Carbon sequestration is the process involved in carbon capture and the long-term storage of atmospheric carbon dioxide or other forms of carbon to mitigate or defer global warming. It has been proposed as a way to slow the atmospheric and marine accumulation of greenhouse gases, which are released by burning fossil fuels.
Carbon dioxide (CO
2) is naturally captured from the atmosphere through biological, chemical, and physical processes. Artificial processes have been devised to produce similar effects, including large-scale, artificial capture and sequestration of industrially produced CO
2 using subsurface saline aquifers, reservoirs, ocean water, aging oil fields, or other carbon sinks.
- 1 Description
- 2 Biological processes
- 3 Physical processes
- 4 Chemical processes
- 5 Obstruction
- 6 See also
- 7 Notes
- 8 Further reading
- 9 External links
- "The process of removing carbon from the atmosphere and depositing it in a reservoir." When carried out deliberately, this may also be referred to as carbon dioxide removal, which is a form of geoengineering.
- Carbon capture and storage, where carbon dioxide is removed from flue gases (e.g., at power stations) before being stored in underground reservoirs.
- Natural biogeochemical cycling of carbon between the atmosphere and reservoirs, such as by chemical weathering of rocks.
Carbon dioxide may be captured as a pure by-product in processes related to petroleum refining or from flue gases from power generation. CO
2 sequestration includes the storage part of carbon capture and storage, which refers to large-scale, artificial capture and sequestration of industrially produced CO
2 using subsurface saline aquifers, reservoirs, ocean water, aging oil fields, or other carbon sinks.
Carbon sequestration describes long-term storage of carbon dioxide or other forms of carbon to either mitigate or defer global warming and avoid dangerous climate change. It has been proposed as a way to slow the atmospheric and marine accumulation of greenhouse gases, which are released by burning fossil fuels.
Carbon dioxide is naturally captured from the atmosphere through biological, chemical or physical processes. Some artificial sequestration techniques exploit these natural processes, while some use entirely artificial processes.
There are three ways that this sequestration can be carried out; post-combustion capture, pre-combustion capture, and oxy-combustion. A wide variety of separation techniques is being pursued, including gas phase separation, absorption into a liquid, and adsorption on a solid, as well as hybrid processes, such as adsorption/membrane systems. These above processes basically will capture carbon emitting from power plants, factories, fuel burning industries and so on.
Biosequestration or carbon sequestration through biological processes affects the global carbon cycle. Examples include major climatic fluctuations, such as the Azolla event, which created the current Arctic climate. Such processes created fossil fuels, as well as clathrate and limestone. By manipulating such processes, geoengineers seek to enhance sequestration.
Peat bogs are a very important carbon store. Peat bogs act as a sink for carbon due to the accumulation of partially decayed biomass that would otherwise continue to decay completely. There is a variance on how much the peatlands act as a carbon sink or carbon source that can be linked to varying climates in different areas of the world and different times of the year. By creating new bogs, or enhancing existing ones, the amount of carbon that is sequestered by bogs would increase.
Reforestation is the replanting of trees on marginal crop and pasture lands to incorporate carbon from atmospheric CO
2 into biomass. For this process to succeed the carbon must not return to the atmosphere from mass burning or rotting when the trees die. To this end, land allotted to the trees must not be converted to other uses and management of the frequency of disturbances might be necessary in order to avoid extreme events. Alternatively, the wood from them must itself be sequestered, e.g., via biochar, bio-energy with carbon storage (BECS), landfill or 'stored' by use in e.g. construction. Short of growth in perpetuity, however, reforestation with long-lived trees (>100 years) will sequester carbon for a more graduated release, minimizing impact during the expected carbon crisis of the 21st century.
Urban Forestry increases the amount of carbon taken up in cities by adding new tree sites and the sequestration of carbon occurs over the lifetime of the tree. It is generally practiced and maintained on smaller scales, like in cities. The results of urban forestry can have different results depending on the type of vegetation that is being used, so it can function as a sink but can also function as a source of emissions. Along with sequestration by the plants which is difficult to measure but seems to have little effect on the overall amount of carbon dioxide that is uptaken, the vegetation can have indirect effects on carbon by reducing need for energy consumption.
Compared to natural vegetation, cropland soils are depleted in soil organic carbon (SOC). When a soil is converted from natural land or semi natural land, such as forests, woodlands, grasslands, steppes and savannas, the SOC content in the soil reduces with about 30–40%. This loss is due to the removal of plant material containing carbon, in terms of harvests. When the land use changes, the carbon in the soil will either increase or decrease, this change will continue until the soil reaches a new equilibrium. Deviations from this equilibrium can also be affected by variated climate . The decreasing of SOC content can be counteracted by increasing the carbon input, this can be done with several strategies, e.g. leave harvest residues on the field, use manure as fertiliser or include perennial crops in the rotation. Perennial crops have larger below ground biomass fraction, which increases the SOC content. Globally, soils are estimated to contain approximately 1,500 gigatons of organic carbon to 1 m depth, more than the amount in vegetation and the atmosphere.
Modification of agricultural practices is a recognized method of carbon sequestration as soil can act as an effective carbon sink offsetting as much as 20% of 2010 carbon dioxide emissions annually. (See No-till)
Carbon emission reduction methods in agriculture can be grouped into two categories: reducing and/or displacing emissions and enhancing carbon removal. Some of these reductions involve increasing the efficiency of farm operations (e.g. more fuel-efficient equipment) while some involve interruptions in the natural carbon cycle. Also, some effective techniques (such as the elimination of stubble burning) can negatively impact other environmental concerns (increased herbicide use to control weeds not destroyed by burning).
