CO2 sequestration
Encyclopedia
Carbon sequestration is the capture of carbon dioxide
and may refer specifically to:
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 gas
es, which are released by burning fossil fuel
s.
Carbon dioxide is naturally captured from the atmosphere through biological, chemical or physical processes. Some anthropogenic sequestration techniques exploit these natural processes, while some use entirely artificial processes.
Carbon dioxide may be captured as a pure by-product in processes related to petroleum refining or from flue gases from power generation. sequestration includes the storage part of carbon capture and storage, which refers to large-scale, permanent artificial capture and sequestration of industrially produced using subsurface saline
aquifers, reservoirs, ocean water, aging oil field
s, or other carbon sinks.
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 fuel
s, as well as clathrate or limestone
. By manipulating such processes, geoengineers seek to enhance sequestration.
is the replanting of trees on marginal crop and pasture
lands to incorporate carbon from atmospheric into biomass
. For this process to succeed the carbon must not return to the atmosphere from burning or rotting when the trees die.http://www.nationalaglawcenter.org/assets/crs/RL31432.pdf To this end, the trees must grow in perpetuity or the wood from them must itself be sequestered, e.g., via biochar
, bio-energy with carbon storage (BECS
) or landfill.
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 (i.e. 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).
s, 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 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 to the atmosphere, tillage incorporates the biomass back into the soil where it can be absorbed and a portion of it stored permanently.
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 atmosperic 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 its complete effects on the marine ecosystem
, including side effects and possibly large deviations from expected behavior. Such effects potentially include release of nitrogen oxide
s, and disruption of the ocean's nutrient balance.
Ian Jones
proposes to fertilize the ocean with urea
, a nitrogen
rich substance, to encourage phytoplankton
growth.
Australian company Ocean Nourishment Corporation (ONC) plans to sink hundreds of tonnes of urea into the ocean to boost -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 , which limits its attractiveness.
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.
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
. Biogenic carbon is recycled naturally in the carbon cycle
. Pyrolysing it to biochar renders the carbon inert so that it remains sequestered in soil. Further, the soil encourages bulking with new organic matter
, which gives additional sequestration benefit.
In the soil, the carbon is unavailable for oxidation to and consequential atmospheric release. This is one technique advocated by prominent 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.
and other geological features, or can be injected into the deep ocean
.
The first large-scale 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
solvent
s 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
.
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 in the state of Texas
alone. The gas comes in part from anthropogenic sources, but is principally from large naturally occurring geologic formations of . It is transported to the oil-producing fields through a large network of over 5000 kilometres (3,106.9 mi) of pipelines. The use of 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 pipeline system does not yet exist in the WCSB. Athabasca oil sands
mining that produces is hundreds of kilometers north of the subsurface heavy oil
reservoirs that could most benefit from injection.
' 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).
Calcium and magnesium are found in nature typically as calcium and magnesium silicates
(such as forsterite
and serpentinite
) and not as binary oxides. For forsterite and serpentine the reactions are:
The following table lists principal metal oxides of Earth's crust
. Theoretically up to 22% of this mineral mass is able to form carbonate
s.
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, for example by reacting at higher temperatures and/or pressures, or by pre-treatment, although this method requires additional energy.
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 .
In Estonia, oil shale
ash
, generated by power stations could be used as sorbent
s for mineral sequestration. The amount of captured averaged 60–65% of the carbonaceous and 10–11% of the total emissions.
processes have been proposed to remove 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 scrubber
s.
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 “geothermal
, sediment, gravitational and hydrate
formation.” Because hydrate is denser than in seawater, the risk of leakage is minimal. Injecting the at depths greater than 2700 metres (8,858.3 ft) ensures that the 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.
or volcanic rock to oceans enhances the solubility pump
, which naturally removes from the atmosphere. Various other scientists have explored this technique, and suggested a variety of different bases
that added to the ocean, increase absorption.
removes hydrochloric acid
from the ocean for neutralization with silicate minerals
or rocks. Electrolysis may contribute to carbon addition to the ocean if not carefully managed.
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
and may refer specifically to:
- "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 geoengineeringGeoengineeringThe concept of Geoengineering refers to the deliberate large-scale engineering and manipulation of the planetary environment to combat or counteract anthropogenic changes in atmospheric chemistry The Intergovernmental Panel on Climate Change concluded in 2007 that geoengineering options, such...
.
- The process of carbon capture and storageCarbon capture and storageCarbon capture and storage , alternatively referred to as carbon capture and sequestration, is a technology to prevent large quantities of from being released into the atmosphere from the use of fossil fuel in power generation and other industries. It is often regarded as a means of mitigating...
