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Carbon capture and storage (CCS) or carbon capture and sequestration is the process of capturing
carbon dioxide
Carbon dioxide ( chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is trans ...
(CO
2) before it enters the atmosphere, transporting it, and storing it (
carbon sequestration
Carbon sequestration is the process of storing carbon in a carbon pool. Carbon dioxide () is naturally captured from the atmosphere through biological, chemical, and physical processes. These changes can be accelerated through changes in lan ...
) for centuries or millennia. Usually the CO
2 is captured from large
point sources, such as a
chemical plant or
biomass power plant
A power station, also referred to as a power plant and sometimes generating station or generating plant, is an industrial facility for the electricity generation, generation of electric power. Power stations are generally connected to an el ...
, and then stored in an underground
geological formation
A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics ( lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock exp ...
. The aim is to prevent the release of CO
2 from
heavy industry
Heavy industry is an industry that involves one or more characteristics such as large and heavy products; large and heavy equipment and facilities (such as heavy equipment, large machine tools, huge buildings and large-scale infrastructure); o ...
with the intent of
mitigating the effects of climate change.
CO
2 has been injected into geological formations for several decades for
enhanced oil recovery and after
separation from natural gas, but this has been criticised for producing more emissions when the gas or oil is burned.
Carbon capture and utilization
Carbon capture and utilization (CCU) is the process of capturing carbon dioxide ( C O2) to be recycled for further usage. Carbon capture and utilization may offer a response to the global challenge of significantly reducing greenhouse gas emissions ...
(CCU) and CCS are sometimes discussed collectively as carbon capture, utilization, and sequestration (CCUS). This is because CCS is a relatively expensive process yielding a product which is often too cheap.
Hence, carbon capture makes economically more sense where the
carbon price
Carbon pricing (or pricing), also known as cap and trade (CAT) or emissions trading scheme (ETS), is a method for nations to reduce global warming. The cost is applied to greenhouse gas emissions in order to encourage polluters to reduce the co ...
is high enough, such as in much of Europe,
or when combined with a utilization process where the cheap CO
2 can be used to produce high-value chemicals to offset the high costs of capture operations.
CO
2 can be captured directly from an industrial source, such as a
cement kiln
Cement kilns are used for the pyroprocessing stage of manufacture of portland and other types of hydraulic cement, in which calcium carbonate reacts with silica-bearing minerals to form a mixture of calcium silicates. Over a billion tonnes of ...
, using a variety of technologies; including
absorption,
adsorption
Adsorption is the adhesion of atoms, ions or molecules from a gas, liquid or dissolved solid to a surface. This process creates a film of the ''adsorbate'' on the surface of the ''adsorbent''. This process differs from absorption, in which ...
,
chemical looping,
membrane gas separation
Gas mixtures can be effectively separated by synthetic membranes made from polymers such as polyamide or cellulose acetate, or from ceramic materials.
While polymeric membranes are economical and technologically useful, they are bounded by their ...
or
gas hydration.
, about one thousandth of global CO
2 emissions are captured by CCS, and most projects are for
fossil gas processing.
Storage of the CO
2 is either in deep geological formations, or in the form of
mineral
In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. (2 ...
carbonate
A carbonate is a salt of carbonic acid (H2CO3), characterized by the presence of the carbonate ion, a polyatomic ion with the formula . The word ''carbonate'' may also refer to a carbonate ester, an organic compound containing the carbonate ...
s.
Pyrogenic carbon capture and storage
Pyrogenic carbon capture and storage (PyCCS) is a proposed carbon sequestration technology that can mitigate climate change while improving soil fertility. It is discussed as a promising technology for greenhouse gas removal.Constanze Werner et ...
(PyCCS) is also being researched. Geological formations are currently considered the most promising sequestration sites. The US
National Energy Technology Laboratory
The National Energy Technology Laboratory (NETL) is a U.S national laboratory under the Department of Energy Office of Fossil Energy. NETL focuses on applied research for the clean production and use of domestic energy resources. NETL perform ...
(NETL) reported that North America has enough storage capacity for more than 900 years worth of CO
2 at current production rates.
A general problem is that long-term predictions about submarine or underground storage security are very difficult and uncertain, and there is still the risk that some CO
2 might leak into the atmosphere. Despite this, a recent evaluation estimates the risk of substantial leakage to be fairly low.
Opponents point out that many CCS projects have failed to deliver on promised emissions reductions. Additionally, opponents argue that carbon capture and storage is only a justification for indefinite fossil fuel usage disguised as marginal emission reductions. One of the most well-known failures is the
FutureGen
FutureGen was a project to demonstrate capture and sequestration of waste carbon dioxide from a coal-fired electrical generating station. The project (renamed FutureGen 2.0) was retrofitting a shuttered coal-fired power plant in Meredosia, Illin ...
program, partnerships between the US federal government and coal energy production companies which were intended to demonstrate ″clean coal″, but never succeeded in producing any carbon-free electricity from coal.
Capture
Capturing CO
2 is most cost-effective at point sources, such as large carbon-based energy facilities, industries with major CO
2 emissions (e.g. cement production, steelmaking),
natural gas processing, synthetic fuel plants and fossil fuel-based
hydrogen production
Hydrogen production is the family of industrial methods for generating hydrogen gas. As of 2020, the majority of hydrogen (∼95%) is produced from fossil fuels by steam reforming of natural gas and other light hydrocarbons, partial oxidation of ...
plants. Extracting CO
2 from air is possible, although the lower concentration of CO
2 in air compared to combustion sources complicates the engineering and makes the process therefore more expensive.
Impurities in CO
2 streams, like sulfurs and water, can have a significant effect on their phase behavior and could pose a significant threat of increased pipeline and well corrosion. In instances where CO
2 impurities exist, especially with air capture, a scrubbing separation process is needed to initially clean the
flue gas
Flue gas is the gas exiting to the atmosphere via a flue, which is a pipe or channel for conveying exhaust gases from a fireplace, oven, furnace, boiler or steam generator. Quite often, the flue gas refers to the combustion exhaust gas produc ...
. It is possible to capture approximately 65% of CO
2 embedded in it and sequester it in a solid form.
Broadly, three distinct technologies exist: post-combustion, pre-combustion, and oxyfuel combustion:
*In ''
post combustion capture Post-combustion capture refers to the removal of ''CO2'' from power station flue gas prior to its compression, transportation and storage in suitable geological formations, as part of carbon capture and storage. A number of different techniques are ...