Soils hold four times the amount of carbon stored in the atmosphere. About half of this is found deep within soils. About 90% of this deep soil C is stabilized by mineral-organic associations.
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.
Enhancing carbon removal
All crops absorb CO
2 during growth and release it after harvest. The goal of agricultural carbon removal is to use the crop and its relation to the carbon cycle to permanently sequester carbon within the soil. This is done by selecting farming methods that return biomass to the soil and enhance the conditions in which the carbon within the plants will be reduced to its elemental nature and stored in a stable state. Methods for accomplishing this include:
- Use cover crops such as grasses and weeds as temporary cover between planting seasons
- Concentrate livestock in small paddocks for days at a time so they graze lightly but evenly. This encourages roots to grow deeper into the soil. Stock also till the soil with their hooves, grinding old grass and manures into the soil.
- Cover bare paddocks with hay or dead vegetation. This protects soil from the sun and allows the soil to hold more water and be more attractive to carbon-capturing microbes.
- Restore degraded land, which slows carbon release while returning the land to agriculture or other use.
Agricultural sequestration practices may have positive effects on soil, air, and water quality, be beneficial to wildlife, and expand food production. On degraded croplands, an increase of 1 ton of soil carbon pool may increase crop yield by 20 to 40 kilograms per hectare of wheat, 10 to 20 kg/ ha for maize, and 0.5 to 1 kg/ha for cowpeas.
The effects of soil sequestration can be reversed. If the soil is disrupted or tillage practices are abandoned, the soil becomes a net source of greenhouse gases. Typically after 15 to 30 years of sequestration, soil becomes saturated and ceases to absorb carbon. This implies that there is a global limit to the amount of carbon that soil can hold.
Many factors affect the costs of carbon sequestration including soil quality, transaction costs and various externalities such as leakage and unforeseen environmental damage. Because reduction of atmospheric CO
2 is a long-term concern, farmers can be reluctant to adopt more expensive agricultural techniques when there is not a clear crop, soil, or economic benefit. Governments such as Australia and New Zealand are considering allowing farmers to sell carbon credits once they document that they have sufficiently increased soil carbon content.
Ocean iron fertilization is an example of such a geoengineering technique. Iron fertilization attempts to encourage phytoplankton growth, which removes carbon from the atmosphere for at least a period of time. This technique is controversial due to limited understanding of its complete effects on the marine ecosystem, including side effects and possibly large deviations from expected behavior. Such effects potentially include release of nitrogen oxides, and disruption of the ocean's nutrient balance.
Natural iron fertilisation events (e.g., deposition of iron-rich dust into ocean waters) can enhance carbon sequestration. Sperm whales act as agents of iron fertilisation when they transport iron from the deep ocean to the surface during prey consumption and defecation. Sperm whales have been shown to increase the levels of primary production and carbon export to the deep ocean by depositing iron rich feces into surface waters of the Southern Ocean. The iron rich feces causes phytoplankton to grow and take up more carbon from the atmosphere. When the phytoplankton dies, some of it sinks to the deep ocean and takes the atmospheric carbon with it. By reducing the abundance of sperm whales in the Southern Ocean, whaling has resulted in an extra 200,000 tonnes of carbon remaining in the atmosphere each year.
Australian company Ocean Nourishment Corporation (ONC) plans to sink hundreds of tonnes of urea into the ocean to boost CO
2-absorbing phytoplankton growth as a way to combat climate change. In 2007, Sydney-based ONC completed an experiment involving 1 tonne of nitrogen in the Sulu Sea off the Philippines.
Encouraging various ocean layers to mix can move nutrients and dissolved gases around, offering avenues for geoengineering. Mixing may be achieved by placing large vertical pipes in the oceans to pump nutrient rich water to the surface, triggering blooms of algae, which store carbon when they grow and export carbon when they die. This produces results somewhat similar to iron fertilization. One side-effect is a short-term rise in CO
2, which limits its attractiveness.
Seaweed grows very fast and can theoretically be harvested and processed to generate biomethane, via Anaerobic Digestion to generate electricity, via Cogeneration/CHP or as a replacement for natural gas. One study suggested that if seaweed farms covered 9% of the ocean they could produce enough biomethane to supply Earth's equivalent demand for fossil fuel energy, remove 53 gigatonnes of CO2 per year from the atmosphere and sustainably produce 200 kg per year of fish, per person, for 10 billion people. Ideal species for such farming and conversion include Laminaria digitata, Fucus serratus and Saccharina latissima.
Bio-energy with carbon capture and storage (BECCS)
BECCS refers to biomass in power stations and boilers that use carbon capture and storage. The carbon sequestered by the biomass would be captured and stored, thus removing carbon dioxide from the atmosphere.
This technology is sometimes referred to as bio-energy with carbon storage, BECS, though this term can also refer to the carbon sequestration potential in other technologies, such as biochar.
Biochar is charcoal created by pyrolysis of biomass waste. The resulting material is added to a landfill or used as a soil improver to create terra preta. Addition of pyrogenic organic carbon (biochar) is a novel strategy to increase the soil-C stock for the long-term and to mitigate global-warming by offsetting the atmospheric C (up to 9.5 Pg C annually).
In the soil, the carbon is unavailable for oxidation to CO
2 and consequential atmospheric release. This is one technique advocated by scientist James Lovelock, creator of the Gaia hypothesis. According to Simon Shackley, "people are talking more about something in the range of one to two billion tonnes a year."
The mechanisms related to biochar are referred to as bio-energy with carbon storage, BECS.
If CO2 were to be injected to the ocean bottom, the pressures would be great enough for CO2 to be in its liquid phase. The idea behind ocean injection would be to have stable, stationary pools of CO2 at the ocean floor. The ocean could potentially hold over a thousand billion tons of CO2. However, this avenue of sequestration isn’t being as actively pursued because of concerns about the impact on ocean life, and concerns about its stability.