, where carbon dioxide is removed from flue gases, such as on power stations, before being stored in underground reservoirs.
- Natural biogeochemical cycling of carbonCarbonCarbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...
between the atmosphereAtmosphereAn atmosphere is a layer of gases that may surround a material body of sufficient mass, and that is held in place by the gravity of the body. An atmosphere may be retained for a longer duration, if the gravity is high and the atmosphere's temperature is low...
and reservoirs, such as by chemical weathering of rocks.
Carbon sequestration describes long-term storage of carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
or other forms of carbon
Carbon
Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...
to either mitigate or defer global warming
Mitigation of global warming
Climate change mitigation is action to decrease the intensity of radiative forcing in order to reduce the potential effects of global warming. Mitigation is distinguished from adaptation to global warming, which involves acting to tolerate the effects of global warming...
and avoid dangerous climate change
Avoiding Dangerous Climate Change
The related terms "avoiding dangerous climate change" and "preventing dangerous anthropogenic interference with the climate system" date to 1995 and earlier, in the Second Assesment Report of the International Panel on Climate Change and previous science it cites.In 2002, the United Nations...
. It has been proposed as a way to slow the atmospheric and marine accumulation of greenhouse gas
Greenhouse gas
A greenhouse gas is a gas in an atmosphere that absorbs and emits radiation within the thermal infrared range. This process is the fundamental cause of the greenhouse effect. The primary greenhouse gases in the Earth's atmosphere are water vapor, carbon dioxide, methane, nitrous oxide, and ozone...
es, which are released by burning fossil fuel
Fossil fuel
Fossil fuels are fuels formed by natural processes such as anaerobic decomposition of buried dead organisms. The age of the organisms and their resulting fossil fuels is typically millions of years, and sometimes exceeds 650 million years...
s.
Carbon dioxide is naturally captured from the atmosphere through biological, chemical or physical processes. Some anthropogenic sequestration techniques exploit these natural processes, while some use entirely artificial processes.
Carbon dioxide may be captured as a pure by-product in processes related to petroleum refining or from flue gases from power generation. sequestration includes the storage part of carbon capture and storage, which refers to large-scale, permanent artificial capture and sequestration of industrially produced using subsurface saline
Saline
Saline may refer to:* Salinity, the salt content of a solution** Saline water, water containing significant concentration of salts* Soil salinity, salt content of soil* Saline , a liquid with salt content to match the human body...
aquifers, reservoirs, ocean water, aging oil field
Oil field
An oil field is a region with an abundance of oil wells extracting petroleum from below ground. Because the oil reservoirs typically extend over a large area, possibly several hundred kilometres across, full exploitation entails multiple wells scattered across the area...
s, or other carbon sinks.
Biological processes
Biosequestration
Biosequestration is the capture and storage of the atmospheric greenhouse gas carbon dioxide by biological processes.This may be by increased photosynthesis ; by enhanced soil carbon trapping in agriculture; or by the use of algal bio sequestration to absorb the carbon...
or carbon sequestration through biological processes affects the Global carbon cycle
Carbon cycle
The carbon cycle is the biogeochemical cycle by which carbon is exchanged among the biosphere, pedosphere, geosphere, hydrosphere, and atmosphere of the Earth...
. Examples include major climatic fluctuations, such as the Azolla event
Azolla event
The Azolla event occurred in the middle Eocene period, around , when blooms of the freshwater fern Azolla are thought to have happened in the Arctic Ocean...
, which created the current Arctic
Arctic
The Arctic is a region located at the northern-most part of the Earth. The Arctic consists of the Arctic Ocean and parts of Canada, Russia, Greenland, the United States, Norway, Sweden, Finland, and Iceland. The Arctic region consists of a vast, ice-covered ocean, surrounded by treeless permafrost...
climate. Such processes created fossil fuel
Fossil fuel
Fossil fuels are fuels formed by natural processes such as anaerobic decomposition of buried dead organisms. The age of the organisms and their resulting fossil fuels is typically millions of years, and sometimes exceeds 650 million years...
s, as well as clathrate or limestone
Limestone
Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....
. By manipulating such processes, geoengineers seek to enhance sequestration.
