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Carbon capture and storage (CCS) is a process in which a relatively pure stream of carbon dioxide (CO2) from industrial sources is separated, treated and transported to a long-term storage location.[1]: 2221 In CCS, the CO2 is captured from a large point source, such as a natural gas processing plant or coal power plant, and typically is stored in a deep geological formation. As of 2022, around 73% of the CO2 captured annually is used for enhanced oil recovery (EOR), a process in which CO2 is injected into partially-depleted oil reservoirs in order to extract more oil and then is left underground.[2] Since EOR utilizes the CO2 in addition to storing it, CCS is also known as carbon capture, utilization, and storage (CCUS).[3] Based on the limited field data available, the IPCC estimates that at appropriately-selected and well-managed storage sites, it is likely that over 99% of CO2 will remain in place for more than 1000 years.[4]: 14
CCS facilities typically require capital investments of up to several billion dollars, and CCS also increases operating costs.[5] Power plants with CCS require around 15-25% more energy to operate,[6] thus they typically burn additional fossil fuel and thus increase the pollution from extracting and transporting fuel. Almost all CCS projects operating today have benefited from government financial support, usually in the form of grants.[7]: 156–160 As of 2023, around 45 commercial CCS facilities are operational and collectively capture about one thousdandth of global CO2 emissions[8]: 32 .
American oil and gas companies developed the processes involved in CCS in the mid 20th century. Originally, these technologies served to purify natural gas and to facilitate oil production. Subsequently, CCS was discussed as a strategy to reduce greenhouse gas emissions.[4][9] In pathways for climate change mitigation, CCS plays a small but critical role. CCS is expensive compared to other methods of reducing emissions such as renewable energy, electrification, and public transit. It is envisioned to reduce emissions in specific niches such as steel production, cement production, and plant retrofits.[10]: 21–24
The effectiveness of CCS projects in reducing carbon emissions depends on the capture efficiency, the additional energy used for CCS itself, and business and technical issues that can keep facilities from operating as designed. Most of the largest CCS implementations have failed to meet their emission-reduction goals.[11] Additionally, there is controversy over whether CCS is beneficial for the climate if the CO2 is used to extract more oil.[12] Some environmental activists and politicians have criticized CCS as a false solution to the climate crisis. They cite the role of the fossil fuel industry in origins of the technology and in lobbying for CCS focused legislation.[13] Critics also argue that CCS is only a justification for indefinite fossil fuel usage and equate to further investments into the environmental and social harms related to the fossil fuel industry.[14][15]
Globally, a number of laws and rules have been issued that either support or mandate the implementation of CCS. In the US, the 2021 Infrastructure Investment and Jobs Act provides support for a variety of CCS projects, and the Inflation Reduction Act of 2022 updates tax credit law to encourage the use of CCS.[16][17] Other countries are also developing programs to support CCS technologies, including Canada, Denmark, China, and the UK.[18][19]
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Transcription
Terminology
The IPCC defines CCS as:
"A process in which a relatively pure stream of carbon dioxide (CO2) from industrial and energy-related sources is separated (captured), conditioned, compressed and transported to a storage location for long-term isolation from the atmosphere."[20]: 2221
The terms carbon capture and storage (CCS) and carbon capture, utilization, and storage (CCUS) are closely related and used interchangeably.[21] Both terms are used predominantly to refer to a process in which captured CO2 is injected into partially-depleted oil reservoirs in order to extract more oil.[21] This is both "utilization" and "storage", as the CO2 left underground is intended to be trapped indefinitely. Prior to 2013, the process was primarily called CCS; since then the more valuable-sounding CCUS has gained popularity.[21]
Around 1% of captured CO2 is used as a feedstock for making products such fertilizer, synthetic fuels, and plastics.[22] These uses are forms of carbon capture and utilization.[23] In some cases, the product durably stores the carbon from the CO2 and thus is also considered to be a form of CCS. To qualify as CCS, carbon storage must be long-term, therefore utilization of CO2 to produce fertilizer, fuel, or chemicals is not CCS because these substances release CO2 when burned or consumed.[23]
Some sources use the term CCS, CCU, or CCUS more broadly, encompassing methods such as direct air capture or tree-planting which remove CO2 from the air.[24][25][26] In this article, the terms are used according to the IPCC's definition, which requires CO2 to be captured from point-sources such as the flue gas of power plants.
