Forests are important carbon reservoirs, due to their biomass and dead organic matter, and through their soil (some peat forest soils in Indonesia reach 40 m thick).

Forest sequestration is small compared to the CO emissions related to the combustion of fossil carbon (coal, oil and natural gas). There is a consensus on the importance of protecting relict forests (Relict (biology)), especially from forest fires, but even the most optimistic scenarios conclude that mass planting of new forests is not enough to offset the balance between increasing greenhouse gas emissions or global warming. For example, reducing U.S. carbon emissions by 7 percent, as stipulated in the Kyoto protocol, would require planting a forest the size of Texas every 30 years, said William H. Schlesinger, dean of the School of Environment and Earth Sciences at Duke University in Durham, North Carolina. To offset their emissions, the most developed regions must plant an area much larger than their entire territory. A larger area than currently available of all emerged lands (fields, roads and cities included) should be forested. However, the potential of planting new forests is not negligible, especially if they are made of dense, hardwood species and the soil is enriched with organic matter, especially in temperate zones of the planet.

The type of forest is important: temperate forests grow the fastest, but further north, peat forests are carbon sinks just the same. Tropical forests were initially considered carbon neutral, but a recent study[7]​ (measurements on more than 2 million trees worldwide) showed that they were generally carbon sinks, a function that could be limited by water stress.

The type of management is also important: a very young forest planted after a clear cutting can have a negative carbon balance, the first 10 or 12 years, losing more carbon than it stores. Logging also often causes soil erosion and loss of soil carbon (significant in temperate and cold climates).

High and mid-latitude forests have a lower albedo effect than lower latitude forests during snowy periods which contributes to global warming. Several programs offer companies to buy plots of forest to protect them (for example: "Cool Earth"), in exchange for "carbon credits" to offset industrial or individual emissions. This approach is debatable. Thus, in October 2007, Davi Kopenawa") (Amerindian shaman (Yanomami) who won the PNUE Global 500 award in 1991), presented Gordon Brown (British Prime Minister) with a report showing that the protection of forests by the land rights of their indigenous populations would protect 15,000 times the area covered by the "Cool Earth" program 2008 (162 million hectares of rainforest already It has been protected, through the recognition of the rights of the people who live there, especially after the movement launched by Chico Mendes in the 1970s).[8]​.

Ocean Retention

The ocean is the main global carbon sink, but it is saturated and starting to acidify.

The addition of micro-particles of iron (hematite) or ferrous sulfate to water has been proposed as a method to boost ocean carbon uptake by plankton. Iron is a natural trace element, a factor that limits the growth of phytoplankton. These are outcrops along the coast ("upwellings") of water from the deep zone of the ocean, contributed by rivers and provided by the deposition of aerosols and dust. Some believe that natural sources of iron have been declining for decades, limiting ecological productivity and ocean biomass (NASA, 2003) and therefore the biological pumping of atmospheric CO by photosynthesis.

In 2002, a test in the Pacific Ocean near Antarctica suggested that between 10,000 and 100,000 carbon atoms are absorbed when one iron atom is added to the sea. Work in Germany (2005) has suggested that any type of carbon biomass in the deep oceans, buried or recycled in the euphotic zone, represents long-term storage of carbon. The contribution of iron nutrients in certain areas of the ocean could increase ocean productivity and limit the disastrous effects of human CO emissions into the atmosphere.

Professor Wolfgang Arlt") of the University of Erlangen-Nuremberg (Germany) intends to inject dissolved CO at great depth, thus ensuring global diffusion. He believes that the CO would have little impact in terms of acidification if injected into the cold, dense waters of the deep ocean, and that the CO injected in Europe would be redistributed around Australia within a century, he believes, without affecting marine life or the life of the seabed.

Others question the reliability of the method, especially in the long term. They argue that the global effects of iron addition on phytoplankton and ocean ecosystems are poorly understood and require further study.

• - Phytoplankton produce clouds by releasing dimethyl sulfate (DMS) that turns into sulfate aerosols in the atmosphere and forms cloud condensation nuclei") (or CCN in English), water vapor is one of the greenhouse gas emissions and clouds contribute to changing insolation, and therefore photosynthesis.