'', the CO
2 is removed after combustion of the fossil fuel—this is the scheme that would apply to fossil-fuel power plants. CO
2 is captured from
flue gas
Flue gas is the gas exiting to the atmosphere via a flue, which is a pipe or channel for conveying exhaust gases from a fireplace, oven, furnace, boiler or steam generator. Quite often, the flue gas refers to the combustion exhaust gas produc ...
es at
power station
A power station, also referred to as a power plant and sometimes generating station or generating plant, is an industrial facility for the generation of electric power. Power stations are generally connected to an electrical grid.
Many ...
s or other point sources. The technology is well understood and is currently used in other industrial applications, although at smaller scale than required in a commercial scale station. Post combustion capture is most popular in research because fossil fuel power plants can be retrofitted to include CCS technology in this configuration.
*The technology for ''pre-combustion'' is widely applied in fertilizer, chemical, gaseous fuel (H
2, CH
4), and power production. In these cases, the fossil fuel is partially oxidized, for instance in a
gasifier
Gasification is a process that converts biomass- or fossil fuel-based carbonaceous materials into gases, including as the largest fractions: nitrogen (N2), carbon monoxide (CO), hydrogen (H2), and carbon dioxide (). This is achieved by reactin ...
. The
CO from the resulting
syngas (CO and H
2) reacts with added steam (H
2O) and is
shifted into CO
2 and H
2. The resulting CO
2 can be captured from a relatively pure exhaust stream. The H
2 can be used as fuel; the CO
2 is removed before combustion. Several advantages and disadvantages apply versus post combustion capture. The CO
2 is removed after combustion, but before the flue gas expands to atmospheric pressure. The capture before expansion, i.e. from pressurized gas, is standard in almost all industrial CO
2 capture processes, at the same scale as required for power plants.
*In ''
oxy-fuel combustion
Oxy-fuel combustion is the process of burning a fuel using pure oxygen, or a mixture of oxygen and recirculated flue gas, instead of air. Since the nitrogen component of air is not heated, fuel consumption is reduced, and higher flame temperatures ...
'' the fuel is burned in pure oxygen instead of air. To limit the resulting flame temperatures to levels common during conventional combustion, cooled flue gas is recirculated and injected into the combustion chamber. The flue gas consists of mainly CO
2 and water vapour, the latter of which is condensed through cooling. The result is an almost pure CO
2 stream. Power plant processes based on
oxyfuel
Oxy-fuel combustion is the process of burning a fuel using pure oxygen, or a mixture of oxygen and recirculated flue gas, instead of air. Since the nitrogen component of air is not heated, fuel consumption is reduced, and higher flame temperatures ...
combustion are sometimes referred to as "zero emission" cycles, because the CO
2 stored is not a fraction removed from the flue gas stream (as in the cases of pre- and post-combustion capture) but the flue gas stream itself. A certain fraction of the CO
2 inevitably end up in the condensed water. To warrant the label "zero emission" the water would thus have to be treated or disposed of appropriately.
Separation technologies
The major technologies proposed for carbon capture are:
*
Membrane
A membrane is a selective barrier; it allows some things to pass through but stops others. Such things may be molecules, ions, or other small particles. Membranes can be generally classified into synthetic membranes and biological membranes. ...
*
Oxyfuel combustion
*
Absorption
* Multiphase absorption
*
Adsorption
Adsorption is the adhesion of atoms, ions or molecules from a gas, liquid or dissolved solid to a surface. This process creates a film of the ''adsorbate'' on the surface of the ''adsorbent''. This process differs from absorption, in which ...
*
Chemical looping combustion
Chemical looping combustion (CLC) is a technological process typically employing a dual fluidized bed system. CLC operated with an interconnected moving bed with a fluidized bed system, has also been employed as a technology process. In CLC, a met ...
*
Calcium looping
* Cryogenic
Absorption, or
carbon scrubbing with
amines
In chemistry, amines (, ) are compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are formally derivatives of ammonia (), wherein one or more hydrogen atoms have been replaced by a substituent such ...
is the dominant capture technology. It is the only carbon capture technology so far that has been used industrially.
Monoethanolamine
Ethanolamine (2-aminoethanol, monoethanolamine, ETA, or MEA) is an organic chemical compound with the formula or . The molecule is bifunctional, containing both a primary amine and a primary alcohol. Ethanolamine is a colorless, viscous liquid ...
(MEA) solutions, the leading amine for capturing CO
2 , have a
heat capacity
Heat capacity or thermal capacity is a physical property of matter, defined as the amount of heat to be supplied to an object to produce a unit change in its temperature. The SI unit of heat capacity is joule per kelvin (J/K).
Heat capacity ...
between 3–4 J/g K since they are mostly water. Higher heat capacities add to the energy penalty in the solvent regeneration step.
About two thirds of CCS cost is attributed to capture, making it the limit to CCS deployment. Optimizing capture would significantly increase CCS feasibility since the transport and storage steps of CCS are rather mature.
An alternate method is
chemical looping combustion
Chemical looping combustion (CLC) is a technological process typically employing a dual fluidized bed system. CLC operated with an interconnected moving bed with a fluidized bed system, has also been employed as a technology process. In CLC, a met ...
(CLC). Looping uses a metal oxide as a solid oxygen carrier. Metal oxide particles react with a solid, liquid or gaseous fuel in a
fluidized bed
A fluidized bed is a physical phenomenon that occurs when a solid particulate substance (usually present in a holding vessel) is under the right conditions so that it behaves like a fluid. The usual way to achieve a fluidize bed is to pump pressur ...
combustor, producing solid metal particles and a mixture of CO
2 and water vapor. The water vapor is condensed, leaving pure CO
2 , which can then be sequestered. The solid metal particles are circulated to another fluidized bed where they react with air, producing heat and regenerating metal oxide particles for return to the combustor. A variant of chemical looping is
calcium looping, which uses the alternating carbonation and then calcination of a
calcium oxide
Calcium oxide (CaO), commonly known as quicklime or burnt lime, is a widely used chemical compound. It is a white, caustic, alkaline, crystalline solid at room temperature. The broadly used term "''lime''" connotes calcium-containing inorganic ...
based carrier.
A 2019 study found CCS plants to be less effective than renewable electricity. The electrical
energy returned on energy invested
In energy economics and ecological energetics, energy return on investment (EROI), also sometimes called energy returned on energy invested (ERoEI), is the ratio of the amount of usable energy (the ''exergy'') delivered from a particular energy re ...
