Can Sucking CO2 Out of the Atmosphere Really Work? | Hacker News Reader

Can Sucking CO2 Out of the Atmosphere Really Work?

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His scheme seems to be, "We can pay for sucking CO2 out of the atmosphere by selling the CO2." Okay, reasonable enough, but just a quick question: doesn't the sold CO2 just get dumped back in the atmosphere?

He suggests that industrial CO2 is used to rejuvenate oil wells, carbonate beverages, and juice up commercial greenhouses. Of those, carbonated beverages CERTAINLY release all their CO2 back into the atmosphere in a time-frame of at most years and probably weeks. I assume that some percentage of the CO2 used in commercial greenhouses is turned into, well, plants (though most plants pretty quickly decay and release their CO2 back into the atmosphere, with the exception perhaps of some woods), but I'd guess that 90%+ of it goes back into the atmosphere. I'm not sure how much of the gas stays underground for decades in the case of pumping CO2 into an oil well.

I suppose the idea is that "the CO2 has to be bought and used anyway" and so this atmosphere-extracted CO2 would displace it, thereby substituting for CO2 that would otherwise be a net addition.

That is, instead of

[other source] -> [atmosphere]

it would be

[atmosphere] -> [atmosphere]

OTOH, there could be a sort of "reverse Jevons effect" here, where this simply bids down the price of CO2 and leads people to simply put it to more uses, so this new source is simply in addition to all those other traditional CO2 sources.

But the premise of this technology is not simply that it mitigates carbon gain in the atmosphere, but that it can actually sink away some of the carbon produced by the (vastly more significant than direct industrial uses of CO2) fossil fuel industry.

If all it can do is mitigate the amount of carbon released into the atmosphere by greenhouses and beverages, then that seems so unimportant that it can't possibly be worth bothering with.

What you're describing is the end game. The CO2 for beverages is only one example of a mid-game strategy to get to the end game.

I can't think of any real industrial uses that seem like they scale up and do not release the used CO2 into the atmosphere.

Where does the CO2 in carbonated beverages come from currently? Is it something produced which would now be displaced resulting in a net reduction? If we're producing CO2 as the product, we could lower that amount by recycling already produced CO2.

Carbonated beverages are a red herring. This page[1] says a can of soda has 2.2g of CO2. If every single person in the world (population 7.125B) drinks 10 cans of coke every day for a year, we will be using 63 Mt of CO2.

Mankind emitted 33615 Mt of CO2 in 2010[2].

[1] http://chemistry.stackexchange.com/questions/9067/what-is-th... [2] http://en.wikipedia.org/wiki/List_of_countries_by_carbon_dio...

(Edit: sorry I at first miscalculated the result to be 6.3 Mt.)

I only intended to point out it is possible to reduce CO2 emissions by recycling it, even it the end product releases the same amount of CO2.

I don't know that we produce CO2 for CO2, or where the numbers lie. Just that the prior post said it gets released anyway, so how can it be an improvement?

Most of the commercial CO2 in the US is captured from natural gas 'sweetening' or from fertilizer production. It's transported from the plants/refineries in a rather substantial pipeline network mostly in the South. Companies like Air Products and Praxair typically buy CO2 off of these pipelines and then clean it up to whatever specification is required (Industrial, Food & Beverage, Pharmaceutical, etc) then sell it to the end users. I wouldn't be surprised if the major beverage companies had their own connections to the pipeline and did their own processing, but they're only a small portion of the commercial CO2 market.

No idea at all.

But even if it is, this is more in the line of mitigating current CO2 increases than "taking CO2 out of the atmosphere." And if you grow the market for carbonated beverages by having cheaper CO2, that market growth will be CO2-positive, not CO2-reducing.

> though most plants pretty quickly decay and release their CO2 back into the atmosphere, with the exception perhaps of some woods

There are ways to keep a fair amount of the carbon. Old plant material should be composted and thus recycled. An alternative is to create biochar and amend soil with it, which has potential to sequester the carbon for millennia. Some farms use a no-till method to add the organic matter into the soil.

Basically, if the commercial greenhouses do anything with their plant waste apart from putting it in a landfill then it's back in the growth cycle of some other plant.

We already have free self-replicating devices that do just that: plants. Just add water.

The oceans are the largest carbon sinks currently: http://en.wikipedia.org/wiki/Carbon_sink. My professor in college predicted that at some point we'll start building highly efficient CO2 sinks out of specific types of plankton and dumping them into the oceans to float around and offset our bad CO2 behavior.