Peat production
Peat bogs are a very important carbon store. By creating new bogs, or enhancing existing ones, carbon can be sequestered.Forestry
ReforestationReforestation
Reforestation is the natural or intentional restocking of existing forests and woodlands that have been depleted, usually through deforestation....
is the replanting of trees on marginal crop and pasture
Pasture
Pasture is land used for grazing. Pasture lands in the narrow sense are enclosed tracts of farmland, grazed by domesticated livestock, such as horses, cattle, sheep or swine. The vegetation of tended pasture, forage, consists mainly of grasses, with an interspersion of legumes and other forbs...
lands to incorporate carbon from atmospheric into biomass
Biomass
Biomass, as a renewable energy source, is biological material from living, or recently living organisms. As an energy source, biomass can either be used directly, or converted into other energy products such as biofuel....
. For this process to succeed the carbon must not return to the atmosphere from burning or rotting when the trees die.http://www.nationalaglawcenter.org/assets/crs/RL31432.pdf To this end, the trees must grow in perpetuity or the wood from them must itself be sequestered, e.g., via biochar
Biochar
Biochar or terra preta is charcoal created by pyrolysis of biomass. Biochar is under investigation as an approach to carbon sequestration via bio-energy with carbon capture and storage. Biochar thus has the potential to help mitigate climate change, via carbon sequestration...
, bio-energy with carbon storage (BECS
Bio-energy with carbon storage
BECS or Bio-Energy with Carbon Storage may refer to:*Bio-energy with carbon capture and storage *The burial or storage of biochar created by partial burning of biomass...
) or landfill.
Agriculture
Globally, soils are estimated to contain approximately 1,500 gigatons of organic carbon, 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 (i.e. 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).
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 fertilizerFertilizer
Fertilizer is any organic or inorganic material of natural or synthetic origin that is added to a soil to supply one or more plant nutrients essential to the growth of plants. A recent assessment found that about 40 to 60% of crop yields are attributable to commercial fertilizer use...
s, less soil disturbance, better irrigation
Irrigation
Irrigation may be defined as the science of artificial application of water to the land or soil. It is used to assist in the growing of agricultural crops, maintenance of landscapes, and revegetation of disturbed soils in dry areas and during periods of inadequate rainfall...
, 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
No-till farming
No-till farming is a way of growing crops from year to year without disturbing the soil through tillage. No-till is an agricultural technique which increases the amount of water and organic matter in the soil and decreases erosion...
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 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 to the atmosphere, tillage incorporates the biomass back into the soil where it can be absorbed and a portion of it stored permanently.
Enhancing carbon removal
All crops absorb 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 cropCover cropCover crops are crops planted primarily to manage soil fertility, soil quality, water, weeds, pests, diseases, biodiversity and wildlife in agroecosystems , ecological systems managed and largely shaped by humans across a range of intensities to produce food, feed, or fiber.Cover crops are of...
s 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
Soil
Soil is a natural body consisting of layers of mineral constituents of variable thicknesses, which differ from the parent materials in their morphological, physical, chemical, and mineralogical characteristics...
, air, and water quality, be beneficial to wildlife
Wildlife
Wildlife includes all non-domesticated plants, animals and other organisms. Domesticating wild plant and animal species for human benefit has occurred many times all over the planet, and has a major impact on the environment, both positive and negative....
, 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
Wheat
Wheat is a cereal grain, originally from the Levant region of the Near East, but now cultivated worldwide. In 2007 world production of wheat was 607 million tons, making it the third most-produced cereal after maize and rice...
, 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 atmosperic 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.
Iron fertilization
Ocean iron fertilization
Iron fertilization
Iron fertilization is the intentional introduction of iron to the upper ocean to stimulate a phytoplankton bloom. This is intended to enhance biological productivity, which can benefit the marine food chain and remove carbon dioxide from the atmosphere. Iron is a trace element necessary for...
is an example of such a geoengineering technique. Iron fertilization
Iron fertilization
Iron fertilization is the intentional introduction of iron to the upper ocean to stimulate a phytoplankton bloom. This is intended to enhance biological productivity, which can benefit the marine food chain and remove carbon dioxide from the atmosphere. Iron is a trace element necessary for...
attempts to encourage phytoplankton
Phytoplankton
Phytoplankton are the autotrophic component of the plankton community. The name comes from the Greek words φυτόν , meaning "plant", and πλαγκτός , meaning "wanderer" or "drifter". Most phytoplankton are too small to be individually seen with the unaided eye...
growth, which removes carbon from the atmosphere for at least a period of time. This technique is controversial due to limited understanding its complete effects on the marine ecosystem
Ecosystem
An ecosystem is a biological environment consisting of all the organisms living in a particular area, as well as all the nonliving , physical components of the environment with which the organisms interact, such as air, soil, water and sunlight....