History and current status
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In the natural gas industry, technology to remove CO2 from raw natural gas has been used since 1930.[29] This processing is essential to make natural gas ready for commercial sale and distribution.[30]: 25 Usually after CO2 is removed it is vented to the atmosphere.[30]: 25 In 1972, American oil companies discovered that large quantities of CO2 could be profitably be used for enhanced oil recovery (EOR).[31] Subsequently, natural gas companies in Texas began capturing the CO2 that was produced by their processing plants, and selling it to local oil producers for EOR.[30]: 25
The use of CCS as a means of reducing anthropogenic CO2 emissions is more recent. In 1977, the Italian physicist Cesare Marchetti proposed that CCS technology could be used to reduce emissions from coal power plants and fuel refineries.[32][33] The first large-scale CO2 capture and injection project with dedicated CO2 storage and monitoring was commissioned at the Sleipner offshore gas field in Norway in 1996.[30]: 25
In 2005, the IPCC released a report highlighting CCS, leading to increased government support for CCS in several countries.[34] Since 1995, plans for hundreds of CCS projects have been announced, most of which have not materialized.[34] One well-known failure is the FutureGen 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 low-carbon electricity from coal.[35][36]
As of 2023, around 45 commercial CCS facilities are operational.[37] In 2020, the International Energy Agency stated, “The story of CCUS has largely been one of unmet expectations: its potential to mitigate climate change has been recognised for decades, but deployment has been slow and so has had only a limited impact on global CO2 emissions.”[30]: 18
CO2 capture
In CCS, CO2 is captured from point sources such as large fossil fuel-based energy facilities, industries with major CO2 emissions (e.g. cement production, steelmaking[38]), natural gas processing, synthetic fuel plants and fossil fuel-based hydrogen production plants. Most studies assume that 85-90% of the CO2 in the flue gas is captured.[39]
A wide variety of separation techniques are being pursued, including gas phase separation, absorption into a liquid, and adsorption on a solid, as well as hybrid processes, such as adsorption/membrane systems.[40] There are three ways that this capturing can be carried out: post-combustion capture, pre-combustion capture, and oxy-combustion:[41]
- In post combustion capture, the CO2 is removed after combustion of the fossil fuel. The technology is well understood and is currently used in other industrial applications, although at much smaller scale than required for a commercial operation.
- The technology for pre-combustion is widely applied in fertilizer, chemical, gaseous fuel (H2, CH4), and power production.[42] In these cases, the fossil fuel is partially oxidized, for instance in a gasifier. The CO from the resulting syngas (CO and H2) reacts with added steam (H2O) and is shifted into CO2 and H2. The resulting CO2 can be captured from a relatively pure exhaust stream. The H2 can be used as fuel; the CO2 is removed before combustion. Several advantages and disadvantages apply versus post combustion capture.[43][44] The CO2 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 CO2 capture processes, at the same scale as required for power plants.[45][46]
- In oxy-fuel combustion[47] 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 CO2 and water vapor, the latter of which is condensed through cooling. The result is an almost pure CO2 stream.
Absorption, or carbon scrubbing with amines is the dominant capture technology. It is the only carbon capture technology so far that has been used industrially.[48] Other technologies proposed for carbon capture are membrane gas separation, chemical looping combustion, calcium looping, and use of metal-organic frameworks:[49][50][51]
Impurities in CO2 streams, like sulfurs and water, can have a significant effect on their phase behavior and could cause increased pipeline and well corrosion. In instances where CO2 impurities exist, a scrubbing separation process is needed to initially clean the flue gas.[52] About two thirds of CCS cost is attributed to capture.
