Is there a possible way to scrub carbon from the atmosphere on a planetary scale?

Title says it all. Probably been asked before

AIUI, it’s possible, but extremely costly. I read in a book somewhere that the cost of scrubbing carbon this way - enough to fix or reverse climate change - was estimated at $30 trillion or more.

It’s called Carbon Capture and Storage:

Plant trillions of trees.

There are two questions here: (a) is it possible to scrub carbon from the atmosphere and either sequester it or re-use it in synthetic fuel, and (b) is the technology scalable and economical enough to cost-effectively reverse climate change?

There are many ongoing projects to accomplish both aspects of (a), though obviously sequestration is key as creating synthetic fuels is barely carbon-neutral. But it’s generally acknowledged that the answer to (b) is almost certainly “no”. That is, carbon capture and sequestration may be useful in some specific cases, particularly at the point of major carbon emissions, but it is very unlikely to ever supplant the need for extensive emissions mitigation and a complete switchover to clean renewable energy and ultimately a net zero-carbon economy.

A gallon of gasoline weight 6.3 pounds. Burning that gasoline produces 19.6 pounds of CO2.

Sequestering all the CO2 from gasoline would require dealing with three times the weight of material as the original gasoline. Now think of all the pipelines, tanker cars and ships that move gasoline around the world, and the scale of the problem becomes evident.

Sequestering carbon may be part of the solution in some small way for some applications, but it will never scale to become the main solution to global warming. That will require nuclear power. Or new energy storage systems we don’t know how to build and also don’t scale well.

Actually, the answer to b) is absolutely not. The problem isn’t just cost, or even the extraordinary amount of energy that would be required to attempt to sequester even 1% of all of the atmospheric carbon produced in the last few decades, but just the fact that the atmosphere is so thin and carbon is so widely distributed that it simply isn’t feasible to process an amount of air necessary to extract that much carbon dioxide at anything like the rate it was put into the atmosphere (and to avoid the most drastic effects of global climate change we would have to extract it much faster than that) even assuming boundless energy and an infinite budget to distribute millions of extractors across the surface of the Earth. And even if we could, we’d still have to cope with carbon being emitted from the ocean and other sinks being released by heating and other climate changes as well as deforestation and wetland depletion.

If we did want to attempt some industrial process of carbon capture and sequestration, it would make far more sense to remove it from the oceans; carbon dioxide dissolved in ocean water is more or less in equilibrium in concentration with the atmosphere, but because of the difference in density between the mediums it is far easier (in theory, at least) to extract more carbon dioxide from the oceans. In addition, reducing acidification of ocean water would help to revitalize coral reefs, which are of course massive carbon sinks. There are concepts for systems that would essentially be solar-powered free-floating platforms sequestering carbon dioxide and actually processing it into synthetic liquid hydrocarbons such as dimethyl ether that could be used as fuel although at the cost of releasing the sequestered carbon, so it is more of a means of offsetting current carbon releases rather than permanent sequestration. However, all of these technologies are at best at a basic proof-of-concept level and would not conceivably be ready for wide deployment inside of a decade even with heroic effort, so as a means of reversing atmospheric carbon levels they aren’t even a ‘Hail Mary’ pass, and are best thought of as technologies for future atmospheric carbon maintenance.

“Plant trillions of trees” is a good idea as far as it goes because there are a multitude of benefits from reforestation of “overdeveloped” (i.e. heavily paved) urban areas and underutilized agricultural land, but as a solution to reverse the effects of climate change it is woefully inadequate because it simply doesn’t sequester carbon quickly enough to be useful, and of course trees and other vegetative matter utilize carbon while they are growing but are then decomposed or can burn, releasing carbon back into the atmosphere. Wetlands actually do a better job of carbon capture, producing carbonaceous peat which is prevented from aerobic decay by being saturated by water and can actually absorb more carbon that it releases. Rebuilding and expanding wetlands also provides a buffer against storm surges that come with rising ocean levels and extreme storm events, and although it comes at the cost of displacing developments on and near oceanfronts, the reality is that these areas are going to become increasingly difficult to defend and inhabit anyway.

Nuclear fission power production would seem to be a good alternative to transition away from the use of fossil fuels for electrical power because the actual process of nuclear fission does not release carbon dioxide, methane, or other ‘greenhouse gases’; however, it comes with a large number of caveats not the least of which is the fact that conventional Generation III and proposed Generation IV nuclear fission power plants are huge facilities requiring millions of tons of concrete, steel, and other materials that have a high carbon footprint to produce, and because all of this is an up-front cost in building the plants even if the lifetime energy budget is carbon-negative, it produces a lot of atmospheric carbon at exactly the time that carbon production needs to be reduced. In addition, there are multiple bottlenecks in expanding nuclear fission power to replace fossil fuel power sources, including suitable siting, the skills necessary to build and maintain safety-critical nuclear plants, and of course the fuel itself which requires extraction, chemical milling, refining, enrichment, and processing, all of which are energy-intensive and polluting activities.