, including side effects and possibly large deviations from expected behavior. Such effects potentially include release of nitrogen oxide
Nitrogen oxide
Nitrogen oxide can refer to a binary compound of oxygen and nitrogen, or a mixture of such compounds:* Nitric oxide, also known as nitrogen monoxide, , nitrogen oxide* Nitrogen dioxide , nitrogen oxide...
s, and disruption of the ocean's nutrient balance.
Urea fertilisation
Ian Jones
Ian Jones
Ian Jones may refer to:*Ian Jones , Australian author and film writer*Ian Jones , New-Zealand rugby player*Ian Jones , British bronze medal winner at the 2008 Summer Paralympics...
proposes to fertilize the ocean with urea
Urea
Urea or carbamide is an organic compound with the chemical formula CO2. The molecule has two —NH2 groups joined by a carbonyl functional group....
, a nitrogen
Nitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...
rich substance, to encourage phytoplankton
Phytoplankton
Phytoplankton are the autotrophic component of the plankton community. The name comes from the Greek words φυτόν , meaning "plant", and πλαγκτός , meaning "wanderer" or "drifter". Most phytoplankton are too small to be individually seen with the unaided eye...
growth.
Australian company Ocean Nourishment Corporation (ONC) plans to sink hundreds of tonnes of urea into the ocean to boost -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.
Mixing layers
Encouraging various ocean layers to mix can move nutrients and dissolved gases around, offering avenues for geoengineering
Geoengineering
The concept of Geoengineering refers to the deliberate large-scale engineering and manipulation of the planetary environment to combat or counteract anthropogenic changes in atmospheric chemistry The Intergovernmental Panel on Climate Change concluded in 2007 that geoengineering options, such...
. 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 , which limits its attractiveness.
Physical processes
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
Bio-energy with carbon storage
BECS or Bio-Energy with Carbon Storage may refer to:*Bio-energy with carbon capture and storage *The burial or storage of biochar created by partial burning of biomass...
, BECS, though this term can also refer to the carbon sequestration potential in other technologies, such as biochar.
Burial
Burying biomass (such as trees) directly, mimics the natural processes that created fossil fuels. Landfills also represents a physical method of sequestration.Biochar burial
BiocharBiochar
Biochar or terra preta is charcoal created by pyrolysis of biomass. Biochar is under investigation as an approach to carbon sequestration via bio-energy with carbon capture and storage. Biochar thus has the potential to help mitigate climate change, via carbon sequestration...
is charcoal
Charcoal
Charcoal is the dark grey residue consisting of carbon, and any remaining ash, obtained by removing water and other volatile constituents from animal and vegetation substances. Charcoal is usually produced by slow pyrolysis, the heating of wood or other substances in the absence of oxygen...
created by pyrolysis
Pyrolysis
Pyrolysis is a thermochemical decomposition of organic material at elevated temperatures without the participation of oxygen. It involves the simultaneous change of chemical composition and physical phase, and is irreversible...
of biomass
Biomass
Biomass, as a renewable energy source, is biological material from living, or recently living organisms. As an energy source, biomass can either be used directly, or converted into other energy products such as biofuel....
waste. The resulting material is added to a landfill
Landfill
A landfill site , is a site for the disposal of waste materials by burial and is the oldest form of waste treatment...
or used as a soil improver to create terra preta
Terra preta
Terra preta is a type of very dark, fertile anthropogenic soil found in the Amazon Basin. Terra preta owes its name to its very high charcoal content, and was indeed made by adding a mixture of charcoal, bone, and manure to the otherwise relatively infertile Amazonian soil, and stays there for...
. Biogenic carbon is recycled naturally in the carbon cycle
Carbon cycle
The carbon cycle is the biogeochemical cycle by which carbon is exchanged among the biosphere, pedosphere, geosphere, hydrosphere, and atmosphere of the Earth...
. Pyrolysing it to biochar renders the carbon inert so that it remains sequestered in soil. Further, the soil encourages bulking with new organic matter
Organic matter
Organic matter is matter that has come from a once-living organism; is capable of decay, or the product of decay; or is composed of organic compounds...
, which gives additional sequestration benefit.
In the soil, the carbon is unavailable for oxidation to and consequential atmospheric release. This is one technique advocated by prominent scientist
Scientist
A scientist in a broad sense is one engaging in a systematic activity to acquire knowledge. In a more restricted sense, a scientist is an individual who uses the scientific method. The person may be an expert in one or more areas of science. This article focuses on the more restricted use of the word...
James Lovelock
James Lovelock
James Lovelock, CH, CBE, FRS is an independent scientist, environmentalist and futurologist who lives in Devon, England. He is best known for proposing the Gaia hypothesis, which postulates that the biosphere is a self-regulating entity with the capacity to keep our planet healthy by controlling...