CO2 transport
After the CO2 has been captured, it is usually compressed into a supercritical fluid. Pipelines are the cheapest way of transporting CO2 in large quantities onshore and, depending on the distance and volumes, offshore.[10]: 103–104 Transport via ship has been researched. CO2 can also be transported by truck or rail, albeit at higher cost per tonne of CO2.[10]: 103–104 There is already an extensive onshore CO2 pipeline network in North America, with a combined length of more than 8000 km, mostly in the United States. There are also two CO2 pipeline systems in Europe and two in the Middle East.[10]: 103–104
CO2 sequestration (storage)
Storing CO2 involves the injection of captured CO2 into a deep underground geological reservoir of porous rock overlaid by an impermeable layer of rocks, which seals the reservoir and prevents the upward migration of CO2 and escape into the atmosphere.[53]: 112 The gas is usually compressed first into a supercritical fluid. When the compressed CO2 is injected into a reservoir, it flows through it, filling the pore space. The reservoir must be at depths greater than 800 metres to retain the CO2 in a dense liquid state.[53]: 112
As of 2022, around 73% of the CO2 captured annually is used for enhanced oil recovery (EOR).[54] In EOR, CO2 is injected into partially depleted oil fields to enhance production. This increases the overall reservoir pressure and improves the mobility of the oil, resulting in a higher flow of oil towards the production wells.[55]: 117
Around 22% of captured CO2 is injected into dedicated geological storage,[54] usually deep saline aquifiers. These are layers of porous and permeable rocks saturated with salty water.[56]: 112 Worldwide, saline formations have higher potential storage capacity than depleted oil wells.[57] Dedicated geologic storage is generally less expensive than EOR because it does not require a high level of CO2 purity and because suitable sites are more numerous, which means pipelines can be shorter.[58]
Various other types of reservoirs for storing captured CO2 are being researched or piloted as of 2021: CO2 could be injected into coal beds for enhanced coal bed methane recovery.[59] Ex-situ mineral carbonation involves reacting CO2 with mine tailings or alkaline industrial waste to form stable minerals such as calcium carbonate.[60] In-situ mineral carbonation involves injecting CO2 and water into underground formations that are rich in highly-reactive rocks such as basalt. There, the CO2 reacts with the rock to stable carbonate minerals relatively quickly.[60][61] Once the mineral carbonation process is complete, there is no risk of CO2 leakage.[62]
The global capacity for underground CO2 storage is potentially very large and is unlikely to be a constraint on the development of CCS.[7]: 112–115 Total storage capacity has been estimated at between 8 000 and 55 000 gigatonnes.[7]: 112–115 However, a smaller fraction will most likely prove to be technically or commercially feasible.[7]: 112–115 Global capacity estimates are uncertain, particularly for saline aquifers where more site characterization and exploration is still needed.[7]: 112–115
Leakage and rupture risks
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Sudden leakage hazards
CO2 is a colorless and odorless gas that accumulates near the ground because it is heavier than air. In humans, exposure to CO2 at concentrations greater than 5% causes the development of hypercapnia and respiratory acidosis. Concentrations of more than 10% may cause convulsions, coma, and death. CO2 levels of more than 30% act rapidly leading to loss of consciousness in seconds.[63]
Pipelines and storage sites can be sources of large accidental releases of CO2 that can endanger local communities. A 2005 IPCC report stated that "existing CO2 pipelines, mostly in areas of low population density, accident numbers reported per kilometre of pipeline are very low and are comparable to those for hydrocarbon pipelines."[4]: 12 The report also stated that the local health and safety risks of geologic CO2 storage were "comparable" to the risks of underground storage of natural gas if good site selection processes, regulatory oversight, monitoring, and incident remediation plans are in place.[4]: 12
While infrequent, accidents can be serious. In 2020 a CO2 pipeline ruptured following a mudslide near Satartia, Mississippi, causing people nearby to lose consciousness.[64] 200 people were evacuated and 45 were hospitalized, and some experienced longer term effects on their health.[65][66] High concentrations CO2 in the air also caused vehicle engines to stop running, hampering the rescue effort.[67]
A severed 19" pipeline section 8 km long could release its 1,300 tonnes in about 3–4 min.[68] At the storage site, the injection pipe can be fitted with non-return valves to prevent an uncontrolled release from the reservoir in case of upstream pipeline damage. Pipelines can be fitted with remotely controlled valves that can limit the release quantity to one pipe section, however, operators in the United States have not been required to retrofit older pipes because of the nonapplication clause found at 49 U.S.C. § 60104(b), which prohibits the Pipeline and Hazardous Materials Safety Administration (PHMSA) from promulgating regulations to existing facilities.[69] The US Pipeline and Hazardous Materials Safety Administration, the agency in charge of pipeline safety, is a notoriously underfunded and understaffed agency.[69]