(EROEI) ratios of both production methods were estimated, accounting for their operational and infrastructural energy costs. Renewable electricity production included solar and wind with sufficient energy storage, plus dispatchable electricity production. Thus, rapid expansion of scalable renewable electricity and storage would be preferable over fossil-fuel with CCS. The study did not consider whether both options could be pursued in parallel.
In 2021 High Hopes proposed using high-altitude balloons to capture CO
2 cryogenically, using hydrogen to lower the already low-temperature atmosphere sufficiently to produce dry ice that is returned to earth for sequestration.
In
sorption enhanced water gas shift
Sorption enhanced water gas shift (SEWGS) is a technology that combines a pre-combustion Carbon capture and storage, carbon capture process with the Water-gas shift reaction, water gas shift reaction (WGS) in order to produce a hydrogen rich stream ...
(SEWGS) technology a pre-combustion carbon capture process, based on solid adsorption, is combined with the
water gas shift reaction
Water (chemical formula ) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as a s ...
(WGS) in order to produce a high pressure hydrogen stream. The CO
2 stream produced can be stored or used for other industrial processes.
Compression
After the CO2 has been captured, it is usually compressed into a
supercritical fluid. The CO2 is compressed so that it can be more easily transported. Compression is done at the capture site. This process requires its own energy source. Like the capture stage, compression is achieved by increasing the parasitic load. Compression of CO2 is an energy intensive procedure that involves multi-stage complex compressors and a power-generated cooling process.
Transport
Large volumes of highly pressurized CO2 are transported via pipelines.
For example, approximately 5,800 km of CO
2 pipelines operated in the US in 2008, and a 160 km pipeline in Norway,
used to transport CO
2 to oil production sites where it is injected into older fields to extract oil. This injection is called ''
enhanced oil recovery''. Pilot programs are in development to test long-term storage in non-oil producing geologic formations. In the United Kingdom, the Parliamentary Office of Science and Technology envisages pipelines as the main UK transport.
In 2021, two companies, namely Navigator Ventures and Summit Carbon Solutions were planning pipelines through the Midwestern US from North Dakota to Illinois to connect ethanol companies to sites where liquefied is injected into porous rock.
Sequestration (storage)
Various approaches have been conceived for permanent storage. These include gaseous storage in deep geological formations (including saline formations and exhausted gas fields), and solid storage by reaction of CO
2 with metal
oxides to produce stable
carbonate
A carbonate is a salt of carbonic acid (H2CO3), characterized by the presence of the carbonate ion, a polyatomic ion with the formula . The word ''carbonate'' may also refer to a carbonate ester, an organic compound containing the carbonate ...
s.
Geological storage
Geo-sequestration, involves injecting CO
2 , generally in
supercritical form, into underground geological formations.
Oil fields,
gas field
A petroleum reservoir or oil and gas reservoir is a subsurface accumulation of hydrocarbons contained in porous or fractured rock formations.
Such reservoirs form when kerogen (ancient plant matter) is created in surrounding rock by the presence ...
s, saline formations, unmineable
coal seam
Coal mining is the process of extracting coal from the ground. Coal is valued for its energy content and since the 1880s has been widely used to generate electricity. Steel and cement industries use coal as a fuel for extraction of iron fro ...
s, and saline-filled basalt formations have been suggested as alternatives. Physical (e.g., highly impermeable
caprock
Caprock or cap rock is a more resistant rock type overlying a less resistant rock type,Kearey, Philip (2001). ''Dictionary of Geology'', 2nd ed., Penguin Reference, London, New York, etc., p. 41.. . analogous to an upper crust on a cake that is ha ...
) and geochemical trapping mechanisms prevent the CO
2 from escaping to the surface.
Unmineable coal seams can be used because CO
2 molecules attach to the coal surface. Technical feasibility depends on the coal bed's permeability. In the process of absorption the coal releases previously absorbed
methane
Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane on Ea ...
, and the methane can be recovered (
enhanced coal bed methane recovery Enhanced coal bed methane recovery is a method of producing additional coalbed methane from a source rock, similar to enhanced oil recovery applied to oil fields. Carbon dioxide (CO2) injected into a bituminous coal bed would occupy pore space ...
). Methane revenues can offset a portion of the cost, although burning the resultant methane, however, produces another stream of CO
2 to be sequestered.
Saline formations contain mineralized brines and have yet to produce benefit to humans. Saline
aquifer
An aquifer is an underground layer of water-bearing, permeable rock, rock fractures, or unconsolidated materials ( gravel, sand, or silt). Groundwater from aquifers can be extracted using a water well. Aquifers vary greatly in their characteris ...
s have occasionally been used for storage of
chemical waste
Chemical waste is any excess, unusable, or unwanted chemical, especially those that cause damage to human health or the environment. Chemical waste may be classified as hazardous waste, non-hazardous waste, universal waste, and household haz ...
in a few cases. The main advantage of saline aquifers is their large potential storage volume and their ubiquity. The major disadvantage of saline aquifers is that relatively little is known about them. To keep the cost of storage acceptable, geophysical exploration may be limited, resulting in larger uncertainty about the aquifer structure. Unlike storage in oil fields or coal beds, no side product offsets the storage cost. ''Trapping mechanisms'' such as structural trapping, residual trapping, solubility trapping and mineral trapping may immobilize the CO
2 underground and reduce leakage risks.
Enhanced oil recovery
CO
2 is occasionally injected into an
oil field as an
enhanced oil recovery technique, but because CO
2 is released when the oil is burned, it is not
carbon neutral
Carbon neutrality is a state of net-zero carbon dioxide emissions. This can be achieved by balancing emissions of carbon dioxide with its removal (often through carbon offsetting) or by eliminating emissions from society (the transition to the "p ...
.
Algae/bacteria
CO
2 can be physically supplied to
algae or
bacteria
Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of prokaryotic microorganisms. Typically a few micrometr ...
that could degrade the CO
2. It would ultimately be ideal to exploit CO
2 metabolizing bacterium ''
Clostridium thermocellum
''Acetivibrio thermocellus'' is an anaerobic, thermophilic bacterium. ''A. thermocellusm'' has garnered research interest due to its cellulolytic and ethanologenic abilities, being capable of directly converting a cellulosic substrate into etha ...
''.
Mineral storage / mineral carbonation
CO
2 exothermically reacts with metal oxides, producing stable carbonates (e.g.
calcite,
magnesite). This process (CO
2-to-stone) occurs naturally over periods of years and is responsible for much surface
limestone
Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms whe ...
.
Olivine
The mineral olivine () is a magnesium iron silicate with the chemical formula . It is a type of nesosilicate or orthosilicate. The primary component of the Earth's upper mantle, it is a common mineral in Earth's subsurface, but weathers quickl ...
is one such metal oxide.
