8.3 Carbon capture and storage

Carbon capture and storage (CCS) is a key technology for reducing greenhouse gas emissions from industrial processes and power generation. It involves capturing CO2 before it enters the atmosphere, then storing it long-term or using it in other applications.

CCS faces challenges in implementation, balancing environmental benefits with economic costs. Various capture methods exist, each with trade-offs between efficiency and expense. Storage options include geological formations, oceans, and mineral carbonation, each with unique considerations.

Fundamentals of carbon capture

• Carbon capture technologies play a crucial role in mitigating climate change by reducing greenhouse gas emissions from industrial processes and power generation
• Implementation of carbon capture systems involves complex policy decisions, balancing environmental benefits with economic considerations and technological feasibility

Definition and purpose

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• Process of capturing carbon dioxide (CO2) emissions from large point sources before they enter the atmosphere
• Aims to reduce the impact of fossil fuel use on global warming and climate change
• Captures CO2 from industrial processes (steel production, cement manufacturing) and power generation facilities
• Captured CO2 can be stored long-term or utilized in various applications (enhanced oil recovery, production of synthetic fuels)

Types of carbon capture

• Post-combustion capture removes CO2 from flue gases after fuel combustion
• Pre-combustion capture converts fuel into a mixture of hydrogen and CO2 before combustion
• Oxy-fuel combustion uses pure oxygen for combustion, producing a concentrated CO2 stream
• Direct air capture extracts CO2 directly from the atmosphere, though currently less efficient than point-source capture

Capture efficiency vs cost

• Capture efficiency refers to the percentage of CO2 emissions successfully captured
• Higher capture efficiencies generally lead to increased costs due to energy requirements and equipment complexity
• Typical capture efficiencies range from 85% to 95% for most commercial technologies
• Cost of capture varies widely depending on the source and technology used
  • Ranges from $40 to$120 per ton of CO2 captured for most current technologies
• Trade-offs between efficiency and cost must be considered in policy decisions and project planning

Carbon storage methods

• Carbon storage, also known as carbon sequestration, is a critical component of the carbon capture and storage (CCS) process
• Effective storage methods are essential for long-term climate change mitigation and require careful consideration of geological, environmental, and economic factors

Geological storage

• Involves injecting captured CO2 into deep underground rock formations
• Suitable storage sites include depleted oil and gas reservoirs, deep saline aquifers, and unminable coal seams
• Relies on impermeable cap rock to prevent CO2 from escaping to the surface
• Monitoring systems track CO2 movement and detect potential leaks
• Storage capacity estimated at 2,000 to 20,000 gigatons of CO2 globally

Ocean storage

• Proposes injecting CO2 into deep ocean waters or seafloor sediments
• Relies on the ocean's natural ability to absorb and store large amounts of CO2
• Raises concerns about ocean acidification and impacts on marine ecosystems
• Currently not widely implemented due to environmental risks and international regulations
• Research ongoing to assess long-term viability and potential consequences

Mineral carbonation

• Process of converting CO2 into stable carbonate minerals through chemical reactions
• Mimics natural weathering processes but accelerates them significantly
• Utilizes abundant minerals like serpentine and olivine as reactants
• Produces stable, solid products that can be used in construction or safely disposed of
• Challenges include high energy requirements and the need for large quantities of minerals

Technological advancements

• Continuous innovation in carbon capture technologies aims to improve efficiency, reduce costs, and expand applicability across various industries
• Advancements in capture methods contribute to the overall effectiveness of CCS as a climate change mitigation strategy

Pre-combustion capture

• Involves converting fuel into a mixture of hydrogen and CO2 before combustion
• Utilizes gasification process for solid fuels or steam reforming for natural gas
• Produces a high-pressure CO2 stream, facilitating easier separation and compression
• Offers potential for hydrogen production as a clean energy carrier
• Challenges include high capital costs and complexity of integration with existing power plants

Post-combustion capture

• Removes CO2 from flue gases after fuel combustion
• Most widely applicable technology for existing power plants and industrial facilities
• Typically uses chemical absorption with amine-based solvents
  • Monoethanolamine (MEA) is a commonly used solvent
• Advanced solvents and membrane technologies under development to improve efficiency
• Retrofitting existing plants possible but can result in significant energy penalties