Long-term leakage rates
In geologic storage, the CO2 is held within the reservoir through several trapping mechanisms: structural trapping by the caprock seal, solubility trapping in pore space water, residual trapping in individual or groups of pores, and mineral trapping by reacting with the reservoir rocks to form carbonate minerals.[53]: 112 Mineral trapping progresses over time but is extremely slow.[70]: 26
Once injected, the CO2 plume tends to rise since it is less dense than its surroundings. Once it encounters a caprock, it will spread laterally until it encounters a gap. If there are fault planes near the injection zone, CO2 could migrate along the fault to the surface, leaking into the atmosphere, which would be potentially dangerous to life in the surrounding area. If the injection of CO2 creates pressures underground that are too high, the formation will fracture, potentially causing an earthquake.[71] While research suggests that earthquakes from injected CO2 would be too small to endanger property, they could be large enough to cause a leak.[72]
The IPCC estimates that at appropriately-selected and well-managed storage sites, it is likely that over 99% of CO2 will remain in place for more than 1000 years, with "likely" meaning a probability of 66% to 90%.[4]: 14,12 Estimates of long-term leakage rates rely on complex simulations since field data is limited.[73] If very large amounts of CO2 are sequestered, even a 1% leakage rate over 1000 years could cause significant impact on the climate for future generations.[74] The IPCC recommends that limits be set to the amount of leakage that can take place.[75][page needed][clarification needed]
Social and environmental impacts
Additional energy requirements
In general, facilities with CCS require 15-25% more energy.[6] The energy consumed by 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 the extracted CO2, while the remaining 10% comes from pumps and fans.[76] CCS technology is expected to use between 10 and 40 percent of the energy produced by a power station.[77][78] CCS would increase the fuel requirement of a gas plant with CCS by about 15%.[79]
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%.[80] Using CCS for natural gas combined cycle (NGCC) plants can decrease operating efficiency from 11 to 22%.[80]
Pollution
Since plants with CCS require more fuel to produce the same amount of electricity or heat, the use of CCS increases the "upstream" environmental problems of fossil fuels. Upstream impacts include pollution caused by coal mining, emissions from the fuel used to transport coal and gas, emissions from gas flaring, and fugitive methane emissions.
Since CCS facilities require more fossil fuel to be burned, this could cause a net increase of non-GHG pollutants from those facilities. However, most of these impacts are controlled by the pollution control equipment already installed at these plants to meet air pollution regulations.[81]
Since liquid amine solutions are used to capture CO2 in many CCS systems, these types of chemicals can also be released as air pollutants if not adequately controlled. Among the chemicals of concern are volatile nitrosamines which are carcinogenic when inhaled or drunk in water.[82][83]
Some studies indicate that when both upstream and downstream impacts are considered, CCS increases air pollution.[84]
Cost
Cost is a significant factor affecting CCS.
CCS facilities typically require upfront capital investments of up to several billion dollars.[5] The energy needed for CCS, 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%.
Almost all CCS projects operating today have benefited from government financial support, largely in the form of capital grants and – to a lesser extent – operational subsidies. Grant funding has played a particularly important role in projects coming online since 2010, with 8 out of 15 projects receiving grants ranging from around USD 55 million (AUD 60 million) in the case of Gorgon in Australia to USD 840 million (CAD 865 million) for Quest in Canada.[7]: 156–160 An explicit carbon price or tax has supported CCS investment in only two cases to date: the Sleipner and Snøhvit projects in Norway, which were subject to a CO2 tax on offshore oil and gas production introduced in 1991.[7]: 156–160
Other applications are possible. CCS trials for coal-fired plants in the early 21st century were economically unviable in most countries,[85] including China,[86] in part because revenue from enhanced oil recovery collapsed with the 2020 oil price collapse.[87]
Role in climate change mitigation
Comparison with other mitigation options
Compared to other options for reducing emissions, CCS is very expensive. For instance, removing CO2 from the flue gas of fossil fuel power plants increases costs by USD $50 - $200 per tonne of CO2 removed.[88]: 38 There are many other ways to reduce emissions that cost less than USD $20 per tonne of avoided CO2 emissions.[89] Options to reduce emissions that have far more potential to reduce emissions at lower cost include public transit, electric vehicles, and various other energy efficiency measures.[88]: 38 Wind and solar power are often the lowest-cost ways to produce electricity, even when compared to power plants that do not use CCS.[88]: 38 Since CCS always adds costs, it is difficult for fossil fuel plants with CCS to compete with renewable energy combined with energy storage, especially as the cost of renewable energy and batteries continues to decline.