River mouths bring large quantities of nutrients and dead material from upriver into the ocean as part of the process that eventually produces fossil fuels. Transporting material such as crop waste out to sea and allowing it to sink exploits this idea to increase carbon storage. International regulations on marine dumping may restrict or prevent use of this technique.
Geological sequestration refers to the storage of CO2 underground in depleted oil and gas reservoirs, saline formations, or deep, un-minable coal beds.
Once CO2 is captured from a gas or coal-fired power plant, it would be compressed to ≈100 bar so that it would be a supercritical fluid. In this fluid form, the CO2 would be easy to transport via pipeline to the place of storage. The CO2 would then be injected deep underground, typically around 1 km, where it would be stable for hundreds to millions of years. At these storage conditions, the density of supercritical CO2 is 600 to 800 kg / m3. For consumers, the cost of electricity from a coal-fired power plant with carbon capture and storage (CCS) is estimated to be 0.01–0.05 $ / kWh higher than without CCS. For reference, the average cost of electricity in the US in 2004 was 0.0762 $ / kWh. In other terms, the cost of CCS would be 20–70 $/ton of CO2 captured. The transportation and injection of CO2 is relatively cheap, with the capture costs accounting for 70–80% of CCS costs.
The important parameters in determining a good site for carbon storage are: rock porosity, rock permeability, absence of faults, and geometry of rock layers. The medium in which the CO2 is to be stored ideally has a high porosity and permeability, such as sandstone or limestone. Sandstone can have a permeability ranging from 1 to 10−5 Darcy, and can have a porosity as high as ≈30%. The porous rock must be capped by a layer of low permeability which acts as a seal, or caprock, for the CO2. Shale is an example of a very good caprock, with a permeability of 10−5 to 10−9 Darcy. Once injected, the CO2 plume will rise via buoyant forces, since it is less dense than its surroundings. Once it encounters a caprock, it will spread laterally until it encounters a gap. If there are fault planes near the injection zone, there is a possibility the CO2 could migrate along the fault to the surface, leaking into the atmosphere, which would be potentially dangerous to life in the surrounding area. Another danger related to carbon sequestration is induced seismicity. If the injection of CO2 creates pressures that are too high underground, the formation will fracture, causing an earthquake.
While trapped in a rock formation, CO2 can be in the supercritical fluid phase or dissolve in groundwater/brine. It can also react with minerals in the geologic formation to precipitate carbonates. See CarbFix.
Worldwide storage capacity in oil and gas reservoirs is estimated to be 675–900 Gt CO2, and in un-minable coal seams is estimated to be 15–200 Gt CO2. Deep saline formations have the largest capacity, which is estimated to be 1,000–10,000 Gt CO2. In the US, there is an estimated 160 Gt CO2 storage capacity.
There are a number of large-scale carbon capture and sequestration projects that have demonstrated the viability and safety of this method of carbon storage, which are summarized here  by the Global CCS Institute. The dominant monitoring technique is seismic imaging, where vibrations are generated that propagate through the subsurface. The geologic structure can be imaged from the refracted/reflected waves.
The first large-scale CO
2 sequestration project which began in 1996 is called Sleipner, and is located in the North Sea where Norway's StatoilHydro strips carbon dioxide from natural gas with amine solvents and disposed of this carbon dioxide in a deep saline aquifer. In 2000, a coal-fueled synthetic natural gas plant in Beulah, North Dakota, became the world's first coal-using plant to capture and store carbon dioxide, at the Weyburn-Midale Carbon Dioxide Project.
2 has been used extensively in enhanced crude oil recovery operations in the United States beginning in 1972. There are in excess of 10,000 wells that inject CO
2 in the state of Texas alone. The gas comes in part from anthropogenic sources, but is principally from large naturally occurring geologic formations of CO
2. It is transported to the oil-producing fields through a large network of over 5,000 kilometres (3,100 mi) of CO
2 pipelines. The use of CO
2 for enhanced oil recovery (EOR) methods in heavy oil reservoirs in the Western Canadian Sedimentary Basin (WCSB) has also been proposed. However, transport cost remains an important hurdle. An extensive CO
2 pipeline system does not yet exist in the WCSB. Athabasca oil sands mining that produces CO
2 is hundreds of kilometers north of the subsurface Heavy crude oil reservoirs that could most benefit from CO
Carbon, in the form of CO
2 can be removed from the atmosphere by chemical processes, and stored in stable carbonate mineral forms. This process is known as 'carbon sequestration by mineral carbonation' or mineral sequestration. The process involves reacting carbon dioxide with abundantly available metal oxides–either magnesium oxide (MgO) or calcium oxide (CaO)–to form stable carbonates. These reactions are exothermic and occur naturally (e.g., the weathering of rock over geologic time periods).
- CaO + CO
2 → CaCO
- MgO + CO
2 → MgCO
4 + 2 CO
2 → 2 MgCO
3 + SiO
4+ 3 CO
2 → 3 MgCO
3 + 2 SiO
2 + 2 H
|Earthen Oxide||Percent of Crust||Carbonate||Enthalpy change|
These reactions are slightly more favorable at low temperatures. This process occurs naturally over geologic time frames and is responsible for much of the Earth's surface limestone. The reaction rate can be made faster however, by reacting at higher temperatures and/or pressures, although this method requires some additional energy. Alternatively, the mineral could be milled to increase its surface area, and exposed to water and constant abrasion to remove the inert Silica as could be achieved naturally by dumping Olivine in the high energy surf of beaches. Experiments suggest the weathering process is reasonably quick (one year) given porous basaltic rocks.