Rocks rich in metal oxides that react with CO
2, such as
MgO
Magnesium oxide ( Mg O), or magnesia, is a white hygroscopic solid mineral that occurs naturally as periclase and is a source of magnesium (see also oxide). It has an empirical formula of MgO and consists of a lattice of Mg2+ ions and O2− ions ...
and
CaO Cao or CAO may refer to:
Mythology
*Cao (bull), a legendary bull in Meitei mythology
Companies or organizations
* Air China Cargo, ICAO airline designator CAO
*CA Oradea, Romanian football club
*CA Osasuna, Spanish football club
*Canadian Assoc ...
as contained in
basalts
Basalt (; ) is an aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the surface of a rocky planet or moon. More than 90% of ...
, have been proven as a viable means to achieve carbon-dioxide mineral storage. The reaction rate can in principle be accelerated with a
catalyst
Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recyc ...
or by increasing temperatures and/or pressures, or by mineral pre-treatment, although this method can require additional energy. The
IPCC
The Intergovernmental Panel on Climate Change (IPCC) is an intergovernmental body of the United Nations. Its job is to advance scientific knowledge about climate change caused by human activities. The World Meteorological Organization (WMO) ...
estimates that a power plant equipped with CCS using mineral storage would need 60–180% more energy than one without.
[ PCC, 2005''IPCC special report on CO2 Capture and Storage''. Prepared by working group III of the Intergovernmental Panel on Climate Change. Metz, B., O. Davidson, H. C. de Coninck, M. Loos, and L.A. Meyer (eds.). Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 442 pp. Available in full a]
www.ipcc.ch
(PDF - 22.8MB) Theoretically, up to 22% of crustal mineral mass is able to form
carbonate
A carbonate is a salt of carbonic acid (H2CO3), characterized by the presence of the carbonate ion, a polyatomic ion with the formula . The word ''carbonate'' may also refer to a carbonate ester, an organic compound containing the carbonate ...
s.
Ultramafic
Ultramafic rocks (also referred to as ultrabasic rocks, although the terms are not wholly equivalent) are igneous and meta-igneous rocks with a very low silica content (less than 45%), generally >18% MgO, high FeO, low potassium, and are composed ...
mine tailings
In mining, tailings are the materials left over after the process of separating the valuable fraction from the uneconomic fraction (gangue) of an ore. Tailings are different to overburden, which is the waste rock or other material that overl ...
are a readily available source of fine-grained metal oxides that could serve this purpose. Accelerating passive CO
2 sequestration via mineral carbonation may be achieved through microbial processes that enhance mineral dissolution and carbonate precipitation.
Cost
Cost is a significant factor affecting CCS. The cost of CCS, plus any subsidies, must be less than the expected cost of emitting CO
2 for a project to be considered economically favorable.
CCS technology is expected to use between 10 and 40 percent of the energy produced by a power station.
[Rochon, Emily et al]
False Hope: Why carbon capture and storage won't save the climate
Greenpeace, May 2008, p. 5. Energy for CCS is called an energy penalty. It has been estimated that about 60% of the penalty originates from the capture process, 30% comes from compression of CO
2 , while the remaining 10% comes from pumps and fans.
CCS would increase the fuel requirement of a plant with CCS by about 15% (gas plant).
The cost of this extra fuel, as well as storage and other system costs, are estimated to increase the costs of energy from a power plant with CCS by 30–60%.
Constructing CCS units is capital intensive. The additional costs of a large-scale CCS demonstration project are estimated to be €0.5–1.1 billion per project over the project lifetime. Other applications are possible. CCS trials for coal-fired plants in the early 21st century were economically unviable in most countries, including China, in part because revenue from enhanced oil recovery collapsed with the 2020 oil price collapse. A
carbon price
Carbon pricing (or pricing), also known as cap and trade (CAT) or emissions trading scheme (ETS), is a method for nations to reduce global warming. The cost is applied to greenhouse gas emissions in order to encourage polluters to reduce the co ...
of at least 100 euros per tonne CO
2 is estimated to be needed to make industrial CCS viable, together with
carbon tariff
An eco-tariff, also known as an environmental tariff or carbon tariff, is a trade barrier erected for the purpose of reducing pollution and improving the environment. These trade barriers may take the form of import or export taxes on products th ...
s. But, as of mid-2022, the
EU Allowance
EU Allowances (EUA) are climate credits (or carbon credits) used in the European Union Emissions Trading Scheme (EU ETS). EU Allowances are issued by the EU Member States into Member State Registry accounts. By April 30 of each year, operators of ...
had never reached that price and the
Carbon Border Adjustment Mechanism
The Carbon Border Adjustment Mechanism (CBAM) is a carbon tariff on carbon intensive products, such as cement and some electricity, imported by the European Union. Currently being legislated as part of the European Green Deal it will to take effec ...
had not yet been implemented. However a company making small modules claims it can get well below that price by mass production by 2022.
According to UK government estimates made in the late 2010s, carbon capture (without storage) is estimated to add 7 GBP per MWh by 2025 to the cost of electricity from a
gas-fired power plant
A gas-fired power plant or gas-fired power station or natural gas power plant is a thermal power station which burns natural gas to generate electricity. Natural gas power stations generate almost a quarter of world electricity and a signifi ...
: however most CO
2 will need to be stored so in total the increase in cost for gas or biomass generated electricity is around 50%.
Business models
Possible business models for industrial carbon capture include:
* Contract for Difference CfDC CO
2 certificate strike price
* Cost Plus open book
* Regulated Asset Base (RAB)
* Tradeable tax credits for CCS
* Tradeable CCS certificates + obligation
* Creation of low carbon market
Governments have provided various types of funding for CCS demonstration projects, including tax credits, allocations and grants.
Clean Development Mechanism
One alternative could be through the
Clean Development Mechanism
The Clean Development Mechanism (CDM) is a United Nations-run carbon offset scheme allowing countries to fund greenhouse gas emissions-reducing projects in other countries and claim the saved emissions as part of their own efforts to meet internat ...
of the
Kyoto Protocol. At
COP16
The 2024 United Nations Biodiversity Conference (COP16) of the Parties to the UN Convention on Biological Diversity
The Convention on Biological Diversity (CBD), known informally as the Biodiversity Convention, is a multilateral treaty. The ...
in 2010, The Subsidiary Body for Scientific and Technological Advice, at its thirty-third session, issued a draft document recommending the inclusion of CCS in geological formations in Clean Development Mechanism project activities. At
COP17
The 2011 United Nations Climate Change Conference (COP17) was held in Durban, South Africa, from 28 November to 11 December 2011 to establish a new treaty to limit carbon emissions.