Analysis of IPCC modeling work shows that mitigation strategies that rely less on CCS would bring about localized, near-term benefits from reduced air and water pollution, human rights violations, and biodiversity loss.[90]
Since CCS can only be used with large, stationary emission sources, it cannot reduce the emissions from burning fossil fuels in vehicles and homes. The IPCC stated in 2022 that “implementation of CCS currently faces technological, economic, institutional, ecological-environmental and socio-cultural barriers.”[91]: 28 To reach targets set in the Paris Agreement, CCS must be accompanied by a steep decline in the production and use of fossil fuels.[92]
Priority uses for CCS
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In the literature on climate change mitigation, CCS is described as having a small but critical role in reducing greenhouse gas emissions.[92][91]: 28 Emissions are relatively difficult or expensive to abate without CCS in the following niches:[10]: 13–14
- Heavy Industry: CCS is one of the few few available technologies that can significantly reduce emissions associated with the production of steel, cement, and various chemicals.[10]: 21–24 The CO2 emissions from these processes come from chemical reactions, in addition to emissions from burning fuels for heat. Cleaner industrial processes are in development but are far from being widely-deployed.[91]: 29
- Retrofits: CCS can be retrofitted to existing coal and natural gas power plants and industrial facilities to enable the continued operation of existing plants while reducing their emissions.[10]: 21–24
- Natural gas processing: CCUS is the only solution to reduce the CO2 emissions from natural gas processing.[10]: 21–24 Lowering emissions associated with production does not reduce the emissions from the gas when it is ultimately combusted.[92]
- Hydrogen: Nearly all hydrogen today is produced from natural gas or coal. Facilities can incorporate CCS to capture the CO2 released in these processes.[10]: 21–24
- Complement to renewable electricity: Although solar and wind energy are typically cheaper, power plants that burn natural gas, biomass, or coal have the advantage of being able to produce electricity in any season and any time of day, and can be dispatched at times of high demand.[10]: 51–52 A small amount of power plant capacity can help to meet the growing need for system flexibility as the share of wind and solar increases.[10]: 51–52 The potential for a robust power grid using 100% renewable energy has been modelled as a feasible option for many regions, which would make fossil CCS in the electricity sector unnecessary.[93]
- Synthetic fuel production: According to the IEA, a supply of CO2 is needed to produce synthetic hydrocarbon fuels, which alongside biofuels are the only practical alternative to fossil fuels for long-haul flights. Limitations on the availability of sustainable biomass mean that these synthetic fuels will be needed for net-zero emissions; the CO2 would need to come from bioenergy production or direct air capture to be carbon-neutral.[10]: 21–24
- Bioenergy with carbon capture and storage
Effectiveness in reducing emissions
The potential for a CCS project to reduce emissions depends on several factors. Major factors include the efficiency of the capture process; the amount of additional energy needed to power CO2 capture, compression, and transport; and the source of the additional energy used. Some studies indicate that under certain circumstances the overall emissions reduction from CCS can be very low, or that adding CCS can even result in higher net CO2 emissions.[94][95] For instance, one study found that the Petra Nova CCS retrofit of a coal power plant would emissions by only 10.8% in its first 20 years.[96]
Many CCS implementations have not sequestered carbon at their designed capacity, either for business or technical reasons. For instance, in the Shute Creek Gas Processing Facility, around half of the CO2 that has been captured has been sold for EOR, and the other half vented to the atmosphere because it could not be profitably sold.[8]: 19 A 2022 analysis of 13 major CCS projects found that most had sequestered far less CO2 than originally expected.[11][8]
Additionally, there is controversy over whether carbon capture followed by EOR is beneficial for the climate. When the oil that is extracted using EOR is subsequently burned, CO2 is released. If these emissions are included in calculations, carbon capture with EOR is usually found to increase overall emissions compared to not using carbon capture at all.[97] If the emissions from burning extracted oil are excluded from calculations, carbon capture with EOR is found to decrease emissions. In arguments for excluding these emissions, it is assumed that oil produced by EOR displaces conventionally-produced oil instead of adding to the global consumption of oil.[97] A 2020 review found that scientific papers were roughly evenly split on the question of whether carbon capture with EOR increased or decreased emissions.[97]
Pace of implementation
As of 2023 CCS captures around 0.1% of global emissions — around 45 million metric tons of CO2.[92] Climate models from the IPCC and the IEA show it capturing around 1 billion metric tons of CO2 by 2030 and several billions of tons by 2050.[92] Technologies for CCS in high-priority niches, such as cement production, are still immature. The IEA notes "a disconnect between the level of maturity of individual CO2 capture technologies and the areas in which they are most needed."[10]: 92