We need to be sucking CO2 out of seawater, not the air. If we suck it out of the air, it has to come back out the ocean before we can grab it. The atmosphere and the ocean are in balance, so grab where the grabbing is good, the ocean.

Right. Creating large pytoplankton biomasses would theoretically pull bicarbonate out of the seawater. It's not unlike how carbon deposits were formed for the natural gas and oil we use today.

The real downside is that if did it at the scale necessary to have an impact, you're also going to be creating HABs (Harmful Algal Blooms) that could potentially change the Earth's climate themselves.

Dump them into the ocean? That's a bit of a scary thought. Not only tinkering with the oceans ecological balance, but also the idea of our genetically engineered plankton spawning out of the control. I'd prefer to keep them in controlled environments.

Iron fertilization (http://en.wikipedia.org/wiki/Iron_fertilization ) is a little less likely to spiral out of control, and once discontinued should stop having an effect in relatively short order. I've brought it up to people and had them say such large scale experiments are too scary to carry out, but we are already engaged in a CO2 experiment of that scale (without much ability to cease the input).

>once discontinued should stop having an effect in relatively short order

Not even close. The largest iron fertilization "experiment" to date was done by Russ George with just 100 tonnes off the Pacific coast of Canada in 2012.

It's now 2014 and the salmon population has quadrupled from the algal bloom. We don't know what sort of impact iron fertilization at scale will have on the ecosystem.

Consider that you could have provided more information without trying to pin down what I was thinking (or could've asked what I was thinking). I've tried several different ways to say that, this one seems the least whiny.

What?

"relatively short" is a pretty fuzzy statement, saying it's "Not even close." invites me to try to argue about what I was thinking when I wrote it (ooh fun), and it isn't all that necessary to your point.

Yes it is, but I have a feeling you're still going to be bitter and worm your way into contonuing to patronize.

I was trying to express frustration (I think unnecessary argumentation often damages discussions here), but I take your point, such things can come across poorly.

We're geoengineering no matter what we do. Might as well geoengineer in a way that we think has a possibility of success.

Yeah, it's a great theory, but in practice there are some obstacles.

Most quick-growing plants have a short life-cycle after which they decay and put their carbon back into the atmosphere. The only plants that really lock up carbon for decades or centuries are trees, and growing new forests is slow and daunting. You can solve the fast-growing plant problem by continuously growing plants (so as the old ones die, new ones lock up the same amount of carbon), but that means that a given acre of land has to be devoted in perpetuity to locking up X amount of carbon. And fast-growing, large plants tend to degrade soil quality -- they need rich nutrients to support that fast growth. They also need water, which is not necessarily locally abundant.

Reforestation is still probably the best way to capture carbon from the atmosphere. Do something where you build a young-growth forest, cut down trees and do something with the wood other than allow it to decay or burn it, let new trees grow. But it's not just a matter of flinging some seeds on the ground and yelling "Done!"

You sound like you've looked into this, but at a glance this seems implausible.

I have a compost pile, and to it I add fast growing plants from my garden. I presume that the carbon mass of the plants has mostly been extracted from atmospheric CO2. Empirically, as time goes on the pile gets larger. I've always presumed that the a significant portion of the resulting pile is carbon. I'd be surprised if any significant fraction of my compost pile were to suddenly evaporate. If I plow the compost into the soil, I'd be even more surprised if it were to disappear.

So while there might be considerable loss of CO2 back to the atmosphere during during the composting process, and while (worse) there might be considerable methane released, isn't it safe to say that the increased carbon mass of the pile represents CO2 that has been removed from the atmosphere? And that if this compost is buried and the soil mass increases, the difference can be counted as sequestered CO2? Where's the flaw in my logic?

Soil respires CO2 (from microbial digestion, primarily), actually probably more actively than your compost pile does because it increases the surface area / mass ratio.

Exactly how long carbon is sequestered in plant litter is an actively researched topic, and the general consensus seems to be that it depends a lot on temperature, soil composition, etc. But the overview is that worldwide, the feeling is that about 3x as much carbon is contained in soil as in living plants, almost all of that carbon being the result of plant litter. On a macroscopic level across all time-frames, clearly the carbon cycle is basically closed, so the amount respired out by the litter is the same amount as in. On a more local level, we may now have a lower-than-usual amount of carbon in the soil, as modern agricultural techniques and deforestation may have released more carbon from the soil than usual.