• - The risk of eutrophication and acidification must be taken into account at the local level, when dead zones are more numerous and spreading.

• - Finally, it is the South Seas that have shown to be poor in iron, while there is no shortage in the Northern Hemisphere, where CO is more important and where biological productivity is higher.

• - A campaign (KEOPS[9]​ showed.[10]​ around the Kerguelen Islands, an area of ​​annual summer phytoplankton bloom, that the phenomenon was correlated with the presence of iron in deep waters, but is at least twice greater with natural iron than in the case of artificial fertilization.

The IPCC is very cautious about the ocean's ability to absorb more carbon, but considers that the assessment of the impact and behavior of CO in the deep ocean needs to be better studied. The IMO and the London Convention) had estimated in late 2008 that activities other than for scientific experiments should be prohibited[11].

Floors

It is estimated that soil storage at the end of the century was around 2,000 gigatonnes of carbon in the form of organic matter. It is almost three times the carbon in the atmosphere, and four times the carbon in plant biomass. However, this function is deteriorating rapidly and especially in cultivated agricultural soils. Increasing the amount of humus and organic matter would improve soil quality and the amount of carbon stored. Direct seeding and fallow can help store carbon. Subsoil stores twice as much as surface soil.

Meadows accumulate enormous amounts of organic matter, mainly in the form of roots and organic matter, which are relatively stable over long periods. But in the world since 1850, a large part of these grasslands have been converted into fields or cities, losing large amounts of carbon through oxidation. A (no-till) use increases carbon stored in the soil, and conversion to well-managed pastures stores even more carbon. Erosion control measures, maintaining vegetative cover in winter and crop rotation also increase the rate of carbon in the soil.

Ecologist Allan Savory has proposed that livestock (especially ruminants) can act as a carbon sink through holistic management "Holistic management (agriculture)"). According to him, following the full carbon cycle can capture more carbon than is emitted.[12]​ One study followed pasture management for 4 years and found that it can act as a carbon sink.[13]​ Other studies have found that holistic management can help mitigate climate change,[14]​ improve biodiversity in rural areas[15]​ and regenerate the ecosystem function and livelihoods of grazing lands.[16]​.

The increase in CO emissions in the air cannot be compensated by the increase in retention in soils. A study[17]​ has shown that long-term exposure to a double rate of CO in the atmosphere strongly accelerates the degradation of organic matter in forest soils of oak forests (=> reduction of soil carbon stocks). Trees have more carbon stored (212 g/m² in the air and 646 g/m² in the roots), but 442 g/m² of carbon had been lost in the soil, mainly on the surface up to 10 cm, apparently due to the impact of CO on the soil (by acidification and stimulation of the enzymatic activity of soil microorganisms, which increases the decomposition of organic matter, and more if there are carbon inputs (manure).

This study must be confirmed by new ones on richer soils, since here these were poor soils where the carbon content was 75% and consisting of fragile carbon chains.

Contenido

Para la fijación artificial del carbono (es decir, sin utilizar el ciclo natural del carbono), primero debe ser capturado y luego almacenado por diferentes medios.

Las plantas de purificación de gas natural deben eliminar el dióxido de carbono para evitar que el hielo carbónico obstruya los camiones cisterna o para impedir que las concentraciones de CO superen el 3% como máximo permitido en la distribución de gas natural.

Además, una de las tecnologías más prometedoras para el almacenamiento de carbono es el almacenaje de CO que proviene de las centrales eléctricas (en el caso del carbón, se conoce como "carbón limpio"). Normalmente, una central eléctrica de reciente producción de 1000 megavatios, de combustión de carbón, emite aproximadamente 6 millones de toneladas de CO al año. El desarrollo de la captura de carbono en las plantas existentes equivale a un aumento de los costos de producción de energía muy elevado. Además, una planta de carbón de 1000 MW, requiere el almacenamiento de 50 millones de barriles de CO al año.

Los costes de producción de la electricidad se han reducido cuando la tecnología de gasificación del carbón se ha utilizado en las instalaciones nuevas, aunque los costes de la electricidad han sido entre un 10 y un 12% más elevados que la producida por la quema de carbono fósil.