CCS implementations involve long approval and construction times and the overall pace of implementation has historically been slow, although there has been an uptick in announced projects following the COVID-19 pandemic.[98] Some observers such as the IEA call for increased commitment to CCS in order to meet targets.[98]: 16 Other observers see the slow pace of implementation as an indication that the technology is fundamentally unlikely to succeed, and call for efforts to be redirected to other mitigation tools such as renewable energy.[84]
Society and culture
Political debate
CCS has been discussed by political actors at least since the start of the UNFCCC[99] negotiations in the beginning of the 1990s, and remains a very divisive issue.[100] Its effectiveness in reducing emissions has been disputed, notably when considering the life-cycle carbon emissions it takes to create CCS systems.[100] Opponents claimed that CCS could legitimize the continued use of fossil fuels, as well obviate commitments on emission reduction.[citation needed]
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.[101][better source needed]
For instance, Greenpeace is strongly against CCS. According to the organization, the use of the technology will keep the world dependent on fossil fuels.[102][better source needed]
On the other hand, BECCS is used in some IPCC scenarios to help meet mitigation targets.[103] 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.[102] They claimed fossil fuels are unavoidable for the near term and consequently, CCS is the quickest way to reduce CO2 emissions.[104]
Some environmental groups raised concerns over leakage given the long storage time required, comparing CCS to storing radioactive waste from nuclear power stations.[105]
Some environmental activists and politicians have criticized CCS as a false solution to the climate crisis. They cite the role of the fossil fuel industry in origins of the technology and in lobbying for CCS focused legislation and argue that it would allow the industry to "greenwash" itself by funding and engaging in things such as tree planting campaigns without significantly cutting their carbon emissions.[106][13]
Equity concerns
Another aspect of CCS that could concern project opponents is that projects only remove carbon dioxide from flue gas. Particulate matter and other toxic gas emissions would continue, which is of particular concern in places in the US where industries are in poor and/or minority communities. In many cases, CCS would not markedly improve the public or environmental health of these communities.[107]
The communities targeted for hosting CCS projects may meet the geologic and technical siting criteria; however, non-technical social characterizations are equally important factors in the success of an individual project and the global deployment of this technology. Failing to provide meaningful engagement with local communities can drive resistance to CCS projects and enable feelings of mistrust and injustice from project developers and supporting government entities.[108]
Social acceptance
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In a 2011 publication it was suggested that people who were already affected by climate change, such as drought, tended to be more supportive of CCS.[109] As of 2014, multiple studies indicated that risk-benefit perception were the most essential components of social acceptance.[110]
In 2021, it was suggested that risk perception was mostly related to concerns on safety issues in terms of hazards from its operations and the possibility of CO2 leakage, which may endanger communities, commodities, and the environment in the vicinity of the infrastructure.[104] Other perceived risks relate to tourism and property values.[110] as of 2011, CCS public perceptions appeared among other controversial technologies to tackle climate change such as nuclear power, wind, and geoengineering[111]
Locally, communities are sensitive to economic factors, including job creation, tourism or related investment.[110] Experience is another relevant feature: 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.[110] Perception of CCS has a strong geographic component. Public perception can depend on the available information about pilot projects, trust in government entities and developers involved, and awareness of successes and failures of CCS projects both locally and globally. These considerations vary by country and by community.[112]
If only considering technical feasibility, countries with no known viable storage sites may dismiss CCS as an option in national emissions reduction strategies. In contrast, countries with several, or an abundance of viable storage sites may consider CCS as essential to reducing emissions.[113]
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, but one experimental study amongst Swiss people from 2011 found that communicating information about monitoring tended to have a negative impact on attitudes.[114] Conversely, approval seems to be reinforced when CCS was compared to natural phenomena.[110]
Connected to how public perception influences the success or failure of a CCS project is consideration for how decision-making processes are implemented equitably and meaningfully for "impacted communities" at all stages of the project. Public participation alone does not encompass all aspects of procedural justice needed for CCS projects to receive the "social license" to operate.[115]
Due to the lack of knowledge, people rely on organizations that they trust.[citation needed] In general, non-governmental organizations and researchers experience higher trust than stakeholders and governments. As of 2009 Opinions amongst NGOs were mixed.[116][117] Moreover, the link between trust and acceptance was at best indirect. Instead, trust had an influence on the perception of risks and benefits.[110]
CCS is embraced by the Shallow ecology worldview,[118] 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 techno-optimists.