Oxy-fuel combustion

• Burns fuel in pure oxygen instead of air, producing a concentrated CO2 stream
• Eliminates the need for nitrogen separation from flue gas
• Requires an air separation unit to produce pure oxygen
• Results in higher combustion temperatures, necessitating flue gas recirculation
• Offers potential for improved efficiency in new power plant designs
• Challenges include high costs of air separation and material constraints due to high temperatures

Policy frameworks

• Effective policy frameworks are crucial for promoting the development and deployment of carbon capture and storage technologies
• Policies must balance environmental goals with economic considerations and technological feasibility

International agreements

• Paris Agreement sets global targets for reducing greenhouse gas emissions
• Includes provisions for technology transfer and financial support for CCS in developing countries
• Clean Development Mechanism (CDM) under Kyoto Protocol allows CCS projects in some contexts
• International Energy Agency (IEA) provides guidelines and recommendations for CCS deployment
• Global CCS Institute facilitates knowledge sharing and collaboration among countries

National regulations

• Vary significantly between countries, reflecting different priorities and resource availability
• May include emissions reduction targets, performance standards for power plants, and permitting processes for CCS projects
• Examples of national initiatives:
  • United States: 45Q tax credit for carbon oxide sequestration
  • European Union: Emissions Trading System (EU ETS) and CCS Directive
  • Australia: Offshore Petroleum and Greenhouse Gas Storage Act
• Regulatory frameworks address liability issues, long-term monitoring requirements, and site selection criteria

Carbon pricing mechanisms

• Create economic incentives for CO2 emission reductions and CCS implementation
• Carbon taxes impose a direct fee on CO2 emissions
• Cap-and-trade systems set overall emission limits and allow trading of emission allowances
• Can generate revenue for funding CCS research and development
• Effectiveness depends on price levels and market stability
• Examples:
  • European Union Emissions Trading System (EU ETS)
  • California Cap-and-Trade Program
  • Canada's federal carbon pricing system

Economic considerations

• Economic factors play a crucial role in the adoption and implementation of carbon capture and storage technologies
• Balancing costs, benefits, and market incentives is essential for creating viable CCS projects and policies

Implementation costs

• Capital expenditures (CAPEX) for CCS projects vary widely depending on technology and scale
  • Range from hundreds of millions to billions of dollars for large-scale projects
• Operational expenditures (OPEX) include energy costs, maintenance, and monitoring
• Cost components:
  • Capture equipment and processes
  • Compression and transportation infrastructure
  • Storage site preparation and injection facilities
  • Long-term monitoring and verification systems
• Levelized cost of electricity (LCOE) increases with CCS implementation
  • Estimates range from 30% to 80% increase depending on technology and fuel type

Market incentives

• Government subsidies and tax credits encourage CCS adoption
  • US 45Q tax credit offers up to $50 per ton of CO2 stored
• Carbon pricing mechanisms create financial incentives for emissions reduction
• Green bonds and sustainable finance initiatives provide funding for CCS projects
• Enhanced oil recovery (EOR) markets offer revenue streams for captured CO2
• Renewable energy certificates (RECs) or carbon credits for CCS projects in some jurisdictions
• Public-private partnerships facilitate risk-sharing and knowledge transfer

Job creation potential

• CCS projects generate employment across various sectors:
  • Engineering and construction during project development
  • Plant operations and maintenance
  • CO2 transportation and storage infrastructure
  • Monitoring and verification services
• Estimated job creation:
  • 5,000 to 30,000 direct jobs per gigaton of CO2 stored annually
  • Additional indirect and induced jobs in related industries
• Skills development and training programs needed to support workforce transition
• Potential for job preservation in fossil fuel industries through CCS implementation
• Regional economic benefits in areas with suitable geological storage sites

Environmental impacts

• Carbon capture and storage technologies aim to mitigate climate change but also have potential environmental consequences that must be carefully considered
• Comprehensive environmental impact assessments are crucial for responsible CCS implementation