El transporte de dióxido de carbono ha de cumplir normas de seguridad severas, ya que es letal en concentraciones superiores al 10%, como lo demuestra la trágica desgasificación del lago Nyos.

Está en estudio el diseño de barcos de transporte de dióxido de carbono según el mismo principio que los barcos de transporte de GNL.

carbon capture

Currently, CO absorption is done on a large scale through the use of amino solvents, especially with monoethanolamine (2-aminoethanol, IUPAC nomenclature). Other techniques being explored include rapid temperature/pressure absorption, gas separation and cryogenics.

In coal-fired power plants, the main alternative to amine-based CO absorption is coal gasification and oxygen-fuel combustion. Gasification produces a primary gas, consisting of hydrogen and carbon monoxide, which is burned to produce carbon dioxide. Oxygen-fuel combustion burns coal with oxygen instead of air, producing only easily separable CO and water vapor. However, this combustion produces extreme temperatures and materials that can withstand this temperature have yet to be created.

Another long-term option is capturing carbon from the air using hydroxides. The air is literally stripped of all its CO2. This idea is an alternative to non-fossil fuels for the transport sectors (car, truck, public transport...).

A test carried out in a 420 megawatt power plant of the Elsam company in Esbjerg (Denmark) was carried out on March 15, 2006,[18]​ within the framework of the European project Castor piloted by the French Petroleum Institute (IFP), which brings together around thirty scientific and industrial partners. The post-combustion process should make it possible to reach half the cost of CO capture, reducing it from 20 to 30 euros per ton.

Its cost in four years (2004-2008) is 16 million euros, of which 8.5 million are financed by the European Union. Castor is intended to validate technologies for large industrial units - power plants, steel, cement, etc. - whose activity generates 10% of European CO emissions, so that this technique is in line with the European price of CO emission permits (€27 per ton).

Afterburner Capture

Emissions from power plants consist of less than 20% carbon dioxide. Therefore, before burying it underground, it must be captured: it is afterburning capture. In contact with an acid gas (such as CO), an aqueous solution of 2-aminoethanol forms a salt at room temperature. The solution is then transported to a closed environment where it is heated to about 120°, which, according to Le Châtelier's principle, releases the (pure) CO and the aqueous 2-aminoethanol solution is regenerated.

The oceans

Direct injection of carbon into the ocean is another type of carbon sequestration option. In this method, CO is injected into deep water, to form a "lake" of liquid CO trapped by the pressure exerted at depth. Experiments carried out between 350 and 3600 meters indicate that liquid CO reacts to pressure by solidifying into methane hydrate, which dissolves little by little in the surrounding waters. The imprisonment is therefore only temporary.

This technique has harmful consequences for the environment. CO reacts with water to form carbonic acid HCO. The biological balance of the seabed, little known, will probably be affected. The effects on benthic life forms in pelagic areas are unknown. From a political point of view, it is doubtful that carbon storage in or under the oceans is in line with the London Convention for the Prevention of Marine Pollution. [1].

Another method of ocean sequestration is the long-term collection of crop residues (such as wheat stalks or hay) into large bales of biomass and their deposition in the "alluvial fan" areas of deep ocean basins. Submerging these residues in alluvial deposits will have the effect of burying them at the bottom of the ocean, capturing the biomass for a very significant time. Alluvial deposits exist in all oceans and seas of the world. world where river deltas penetrate the continental shelf, such as the Mississippi alluvial deposit in the Gulf of Mexico and the Nile deposit in the Mediterranean.

Specific use of algae

The City of Libourne has plans to equip one of its car parks with CO-absorbing lamps. They would be equipped with a tank containing algae. These, placed near a light source, absorb carbon dioxide and emit oxygen.[19]​.

Selection of adapted organisms can give significant returns. It is estimated that a device of this type, with a volume of 1.5 m³, could absorb up to one ton of CO.