, creator of the Gaia hypothesis
Gaia hypothesis
The Gaia hypothesis, also known as Gaia theory or Gaia principle, proposes that all organisms and their inorganic surroundings on Earth are closely integrated to form a single and self-regulating complex system, maintaining the conditions for life on the planet.The scientific investigation of the...
. 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
Bio-energy with carbon storage
BECS or Bio-Energy with Carbon Storage may refer to:*Bio-energy with carbon capture and storage *The burial or storage of biochar created by partial burning of biomass...
, BECS.
Ocean storage
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.Subterranean injection
Carbon dioxide can be injected into depleted oil and gas reservoirsOil well
An oil well is a general term for any boring through the earth's surface that is designed to find and acquire petroleum oil hydrocarbons. Usually some natural gas is produced along with the oil. A well that is designed to produce mainly or only gas may be termed a gas well.-History:The earliest...
and other geological features, or can be injected into the deep ocean
Ocean
An ocean is a major body of saline water, and a principal component of the hydrosphere. Approximately 71% of the Earth's surface is covered by ocean, a continuous body of water that is customarily divided into several principal oceans and smaller seas.More than half of this area is over 3,000...
.
The first large-scale sequestration project which began in 1996 is called Sleipner
Sleipner
Sleipnir is an eight-legged horse in Norse mythology. Sleipnir or Sleipner may also refer to:Ships and offshore* Sleipner gas field** Sleipner A, an offshore platform...
, and is located in the North Sea
North Sea
In the southwest, beyond the Straits of Dover, the North Sea becomes the English Channel connecting to the Atlantic Ocean. In the east, it connects to the Baltic Sea via the Skagerrak and Kattegat, narrow straits that separate Denmark from Norway and Sweden respectively...
where Norway's StatoilHydro
StatoilHydro
Statoil ASA, trading as Statoil and formerly known as StatoilHydro, is a Norwegian energy company, formed by the 2007 merger of Statoil with the oil and gas division of Norsk Hydro. The Government of Norway is the largest shareholder in Statoil with 67% of the shares...
strips carbon dioxide from natural gas
Natural gas
Natural gas is a naturally occurring gas mixture consisting primarily of methane, typically with 0–20% higher hydrocarbons . It is found associated with other hydrocarbon fuel, in coal beds, as methane clathrates, and is an important fuel source and a major feedstock for fertilizers.Most natural...
with amine
Amine
Amines are organic compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are derivatives of ammonia, wherein one or more hydrogen atoms have been replaced by a substituent such as an alkyl or aryl group. Important amines include amino acids, biogenic amines,...
solvent
Solvent
A solvent is a liquid, solid, or gas that dissolves another solid, liquid, or gaseous solute, resulting in a solution that is soluble in a certain volume of solvent at a specified temperature...
s and disposed of this carbon dioxide in a deep saline
Saline water
Saline water is a general term for water that contains a significant concentration of dissolved salts . The concentration is usually expressed in parts per million of salt....
aquifer
Aquifer
An aquifer is a wet underground layer of water-bearing permeable rock or unconsolidated materials from which groundwater can be usefully extracted using a water well. The study of water flow in aquifers and the characterization of aquifers is called hydrogeology...
. In 2000, a coal-fueled synthetic natural gas plant in Beulah, North Dakota
Beulah, North Dakota
At the 2000 census, there were 3,152 people, 1,213 households, and 851 families residing in the city. The population density was 1,307.8 inhabitants per square mile . There were 1,475 housing units at an average density of 612.0 per square mile...
, became the world's first coal using plant to capture and store carbon dioxide, at the Weyburn-Midale Carbon Dioxide Project
Weyburn-Midale Carbon Dioxide Project
The Weyburn-Midale Carbon Dioxide Project is, as of 2008, the world's largest carbon capture and storage project...
.
has been used extensively in enhanced crude oil recovery operations in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
beginning in 1972. There are in excess of 10,000 wells that inject in the state of Texas
Texas
Texas is the second largest U.S. state by both area and population, and the largest state by area in the contiguous United States.The name, based on the Caddo word "Tejas" meaning "friends" or "allies", was applied by the Spanish to the Caddo themselves and to the region of their settlement in...
alone. The gas comes in part from anthropogenic sources, but is principally from large naturally occurring geologic formations of . It is transported to the oil-producing fields through a large network of over 5000 kilometres (3,106.9 mi) of pipelines. The use of for enhanced oil recovery
Enhanced oil recovery
Enhanced Oil Recovery is a generic term for techniques for increasing the amount of crude oil that can be extracted from an oil field...