2 naturally reacts with peridotite rock in surface exposures of ophiolites, notably in Oman. It has been suggested that this process can be enhanced to carry out natural mineralisation of CO
When CO2 is dissolved in water and injected into hot basaltic rocks underground it has been shown that the CO2 reacts with the basalt to form solid carbonate minerals. A test plant in Iceland started up in October 2017, extracting up to 50 tons of CO2 a year from the atmosphere and storing it underground in basaltic rock.
Researchers from British Columbia, developed a low cost process for the production of magnesite, also known as magnesium carbonate, which can sequester CO2 from the air, or at the point of air pollution, eg. at a power plant. The crystals are naturally occurring, but accumulation is usually very slow.
Traditional cement manufacture releases large amounts of carbon dioxide, but newly developed cement types from Novacem can absorb CO
2 from ambient air during hardening. A similar technique was pioneered by TecEco, which has been producing "EcoCement" since 2002. A Canadian startup CarbonCure takes captured CO2 and injects it into concrete as it's being mixed.
In Estonia, oil shale ash, generated by power stations could be used as sorbents for CO
2 mineral sequestration. The amount of CO
2 captured averaged 60 to 65% of the carbonaceous CO
2 and 10 to 11% of the total CO
Various carbon dioxide scrubbing processes have been proposed to remove CO
2 from the air, usually using a variant of the Kraft process. Carbon dioxide scrubbing variants exist based on potassium carbonate, which can be used to create liquid fuels, or on sodium hydroxide. These notably include artificial trees proposed by Klaus Lackner to remove carbon dioxide from the atmosphere using chemical scrubbers.
Carbon dioxide sequestration in basalt involves the injecting of CO
2 into deep-sea formations. The CO
2 first mixes with seawater and then reacts with the basalt, both of which are alkaline-rich elements. This reaction results in the release of Ca2+ and Mg2+ ions forming stable carbonate minerals.
Underwater basalt offers a good alternative to other forms of oceanic carbon storage because it has a number of trapping measures to ensure added protection against leakage. These measures include “geochemical, sediment, gravitational and hydrate formation.” Because CO
2 hydrate is denser than CO
2 in seawater, the risk of leakage is minimal. Injecting the CO
2 at depths greater than 2,700 meters (8,900 ft) ensures that the CO
2 has a greater density than seawater, causing it to sink.
One possible injection site is Juan de Fuca plate. Researchers at the Lamont-Doherty Earth Observatory found that this plate at the western coast of the United States has a possible storage capacity of 208 gigatons. This could cover the entire current U.S. carbon emissions for over 100 years.
This process is undergoing tests as part of the CarbFix project, resulting in 95% of the injected 250 tonnes of CO2 to solidify into calcite in 2 years, using 25 tonnes of water per tonne of CO2.
Carbon dioxide forms carbonic acid when dissolved in water, so ocean acidification is a significant consequence of elevated carbon dioxide levels, and limits the rate at which it can be absorbed into the ocean (the solubility pump). A variety of different bases have been suggested that could neutralize the acid and thus increase CO
2 absorption. For example, adding crushed limestone to oceans enhances the absorption of carbon dioxide. Another approach is to add sodium hydroxide to oceans which is produced by electrolysis of salt water or brine, while eliminating the waste hydrochloric acid by reaction with a volcanic silicate rock such as enstatite, effectively increasing the rate of natural weathering of these rocks to restore ocean pH.
Danger of leaks
Carbon dioxide may be stored deep underground. At depth, hydrostatic pressure acts to keep it in a liquid state. Reservoir design faults, rock fissures and tectonic processes may act to release the gas stored into the ocean or atmosphere.
The use of the technology would add an additional 1–5 cents of cost per kilowatt hour, according to estimate made by the Intergovernmental Panel on Climate Change. The financial costs of modern coal technology would nearly double if use of CCS technology were to be required by regulation. The cost of CCS technology differs with the different types of capture technologies being used and with the different sites that it is implemented in, but the costs tend to increase with CCS capture implementation. One study conducted predicted that with new technologies these costs could be lowered but would remain slightly higher than prices without CCS technologies.
The energy requirements of sequestration processes may be significant. In one paper, sequestration consumed 25 percent of the plant's rated 600 megawatt output capacity.
- After adding CO2 capture and compression, the capacity of the coal-fired power plant is reduced to 457 MW.
- Bio-energy with carbon capture and storage
- Blue Carbon
- CarbonFix Standard
- Carbon capture and storage
- Carbon carousel
- Woodland Carbon Code
- Sedjo, Roger; Sohngen, Brent (2012). "Carbon Sequestration in Forests and Soils". Annual Review of Resource Economics. 4: 127–144. doi:10.1146/annurev-resource-083110-115941.
- Hodrien, Chris (October 24, 2008). Squaring the Circle on Coal – Carbon Capture and Storage. Claverton Energy Group Conference, Bath. Archived from the original (PDF) on May 31, 2009. Retrieved May 9, 2010.
- "Energy Terms Glossary S". Nebraska Energy Office. Archived from the original on May 27, 2010. Retrieved May 9, 2010.
- "Glossary of climate change acronyms". United Nations Framework Convention on Climate Change. Retrieved July 15, 2010.
- "Alberta producers rewarded for use of CO2 in enhanced oil recovery". PointCarbon. May 25, 2004. Archived from the original on May 6, 2008. Retrieved August 21, 2015.
- Strack, ed. by Maria (2008). Peatlands and climate change. Calgary: University of Calgary. pp. 13–23. ISBN 978-952-99401-1-0. Retrieved 16 November 2016.
- Lovett, Richard (May 3, 2008). "Burying biomass to fight climate change". New Scientist (2654). Retrieved May 9, 2010. (Subscription required (help)).