In fact, the United States is not even able to produce half of the moderately enriched 235Uranium fuel for the current 93 nuclear power plants currently in operation in this country; scaling up to the nearly two orders of magnitude increase in nuclear power facilities would require expanding fuel enrichment by about a factor of 200, which is a daunting prospect considering that most previously operational enrichment facilities are now Superfund cleanup sites and few communities would be willing to play host to enrichment facilities regardless of the employment opportunities they would bring. Multiply that by all of the developed nations which could also consider nuclear fission as a comprehensive alternative to fossil fuels and then factor in all of the developing nations for which the capital cost and technical sophistication of nuclear power is simply not a plausible option, and fission becomes far less attractive even before you get into the geopolitics of uranium sources and the costs of expended fuel disposal and end-of-life remediation of the plants themselves.

This is not to suggest that nuclear fission is not one part of a future energy portfolio; as a baseload electrical power supply its only parity is natural gas, and future developments in nuclear fission technology can mitigate some of the costs and problems with current Gen III plants, but it is far from a panacea even setting aside the practical problems with implementation, and the costs of renewables (particularly photovoltaic solar) have dropped so fast that it is arguable that research into ways to store excess peak power production and improve current electrical grids are a better investment than building thousands of nuclear power plants.

Getting back to the o.p., the only practical near term means of carbon capture and sequestration that has any hope of making a dent in emissions is point-of-source sequestration, i.e. capturing carbon before it is actually emitted into the atmosphere. Unfortunately, although the technology is theoretically viable (to a limited extent, particularly for coal), it is generally used as a smokescreen and PR effort by carbon emitters to establish the pretense of doing a minimum ‘something’ about carbon emissions while actually doing fuck-all by any practical measure. On top of that, the same energy producers then use those PR campaigns to convince end users that it is somehow their personal responsibility to reduce carbon emissions on essentially the same basis that has convinced the general public that they are responsible for packaging waste by shaming them into not using drinking straws.

For your entertainment and edification: The Juice Media “Honest Government Ad” on CCS, followed by a more serious in-depth discussion on the issues and manipulation of public perception:


So, to summarize: We’re doomed?

Carbon capture plant to extract CO2 from the air, produce some kind of commercial product with that, which they can sell:

This article, from a few years ago, isn’t the one I was looking for. I saw a current article just recently (like, yesterday?) that I can’t find now, about a similar plant (in Iceland) about to open, that will be the world’s biggest so far. Article discusses the economics of this, which isn’t commercially feasible yet, but perhaps can become so with further development and up-scaling. I’m continuing to look for this article . . .

ETA: Okay, here’s a current article about the new carbon capture plant, called “Orca”, in Iceland:

More ETA: The company producing this is Climeworks. Here is their own web site promoting this project:

Well, we need to stop thinking in terms of PR technomagic pixie dust solutions that are going to reverse the last fifty years of carbon emissions which represent the release of as much of the carbon sequestered by natural processes over the last 2.5 million years (and in terms of oil and coal, energy resources that have been produced and condense over 300 million years), and we need to start thinking in terms of adaptation and mitigation to inevitable changes in climate. That is, if we want to remain a viable society with the resources for technological innovation and advancement instead of a straggling has-been civilization clinging onto scraps of past honorarium.

If we’d made the decision to start addressing this problem earlier—say, circa 1990 at the end of the Cold War, when the United States and its allies could have rededicated monies and efforts from that ideological threat to the existential hazard of climate change—then we could have possible converted much of the coal and petrofuel based economy to more sustainable sources via technology development. Instead, we doubled down on coal and oil—at times actively shutting down efforts to develop alternative and more sustainable transportation fuels like methanol and DME, or wide scale development of solar and wind power—in spite of the established science that climate change was a real threat. Now we are so deeply invested in fuel that it took decades of coal becoming progressively more fiscally unviable before we abandoned it, notwithstanding the evident environmental destruction of mountaintop removal, and extracting oil from increasingly poorer sources via hydraulic fracturing and wastewater injection, placing the US in the desperate situation of not having a real backup plan.

