Talk:Carbon sequestration

Section on mineralization and deep sea sediments

I've recently moved a textblock, see this change. I've moved it from Direct deep-sea carbon dioxide injection, formerly called ocean storage of carbon dioxide on advice by Gabby Kitch: "Mineralization and deep sea sediments" section is an active area of research, which would be coupled with direct ocean capture of CO2. The mineralization section is related to basalt storage do you could collate them together and/or subset as needed." It's quite possible that the text block will need condensing and updating. I'll try to do that later. EMsmile (talk) 13:26, 1 December 2022 (UTC)

Is this image useful here?

Relationship between above-ground yield (diagonal lines), soil organic carbon (X axis), and soil's potential for successful/unsuccessful carbon sequestration (Y axis). Basically, the higher the yield, the more land is usable as a GHG mitigation tool (including relatively carbon rich land).

I've just taken out the image to the right from the article on energy crop as I felt it was too complicated for that article. Would it fit for this article? Check also if any of the content about carbon neutrality at energy crop, biomass (energy) or bioenergy fits here and should be partially moved, copied or linked? EMsmile (talk) 09:08, 25 January 2023 (UTC)

Thanks for this EMsmile

This diagram is specific to a perennial tall grass, Miscanthus which produces high yields. The diagram is found in the WP article https://en.wikipedia.org/wiki/Miscanthus_%C3%97_giganteus

The diagram indicates that carbon sequestration is only occurring when the SOC is on the low to mid range and this switches to net emissions of carbon in the mid to high range of SOC. The conclusion is that carbon depleted soils will sequester carbon while fertile carbon rich soils will not sequester. If this is the message, then the diagram is useful for the article. That is "carbon-depleted soils will sequester more than fertile carbon rich soils if perennial grasses are grown on them."

But the existing caption (repeated from the Miscanthus article) provides a rather confusing message which needs to be corrected: "Basically, the higher the yield, the more land is usable as a GHG mitigation tool (including relatively carbon rich land)" ie this is not for carbon rich land as far as I can see. ASRASR (talk) 11:37, 1 February 2023 (UTC)

Thanks. I don't understand it all but leave it up to you to decide if or how you want to include this image in the article or not. Thanks again for working on this article. EMsmile (talk)

Is this useful for the geological sequestration section?

I've cut out the below content from carbon sink and wonder if any of it is useful for this article, or if it's already all here. It seems a bit outdated and poorly sourced anyway. Or should it rather be merged into carbon capture and storage as it's really all about storage?

Geological sequestration

The method of geo-sequestration or geological storage involves injecting carbon dioxide directly into underground geological formations. Declining oil fields, saline aquifers, and unmineable coal seams have been suggested as storage sites. Caverns and old mines that are commonly used to store natural gas are not considered, because of a lack of storage safety.

CO₂ has been injected into declining oil fields for more than 40 years, to increase oil recovery. This option is attractive because the storage costs are offset by the sale of additional oil that is recovered. Typically, 10–15% additional recovery of the original oil in place is possible. Further benefits are the existing infrastructure and the geophysical and geological information about the oil field that is available from the oil exploration. Another benefit of injecting CO₂ into oil fields is that CO₂ is soluble in oil. Dissolving CO₂ in oil lowers the viscosity of the oil and reduces its interfacial tension which increases the oils mobility. All oil fields have a geological barrier preventing upward migration of oil. As most oil and gas has been in place for millions to tens of millions of years, depleted oil and gas reservoirs can contain carbon dioxide for millennia. Identified possible problems are the many 'leak' opportunities provided by old oil wells, the need for high injection pressures and acidification which can damage the geological barrier. Other disadvantages of old oil fields are their limited geographic distribution and depths, which require high injection pressures for sequestration. Below a depth of about 1000 m, carbon dioxide is injected as a supercritical fluid, a material with the density of a liquid, but the viscosity and diffusivity of a gas. Unmineable coal seams can be used to store CO₂, because CO₂ absorbs to the coal surface, ensuring safe long-term storage. In the process it releases methane that was previously adsorbed to the coal surface and that may be recovered. Again the sale of the methane can be used to offset the cost of the CO₂ storage. Release or burning of methane would of course at least partially offset the obtained sequestration result – except when the gas is allowed to escape into the atmosphere in significant quantities: methane has a 80-fold higher global warming potential than CO₂ (during the first twenty years).