- McDermott, Matthew (August 22, 2008). "Can Aerial Reforestation Help Slow Climate Change? Discovery Project Earth Examines Re-Engineering the Planet's Possibilities". TreeHugger. Retrieved May 9, 2010.
- Gorte, Ross W. (March 29, 2007). CRS Report for Congress: Carbon Sequestration in Forests (PDF) (Report). Congressional Research Service. Retrieved August 21, 2015.
- McPherson, E. Gregory; Xiao, Qingfu; Aguaron, Elena (December 2013). "A new approach to quantify and map carbon stored, sequestered and emissions avoided by urban forests" (PDF). Landscape and Urban Planning. 120: 70–84. doi:10.1016/j.landurbplan.2013.08.005. Retrieved August 21, 2015.
- Velasco, Erik; Roth, Matthias; Norford, Leslie; Molina, Luisa T. (April 2016). "Does urban vegetation enhance carbon sequestration?". Landscape and Urban Planning. 148: 99–107. doi:10.1016/j.landurbplan.2015.12.003.
- Nelson, Robert (July 1999). "Carbon Sequestration: A Better Alternative for Climate Change?".[dead link]
- Poeplau, Christopher; Don, Axel (2015-02-01). "Carbon sequestration in agricultural soils via cultivation of cover crops – A meta-analysis". Agriculture, Ecosystems & Environment. 200 (Supplement C): 33–41. doi:10.1016/j.agee.2014.10.024.
- Goglio, Pietro; Smith, Ward N.; Grant, Brian B.; Desjardins, Raymond L.; McConkey, Brian G.; Campbell, Con A.; Nemecek, Thomas (2015-10-01). "Accounting for soil carbon changes in agricultural life cycle assessment (LCA): a review". Journal of Cleaner Production. 104: 23–39. doi:10.1016/j.jclepro.2015.05.040. ISSN 0959-6526.
- Batjes, Niels H. (June 1996). "Total carbon and nitrogen in the soils of the world". European Journal of Soil Science. 47 (2): 151–163. doi:10.1111/j.1365-2389.1996.tb01386.x.
- Smith, Pete (2007). "Soil Organic Carbon Dynamics and Land-Use Change". In Braimoh, Ademola K.; Vlek, Paul L.G. Land Use and Soil Resources. Stockholm, Sweden: Springer. ISBN 978-1-4020-6777-8. LCCN 2007941782. Retrieved August 21, 2015.
- "Iowa's Climate-Change Wisdom". New York Times. Archived from the original on November 23, 2015. Retrieved 2015-11-21.
- Tarnocai, C.; Canadell, J.G.; Schuur, E.A.G.; Kuhry, P.; Mazhitova, G.; Zimov, S. (2009-06-01). "Soil organic carbon pools in the northern circumpolar permafrost region". Global Biogeochemical Cycles. 23 (2): GB2023. Bibcode:2009GBioC..23.2023T. doi:10.1029/2008gb003327. ISSN 1944-9224.
- Schmidt, Torn, Abiven, Dittmar, Guggenberger, Janssens, Kleber, Kogel-Knabner, Lehmann, Manning, Nannipieri, Rasse, Weiner, Trumbore, M.W.I., M.S., S., T., G., I.A., M., I., J., D.A.C., P., D.P., S., S.E. (2011). "Persistence of soil organic matter as an ecosystem property" (PDF). Nature (Submitted manuscript). 478 (7367): 49–56. Bibcode:2011Natur.478...49S. doi:10.1038/nature10386. PMID 21979045.
- Kleber, Eusterhues, Keiluweit, Mikutta, Mikutta, S. Nico., Markus, Karin, Marco, Christian, Robert, Peter (2015). Advances in Agronomy Chapter 1 Mineral - Organic Associations : Formation , Properties , and Relevance in Soil Environments. Academic Press. pp. Chapter 1, 1–140.
- "FACTBOX: Carbon farming on rise in Australia". Reuters. June 16, 2009. Retrieved May 9, 2010.
- Sundermeiera, A.P.; Islam, K.R.; Raut, Y.; Reeder, R.C.; Dick, W.A. (September 2010). "Continuous No-Till Impacts on Soil Biophysical Carbon Sequestration". Soil Science Society of America Journal. 75 (5): 1779–1788. Bibcode:2011SSASJ..75.1779S. doi:10.2136/sssaj2010.0334. Retrieved August 21, 2015.
- Smith, Pete; Martino, Daniel; Cai, Zucong; et al. (February 2008). "Greenhouse gas mitigation in agriculture". Philosophical Transactions of the Royal Society B. 363 (1492): 789–813. doi:10.1098/rstb.2007.2184. PMC 2610110. PMID 17827109..
- "Environmental Co Benefits of Sequestration Practices. 2006. June 1, 2009". Archived from the original on May 11, 2009.
- Lal, R. (June 11, 2004). "Soil Carbon Sequestration Impacts on Global Climate Change and Food Security". Science. 304 (5677): 1623–1627. Bibcode:2004Sci...304.1623L. doi:10.1126/science.1097396. PMID 15192216. (Subscription required (help)).
- "Addressing Reversibility (Duration) for Projects". US Environmental Protection Agency. 2006. June 1, 2009. Archived from the original on October 13, 2008.
- Renwick, A.; Ball, A.; Pretty, J.N. (August 2002). "Biological and Policy Constraints on the Adoption of Carbon Farming in Temperate Regions". Philosophical Transactions of the Royal Society A. 360 (1797): 1721–40. Bibcode:2002RSPTA.360.1721R. doi:10.1098/rsta.2002.1028. PMID 12460494. pp. 1722, 1726—29.