A treaty was not established, but the conference agreed to est ...
in
Durban
Durban ( ) ( zu, eThekwini, from meaning 'the port' also called zu, eZibubulungwini for the mountain range that terminates in the area), nicknamed ''Durbs'',Ishani ChettyCity nicknames in SA and across the worldArticle on ''news24.com'' from ...
, a final agreement was reached enabling CCS projects to receive support through the Clean Development Mechanism.
Environmental effects
Alkaline solvents
CO
2 can be captured with alkaline solvents at low temperatures in the absorber and released CO
2 at higher temperatures in a desorber. Chilled ammonia CCS plants emit
ammonia
Ammonia is an inorganic compound of nitrogen and hydrogen with the formula . A stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct pungent smell. Biologically, it is a common nitrogenous wa ...
. "Functionalized Ammonia" emits less ammonia, but amines may form secondary amines that emit volatile
nitrosamines
In organic chemistry, nitrosamines (or more formally ''N''-Nitrosamines) are organic compounds with the chemical structure , where R is usually an alkyl group. They feature a nitroso group () bonded to a deprotonated amine. Most nitrosamines ar ...
by a side reaction with
nitrogen dioxide
Nitrogen dioxide is a chemical compound with the formula . It is one of several nitrogen oxides. is an intermediate in the industrial synthesis of nitric acid, millions of tons of which are produced each year for use primarily in the productio ...
, which is present in any flue gas. Alternative amines with little to no vapor pressure can avoid these emissions. Nevertheless, practically 100% of remaining sulfur dioxide from the plant is washed out of the flue gas, along with dust/ash.
Natural gas processing and enhanced oil recovery
The
Institute for Energy Economics & Financial Analysis has criticised companies for not reporting
greenhouse gas emissions from the use of their products.
CO2 from
natural-gas processing
Natural-gas processing is a range of industrial processes designed to purify raw natural gas by removing impurities, contaminants and higher molecular mass hydrocarbons to produce what is known as ''pipeline quality'' dry natural gas. Natural gas ...
is often used for EOR.
It has been suggested that enhanced oil recovery only be allowed to use anthropogenic CO2 and should only receive financial incentives such as tax credits when carbon negative, which is generally only in the early years of a project.
Gas and coal-fired power plants
Although the global total CO2 emitted by fossil fuel power plants is very large, coal plant flue gas typically only contains 10–14% CO2, and gas power plants only 4–5% CO2.
Cost per tonne CO2 increases as the
capacity factor
The net capacity factor is the unitless ratio of actual electrical energy output over a given period of time to the theoretical maximum electrical energy output over that period. The theoretical maximum energy output of a given installation is def ...
decreases (the plant is used less - for example only for
times of highest demand or
in emergencies).
The extra energy requirements deriving from CCS for
natural gas combined cycle
A combined cycle power plant is an assembly of heat engines that work in tandem from the same source of heat, converting it into mechanical energy. On land, when used to make electricity the most common type is called a combined cycle gas turb ...
(NGCC) plants range from 11 to 22%.
Fuel use and environmental problems (e.g.,
methane emissions
Increasing methane emissions are a major contributor to the rising concentration of greenhouse gases in Earth's atmosphere, and are responsible for up to one-third of near-term global heating. During 2019, about 60% (360 million tons) of methane r ...
) arising from gas extraction increase accordingly. Plants equipped with
selective catalytic reduction
Selective catalytic reduction (SCR) is a means of converting nitrogen oxides, also referred to as with the aid of a catalyst into diatomic nitrogen (), and water (). A reductant, typically anhydrous ammonia (), aqueous ammonia (), or a urea () ...
systems for
nitrogen oxides produced during combustion require proportionally greater amounts of
ammonia
Ammonia is an inorganic compound of nitrogen and hydrogen with the formula . A stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct pungent smell. Biologically, it is a common nitrogenous wa ...
.
A 2020 study concluded that half as much CCS might be installed in coal-fired plants as in gas-fired: these would be mainly in China and India. However a 2022 study concluded that it would be too expensive for
coal power in China
China is the largest producer and consumer of coal in the world. It is also the largest user of coal-generated electricity, with over a thousand coal-fired power stations. The share of coal in the energy mix declined during the 2010s, falli ...
.
For super-critical pulverized coal (PC) plants, CCS' energy requirements range from 24 to 40%, while for coal-based gasification combined cycle (IGCC) systems it is 14–25%.
Fuel use and environmental problems arising from coal extraction increase accordingly. Plants equipped with
flue-gas desulfurization (FGD) systems for
sulfur dioxide control require proportionally greater amounts of
limestone
Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms whe ...
, and systems equipped with
selective catalytic reduction
Selective catalytic reduction (SCR) is a means of converting nitrogen oxides, also referred to as with the aid of a catalyst into diatomic nitrogen (), and water (). A reductant, typically anhydrous ammonia (), aqueous ammonia (), or a urea () ...
systems for
nitrogen oxides produced during combustion require proportionally greater amounts of
ammonia
Ammonia is an inorganic compound of nitrogen and hydrogen with the formula . A stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct pungent smell. Biologically, it is a common nitrogenous wa ...
.
Boundary Dam
Boundary Dam is a concrete arch gravity-type hydroelectric dam, finished in 1967, on the Pend Oreille River, in the U.S. state of Washington. The dam is located in the northeast corner of Washington state. It is operated by Seattle City Light an ...
is the only coal-fired power station which uses post-combustion CCS.
Leakage
Long-term retention
IPCC estimates that leakage risks at properly managed sites are comparable to those associated with current hydrocarbon activity. It recommends that limits be set to the amount of leakage that can take place. However, this finding is contested given the lack of experience. CO
2 could be trapped for millions of years, and although some leakage may occur, appropriate storage sites are likely to retain over 99% for over 1000 years.
Mineral storage is not regarded as presenting any leakage risks.
Norway's
Sleipner gas field
Oil from the Sleipner field.
The Sleipner gas field is a natural gas field in the block 15/9 of the North Sea, about west of Stavanger, Norway. Two parts of the field are in production, Sleipner West (proven in 1974), and Sleipner East (1981) ...
is the oldest industrial scale retention project. An environmental assessment conducted after ten years of operation concluded that geosequestration was the most definite form of permanent geological storage method:
Available geological information shows absence of major tectonic events after the deposition of the Utsira formation aline reservoir This implies that the geological environment is tectonically stable and a site suitable for CO2 storage. The solubility trapping sthe most permanent and secure form of geological storage.