Saline aquifers contain highly mineralized brines and have so far been considered of no benefit to humans except in a few cases where they have been used for the storage of chemical waste. Their advantages include a large potential storage volume and relatively common occurrence reducing the distance over which CO₂ has to be transported. The major disadvantage of saline aquifers is that relatively little is known about them compared to oil fields. Another disadvantage of saline aquifers is that as the salinity of the water increases, less CO₂ can be dissolved into aqueous solution. To keep the cost of storage acceptable the geophysical exploration may be limited, resulting in larger uncertainty about the structure of a given aquifer. Unlike storage in oil fields or coal beds, no side product will offset the storage cost. Leakage of CO₂ back into the atmosphere may be a problem in saline-aquifer storage. However, current research shows that several trapping mechanisms immobilize the CO₂ underground, reducing the risk of leakage. EMsmile (talk) 11:53, 3 February 2023 (UTC)

References

EMsmile (talk) 11:53, 3 February 2023 (UTC)

Please add better info about terminology

The first section is called "description" which is a strange section heading. Can we please split that up into one on Terminology (or "definition") and the other part might be about "Types" or "Components"? I feel we need a section on terminology as it's all a bit of a mess. Compare with the definitions section at climate change mitigation which I think is useful. Here in this article we have a hatnote and the hatnote text could be explained in a definitions section: "This article is about storing carbon for a long time so that it is not in the atmosphere. For removing carbon dioxide from point sources before it enters the atmosphere, see Carbon capture and storage. For removing carbon dioxide from the atmosphere, see Carbon dioxide removal." . Also it would be helpful to have a sentence to explain how carbon sequestration differs from the concept of carbon sink. Also, can we please have a better first sentence? Currently it's "Carbon sequestration is the process of storing carbon in a carbon pool". I find it very strange that it talks about carbon pool which then redirects to carbon cycle. EMsmile (talk) 12:52, 3 February 2023 (UTC)

Also compare with how carbon sequestration is framed in the main climate change article: https://en.wikipedia.org/wiki/Climate_change#Carbon_sequestration. It says there "Natural carbon sinks can be enhanced to sequester significantly larger amounts of CO2 beyond naturally occurring levels.". Interesting the adjective "natural", does that mean we also have artificial carbon sinks? I guess that's those wooden buildings maybe? EMsmile (talk) 13:00, 3 February 2023 (UTC)

I've had a go at it myself now. Please check if I am on the right track. If there are even more definitions of the term around, let's add them. So far I have added two. EMsmile (talk) 14:31, 6 February 2023 (UTC)

Can we have a better first sentence? And more questions.

The first sentence currently says "Carbon sequestration is the process of storing carbon in a carbon pool" which is taken from the Glossary of the IPCC AR 6 WG I report. I am all for using IPCC reports but in this case I am finding this unsuitable for a first sentence of a Wikipedia article. Can we improve it? It is unclear what is meant. The word "carbon pool" redirects to carbon cycle in Wikipedia. But in the IPCC glossary, a carbon pool is explained as "Pool, carbon and nitrogen: A reservoir in the Earth system where elements, such as carbon and nitrogen, reside in various chemical forms for a period of time. See also Reservoir, Sequestration, Sequestration potential, Sink, Source and Uptake." - Overall, I am finding this entire article avery unclear. It overlaps a lot with the "storage" component of the article carbon capture and storage. The short description of the article says Capture and long-term storage of atmospheric carbon dioxide. EMsmile (talk) 10:58, 6 February 2023 (UTC)

Also, interestingly, this article only exists in 10 other languages in Wikipedia (it does not exist in German and French). As the German Wikipedia is normally very advanced on all the climate change topics it does make me wonder. Maybe it overlaps too much with related topics, e.g. carbon sink. EMsmile (talk) 10:58, 6 February 2023 (UTC)

I've done a bit of work on the first sentence and on the terminology section now. Needs further eyes and brain power. EMsmile (talk) 14:32, 6 February 2023 (UTC)

Removed content about reducing emissions

I've removed this content as it was deviating from the main topic (emissions are the subject of the article greenhouse gas emissions from agriculture. Also it was unsourced; some of it unsourced since 2010. EMsmile (talk) 12:16, 7 February 2023 (UTC)

Reducing emissions

Increasing yields and efficiency generally reduces emissions as well, since more food results from the same or less effort. Techniques include more accurate use of fertilizers, less soil disturbance, better irrigation, and crop strains bred for locally beneficial traits and increased yields.

Replacing more energy intensive farming operations can also reduce emissions. Reduced or no-till farming requires less machine use and burns correspondingly less fuel per acre. However, no-till usually increases use of weed-control chemicals and the residue now left on the soil surface is more likely to release its CO
₂ to the atmosphere as it decays, reducing the net carbon reduction.

In practice, most farming operations that incorporate post-harvest crop residues, wastes and byproducts back into the soil provide a carbon storage benefit. This is particularly the case for practices such as field burning of stubble – rather than releasing almost all of the stored CO
₂ to the atmosphere, tillage incorporates the biomass back into the soil. EMsmile (talk) 12:16, 7 February 2023 (UTC)

Useful content about sediment?