- Traufetter, Gerald (January 2, 2009). "Cold Carbon Sink: Slowing Global Warming with Antarctic Iron". Spiegel Online. Retrieved May 9, 2010.
- Jin, X.; Gruber, N.; Frenzel1, H.; Doney, S.C.; McWilliams, J.C. (2008). "The impact on atmospheric CO
2 of iron fertilization induced changes in the ocean's biological pump". Biogeosciences. 5 (2): 385–406. doi:10.5194/bg-5-385-2008. Retrieved May 9, 2010.
- Monastersky, Richard (September 30, 1995). "Iron versus the Greenhouse - Oceanographers cautiously explore a global warming therapy". Science News. Retrieved May 9, 2010.
- Monastersky, Richard (September 30, 1995). "Iron versus the Greenhouse: Oceanographers cautiously explore a global warming therapy". Science News. 148 (14): 220–222. doi:10.2307/4018225. JSTOR 4018225. Retrieved August 21, 2015. (Subscription required (help)).
- "WWF condemns Planktos Inc. iron-seeding plan in the Galapagos". Geoengineering Monitor. June 27, 2007. Retrieved August 21, 2015.
- Fogarty, David (December 15, 2008). "Scientists urge caution in ocean-CO
2 capture schemes". Alertnet.org. Archived from the original on August 3, 2009. Retrieved May 9, 2010.
- Lavery, Trish J.; Roudnew, Ben; Gill, Peter; et al. (October 11, 2010). "Iron defecation by sperm whales stimulates carbon export in the Southern Ocean". Proceedings of the Royal Society B. 277 (1699): 3527–3531. doi:10.1098/rspb.2010.0863. PMC 2982231. PMID 20554546.
- "Multiplying the ocean's CO2 guzzlers". February 19, 2007 – via news.bbc.co.uk.
- Salleh, Anna (November 9, 2007). "Urea 'climate solution' may backfire". ABC Science. Australian Broadcasting Commission. Retrieved May 9, 2010.
- Lovelock, James E.; Rapley, Chris G. (September 27, 2007). "Ocean pipes could help the earth to cure itself". Nature. 449 (7161): 403. Bibcode:2007Natur.449..403L. doi:10.1038/449403a. PMID 17898747. (Subscription required (help)).
- Pearce, Fred (September 26, 2007). "Ocean pumps could counter global warming". New Scientist. Retrieved May 9, 2010.
- Duke, John H. (2008). "A proposal to force vertical mixing of the Pacific Equatorial Undercurrent to create a system of equatorially trapped coupled convection that counteracts global warming" (PDF). Geophysical Research Abstracts. Retrieved May 9, 2010.
- Dutreuil, S.; Bopp, L.; Tagliabue, A. (May 25, 2009). "Impact of enhanced vertical mixing on marine biogeochemistry: lessons for geo-engineering and natural variability". Biogeosciences. 6 (5): 901–912. doi:10.5194/bg-6-901-2009. Retrieved August 21, 2015.
- Flannery, Tim (20 November 2015). "Climate crisis: seaweed, coffee and cement could save the planet". The Guardian. Guardian Media Group. Retrieved 25 November 2015.
- Vanegasa, C. H.; Bartletta, J. (11 Feb 2013). "Green energy from marine algae: biogas production and composition from the anaerobic digestion of Irish seaweed species". Environmental Technology. 34 (15): 2277–2283. doi:10.1080/09593330.2013.765922. PMID 24350482.
- Fisher, Brian; Nakicenovic, Nebojsa; et al. (2007). "Issues related to mitigation in the long term context, In Climate Change 2007: Mitigation.". Fourth Assessment Report of the Inter-governmental Panel on Climate Change (PDF) (Report). Cambridge University Press. Retrieved August 21, 2015.
- Obersteiner, M.; Azar, Christian; Kauppi, P.; et al. (October 26, 2001). "Managing climate risk". Science. 294 (5543): 786–87. doi:10.1126/science.294.5543.786b. PMID 11681318. (Subscription required (help)).
- Azar, Christian; et al. (January 2006). "Carbon Capture and Storage From Fossil Fuels and Biomass – Costs and Potential Role in Stabilizing the Atmosphere". Climatic Change. 74 (1–3): 47–79. doi:10.1007/s10584-005-3484-7.
- Zeng, Ning (2008). "Carbon sequestration via wood burial". Carbon Balance and Management. 3 (1): 1. doi:10.1186/1750-0680-3-1. PMC 2266747. PMID 18173850.
- Lovett, Richard (May 3, 2008). "Burying biomass to fight climate change". New Scientist (2654). Retrieved May 9, 2010. (Subscription required (help)).
- Lehmann, J.; Gaunt, J.; Rondon, M. (2006). "Bio-char sequestration in terrestrial ecosystems – a review" (PDF). Mitigation and Adaptation Strategies for Global Change (Submitted manuscript). 11 (2): 403–427. CiteSeerX 10.1.1.183.1147. doi:10.1007/s11027-005-9006-5.
- "International Biochar Initiative | International Biochar Initiative". Biochar-international.org. Retrieved May 9, 2010.
- Balal Yousaf, Guijian Liu, Ruwei Wang, Qumber Abbas, Muhammad Imtiaz, Ruijia Liu: Investigating the biochar effects on C-mineralization and sequestration of carbon in soil compared with conventional amendments using stable isotope (δ13C) approach. GCB Bioenergy 2016; doi:10.1111/gcbb.12401
- Gaia Vince (January 23, 2009). "One last chance to save mankind". New Scientist. Retrieved May 9, 2010.(subscription required)
- Harvey, Fiona (February 27, 2009). "Black is the new green". Financial Times. Retrieved March 4, 2009.