The Castor project includes the study of four places for the geological storage of CO: The Casablanca oil reserve located along the northeast coast of Spain, the Atzbach-Schwanenstadt natural gas deposit (Austria), the Snøhvit aquifer (Norway) and the K12B natural gas field exploited by Gaz de France in the Netherlands, in which it is necessary to ensure tightness. Other similar projects are being carried out around the world.

According to the BRGM")[20]​ 20 million tons of carbon dioxide each year will be stored in saline aquifers. Saline aquifers are formed by groundwater that is too salty to be used. Their capacity is estimated between 400 to 10 billion tons. The gas must be injected to a depth of at least 800 meters and under 800 bar of pressure at a temperature of 40 degrees in a "supercritical" form in equilibrium with their environment.

Geological storage

This technique uses the injection of carbon dioxide directly into underground geological formations. Oil fields and saline aquifers are ideal storage sites. Caves and ancient mines commonly used to store natural gas are not used due to lack of storage security.

CO is injected into declining oil fields for more than 30 years to increase the rate of oil recovery. This option is attractive because the cost of storage is offset by the sale of additional oil that has been generated. Other benefits of this technique come from the use of existing infrastructure and geophysical and geological studies carried out by oil exploration. All oil fields have a geological barrier that prevents the release of gaseous fluids (such as CO) in the future.

The disadvantages of oil fields lie in their geographical distribution and limited capacity.

The Kyoto Protocol argues that vegetation absorbs CO, countries with large forests can deduct a certain portion of their emissions (article 3, section 3 of the Kyoto Protocol) by facilitating access to the emission level that has been set.

It is estimated that by the 2030s, fossil fuels will represent more than three quarters of the energy used. Those who know how to capture CO at its source (22% of emissions come from industry and 39% from electricity) will have a powerful instrument in the future global emissions trading market.[18]​.

• - Carbon cycle.

• - Global warming.

• - Climate change.

• - Greenhouse gas.

• - Blue carbon.

• - This work contains a translation derived from «Puits de carbone» from French Wikipedia, published by its editors under the GNU Free Documentation License and the Creative Commons Attribution-ShareAlike 4.0 International License.

• - Manicore note on the capacity of the carbon puits to absorb or non-surplus CO.

Forests are important carbon reservoirs, due to their biomass and dead organic matter, and through their soil (some peat forest soils in Indonesia reach 40 m thick).

Forest sequestration is small compared to the CO emissions related to the combustion of fossil carbon (coal, oil and natural gas). There is a consensus on the importance of protecting relict forests (Relict (biology)), especially from forest fires, but even the most optimistic scenarios conclude that mass planting of new forests is not enough to offset the balance between increasing greenhouse gas emissions or global warming. For example, reducing U.S. carbon emissions by 7 percent, as stipulated in the Kyoto protocol, would require planting a forest the size of Texas every 30 years, said William H. Schlesinger, dean of the School of Environment and Earth Sciences at Duke University in Durham, North Carolina. To offset their emissions, the most developed regions must plant an area much larger than their entire territory. A larger area than currently available of all emerged lands (fields, roads and cities included) should be forested. However, the potential of planting new forests is not negligible, especially if they are made of dense, hardwood species and the soil is enriched with organic matter, especially in temperate zones of the planet.

The type of forest is important: temperate forests grow the fastest, but further north, peat forests are carbon sinks just the same. Tropical forests were initially considered carbon neutral, but a recent study[7]​ (measurements on more than 2 million trees worldwide) showed that they were generally carbon sinks, a function that could be limited by water stress.

The type of management is also important: a very young forest planted after a clear cutting can have a negative carbon balance, the first 10 or 12 years, losing more carbon than it stores. Logging also often causes soil erosion and loss of soil carbon (significant in temperate and cold climates).

High and mid-latitude forests have a lower albedo effect than lower latitude forests during snowy periods which contributes to global warming. Several programs offer companies to buy plots of forest to protect them (for example: "Cool Earth"), in exchange for "carbon credits" to offset industrial or individual emissions. This approach is debatable. Thus, in October 2007, Davi Kopenawa") (Amerindian shaman (Yanomami) who won the PNUE Global 500 award in 1991), presented Gordon Brown (British Prime Minister) with a report showing that the protection of forests by the land rights of their indigenous populations would protect 15,000 times the area covered by the "Cool Earth" program 2008 (162 million hectares of rainforest already It has been protected, through the recognition of the rights of the people who live there, especially after the movement launched by Chico Mendes in the 1970s).[8]​.