I think this text block that I have just cut out of blue carbon fits better here. But as I am not 100%, I am copying it to the talk page first:

Sedimentation and blue carbon burial

Ways one blue carbon habitat can influence carbon processing in an adjacent blue carbon habitat 

Carbon cycle

Organic carbon is only sequestered from the oceanic system if it reaches the sea floor and gets covered by a layer of sediment. Reduced oxygen levels in buried environments mean that tiny bacteria who eat organic matter and respire CO₂ cannot decompose the carbon, so it is removed from the system permanently. Organic matter that sinks but is not buried by a sufficiently deep layer of sediment is subject to re-suspension by changing ocean currents, bioturbation by organisms that live in the top layer of marine sediments, and decomposition by heterotrophic bacteria. If any of these processes occur, the organic carbon is released back into the system. Carbon sequestration takes place only if burial rates by sediment are greater than the long term rates of erosion, bioturbation, and decomposition.

Spatial variability in sedimentation

Sedimentation is the rate at which floating or suspended particulate matter sinks and accumulates on the ocean floor. The faster (more energetic) the current, the more sediment it can pick up. As sediment laden currents slow, the particles fall out of suspension and come to rest on the sea floor. In other words, fast currents can carry many heavy grains, while a slow current can pick up only tiny pieces. As one can imagine, different places in the ocean vary drastically when it comes to the amount of suspended sediment and rate of deposition.

Open ocean

The open ocean has very low sedimentation rates because most of the sediments that make it here are carried by the wind. Wind transport accounts for only a small fraction of the total sediment delivery to the oceans. Additionally, there is much less plant and animal life living in the open ocean that could be buried. Therefore, carbon burial rates are relatively slow in the open ocean.

Coastal margins

Coastal margins have high sedimentation rates due to sediment input by rivers, which account for the vast majority of sediment delivery to the ocean. In most cases, sediments are deposited near the river mouth or are transported in the alongshore direction due to wave forcing. In some places sediment falls into submarine canyons and is transported off-shelf, if the canyon is sufficiently large or the shelf is narrow. Coastal margins also contain diverse and plentiful marine species, especially in places that experience periodic upwelling. More marine life combined with higher sedimentation rates on coastal margins creates hotspots for carbon burial.

Submarine canyons

Marine canyons are magnets for sediment because as currents carry sediment on the shelf in the alongshore direction, the path of the current crosses canyons perpendicularly. When the same amount of water flow is suddenly in much deeper water it slows down and deposits sediment. Due to the extreme depositional environment, carbon burial rates in the Nazare Canyon near Portugal are 30 times greater than the adjacent continental slope. This canyon alone accounts for about 0.03% of global terrestrial organic carbon burial in marine sediments. This may not seem like much, but the Nazarre submarine canyon only makes up 0.0001% of the area of the worlds ocean floor. EMsmile (talk) 11:48, 8 February 2023 (UTC)

To EMsmile I don't think the first paragraph dealing with "sedimentation and blue carbon burial" merits placement in the "carbon sequestration" article for several reasons. The first sentence is rather misleading. It reads "Organic carbon is only sequestered from the oceanic system if it reaches the sea floor and gets covered by a layer of sediment". This is confusing since sediment is composed of both organic and inorganic material. So the logic is flawed. One would need to specify "inorganic" sediment which rarely exists on its own. There is however a more fundamental flaw in the reasoning. Organic carbon is still subject to methanogenesis under anaerobic conditions and thus can escape as methane gas. So the statement about it being permanently sequestered is questionable unless we are talking about super depths with such high pressure that the methane hydrate would not escape back to the atmosphere. How significant blue carbon burial is for sequestration would need to be clearly stated and referenced before going ahead. So I think I would put the section back where it came from. The 4 paragraphs that follow deal mainly with the process of sedimentation in various marine areas and not carbon sequestration per se so I would put these back where they came as well. ASRASR (talk) 23:34, 28 February 2023 (UTC)

OK, then we just leave it where it is for now (parked on the talk page). I don't want to move it back to where it came from (blue carbon) because it doesn't fit there either. It goes into too much detail and its not well sourced. Also, I checked in the IPCC AR 6 WG I report and the term "blue carbon burial" is not mentioned there. Marine sediment is included but I didn't find content on the importance of any blue carbon burial so I assume it is not a significant sink at this stage. We could maybe look out to see if there are other publications that explain a bit more about sediment and the potential for burial in the deep ocean floor (if that is of relevance here). EMsmile (talk) 00:21, 1 March 2023 (UTC)

References

EMsmile (talk) 11:48, 8 February 2023 (UTC)

Lead section - undue weight on artificial methods

I'm concerned that the lead section of this article is heavily weighted towards human intervention, and particularly on deep geologic storage of carbon dioxide. The lead says nothing about the carbon-sequestering value of leaving old growth forests, peatlands, and native grasslands alone. Deep geologic storage of carbon dioxide, which is an expensive and thus-far little-used technology, is mentioned three times:

1. "within carbon capture and storage projects"
2. "Artificial processes have been devised to produce similar effects, including large-scale, artificial capture and sequestration of industrially produced CO2 using subsurface saline aquifers or aging oil fields. Other technologies that work with carbon sequestration include bio-energy with carbon capture and storage, biochar, enhanced weathering, direct air carbon capture and sequestration (DACCS)."
3. "Carbon dioxide that has been removed from the atmosphere can also be stored in the Earth's crust by injecting it into the subsurface"

By rough estimates, anthropogenic carbon removal sequesters 2 gigatons of CO2 per year, including a tiny amount of deep geologic sequestration. Non-anthropogenic processes sequester around 10 times as much. I will add a POV tag to the article as I think this bias in the lead is severe. Clayoquot (talk | contribs) 22:32, 16 April 2023 (UTC)

Where do we stand with this now? I noticed that User:Jack4576 removed the tag that Clayoquot had added, in this edit with this edit summary: "there are presently no active NPOV or neutrality discussions on the talk page". Does that mean the issue with the lead has been resolved? EMsmile (talk) 14:15, 14 March 2024 (UTC)

I see some of the repetition around DAC has been removed, which is good. However, I don't think the issues with the lead have been resolved. My comment above saying there is nothing about the carbon-sequestering value of leaving old growth forests, peatlands, and native grasslands alone. has not been addressed. The following has also been removed, which makes the lead even less informative about the significance of vegetation:

Forests, kelp beds, and other forms of plant life absorb carbon dioxide from the air as they grow, and bind it into biomass. However, these biological stores are considered volatile carbon sinks as the long-term sequestration cannot be guaranteed. For example, natural events, such as wildfires or disease, economic pressures and changing political priorities can result in the sequestered carbon being released back into the atmosphere.

Clayoquot (talk | contribs) 16:38, 14 March 2024 (UTC)

Hello, I had moved that paragraph today from the lead to the main text as I felt it wasn't a suitable summary. The content about a carbon sink being "volatile" or not was not described in the main text yet. In the lead, this information about it being a volatile carbon sink was confusing to me. It sounded like volatile means not really a carbon sequestration, at least not a long-term one. Do we understand carbon sequestration as storage regardless if long or short-term? Perhaps we could clarify this with a sentence or two in the definition section and then summarise it in the lead. EMsmile (talk) 21:36, 14 March 2024 (UTC)

I also plan to move big chunks of this article from the "geologic sequestration" section to the carbon capture and storage article as I think it fits better there. Unless there are objections. EMsmile (talk) 21:37, 14 March 2024 (UTC)

Carbon sequestration can be either short or long term. Instead of "volatile" you can just say "impermanent". The points in the section that you removed are important for the lead. "Forests, kelp beds, and other forms of plant life absorb carbon dioxide from the air as they grow, and bind it into biomass" is the most important sentence in the article. One of the most important sentences in the encyclopedia, I would venture to say. Clayoquot (talk | contribs) 00:02, 15 March 2024 (UTC)

Feel free to put it back in. Would be good if you could also explain there the issue of permanent versus impermanent. When C sequestration is done as part of CCS then it's meant to be permanent. When C sequestration is done as part of normal photosynthesis then it's not permanent, right? Maybe the issue is that the term "carbon sequestration" is used with different connotations in the biology context (natural carbon cycle) versus the climate change mitigation context (locking away carbon). But I am just guessing.

I don't follow you though when you say "One of the most important sentences in the encyclopedia, I would venture to say". How so? Isn't it just a sentence that describes the basics of photosynthesis? "plant life absorbs carbon dioxide from the air as they grow, and bind it into biomass". How is this so special?

What about my other suggestions about moving stuff out and trimming the article down (and the edits that I did yesterday). I see it as a high level article that should not go into too much detail for all the different processes, natural or engineered ones. - Pinging User:InformationToKnowledge as I always find it interesting when they critique an article. EMsmile (talk) 09:39, 15 March 2024 (UTC)

I put it back in. I don't have the energy for further discussion on this. Clayoquot (talk | contribs) 06:24, 18 March 2024 (UTC)

Example of orange peels removed

I've removed this recently added text block as I felt it was too specific an example and didn't really fit into this kind of high level overview article. Please discuss if you think it really does belong here:

"In 1997-1998, approximately 12,000 tons of orange peels were dumped on degraded land in Costa Rica. In 2013, researchers found the land had more tree biomass, more forest canopy, and richer soil than unfertilized land nearby. Princeton University ecologist Timothy Treuer remarked "This is one of the only instances I've ever heard of where you can have cost-negative carbon sequestration."" EMsmile (talk) 14:18, 14 August 2023 (UTC)

References

EMsmile (talk) 14:18, 14 August 2023 (UTC)