(EOR) methods in heavy oil reservoirs in the Western Canadian Sedimentary Basin
Western Canadian Sedimentary Basin
The Western Canadian Sedimentary Basin is a vast sedimentary basin underlying of Western Canada including southwestern Manitoba, southern Saskatchewan, Alberta, northeastern British Columbia and the southwest corner of the Northwest Territories. It consists of a massive wedge of sedimentary rock...
(WCSB) has also been proposed. However, transport cost remains an important hurdle. An extensive pipeline system does not yet exist in the WCSB. Athabasca oil sands
Athabasca Oil Sands
The Athabasca oil sands are large deposits of bitumen, or extremely heavy crude oil, located in northeastern Alberta, Canada - roughly centred on the boomtown of Fort McMurray...
mining that produces is hundreds of kilometers north of the subsurface heavy oil
Heavy oil
Heavy oil may refer to:*Fuel oil that contains residual oil left over from distillation.*Heavy crude oil, viscous crude oil.*Coal tar creosote, a wood preservative and waterproofing agent....
reservoirs that could most benefit from injection.
Chemical processes
Carbon, in the form of 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 carbonationCarbonation
Carbonation is the process of dissolving carbon dioxide in water. The process usually involves carbon dioxide under high pressure. When the pressure is reduced, the carbon dioxide is released from the solution as small bubbles, which cause the solution to "fizz." This effect is seen in carbonated...
' or mineral sequestration. The process involves reacting carbon dioxide with abundantly available metal oxides–either magnesium oxide
Magnesium oxide
Magnesium oxide , or magnesia, is a white hygroscopic solid mineral that occurs naturally as periclase and is a source of magnesium . It has an empirical formula of and consists of a lattice of Mg2+ ions and O2– ions held together by ionic bonds...
(MgO) or calcium oxide
Calcium oxide
Calcium oxide , commonly known as quicklime or burnt lime, is a widely used chemical compound. It is a white, caustic, alkaline crystalline solid at room temperature....
(CaO)–to form stable carbonates. These reactions are exothermic
Exothermic
In thermodynamics, the term exothermic describes a process or reaction that releases energy from the system, usually in the form of heat, but also in the form of light , electricity , or sound...
and occur naturally (e.g., the weathering
Weathering
Weathering is the breaking down of rocks, soils and minerals as well as artificial materials through contact with the Earth's atmosphere, biota and waters...
of rock over geologic time periods).
- CaO + →
- MgO + →
Calcium and magnesium are found in nature typically as calcium and magnesium silicates
Silicate minerals
The silicate minerals make up the largest and most important class of rock-forming minerals, constituting approximately 90 percent of the crust of the Earth. They are classified based on the structure of their silicate group...
(such as forsterite
Forsterite
Forsterite is the magnesium rich end-member of the olivine solid solution series. Forsterite crystallizes in the orthorhombic system with cell parameters a 4.75 Å , b 10.20 Å and c 5.98 Å .Forsterite is associated with igneous and metamorphic rocks and has also been found in meteorites...
and serpentinite
Serpentinite
Serpentinite is a rock composed of one or more serpentine group minerals. Minerals in this group are formed by serpentinization, a hydration and metamorphic transformation of ultramafic rock from the Earth's mantle...
) and not as binary oxides. For forsterite and serpentine the reactions are:
- + 2 = 2 +
- + 3 = 3 + 2 + 2
The following table lists principal metal oxides of Earth's crust
Crust (geology)
In geology, the crust is the outermost solid shell of a rocky planet or natural satellite, which is chemically distinct from the underlying mantle...
. Theoretically up to 22% of this mineral mass is able to form carbonate
Carbonate
In chemistry, a carbonate is a salt of carbonic acid, characterized by the presence of the carbonate ion, . The name may also mean an ester of carbonic acid, an organic compound containing the carbonate group C2....
s.