Ocean Retention

The ocean is the main global carbon sink, but it is saturated and starting to acidify.

The addition of micro-particles of iron (hematite) or ferrous sulfate to water has been proposed as a method to boost ocean carbon uptake by plankton. Iron is a natural trace element, a factor that limits the growth of phytoplankton. These are outcrops along the coast ("upwellings") of water from the deep zone of the ocean, contributed by rivers and provided by the deposition of aerosols and dust. Some believe that natural sources of iron have been declining for decades, limiting ecological productivity and ocean biomass (NASA, 2003) and therefore the biological pumping of atmospheric CO by photosynthesis.

In 2002, a test in the Pacific Ocean near Antarctica suggested that between 10,000 and 100,000 carbon atoms are absorbed when one iron atom is added to the sea. Work in Germany (2005) has suggested that any type of carbon biomass in the deep oceans, buried or recycled in the euphotic zone, represents long-term storage of carbon. The contribution of iron nutrients in certain areas of the ocean could increase ocean productivity and limit the disastrous effects of human CO emissions into the atmosphere.

Professor Wolfgang Arlt") of the University of Erlangen-Nuremberg (Germany) intends to inject dissolved CO at great depth, thus ensuring global diffusion. He believes that the CO would have little impact in terms of acidification if injected into the cold, dense waters of the deep ocean, and that the CO injected in Europe would be redistributed around Australia within a century, he believes, without affecting marine life or the life of the seabed.

Others question the reliability of the method, especially in the long term. They argue that the global effects of iron addition on phytoplankton and ocean ecosystems are poorly understood and require further study.

• - Phytoplankton produce clouds by releasing dimethyl sulfate (DMS) that turns into sulfate aerosols in the atmosphere and forms cloud condensation nuclei") (or CCN in English), water vapor is one of the greenhouse gas emissions and clouds contribute to changing insolation, and therefore photosynthesis.

• - The risk of eutrophication and acidification must be taken into account at the local level, when dead zones are more numerous and spreading.

• - Finally, it is the South Seas that have shown to be poor in iron, while there is no shortage in the Northern Hemisphere, where CO is more important and where biological productivity is higher.

• - A campaign (KEOPS[9]​ showed.[10]​ around the Kerguelen Islands, an area of ​​annual summer phytoplankton bloom, that the phenomenon was correlated with the presence of iron in deep waters, but is at least twice greater with natural iron than in the case of artificial fertilization.

The IPCC is very cautious about the ocean's ability to absorb more carbon, but considers that the assessment of the impact and behavior of CO in the deep ocean needs to be better studied. The IMO and the London Convention) had estimated in late 2008 that activities other than for scientific experiments should be prohibited[11].

Floors

It is estimated that soil storage at the end of the century was around 2,000 gigatonnes of carbon in the form of organic matter. It is almost three times the carbon in the atmosphere, and four times the carbon in plant biomass. However, this function is deteriorating rapidly and especially in cultivated agricultural soils. Increasing the amount of humus and organic matter would improve soil quality and the amount of carbon stored. Direct seeding and fallow can help store carbon. Subsoil stores twice as much as surface soil.

Meadows accumulate enormous amounts of organic matter, mainly in the form of roots and organic matter, which are relatively stable over long periods. But in the world since 1850, a large part of these grasslands have been converted into fields or cities, losing large amounts of carbon through oxidation. A (no-till) use increases carbon stored in the soil, and conversion to well-managed pastures stores even more carbon. Erosion control measures, maintaining vegetative cover in winter and crop rotation also increase the rate of carbon in the soil.

Ecologist Allan Savory has proposed that livestock (especially ruminants) can act as a carbon sink through holistic management "Holistic management (agriculture)"). According to him, following the full carbon cycle can capture more carbon than is emitted.[12]​ One study followed pasture management for 4 years and found that it can act as a carbon sink.[13]​ Other studies have found that holistic management can help mitigate climate change,[14]​ improve biodiversity in rural areas[15]​ and regenerate the ecosystem function and livelihoods of grazing lands.[16]​.