- Benson, S.M.; Surles, T. (2006-10-01). "Carbon Dioxide Capture and Storage: An Overview With Emphasis on Capture and Storage in Deep Geological Formations". Proceedings of the IEEE. 94 (10): 1795–1805. doi:10.1109/JPROC.2006.883718. ISSN 0018-9219.
- Stuart E. Strand; Benford, Gregory (January 12, 2009). "Ocean Sequestration of Crop Residue Carbon: Recycling Fossil Fuel Carbon Back to Deep Sediments". Environmental Science & Technology. 43 (4): 1000–1007. Bibcode:2009EnST...43.1000S. doi:10.1021/es8015556.
- Aydin, Gokhan; Karakurt, Izzet; Aydiner, Kerim (2010-09-01). "Evaluation of geologic storage options of CO2: Applicability, cost, storage capacity and safety". Energy Policy. Special Section on Carbon Emissions and Carbon Management in Cities with Regular Papers. 38 (9): 5072–5080. doi:10.1016/j.enpol.2010.04.035.
- Smit, Berend; Reimer, Jeffrey A.; Oldenburg, Curtis M.; Bourg, Ian C. (2014). Introduction to Carbon Capture and Sequestration. London: Imperial College Press. ISBN 978-1783263288.
- "Large-scale CCS facilities". www.globalccsinstitute.com. Global Carbon Capture and Storage Institute.
- "Weyburn-Midale CO
2 Project, World's first CO
2 measuring, monitoring and verification initiative". Petroleum Technology Research Centre. Retrieved April 9, 2009.
- "Subscription Verification". Dailyoilbulletin.com. Retrieved May 9, 2010.[dead link]
- Bouwman, Elisabeth; Angamuthu, Raja; Byers, Philip; Lutz, Martin; Spek, Anthony L. (July 15, 2010). "Electrocatalytic CO2 Conversion to Oxalate by a Copper Complex". Science. 327 (5393): 313–315. Bibcode:2010Sci...327..313A. CiteSeerX 10.1.1.1009.2076. doi:10.1126/science.1177981. PMID 20075248. Retrieved 26 September 2014.
- Herzog, Howard (March 14, 2002). "Carbon Sequestration via Mineral Carbonation: Overview and Assessment" (PDF). Massachusetts Institute of Technology. Retrieved March 5, 2009.
- Goldberg, Philip; Zhong-Ying Chen; O'Connor, William; Walters, Richard; Ziock Hans (1998). "CO
2 Mineral Sequestration Studies in US" (PDF). National Energy Technology Laboratory. Retrieved March 6, 2009.
- Schuiling, R.D.; Boer, de P.L. (2011). "Rolling stones; fast weathering of olivine in shallow seas for cost-effective CO2 capture and mitigation of global warming and ocean acidification" (PDF). Earth Syst. Dynam. Discuss. 2 (2): 551–568. Bibcode:2011ESDD....2..551S. doi:10.5194/esdd-2-551-2011.
- Yirka, Bob. "Researchers find carbon reactions with basalt can form carbonate minerals faster than thought". Phys.org. Omicron Technology Ltd. Retrieved 25 April 2014.
- Matter, Juerg M.; Stute, Martin; Snæbjörnsdottir, Sandra O.; Oelkers, Eric H.; Gislason, Sigurdur R.; Aradottir, Edda S.; Sigfusson, Bergur; Gunnarsson, Ingvi; Sigurdardottir, Holmfridur; Gunlaugsson, Einar; Axelsson, Gudni; Alfredsson, Helgi A.; Wolff-Boenisch, Domenik; Mesfin, Kiflom; Fernandez de la Reguera Taya, Diana; Hall, Jennifer; Dideriksen, Knud; Broecker, Wallace S. (June 10, 2016). "Rapid carbon mineralization for permanent disposal of anthropogenic carbon dioxide emissions". Science. 352 (6291): 1312–1314. Bibcode:2016Sci...352.1312M. doi:10.1126/science.aad8132. PMID 27284192. Retrieved 10 June 2016.
- Peter B. Kelemen1 and Jürg Matter (November 3, 2008). "In situ carbonation of peridotite for CO
2 storage". Proc. Natl. Acad. Sci. USA. 105 (45): 17295–300. Bibcode:2008PNAS..10517295K. doi:10.1073/pnas.0805794105. PMC 2582290.
- Timothy Gardner (November 7, 2008). "Scientists say a rock can soak up carbon dioxide | Reuters". Uk.reuters.com. Retrieved May 9, 2010.
- Le Page, Michael (2016-06-19). "CO2 injected deep underground turns to rock – and stays there". New Scientist. Retrieved 2017-12-04.
- Proctor, Darrell (2017-12-01). "Test of Carbon Capture Technology Underway at Iceland Geothermal Plant". POWER Magazine. Retrieved 2017-12-04.
- "This carbon-sucking mineral could help slow down climate change". Fast Company. 2018.
- "Novacem". Imperial Innovations. May 6, 2008. Retrieved May 9, 2010.
- Jha, Alok (December 31, 2008). "Revealed: The cement that eats carbon dioxide". The Guardian. London. Retrieved April 3, 2010.
- "Home". TecEco. July 1, 1983. Retrieved May 9, 2010.
- Lord, Bronte. "This concrete can trap CO2 emissions forever". CNNMoney. Retrieved 2018-06-17.
- Uibu, Mai; Uus, Mati; Kuusik, Rein (February 2008). "CO
2 mineral sequestration in oil-shale wastes from Estonian power production". Journal of Environmental Management. 90 (2): 1253–60. doi:10.1016/j.jenvman.2008.07.012. PMID 18793821.