| Earthen Oxide | Percent of Crust | Carbonate | Enthalpy change Standard enthalpy change of reaction The standard enthalpy of reaction is the enthalpy change that occurs in a system when one mole of matter is transformed by a chemical reaction under standard conditions.For a generic chemical reaction... (kJ/mol) |
|---|---|---|---|
| 59.71 | |||
| 15.41 | |||
| CaO | 4.90 | Calcium carbonate Calcium carbonate is a chemical compound with the formula CaCO3. It is a common substance found in rocks in all parts of the world, and is the main component of shells of marine organisms, snails, coal balls, pearls, and eggshells. Calcium carbonate is the active ingredient in agricultural lime,... |
-179 |
| MgO | 4.36 | Magnesium carbonate Magnesium carbonate, MgCO3, is a white solid that occurs in nature as a mineral. Several hydrated and basic forms of magnesium carbonate also exist as minerals... |
-117 |
| 3.55 | Sodium carbonate Sodium carbonate , Na2CO3 is a sodium salt of carbonic acid. It most commonly occurs as a crystalline heptahydrate, which readily effloresces to form a white powder, the monohydrate. Sodium carbonate is domestically well-known for its everyday use as a water softener. It can be extracted from the... |
||
| FeO | 3.52 | ||
| 2.80 | Potassium carbonate Potassium carbonate is a white salt, soluble in water , which forms a strongly alkaline solution. It can be made as the product of potassium hydroxide's absorbent reaction with carbon dioxide. It is deliquescent, often appearing a damp or wet solid... |
||
| 2.63 | |||
| 21.76 | All Carbonates |
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
Limestone
Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....
. The reaction rate can be made faster, for example by reacting at higher temperatures and/or pressures, or by pre-treatment, although this method requires additional energy.
naturally reacts with peridotite
Peridotite
A peridotite is a dense, coarse-grained igneous rock, consisting mostly of the minerals olivine and pyroxene. Peridotite is ultramafic, as the rock contains less than 45% silica. It is high in magnesium, reflecting the high proportions of magnesium-rich olivine, with appreciable iron...
rock in surface exposures of ophiolites, notably in Oman
Oman
Oman , officially called the Sultanate of Oman , is an Arab state in southwest Asia on the southeast coast of the Arabian Peninsula. It is bordered by the United Arab Emirates to the northwest, Saudi Arabia to the west, and Yemen to the southwest. The coast is formed by the Arabian Sea on the...
. It has been suggested that this process can be enhanced to carry out natural mineralisation of .
Industrial use
Traditional cement manufacture releases large amounts of carbon dioxide, but newly developed cement types from Novacem can absorb from ambient air during hardening. A similar technique was pioneered by TecEco, which has been producing "EcoCement" since 2002.In Estonia, oil shale
Oil shale
Oil shale, an organic-rich fine-grained sedimentary rock, contains significant amounts of kerogen from which liquid hydrocarbons called shale oil can be produced...
ash
Bottom ash
Bottom ash refers to part of the non-combustible residues of combustion. In an industrial context, it usually refers to coal combustion and comprises traces of combustibles embedded in forming clinkers and sticking to hot side walls of a coal-burning furnace during its operation. The portion of...
, generated by power stations could be used as sorbent
Sorbent
A sorbent is a material used to absorb liquids or gases. Examples include:*A material similar to molecular sieve material. It has a large internal surface area and good thermal conductivity. It is typically supplied in pellets of 1 mm to 2 mm diameter and roughly 5 mm length or as...
s for mineral sequestration. The amount of captured averaged 60–65% of the carbonaceous and 10–11% of the total emissions.
Chemical scrubbers
Various carbon dioxide scrubbingCarbon dioxide scrubber
A carbon dioxide scrubber is a device which absorbs carbon dioxide . It is used to treat exhaust gases from industrial plants or from exhaled air in life support systems such as rebreathers or in spacecraft, submersible craft or airtight chambers...
processes have been proposed to remove from the air, usually using a variant of the Kraft process
Kraft process
The kraft process describes a technology for conversion of wood into wood pulp consisting of almost pure cellulose fibers...
. Carbon dioxide scrubbing variants exist based on potassium carbonate
Potassium carbonate
Potassium carbonate is a white salt, soluble in water , which forms a strongly alkaline solution. It can be made as the product of potassium hydroxide's absorbent reaction with carbon dioxide. It is deliquescent, often appearing a damp or wet solid...
, which can be used to create liquid fuels, or on sodium hydroxide. These notably include artificial trees proposed by Klaus Lackner
Klaus Lackner
Klaus Lackner is a professor in the Department of Earth and Environmental Engineering at Columbia University and co-founder of in Tucson, AZ. Lackner pioneered the concept of carbon dioxide air capture as a means for climate change mitigation, i.e. abating emissions of greenhouse gases into the...
to remove carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
from the atmosphere
Atmosphere
An atmosphere is a layer of gases that may surround a material body of sufficient mass, and that is held in place by the gravity of the body. An atmosphere may be retained for a longer duration, if the gravity is high and the atmosphere's temperature is low...
using chemical scrubber
Scrubber
Scrubber systems are a diverse group of air pollution control devices that can be used to remove some particulates and/or gases from industrial exhaust streams. Traditionally, the term "scrubber" has referred to pollution control devices that use liquid to wash unwanted pollutants from a gas stream...
s.