In March 2009 StatoilHydro issued a study documenting the slow spread of CO
2 in the formation after more than 10 years operation.
Gas leakage into the atmosphere may be detected via atmospheric gas monitoring, and can be quantified directly via
eddy covariance
The eddy covariance (also known as eddy correlation and eddy flux) is a key atmospheric measurement technique to measure and calculate vertical turbulent fluxes within atmospheric boundary layers. The method analyses high-frequency wind and scal ...
flux measurements.
Sudden leakage hazards
Transmission pipelines may leak or rupture. Pipelines can be fitted with remotely controlled valves that can limit the release quantity to one pipe section. For example, a severed 19" pipeline section 8 km long could release its 1,300 tonnes in about 3–4 min.
At the storage site, the injection pipe can be fitted with
non-return valve
A check valve, non-return valve, reflux valve, retention valve, foot valve, or one-way valve is a valve that normally allows fluid (liquid or gas) to flow through it in only one direction.
Check valves are two-port valves, meaning they have ...
s to prevent an uncontrolled release from the reservoir in case of upstream pipeline damage.
Large-scale releases present asphyxiation risk. In the
1953 Menzengraben mining accident, several thousand tonnes were released and asphyxiated a person 300 meters away.
Malfunction of a CO
2 industrial fire suppression system in a large warehouse released 50 t CO
2 after which 14 people collapsed on the nearby public road.
In the
Berkel en Rodenrijs
270px, Town sign
Berkel en Rodenrijs () is a town and former municipality in the municipality of Lansingerland, in the province of South Holland, The Netherlands. The town is very close to ROTTERDAM
History
Berkel en Rodenrijs was founded in t ...
incident in December 2008 a modest release from a pipeline under a bridge killed some ducks sheltering there.
[ (in Dutch)]
Monitoring
Monitoring allows leak detection with enough warning to minimize the amount lost, and to quantify the leak size. Monitoring can be done at both the surface and subsurface levels.
Subsurface
Subsurface monitoring can directly and/or indirectly track the reservoir's status. One direct method involves drilling deep enough to collect a sample. This drilling can be expensive due to the rock's physical properties. It also provides data only at a specific location.
One indirect method sends sound or electromagnetic waves into the reservoir which reflects back for interpretation. This approach provides data over a much larger region; although with less precision.
Both direct and indirect monitoring can be done intermittently or continuously.
Seismic
Seismic monitoring is a type of indirect monitoring. It is done by creating seismic waves either at the surface using a seismic vibrator, or inside a well using a Rotating unbalance, spinning eccentric mass. These waves propagate through geological layers and reflect back, creating patterns that are recorded by seismic sensors placed on the surface or in boreholes. It can identify migration pathways of the CO
2 plume.
Examples of seismic monitoring of geological sequestration are the Sleipner gas field, Sleipner sequestration project, the Frio CO
2 injection test and the Carbon capture and storage in Australia#CO2CRC Otway Project, CO2CRC Otway Project. Seismic monitoring can confirm the presence of CO
2 in a given region and map its lateral distribution, but is not sensitive to the concentration.
Tracer
Organic chemical tracers, using no radioactive nor Cadmium components, can be used during the injection phase in a CCS project where CO
2 is injected into an existing oil or gas field, either for EOR, pressure support or storage. Tracers and methodologies are compatible with CO
2 – and at the same time unique and distinguishable from the CO
2 itself or other molecules present in the sub-surface. Using laboratory methodology with an extreme detectability for tracer, regular samples at the producing wells will detect if injected CO
2 has migrated from the injection point to the producing well. Therefore, a small tracer amount is sufficient to monitor large scale subsurface flow patterns. For this reason, tracer methodology is well-suited to monitor the state and possible movements of CO
2 in CCS projects. Tracers can therefore be an aid in CCS projects by acting as an assurance that CO
2 is contained in the desired location sub-surface. In the past, this technology has been used to monitor and study movements in CCS projects in Algeria (Mathieson et al. “In Salah CO 2 Storage JIP: CO 2 sequestration monitoring and verification technologies applied at Krechba, Algeria”, Energy Procedia 4:3596-3603), in the Netherlands (Vandeweijer et al. “Monitoring the CO
2 injection site: K12B”, Energy Procedia 4 (2011) 5471–5478) as well as in Norway (Snøhvit).
Surface
Eddy covariance is a surface monitoring technique that measures the flux of CO
2 from the ground's surface. It involves measuring CO
2 concentrations as well as vertical wind velocities using an anemometer. This provides a measure of the vertical CO
2 flux. Eddy covariance towers could potentially detect leaks, after accounting for the natural carbon cycle, such as photosynthesis and plant respiration. An example of eddy covariance techniques is the Shallow Release test. Another similar approach is to use accumulation chambers for spot monitoring. These chambers are sealed to the ground with an inlet and outlet flow stream connected to a gas analyzer.
They also measure vertical flux. Monitoring a large site would require a network of chambers.
InSAR
InSAR monitoring involves a satellite sending signals down to the Earth's surface where it is reflected back to the satellite's receiver. The satellite is thereby able to measure the distance to that point.
CO
2 injection into deep sublayers of geological sites creates high pressures. These layers affect layers above and below them, change the surface landscape. In areas of stored CO
2 , the ground's surface often rises due to the high pressures. These changes correspond to a measurable change in the distance from the satellite.
Carbon capture and utilization (CCU)
Social acceptance
Multiple studies indicate that risk and benefit perception are the most essential components of social acceptance.
Risk perception is mostly related to the concerns on its safety issues in terms of hazards from its operations and the possibility of CO
2 leakage which may endanger communities, commodities, and the environment in the vicinity of the infrastructure.
Other perceived risks relate to tourism and property values.
People who are already affected by climate change, such as drought,
tend to be more supportive of CCS. Locally, communities are sensitive to economic factors, including job creation, tourism or related investment.
Experience is another relevant feature. Several field studies concluded that people already involved or used to industry are likely to accept the technology. In the same way, communities who have been negatively affected by any industrial activity are also less supportive of CCS.
Few members of the public know about CCS. This can allow misconceptions that lead to less approval. No strong evidence links knowledge of CCS and public acceptance. However, one study found that communicating information about monitoring tends to have a negative impact on attitudes. Conversely, approval seems to be reinforced when CCS is compared to natural phenomena.