- Chang, Kenneth (February 19, 2008). "Scientists Would Turn Greenhouse Gas Into Gasoline". The New York Times. Retrieved April 3, 2010.
- Frank Zeman (2007). "Energy and Material Balance of CO2 Capture from Ambient Air". Environ. Sci. Technol. 41 (21): 7558–63. Bibcode:2007EnST...41.7558Z. doi:10.1021/es070874m. PMID 18044541.
- "Chemical 'sponge' could filterCO
2 from the air". New Scientist. October 3, 2007. Retrieved May 9, 2010.
- "New Device Vacuums Away Carbon Dioxide". LiveScience. May 1, 2007. Retrieved May 9, 2010.
- Adam, David (May 31, 2008). "Could US scientist's 'CO
2 catcher' help to slow warming?". The Guardian. London. Retrieved April 3, 2010.
- David S. Goldberg; Taro Takahashi; Angela L. Slagle (2008). "Carbon dioxide sequestration in deep-sea basalt". Proc. Natl. Acad. Sci. USA. 105 (29): 9920–25. Bibcode:2008PNAS..105.9920G. doi:10.1073/pnas.0804397105. PMC 2464617. PMID 18626013.
- "Carbon storage in undersea basalt offers extra security". environmentalresearchweb. July 15, 2008. Retrieved May 9, 2010.
- "Scientists turn carbon dioxide into stone to combat global warming". The Verge. Vox Media. 10 June 2016. Retrieved 11 June 2016.
- Kheshgi, H.S. (1995). "Sequestering atmospheric carbon dioxide by increasing ocean alkalinity". Energy. 20 (9): 915–922. doi:10.1016/0360-5442(95)00035-F.
- K.S. Lackner; C.H. Wendt; D.P. Butt; E.L. Joyce; D.H. Sharp (1995). "Carbon dioxide disposal in carbonate minerals". Energy. 20 (11): 1153–70. doi:10.1016/0360-5442(95)00071-N.
- K.S. Lackner; D.P. Butt; C.H. Wendt (1997). "Progress on binding CO
2 in mineral substrates" (PDF). Energy Conversion and Management (Submitted manuscript). 38: S259–S264. doi:10.1016/S0196-8904(96)00279-8.
- Rau, Greg H.; Caldeira, Ken (November 1999). "Enhanced carbonate dissolution: A means of sequestering waste CO
2 as ocean bicarbonate" (PDF). Energy Conversion and Management. 40 (17): 1803–1813. doi:10.1016/S0196-8904(99)00071-0. (Subscription required (help)).
- Rau, Greg H.; Knauss, Kevin G.; Langer, William H.; Caldeira, Ken (August 2007). "Reducing energy-related CO
2 emissions using accelerated weathering of limestone". Energy. 32 (8): 1471–7. doi:10.1016/j.energy.2006.10.011. (Subscription required (help)).
- Harvey, L.D.D. (2008). "Mitigating the atmospheric CO
2 increase and ocean acidification by adding limestone powder to upwelling regions". Journal of Geophysical Research. 113: C04028. Bibcode:2008JGRC..11304028H. doi:10.1029/2007JC004373.
- "Scientists enhance Mother Nature's carbon handling mechanism". Penn State Live. November 7, 2007. Archived from the original on June 3, 2010.
- Kurt Zenz House; Christopher H. House; Daniel P. Schrag; Michael J. Aziz (2007). "Electrochemical Acceleration of Chemical Weathering as an Energetically Feasible Approach to Mitigating Anthropogenic Climate Change". Environ. Sci. Technol. 41 (24): 8464–8470. Bibcode:2007EnST...41.8464H. doi:10.1021/es0701816. PMID 18200880.
- Clover, Charles (November 7, 2007). "Global warming 'cure' found by scientists". The Daily Telegraph. London. Retrieved April 3, 2010.
- DeMonte, Adena (July 2007). "The Cost of Carbon Capture". Gigaom. Retrieved August 21, 2015.[unreliable source?]
- Gibbins, Jon; Chalmers, Hannah (December 2008). "Carbon Capture and Storage" (PDF). Energy Policy. 36 (12): 4317–4322. CiteSeerX 10.1.1.370.8479. doi:10.1016/j.enpol.2008.09.058.
- David, Jeremy; Herzog, Howard (2012). "The Cost of Carbon Capture" (PDF). BASE. Retrieved 16 November 2016.
- Spath, Pamela L.; Mann, Margaret K. (September 22, 2002). The Net Energy and Global Warming Potential of Biomass Power compared to Coal-fired Electricity with CO2 Sequestration – A Life Cycle Approach (PDF). Bioenergy 2002 Bioenergy for the Environment. Boise, Idaho. Retrieved August 21, 2015.[permanent dead link]
- Biello, David (January 2016). "The Carbon Capture Fallacy". Scientific American. 314 (1): 58–65. Bibcode:2015SciAm.314a..58B. doi:10.1038/scientificamerican0116-58. PMID 26887197.
- GA Mansoori, N Enayati, LB Agyarko (2016), Energy: Sources, Utilization, Legislation, Sustainability, Illinois as Model State, World Sci. Pub. Co., ISBN 978-9814704007
- Carbon Sequestration Leadership Forum International carbon capture and storage initiative.
- UK Carbon Capture and Storage Consortium Overview of the UK academic consortium focused on researching issues related to Carbon Capture and Storage.
- Sieves put a lid on greenhouse gas
- The capture, utilization and disposal of carbon dioxide from fossil fuel-fired power plants.
- Carbon Capture and Storage Information Center (Chinese + English)
- Carbon Sequestration: Science, Technology, and Policy MIT program covers carbon capture and storage (CCS)
- Link to video, UK Looks for Natural Products in Kentucky's Unique Environments