CCS is an "end-of-pipe" solution[110] which reduces atmospheric CO2, that can be used alongside minimizing the use of fossil fuel.[110][118]
Government programs
In the US, a number of laws and rules have been issued to either support or require the use of CCS technologies. The 2021 Infrastructure Investment and Jobs Act designates over $3 billion for a variety of CCS demonstration projects. A similar amount is provided for regional CCS hubs that focus on the broader capture, transport, and either storage or use of captured CO2. Hundreds of millions more are dedicated annually to loan guarantees supporting CO2 transport infrastructure.[16] The Inflation Reduction Act of 2022 (IRA) updates tax credit law to encourage the use of carbon capture and storage. Tax incentives under the law are $85/tonne for CO2 capture and storage in saline geologic formations from industrial and power plants. Incentives for CO2 capture and utilization from these plants are $60/tonne. Thresholds for the total amount of CO2 needing to be captured are also lower, and so more facilities will be able to make use of the credits.[17] Within the US, although the federal government may fully or partially fund CCS pilot projects, local or community jurisdictions would likely administer CCS project siting and construction.[119]
In September 2020, the US Department of Energy awarded $72 million in federal funding to support the development and advancement of carbon capture technologies.[120]
In 2023 the US EPA issued a rule proposing that CCS be required in order to achieve a 90% emission reduction for existing coal-fired and natural gas power plants. That rule would become effective in the 2035-2040 time period.[121] For natural gas power plants, the rule would require 90 percent capture of CO2 using CCS by 2035, or co-firing of 30% low-GHG hydrogen beginning in 2032 and co-firing 96% low-GHG hydrogen beginning in 2038. In that rule EPA identified CCS as a viable technology for controlling CO2 emissions.[121] Costs of using CCS technology were estimated to be, on average, $14/ton of CO2 reduced for coal plants. The impact on the cost of electricity generation from coal plants was estimated as $12/ MWh. These are considered by EPA to be reasonable air pollution control costs.[122]
In Norway, CCS 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.[123]
Other countries are also developing programs to support CCS technologies. Canada has established a C$2.6 billion tax credit for CCS projects and Saskatchewan extended its 20 per cent tax credit under the province’s Oil Infrastructure Investment Program to pipelines carrying CO2. In Europe, Denmark has recently announced €5 billion in subsidies for CCS. The Chinese State Council has now issued more than 10 national policies and guidelines promoting CCS, including the Outline of the 14th Five-Year Plan (2021–2025) for National Economic and Social Development and Vision 2035 of China.[18] In the UK the CCUS roadmap outlines joint government and industry commitments to the deployment of CCUS and sets out an approach to delivering four CCUS low carbon industrial clusters, capturing 20-30 MtCO2 per year by 2030.[19]
Related concepts
CO2 utilization in products
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While nearly all utilization of CO2 is for enhanced oil recovery, CO2 can be used as a feedstock for making various types of products. As of 2022, usage in products consumes around 1% of the CO2 captured each year.[124] As of 2023, it is commercially feasible to produce the following products from captured CO2: methanol, urea, polycarbonates, polyols, polyurethane, and salicylic acids.[125] Methanol is currently primarily used to produce other chemicals, with potential for more widespread future use as a fuel.[126] Urea is used in the production of fertilizers.[127]: 55
Technologies for sequestering CO2 in mineral carbonate products have been demonstrated, but are not ready for commercial deployment as of 2023.[125] Research is ongoing into processes to incorporate CO2 into concrete or building aggregate. The utilization of CO2 in construction materials holds promise for deployment at large scale,[128] and is the only foreseeable CO2 use that is permanent enough to qualify as storage.[129] Other potential uses for captured CO2 that are being researched include the creation of synthetic fuels, various chemicals and plastics, and the cultivation of algae.[125] The production of fuels and chemicals from CO2 is highly energy-intensive.[129]
Capturing CO2 for use in products does not necessarily reduce emissions.[127]: 111 The climate benefits associated with CO2 use primarily arise from displacing products that have higher life-cycle emissions.: 111 The amount of climate benefit varies depending on how long the product lasts before it re-releases the CO2, the amount and source of energy used in production, whether the product would otherwise be produced using fossil fuels, and the source of the captured CO2.[127]: 111 Higher emissions reductions are achieved if CO2 is captured from bioenergy as opposed to fossil fuels.[127]: 111
The potential for CO2 utilization in products is small compared to the total volume of CO2 that could foreseeably be captured. For instance, in the International Energy Agency (IEA) scenario for achieving net zero emissions by 2050, over 95% of captured CO2 is geologically sequestered and less than 5% is used in products.[129] According to the IEA, products created from captured CO2 are likely to cost a lot more than conventional and alternative low-carbon products.[127]: 110
Bioenergy with carbon capture and storage (BECCS)
Direct air carbon capture and sequestration (DACCS)
Direct air capture (DAC) is the use of chemical or physical processes to extract carbon dioxide directly from the ambient air.[132] If the extracted CO2 is then sequestered in safe long-term storage (called direct air carbon capture and sequestration (DACCS)), the overall process will achieve carbon dioxide removal and be a "negative emissions technology" (NET).