Empirical results seem to confirm the intuition that woods and such sequester carbon longer than quicker-decaying substances, and indeed how could they not?

So as a very, very rough rule of thumb, I'd say that you'd expect a fast-growing plant to sequester carbon for roughly 2-3x its lifespan (and of course some of that is carbon release happens quickly and some more slowly).

Looking into it a little more, I was definitely underestimating the amount of CO2 released from soil after the incorporation of compost. But I'm a little confused by your rule-of-thumb, or more particularly, the assumption that the soil carbon levels are constant.

While the percentage may remain constant in the steady state, why doesn't the soil mass increase? For example, I presume the total mass of carbon in the soil is greater now than it was prior to the evolution of green plants. At what point did it transition from accumulation to steady-state?

I'm not saying it didn't, just that I don't understand the logic that it must have. For example, I'd guess that there is more absolute organic matter in the soil in the northern US now than there was just after the retreat of the glaciers. Is this false? In the absence of erosion (and human agriculture) I'd presumed this process was still continuing.

Also: where was all the carbon hundreds of millions of years ago before it was turned into fossil fuels? I guess "steady state" is a relative term when you get to long time periods.

Your ever-growing compost pile might be analogous to peatlands, but on the other hand it will probably just be returned back to the atmosphere in the next 100 years. The future occupants of your property are unlikely to continue your experiment :)

My guess is that anything we gain in that regard is more than offset by all the land that's covered in asphalt and concrete and also modern farming techniques and general deforestation. Very little carbon sequestration going on in the modern world..

On a medium-long timescale, it has to be basically even, right? If the amount of carbon captured in the soil were secularly increasing at 10% per century, then we wouldn't have any carbon anywhere besides the soil -- even if it was all released at the last ice age.

If the amount of carbon in the soil is secularly increasing at 0.01% per century, well, that's maybe interesting geologically, but for the purposes of handling climate change in the next century or two, we can treat that as equivalent to "it's steady state."

It can't really be even, though. Otherwise how did all the fossil fuels form? Over geological time periods the co2 and o2 levels vary greatly. Maybe if not for mankind the atmosphere would actually have eventually ended up co2-poor over time ;)

But I guess that timeframe isn't very relevant to any climate change we'll be experiencing in the near future.

Decomposing involves releasing the carbon from the plant fibers back into the atmosphere as CO2 usually.

To quote the EPA "Composting also results in biogenic CO2 emissions associated with decomposition, both during the composting process and after the compost is added to the soil." - http://www.epa.gov/climatechange/wycd/waste/downloads/compos...

It's a great article (better than I had found, thanks!), but I think it says pretty clearly that although there are significant losses due to CO2 being released during the composting process, the net effect is large and positive:

"Overall, EPA estimates that centralized composting of organics results in net carbon storage of 0.20 MTCO2E per wet short ton of organic inputs composted and applied to agricultural soil."

"Based on the expert judgment of Dr. Michael Cole from the University of Illinois, EPA found that between 4 to 20 percent of the carbon in compost degrades very quickly, and the remainder can be considered either slow or passive. Dr. Cole found 400 years to be the average of the reported sequestration times of carbon in the soil."

Elsewhere they mention that the carbon content of wet compost is about 20%. Again, so while the conversion is not perfect, is there dispute that composting green materials and adding the compost to the soil results in net CO2 sequestration?

The sticking point seems to be the energy required to process the CO2. How to get that energy in a way that doesn't produce more CO2 than is captured seems like a hard problem, approaching a violation of the laws of thermodynamics.

Perhaps the reason he's gotten little interest so far is that he hasn't shown his process to be CO2-negative, and the experts are skeptical of what might amount to a very complicated version of yet another perpetual motion machine.

I don't think nuclear, solar, wind or hydro plants produce much CO2.

The whole premise of carbon capture is that we're still burning fossil fuels. If the world literally eliminated 100% of carbon emissions then biological carbon sinks (plants) would eventually restore the natural equilibrium, the problem is we're burning more carbon than they can keep up with.

Using nuclear power to sequester carbon is useless if someone else is still using carbon to power their air conditioner or whatever, you would do better to just use the nuclear power to run the air conditioner.

> If the world literally eliminated 100% of carbon emissions then biological carbon sinks (plants) would eventually restore the natural equilibrium

Unfortunately this would take several centuries, maybe a 1000 years. Weirdly enough this is sometimes used as an argument not to cut emissions[1].