The irony of this is that there is direct historical precedent, not only in the obvious resource depletion examples like the deforestation of the British Isles, but in unrelenting depletion with long-term consequences, most notably the extraction of peat in the Netherlands which fueled their manufactured goods industry and allowed them to dominate the European economy through the beginning of the 18th Century when they suffered near-collapse and left the country with over a quarter of the country below mean sea level, the consequences with which they are still coping today. There is no magic spell that will fill in Holland’s peat bogs back to pre-1100 CE levels, and there is no siphon that is going to suck all of the CO2 from the atmosphere that is been released into it since the beginning of the Industrial Revolution. Decarbonizing energy production and mitigating what carbon emissions are unavoidable is a start, but it isn’t as if there is any measures that can be taken that will reverse the alterations to the climate system in anything like a human lifetime. The sooner we start to address the problem with that framing in mind, the better equipped we will (hypothetically) be to come up with practicable solutions.

Of course, we won’t do that. We’ll bullshit about ‘clean coal’ and spin fantasies about nuclear plants that nobody wants in their neighborhood running on fuel that isn’t available, and build ineffectual sea walls and continue to live on sandbars like Imperial Beach or Miami Beach until they are subsumed, and will use up ‘fossil water’ aquifers and grow citrus in the desert until agriculture is no longer viable, and in general just assume the future is somebody else’s problem, because that is what we’re good at.


I’ll take that as a “Yes”.

I seem to remember several expensive though realistic possibilities offered in the book Freakonomics.

I share Stranger’s pessimism and agree with his points.

However, there is Ammonia - a completely Carbon free fuel, which is made entirely out of solar and wind. Things move slow in the Fuels Industry - however I am seeing Ammonia make rapid strides. Here is the shipping industry, for example : Why the Shipping Industry Is Betting Big on Ammonia - IEEE Spectrum.

And then finally, if all these options of reducing Carbon Emissions are exhausted, then we will probably get into global dimming technologies / climate engineering. Global dimming technologies are in their infancy and not much is well understood - and it is real fear that they do more damage than good. It involves spraying particles in the upper atmosphere that reflect sun’s rays away from earth.

The way things have gone last 20 years was that big oil companies were doing symbolic carbon emissions cut here and there - while they continued to emit (this was called greenwashing). But there is a definite trend with BP and Shell and the like selling oil assets. I do see that Carbon Emissions will go down - but will it make a dent or not, is debatable.

There was a report several years ago about a US Navy project to capture CO2 from ocean water and synthesize jet fuel from it. It would be installed on aircraft carriers, of course. I think there was a pilot project at the time. I haven’t heard anything about it since then, so have no idea if it’s still going forward or not. Of course the Navy’s main reason is not environmental, but rather to reduce their dependence on delivery of fuel at sea.

A search found they’re still working on it, but have made progress:

Its never going to be reality. CO2 to CO conversion even on land is very cumbersome , then the Fisher Tropsch needed to convert to hydrocarbons is even more cumbersome. These reactions are finicky and need their own dedicated team - so half of the submarine crew will have to be chemical plant operators / engineers.

The trees will eventually die. And rot. And when they rot, the carbon is returned to the air. So perhaps a better idea is this: plant trillions of trees, let them mature, cut them down, then store them in big warehouses. Of course, this will only work if you’re putting less carbon into the air (from chainsaws and truck exhaust) than the carbon contained in the trees.

According to the link, they’ve found a new catalyst which makes CO2 to CO conversion easier and faster. The future research is to find catalysts to do the Fischer-Tropsch thing.

Who said anything about submarines? This is meant for aircraft carriers and making jet fuel.

That is all academic work - and important but an extremely small amount of research catalysts make it to the real industry because lab experiments are conducted at very controlled purities. The case in example is the plethora of academic papers in the 2005 time frame claiming that Hydrogen is the new fuel and how fuel cells / onboard catalysis was going to be in every car.

10-20 years is not unusual for a catalyst to make it from research to industry. Many of the Catalysts we use today are at least 50+ years old.

Yeah - and they have been doing that since the second world war. Guess what : there are a handful of Fisher -Tropsch processes in the world in production with Sasol’s Cobalt based catalyst taking the lead - but even then it wont be feasible for an offshore application because of size and operability constraints.

Faced with these constraints, China went with DME. They converted CO (syngas) to Methanol and then to DME.

My mistake. Assume more than half of the aircraft carrier to be taken up by the plant.

Or bioengineer some new type of tree, plant, microbe, whatever that 1: takes in a high amount of CO2, 2 stores it in a way that it is unlikely to return to the atmosphere when the thing dies.

Everyone thinks trees are great and we should plant more trees and stop deforestation. First of all, the CO2 levels have are not at all reducible by planting trees.

And second, when it comes to paying countries to not cut down forests, people look the other way. Take Brazil and the US , for example.

Bottomline : Don’t look for trees to reverse climate change.