The increase in CO emissions in the air cannot be compensated by the increase in retention in soils. A study[17]​ has shown that long-term exposure to a double rate of CO in the atmosphere strongly accelerates the degradation of organic matter in forest soils of oak forests (=> reduction of soil carbon stocks). Trees have more carbon stored (212 g/m² in the air and 646 g/m² in the roots), but 442 g/m² of carbon had been lost in the soil, mainly on the surface up to 10 cm, apparently due to the impact of CO on the soil (by acidification and stimulation of the enzymatic activity of soil microorganisms, which increases the decomposition of organic matter, and more if there are carbon inputs (manure).

This study must be confirmed by new ones on richer soils, since here these were poor soils where the carbon content was 75% and consisting of fragile carbon chains.

Contenido

Para la fijación artificial del carbono (es decir, sin utilizar el ciclo natural del carbono), primero debe ser capturado y luego almacenado por diferentes medios.

Las plantas de purificación de gas natural deben eliminar el dióxido de carbono para evitar que el hielo carbónico obstruya los camiones cisterna o para impedir que las concentraciones de CO superen el 3% como máximo permitido en la distribución de gas natural.

Además, una de las tecnologías más prometedoras para el almacenamiento de carbono es el almacenaje de CO que proviene de las centrales eléctricas (en el caso del carbón, se conoce como "carbón limpio"). Normalmente, una central eléctrica de reciente producción de 1000 megavatios, de combustión de carbón, emite aproximadamente 6 millones de toneladas de CO al año. El desarrollo de la captura de carbono en las plantas existentes equivale a un aumento de los costos de producción de energía muy elevado. Además, una planta de carbón de 1000 MW, requiere el almacenamiento de 50 millones de barriles de CO al año.

Los costes de producción de la electricidad se han reducido cuando la tecnología de gasificación del carbón se ha utilizado en las instalaciones nuevas, aunque los costes de la electricidad han sido entre un 10 y un 12% más elevados que la producida por la quema de carbono fósil.

El transporte de dióxido de carbono ha de cumplir normas de seguridad severas, ya que es letal en concentraciones superiores al 10%, como lo demuestra la trágica desgasificación del lago Nyos.

Está en estudio el diseño de barcos de transporte de dióxido de carbono según el mismo principio que los barcos de transporte de GNL.

carbon capture

Currently, CO absorption is done on a large scale through the use of amino solvents, especially with monoethanolamine (2-aminoethanol, IUPAC nomenclature). Other techniques being explored include rapid temperature/pressure absorption, gas separation and cryogenics.

In coal-fired power plants, the main alternative to amine-based CO absorption is coal gasification and oxygen-fuel combustion. Gasification produces a primary gas, consisting of hydrogen and carbon monoxide, which is burned to produce carbon dioxide. Oxygen-fuel combustion burns coal with oxygen instead of air, producing only easily separable CO and water vapor. However, this combustion produces extreme temperatures and materials that can withstand this temperature have yet to be created.

Another long-term option is capturing carbon from the air using hydroxides. The air is literally stripped of all its CO2. This idea is an alternative to non-fossil fuels for the transport sectors (car, truck, public transport...).

A test carried out in a 420 megawatt power plant of the Elsam company in Esbjerg (Denmark) was carried out on March 15, 2006,[18]​ within the framework of the European project Castor piloted by the French Petroleum Institute (IFP), which brings together around thirty scientific and industrial partners. The post-combustion process should make it possible to reach half the cost of CO capture, reducing it from 20 to 30 euros per ton.

Its cost in four years (2004-2008) is 16 million euros, of which 8.5 million are financed by the European Union. Castor is intended to validate technologies for large industrial units - power plants, steel, cement, etc. - whose activity generates 10% of European CO emissions, so that this technique is in line with the European price of CO emission permits (€27 per ton).