Also, we're not in equilibrium right now. The consequences of the CO2 that is already emitted have not yet fully manifested themselves. If we don't want to live for centuries with those consequences, then cutting all emissions is not enough. We'll have to actively remove CO2 from the atmosphere somehow.

[1] http://blogs.news.com.au/heraldsun/andrewbolt/index.php/hera...

There are lots of good reasons to burn carbon to produce energy. What we need is a carbon tax that goes to operations such as these, bound to the waste energy from nuclear or solar plants, for example. That way the carbon emissions can be offset by the carbon intake.

Maybe we could burn all the carbon we wanted, at a rate even far exceeding the rate we make carbon emissions today, if those emissions were balanced with large-scale carbon removal. If that carbon removal produced fuel, that would be fine - the balance would be a lot closer to zero, and more importantly, we could have a control on the acceptable carbon in the atmosphere.

There is no "burn all the carbon we wanted" regardless of climate change because we're eventually going to run out of cheap oil. The cost of recovering it will eventually exceed the cost of renewable energy. The problem is that waiting until that point to stop burning oil and coal would do catastrophic damage to the planet.

The thing that makes much better sense is to have a carbon tax and use the money to subsidize non-fossil energy on a per KWh basis, and set the amount such that it makes non-fossil energy cheaper. Do that and the market would sort it out in short order.

We are in complete agreement in that the way out of the current mess is a world-scale governmental movement to assert policy change that at least tries to solve the problem of human created environmental change, and carbon dioxide specifically.

I don't think we will run out of "cheap" oil though, since oil can be produced from coal and coal is hugely abundant. I agree that waiting for oil to become more expensive than renewables before investing in renewables, or in other words expecting free market dynamics to solve the problem, is not going to work.

That's true, but if electric vehicles don't take over the world, a useful application could be to use nuclear power to make liquid fuels. We could have a carbon-neutral civilization with the same cars, gas stations, and pipelines we have right now.

The manufacturing, maintenance, & mining processes backing them do, albeit less than, e.g., a coal-fired power plant.

I've wondered why we can't capture carbon by using plant matter (or by-products) to meet existing needs for durable goods like buildings and manufactured good that end up in landfills.

Capturing CO2 this way doesn't require storage tanks or energy capture. Has there been any research along these lines?

What does this mean? People living in live trees?

Dead trees (cellulose) keep the carbon pretty fine.

Build more wooded houses, etc. It's important to not let them rot, though, because this releases CO₂ back to the atmosphere.

I thought that when wood and other plants rotted, the main result was a lot of soil which I thought was heavily carbon, from the plants, from CO2, from the atmosphere.

Maybe I'm wrong about this?

Or, growing up, Dad put a lot of ammonium nitrate NH4NO3 fertilizer on the lawn. Then the lawn grew fast enough that I got the job to mow the grass twice a week instead of once each other week. After growing up in that house with that lawn, all the grass clippings raised the level of the top soil by about 1.5" -- this was easy to see next to the concrete driveway and walk ways which I observed close at hand as I ran the electric edger, with its 35,000 RPM motor, between the concrete and the lawn. So, CO2 from the atmosphere turned into grass turned into grass clippings turned into top soil which no doubt had a lot of carbon, originally from the CO2 in the atmosphere. While this is many years later and I moved away long ago, I have to believe that that top soil is still there and very much is not going anywhere, certainly not as CO2 back into the atmosphere.

Net, a lawn commonly does sequester carbon from CO2 in the atmosphere. Here I'm just giving this point as a biological fact and without any judgment about this situation being good, bad, or otherwise for anything in particular.

"Rotting" usually means being slowly consumed by fungi and bacteria, which ultimately break a good part of the cellulose down to very simple compounds like CO₂ and water.

Given that we need to stop emitting carbon into the air within the next few decades to avoid predictions for disaster, I think we should do whatever we can? Energy companies make a great deal of money, and they have a social responsibility to not drive up pollution. It's not just at the infrastructure level, people can also drive less and eat less meat.

I emit carbon each time I exhale. But I would not be surprised if I'm surrounded by sentient vegetables.

The debate about climate change is much more productive. Eventually someone has to realize we have to stop mistreating the ocean.

Do my personal choices really effect the greenhouse gases in the air? I am not sure that they do any more.

don't trees and plants do this? Could'nt we just plant more. Especially on top of buildings?

We could try it! You can do a home experiment with a bottle, some baking soda and vinegar maybe, a lamp and a thermometer to demonstrate how adding CO2 increases the temperature.

Scares the holy-bejeebers out of the kids.

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