Due to the lack of knowledge, people rely on organizations that they trust. In general, non-governmental organizations and researchers experience higher trust than stakeholders and governments. #Environmental NGOs, Opinions amongst NGOs are mixed.
Moreover, the link between trust and acceptance is at best indirect. Instead, trust has an influence on the perception of risks and benefits.
CCS is embraced by the Shallow ecology, shallow ecology worldview,
which promotes the search for solutions to the effects of climate change in lieu of/in addition to addressing the causes. This involves the use of advancing technology and CCS acceptance is common among Technological utopianism, techno-optimists. CCS is an "end-of-pipe" solution
that reduces atmospheric CO
2, instead of minimizing the use of fossil fuel.
[
On 21 January 2021, Elon Musk announced he was donating $100m for a prize for best carbon capture technology.
]
Environmental justice
Carbon capture facilities are often designed to be located near existing oil and gas infrastructure.
A 2021 ''DeSmog Blog'' story highlighted, "CCS hubs are likely be sites in communities already being impacted by the climate crisis like Lake Charles, Louisiana, Lake Charles and those along the Mississippi River corridor, where most of the state carbon pollution is emitted from fossil fuel power plants. Exxon, for example, i
backing a carbon storage project
in Houston Ship Channel, Houston's shipping channel, another environmental justice community."
Political debate
CCS has been discussed by political actors at least since the start of the UNFCCC negotiations in the beginning of the 1990s, and remains a very divisive issue.
Some environmental groups raised concerns over leakage given the long storage time required, comparing CCS to storing radioactive waste from nuclear power stations.
Other controversies arose from the use of CCS by policy makers as a tool to fight climate change. In the IPCC's Sixth Assessment Report in 2022, most pathways to keep the increase of global temperature below 2 °C include the use of negative emission technologies (NETs).
Carbon emission status-quo
Opponents claimed that CCS could legitimize the continued use of fossil fuels, as well obviate commitments on emission reduction.
Some examples such as in Norway shows that CCS and other carbon removal technologies gained traction because it allowed the country to pursue its interests regarding the petroleum industry. Norway was a pioneer in emission mitigation, and established a CO2 tax in 1991.
Environmental NGOs
Environmental NGOs are not in widespread agreement about CCS as a potential climate mitigation tool. The main disagreement amid NGOs is whether CCS will reduce CO2 emissions or just perpetuate the use of fossil fuels.
For instance, Greenpeace is strongly against CCS. According to the organization, the use of the technology will keep the world dependent on fossil fuels.
On the other hand, BECCS is used in some IPCC scenarios to help meet mitigation targets. Adopting the IPCC argument that CO2 emissions need to be reduced by 2050 to avoid dramatic consequences, the Bellona Foundation justified CCS as a mitigation action. They claimed fossil fuels are unavoidable for the near term and consequently, CCS is the quickest way to reduce CO2 emissions.
Example projects
According to the Global CCS Institute, in 2020 there was about 40 million tons CO2 per year capacity of CCS in operation and 50 million tons per year in development. In contrast, the world emits about 38 billion tonnes of CO2 every year, so CCS captured about one thousandth of the 2020 CO2 emissions. Iron and steel industry, Iron and steel is expected to dominate industrial CCS in Europe, although there are alternative ways of decarbonizing steel.
CCS and climate change mitigation
CCS can be employed to achieve a number of goals regarding climate change mitigation, such as preventing average global temperature from reaching certain levels above the pre-industrial average. In December 2015, the Paris Agreement articulated a census to not exceed pre-industrial global temperatures by more than 2 °C and recognized that different countries would have different Intended Nationally Determined Contributions, contributions to help realize this goal. Under the Paris Agreement, different scenarios and climate models were analyzed for different temperature goals considering a wide range of mitigation methods from a temperature goal of less than 2 °C to an upper limit of exactly 2 °C increase above the pre-industrial average.
The terms CCS and CCUS (Carbon Capture, Utilization, and Storage) are often used interchangeably. The difference between the two is the specified 'utilization' of the captured carbon and refers to its use for other applications, such as enhanced oil recovery (EOR), potentially making liquid Carbon capture and utilisation, fuel, or the manufacturing of useful consumer goods, such as plastics. Since both approaches capture emitted CO2 and effectively store it, whether that be under-ground in geological formations or long-term trapping in material products, the two terms are often treated the same.
CCS is considered as a basis of one climate stabilization wedge, which is a proposed climate mitigation action to reduce approximately 1 billion tonnes of carbon emissions over 50 years.
CCS and different climate models
Large scale CCS plays a crucial role in reaching climate change stabilization. According to the IPCC, the carbon emission patterns can greatly vary based on the uncertainty of human power consumption. A file regarding the fluctuations of greenhouse gas emissions is shown to the right. However, CCS' primarily role is to delay the shift from fossil fuels and thereby reducing transition costs. The implementation of default technology assumptions would cost 29-297% more over the century than efforts without CCS for a 430-480 ppm CO2/yr scenario. The Paris agreement upholds a goal to reach no more than a 2.0 °C increase above pre-industrial temperatures. If the 2.0 °C goal is to be reached in time, CCS must be utilized to achieve net zero emissions by 2060-2070. After 2060-2070, negative emissions will need to be achieved to remain below the 2.0 °C target. The variations in methods depend heavily on the climate change model being used and the anticipated energy consumption patterns. It is widely agreed upon, however, that CCS would need to be utilized if there is to be any negative climate change mitigation.
CCS and 2.0°C target
The concept of a 2.0 °C came to light in the European Union of 1996 where the goal was to reduce the global temperature range relative pre-industrial levels. The decision of the 2 °C range was decided mostly on the evidence that many ecosystems are at risk if average global temperatures exceeded this limit. In order to limit the anthropogenic emissions such that there is no more than a 2 °C change relative to the periods between 1861 and 1880, carbon emissions would need to be limited to about 1000 GtC by 2100 since that period. However, by the end of 2011 about half of the budget was already released (445 GtC) indicating that a lower budget is necessary.
A distinctive path that aims for a 2.0 °C limit might have complications. The first complication involves the lack of positive feedback loops in IPCC
The Intergovernmental Panel on Climate Change (IPCC) is an intergovernmental body of the United Nations. Its job is to advance scientific knowledge about climate change caused by human activities. The World Meteorological Organization (WMO) ...
climate models. These loops include reduction of ice sheet size, which would mean less sunlight is reflected and more is absorbed by the darker colored ground or water, and the potential release of greenhouse gases by thawing tundra. Since the lifetime of CO2 in the climate atmosphere is so long, these feedback loops have to be taken into consideration. Another important factor to consider is that a 2.0 °C scenario necessitates tapping into alternative fossil fuels sources that are harder to obtain. Some examples of these methods are the exploitation of tar sands, tar shales, hydrofracking for oil and gas, coal mining, drilling in the Arctic, Amazon, and deep ocean. Therefore, 2.0 °C scenarios result in more CO2 produced per unit of usable energy. Further, the danger of extra released CH4 via mining processes must be taken into account.