Afterburner Capture

Emissions from power plants consist of less than 20% carbon dioxide. Therefore, before burying it underground, it must be captured: it is afterburning capture. In contact with an acid gas (such as CO), an aqueous solution of 2-aminoethanol forms a salt at room temperature. The solution is then transported to a closed environment where it is heated to about 120°, which, according to Le Châtelier's principle, releases the (pure) CO and the aqueous 2-aminoethanol solution is regenerated.

The oceans

Direct injection of carbon into the ocean is another type of carbon sequestration option. In this method, CO is injected into deep water, to form a "lake" of liquid CO trapped by the pressure exerted at depth. Experiments carried out between 350 and 3600 meters indicate that liquid CO reacts to pressure by solidifying into methane hydrate, which dissolves little by little in the surrounding waters. The imprisonment is therefore only temporary.

This technique has harmful consequences for the environment. CO reacts with water to form carbonic acid HCO. The biological balance of the seabed, little known, will probably be affected. The effects on benthic life forms in pelagic areas are unknown. From a political point of view, it is doubtful that carbon storage in or under the oceans is in line with the London Convention for the Prevention of Marine Pollution. [1].

Another method of ocean sequestration is the long-term collection of crop residues (such as wheat stalks or hay) into large bales of biomass and their deposition in the "alluvial fan" areas of deep ocean basins. Submerging these residues in alluvial deposits will have the effect of burying them at the bottom of the ocean, capturing the biomass for a very significant time. Alluvial deposits exist in all oceans and seas of the world. world where river deltas penetrate the continental shelf, such as the Mississippi alluvial deposit in the Gulf of Mexico and the Nile deposit in the Mediterranean.

Specific use of algae

The City of Libourne has plans to equip one of its car parks with CO-absorbing lamps. They would be equipped with a tank containing algae. These, placed near a light source, absorb carbon dioxide and emit oxygen.[19]​.

Selection of adapted organisms can give significant returns. It is estimated that a device of this type, with a volume of 1.5 m³, could absorb up to one ton of CO.

The Castor project includes the study of four places for the geological storage of CO: The Casablanca oil reserve located along the northeast coast of Spain, the Atzbach-Schwanenstadt natural gas deposit (Austria), the Snøhvit aquifer (Norway) and the K12B natural gas field exploited by Gaz de France in the Netherlands, in which it is necessary to ensure tightness. Other similar projects are being carried out around the world.

According to the BRGM")[20]​ 20 million tons of carbon dioxide each year will be stored in saline aquifers. Saline aquifers are formed by groundwater that is too salty to be used. Their capacity is estimated between 400 to 10 billion tons. The gas must be injected to a depth of at least 800 meters and under 800 bar of pressure at a temperature of 40 degrees in a "supercritical" form in equilibrium with their environment.

Geological storage

This technique uses the injection of carbon dioxide directly into underground geological formations. Oil fields and saline aquifers are ideal storage sites. Caves and ancient mines commonly used to store natural gas are not used due to lack of storage security.

CO is injected into declining oil fields for more than 30 years to increase the rate of oil recovery. This option is attractive because the cost of storage is offset by the sale of additional oil that has been generated. Other benefits of this technique come from the use of existing infrastructure and geophysical and geological studies carried out by oil exploration. All oil fields have a geological barrier that prevents the release of gaseous fluids (such as CO) in the future.

The disadvantages of oil fields lie in their geographical distribution and limited capacity.

The Kyoto Protocol argues that vegetation absorbs CO, countries with large forests can deduct a certain portion of their emissions (article 3, section 3 of the Kyoto Protocol) by facilitating access to the emission level that has been set.

It is estimated that by the 2030s, fossil fuels will represent more than three quarters of the energy used. Those who know how to capture CO at its source (22% of emissions come from industry and 39% from electricity) will have a powerful instrument in the future global emissions trading market.[18]​.

• - Carbon cycle.

• - Global warming.

• - Climate change.

• - Greenhouse gas.

• - Blue carbon.

• - This work contains a translation derived from «Puits de carbone» from French Wikipedia, published by its editors under the GNU Free Documentation License and the Creative Commons Attribution-ShareAlike 4.0 International License.

• - Manicore note on the capacity of the carbon puits to absorb or non-surplus CO.