The carbon dioxide (CO2) is captured directly from the ambient air; this is contrast to carbon capture and storage (CCS) which captures CO2 from point sources, such as a cement factory or a bioenergy plant.[133] After the capture, DAC generates a concentrated stream of CO2 for sequestration or utilization. Carbon dioxide removal is achieved when ambient air makes contact with chemical media, typically an aqueous alkaline solvent[134] or sorbents.[135] These chemical media are subsequently stripped of CO2 through the application of energy (namely heat), resulting in a CO2 stream that can undergo dehydration and compression, while simultaneously regenerating the chemical media for reuse.See also
- List of carbon capture and storage projects
- Timeline of carbon capture and storage
- Carbon sink
- Carbon storage in the North Sea
- Climate engineering
- Greenwashing
- Life-cycle greenhouse gas emissions of energy sources
- Low-carbon economy
- Methane pyrolysis
- Oceanic carbon cycle
- Solid sorbents for carbon capture
References
- ^ IPCC, 2021: Annex VII: Glossary [Matthews, J.B.R., V. Möller, R. van Diemen, J.S. Fuglestvedt, V. Masson-Delmotte, C. Méndez, S. Semenov, A. Reisinger (eds.)]. In Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [Masson-Delmotte, V., P. Zhai, A. Pirani, S.L. Connors, C. Péan, S. Berger, N. Caud, Y. Chen, L. Goldfarb, M.I. Gomis, M. Huang, K. Leitzell, E. Lonnoy, J.B.R. Matthews, T.K. Maycock, T. Waterfield, O. Yelekçi, R. Yu, and B. Zhou (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, pp. 2215–2256, doi:10.1017/9781009157896.022.
- ^ Robertson, Bruce; Mousavian, Milad (1 September 2022). "The carbon capture crux: Lessons learned" (PDF). Institute for Energy Economics and Financial Analysis. p. 10. Retrieved 27 June 2024.
- ^ Sekera, June; Lichtenberger, Andreas (6 October 2020). "Assessing Carbon Capture: Public Policy, Science, and Societal Need: A Review of the Literature on Industrial Carbon Removal". Biophysical Economics and Sustainability. 5 (3): 14. Bibcode:2020BpES....5...14S. doi:10.1007/s41247-020-00080-5.
- ^ a b c d e Metz, Bert; Davidson, Ogunlade; De Conink, Heleen; Loos, Manuela; Meyer, Leo, eds. (March 2018). "IPCC Special Report on Carbon Dioxide Capture and Storage" (PDF). Intergovernmental Panel on Climate Change; Cambridge University Press. Retrieved 16 August 2023.
- ^ a b Lipponen, Juho; McCulloch, Samantha; Keeling, Simon; Stanley, Tristan; Berghout, Niels; Berly, Thomas (July 2017). "The Politics of Large-scale CCS Deployment". Energy Procedia. 114: 7581–7595. Bibcode:2017EnPro.114.7581L. doi:10.1016/j.egypro.2017.03.1890.
- ^ a b "Carbon capture and storage could also impact air pollution — European Environment Agency". www.eea.europa.eu. Retrieved 30 August 2024.
- ^ a b c d e f g
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Opponents of CCS claim it distracts from the need to invest in renewables and is being pushed by the fossil fuel industry so that it can continue drilling for oil and gas.
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