Different models are based on when the peak of carbon emissions happen on a global scale. In one article regarding the 2.0 °C scenario with respect to pre-industrial levels, possible approaches are short term and long term emission resolutions as well as the considering the cost effectiveness of different solutions to reduce carbon emissions. Short term goals are set to quantify progress towards the temperature goal. In a short term goal, looking ahead to the year 2020, the allowable carbon emissions must be between 41 and 55 GtCO2 per year. The short term 2 °C scenario is not feasible without CCS.
Currently, greenhouse gas emissions would need to be reduced by 7 Gt of carbon equivalent each year by 2050 to achieve 2 °C stabilization. This requires power generation with CCS at 800 coal-fired power plants of 1 GW energy generation capacity, 180 coal-synfuel plants, or natural gas plants worth 1,600 GW. In this scenario, one of the wedges, or 1 Gt of carbon is accounted for by CCUS.
CCS and below 2.0°C target
Achieving below 2.0°C target
A change of temperature below 2 °C is, to certain extent, almost impossible to achieve due to the current carbon emission practices. The IPCC notes that it is difficult to assess a climate mitigation scenario that would limit average global temperature increase to only 1.5 °C above pre-industrial levels. This is mainly due to the fact that few reliable multi-model studies have been conducted to thoroughly explore this scenario. Nevertheless, what few studies that have been done agree that mitigation technologies must be implemented immediately and scaled up quickly and reflect energy demand decrease. A change below 1 °C with respect to pre-industrial era is now inconceivable because by 2017 there was already an increase of 1 °C.
Because of the immediate inability to control the temperature at the 1 °C target, the next realistic target is 1.5 °C. There is enough confidence that past emissions alone (pre-industrial time) will not be enough to go beyond the 1.5 °C target. In other words, if all anthropogenic emissions were stopped today (reduced to zero), any increase beyond the 1 °C change for more than half of a degree before 2100 is unlikely. If anthropogenic emission are considered, the probability for the planet increasing for more than 1.5 °C before 2100 are high. Then, scenarios where the degree change is maintain below 1.5 °C are very challenging to achieve but not impossible.
For a below 2.0 °C target, Shared socioeconomic pathways (SSPs) had been developed adding a socio-economic dimension to the integrative work started by Representative Concentration Pathway, RCPs models. The advantage of using SSPs is that they incorporate social standards, fossil fuel use, geographical development, and high energy demand. SSPs also incorporate the use of six other models such as GCAM4, IMAGE, MESSAGE-GLOBIOM, and REMIND-MAgPIE. The combination of models and scenarios concluded that by 2050, annual CO2 emissions are in the range between 9 and 13 billion tons of CO2. All of the scenarios estimated that temperature will remain below 2.0 °C change with a 66% probability of success. To do so, a 1.9 W/m2 within the year 2100 is necessary. Net zero GHG emissions have to be achieved between 2055 and 2075, and CO2 emissions have to be in a range between 175 and 475 GtCO2 between the years 2016-2100. All SSPs scenarios show a shift away from unabated fossil fuels, that is process without CCS.
Assumptions for below 2.0°C target
To achieve a 1.5 °C target before 2100, the following assumptions have to be considered; emissions have to peak by 2020 and decline after that, it will be necessary to reduce net CO2 emissions to zero and negative emissions have to be a reality by the second half of the 21st century. For this assumptions to take place, CCS has to be implemented in factories that accompany the use of fossil fuels. Because emissions reduction has to be implemented more rigorously for a 1.5 °C target, methods such as BEECS, and natural climate solutions such as afforestation can be used to aim in the reduction of global emissions. Bio-energy with carbon capture and storage, BECCS is necessary to achieve a 1.5 °C. It is estimated by the models that with the help of BECCS, between 150 and 12000 GtCO2 still have to be removed from the atmosphere.
Another negative emission strategy which includes CCS can also be approached through DACCS. Direct Air Carbon Capture and Sequestration (DACCS) is a carbon dioxide removal, carbon negative technology that utilizes solid amine based capture and it has proven to capture carbon dioxide from the air even though content of the air is much lower than of a flue gas from a coal plant. However, it would require renewable energies to power since approximately 400kJ of work is needed per mole of CO2 capture. Furthermore, it is estimated that the total system cost is $1,000 per tonne of CO2, according to an economic and energetic analysis from 2011.
Going forward in the utilization of models such as SSPss and RCP, feasibility of the model has to be to take into consideration. Feasibility includes concerns in various fields, such as geophysics, technology, economics, social acceptance, and politics, all of which can serve to facilitate or obstruct the carbon capture and sequestration of emissions needed in order to achieve the global temperature targets. Uncertainty in feasibility is especially a problem with more strict temperatures limits such as 1.5 °C. Real world feasibility of SSPs models, or any other models, in general are coarse approximations of reality.
See also
* Bio-energy with carbon capture and storage
* Biological pump
* Biosequestration
* CCS and climate change mitigation
* Carbon capture and storage (timeline)
* Carbon dioxide removal
* Carbon sequestration
* Carbon sink
* Carbon storage in the North Sea
* Climate engineering
* Coal pollution mitigation
* Eddy covariance
* Exhaust gas
* Flue gas
* Flue-gas desulfurization
* Flue-gas stack
* Integrated gasification combined cycle
* Life-cycle greenhouse-gas emissions of energy sources
* Limnic eruption
* Low-carbon economy
* Methane pyrolysis
* North East of England Process Industry Cluster
* Solid sorbents for carbon capture
References
Further reading
*
*
*
External links
*
DOE Fossil Energy
Department of Energy programs in CO2 capture and storage
US Department of Energy
US Gulf coast
Zero Emissions Platform - technical adviser to the EU Commission on the deployment of CCS and CCU
National Assessment of Geologic CO2 Storage Resources: Results
United States Geological Survey
MIT Carbon Capture and Sequestration
{{DEFAULTSORT:Carbon Capture And Storage
Carbon capture and storage
Bright green environmentalism
Emissions reduction
Gas technologies
Climate change and the environment
Climate change mitigation