derided by the scientists in the book for furthering climate problems dramatically by turning a normally heat reflective surface into a heat absorbent surface.
Worth investigating before committing our deserts to power collection.
Besides, they don't have to be buried that deep. People are still finding intact bodies in bogs in England from thousands of years ago. They're just a few feet down.
In the desert things decay pretty slowly, too. See Sylvester, the cowboy mummy in a museum in Seattle that was found in a sand dune in Arizona with a bullet hole in him.
To start reversing the CO2 emission we would need as many trees it takes to take up the current CO2 emissions and then a bit more.
From what I found you can estimate every m³ (a bit less than 1 American fridge) of Wood stores 1 ton of CO2. Say each hectare of Forest with fast growing trees produces ~ 10m³ per year (more when they are cut down but they need to grow over a decade+. So if they take 10 years that is 100m³ wood yield at the end).
Humanity produced by some estimates 37 billion tons of CO2 in 2020. That means you need 3.7 billion hectare of forest.
The USA has a land area of 157.7 million hectare. So you need an area of 23 times the LAND area of the United States of America just for trees just to HALT CO² at today's level.
How well are fast growing trees growing in the Arizona desert btw?
You're right that trees cannot be 100% of the solution. But they can be a big part of it.
> you think 25 years is enough to store CO2 in?
It's starting to rot at 25 years, lying in the rain and mud and beetles. There are logs much much older than that lying around the local woods. There are stumps over a century old. My house is 25 years old, and the wood structure that has been kept dry has no rot at all. None. Zero. Simply by keeping it dry.
Also I live in a house made from wood, stone, straw and dirt. Depending on how you count its about 400 years old. before that it burned to the ground once. And the Wooden parts aren't actually that old they have been replaced as recently as 100 years ago. the inside has been redone in the 80ies tho and a lot of the wood got taken out.
Its silly to argue for wood as a storage medium even on the basis of that.
Limited to rot resistant trees, such as cedars. Even then, not shielded from the rain for 25 years and not seeing much rot would be amazing.
The ancient Egyptian tombs preserved things very well as long as the tomb stayed dry.
This story sounded so cool, I just looked it up. Unfortunately, the bullet hole is apparently fake and the reason he didn't decay is because an embalmer deliberately mummified him immediately after his death by injecting him with an arsenic-based fluid, which killed off all the bacteria and insects invading the body.
Cheaper than building a zillion solar panels.
Looks like about 250 million tons a year. Less than a hundredth of the solar farm and carbon capture machines.
We are currently emitting ~37B tons of CO2 per year. That's ~0.375 C, so assuming we only store the carbon, that's ~10B tons of C per year.
For reference, the Empire State Building is ~365K tons - so you'd need to build ~30 thousand empire state buildings per year with the captured carbon.
Which, yes, you then need 30,000 of so it doesn't make the whole thing that much easier.
12/44th of the mass of CO2 is from carbon, so that is 4 x 10^18 g of carbon to deal with if we wanted to store all the carbon current in atmospheric CO2.
The density of carbon depends on what form it is in--diamond is a lot denser than graphite, which is a lot denser than carbon powder. Let's store it as graphite, which has a density of 2.2 g/cm^3.
We'd need 1.8 x 10^18 cm^3 for that much powdered carbon, or 1.8 x 10^12 m^3, or 1800 km^3.
But remember that we are getting all this carbon we need to deal with using energy from massive solar farms. Put the solar panels a few meters off the ground, and dump the graphite under the solar panels. If the graphite was dumped into a pile 1 m tall it would need 1800 km^2 of area.
That would be just a tiny fraction of the area available under the amount of panels we'd have to be using to capture that much carbon. Spread evenly under all the panels it would be less than a millimeter.
Perhaps I should have said increasing the amount of equilibrium biomass or something to more clearly include rewilding or ecosystem changes. It’s not just plants that are a carbon store, after all.
I don’t think this is likely to represent a full solution, if that is the subtext to your comment.
A single 708 km x 708 km would have these corners (Paris, Berlin, Vienna, Milan):https://goo.gl/maps/DTxdVCcK3aYUEirw8 (Rough approximation!)
30 of these: 21,240 km x 21,240 km
Factoid actually means something that sounds true but isn't, which is exactly the case with the post you're referring to because they didn't account for the extra losses on top of the base thermodynamics.
"a small probably unimportant but interesting fact"
China will likely become carbon neutral before the US, current coal plants notwithstanding.
We’re still burning record amounts of coal for energy.
https://www.forbes.com/sites/rrapier/2023/09/04/global-coal-...
Will these processes need to wait until we can get the proper amount of renewable energy?