Basalt storage
Carbon dioxide sequestration in basalt involves the injecting of into deep-sea formations. The first mixes with seawater and then reacts with the basalt, both of which are alkaline-rich elements. This reaction results in the release of and 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 “geothermal
Geothermal
Geothermal is related to energy and may refer to:* The geothermal gradient and associated heat flows from within the Earth- Renewable technology :...
, sediment, gravitational and hydrate
Hydrate
Hydrate is a term used in inorganic chemistry and organic chemistry to indicate that a substance contains water. The chemical state of the water varies widely between hydrates, some of which were so labeled before their chemical structure was understood....
formation.” Because hydrate is denser than in seawater, the risk of leakage is minimal. Injecting the at depths greater than 2700 metres (8,858.3 ft) ensures that the has a greater density than seawater, causing it to sink.
One possible injection site is Juan de Fuca plate
Juan de Fuca Plate
The Juan de Fuca Plate, named after the explorer of the same name, is a tectonic plate, generated from the Juan de Fuca Ridge, and subducting under the northerly portion of the western side of the North American Plate at the Cascadia subduction zone...
. Researchers at the Lamont-Doherty Earth Observatory
Lamont-Doherty Earth Observatory
The Lamont–Doherty Earth Observatory is a research unit of Columbia University located on a campus in Palisades, N.Y., north of Manhattan on the Hudson River.- History :...
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
Greenhouse gas emissions by the United States
Until 2006, the United States was the largest emitter of carbon dioxide emissions. China has been the top emitter since 2006. However both the emissions as a result of manufacturing exports and the emissions avoided by product imports are not considered...
for over 100 years.
This process is undergoing tests as part of the CarbFix
CarbFix
CarbFix is a project in Iceland intended to lock away carbon dioxide by reacting it with basaltic rocks. Work on the project began in 2007. The CarbFix team involves American and Icelandic designers researchers including Iceland geologist Sigurdur Reynir Gislason serving as chief scientist, project...
project.
Acid neutralisation
Adding crushed limestoneLimestone
Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....
or volcanic rock to oceans enhances the solubility pump
Solubility pump
In oceanic biogeochemistry, the solubility pump is a physico-chemical process that transports carbon from the ocean's surface to its interior.-Overview:...
, which naturally removes from the atmosphere. Various other scientists have explored this technique, and suggested a variety of different bases
Base (chemistry)
For the term in genetics, see base A base in chemistry is a substance that can accept hydrogen ions or more generally, donate electron pairs. A soluble base is referred to as an alkali if it contains and releases hydroxide ions quantitatively...
that added to the ocean, increase absorption.
Hydrochloric acid removal
ElectrolysisElectrolysis
In chemistry and manufacturing, electrolysis is a method of using a direct electric current to drive an otherwise non-spontaneous chemical reaction...
removes hydrochloric acid
Hydrochloric acid
Hydrochloric acid is a solution of hydrogen chloride in water, that is a highly corrosive, strong mineral acid with many industrial uses. It is found naturally in gastric acid....
from the ocean for neutralization with silicate minerals
Silicate minerals
The silicate minerals make up the largest and most important class of rock-forming minerals, constituting approximately 90 percent of the crust of the Earth. They are classified based on the structure of their silicate group...
or rocks. Electrolysis may contribute to carbon addition to the ocean if not carefully managed.
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.Financial Costs
Some argue that the cost of carbon sequestration would actually increase over time. 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 implemented.Energy requirements
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.
See also
- Bio-energy with carbon capture and storageBio-energy with carbon capture and storageBio-energy with carbon capture and storage is a greenhouse gas mitigation technology which produces negative carbon emissions by combining biomass use with geologic carbon capture and storage....
- CarbonFix StandardCarbonFix StandardThe CarbonFix Standard is an initiative supported by over 60 organisations promotes the development of climate forestation projects to sequester carbon from the atmosphere...
- Carbon capture and storageCarbon capture and storageCarbon capture and storage , alternatively referred to as carbon capture and sequestration, is a technology to prevent large quantities of from being released into the atmosphere from the use of fossil fuel in power generation and other industries. It is often regarded as a means of mitigating...
External links
- Research Program on Carbon Sequestration at the Cluster of Excellence "Future Ocean", Kiel
- Carbon Sequestration Leadership Forum International carbon capture and storage initiative.
- Scottish Centre for Carbon Storage Research Carbon Capture and Storage Research in Edinburgh, Scotland.
- 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)
- Sequestration with Enhanced Coal Bed Methane Recovery