Reduced greenhouse gas emissions

• Primary goal of CCS to significantly reduce CO2 emissions from large point sources
• Potential to capture 85-95% of CO2 emissions from power plants and industrial facilities
• Contributes to meeting national and international climate change mitigation targets
• Allows continued use of fossil fuels while reducing their carbon footprint
• Estimated global mitigation potential of 10-55 gigatons of CO2 by 2050 (IPCC)

Potential risks and concerns

• CO2 leakage from storage sites poses environmental and safety hazards
  • Groundwater contamination
  • Soil acidification
  • Asphyxiation risk in case of sudden large-scale releases
• Induced seismicity from CO2 injection in geological formations
• Energy penalty of CCS processes may lead to increased fuel consumption
• Transportation risks associated with CO2 pipelines and shipping
• Potential for negative impacts on local air quality due to increased particulate matter emissions

Ecosystem effects

• Ocean storage methods may lead to acidification and harm marine ecosystems
• Land use changes for CCS infrastructure and pipelines
• Potential impacts on subsurface microbial communities in geological storage sites
• Mineral carbonation processes may require large-scale mining operations
• Positive effects on terrestrial ecosystems through reduced acid rain and climate change mitigation
• Monitoring programs necessary to assess long-term ecological impacts of CCS projects

Social and ethical implications

• Implementation of carbon capture and storage technologies raises important social and ethical questions that must be addressed in policy-making and project planning
• Balancing environmental benefits with social equity and long-term sustainability is crucial for responsible CCS deployment

Public perception

• Varied levels of awareness and understanding of CCS technologies among the general public
• Concerns about safety and long-term effectiveness influence public acceptance
• NIMBY (Not In My Backyard) attitudes may affect siting of CCS facilities and storage sites
• Media coverage and communication strategies play a crucial role in shaping public opinion
• Factors influencing perception:
  • Trust in implementing organizations and regulatory bodies
  • Perceived risks and benefits
  • Local economic impacts and job creation potential
  • Previous experiences with similar technologies or industries

Environmental justice issues

• Potential for disproportionate impacts on low-income and minority communities
• Siting of CCS facilities may follow historical patterns of industrial development
• Concerns about perpetuating reliance on fossil fuels in vulnerable communities
• Need for inclusive decision-making processes and community engagement
• Importance of fair distribution of benefits and risks associated with CCS projects
• Consideration of cumulative environmental impacts in already burdened areas

Intergenerational equity

• Long-term storage of CO2 raises questions about responsibilities to future generations
• Ethical considerations of passing on risks and monitoring obligations
• Balancing immediate climate action with potential future consequences
• Importance of developing robust long-term governance structures for CCS projects
• Consideration of alternative climate mitigation strategies and their intergenerational impacts
• Need for transparent decision-making processes that consider future scenarios and uncertainties

Integration with energy systems

• Successful integration of carbon capture and storage technologies with existing and future energy systems is crucial for widespread adoption and effectiveness
• Requires careful consideration of technical, economic, and policy factors to ensure compatibility and efficiency

Role in fossil fuel industries

• Enables continued use of coal, oil, and natural gas while reducing carbon emissions
• Potential to extend the lifespan of existing fossil fuel power plants
• Applications in hard-to-decarbonize industries (cement, steel production)
• Integration with enhanced oil recovery (EOR) operations
  • Provides economic incentive for CCS implementation
  • Raises questions about overall carbon balance and fossil fuel dependence
• Challenges in retrofitting existing plants with CCS technology
  • Space constraints
  • Efficiency losses
  • High capital costs

Compatibility with renewables

• CCS on biomass power plants (BECCS) can achieve negative emissions
• Potential for using excess renewable energy for direct air capture
• Hydrogen production with CCS as a complement to intermittent renewables
• Balancing baseload power from CCS-equipped plants with variable renewable sources
• Integration of CCS with energy storage technologies for grid stability
• Challenges in optimizing dispatch and load-following capabilities of CCS plants

Grid stability considerations

• Impact of CCS energy requirements on overall grid demand
• Need for flexible operation of CCS-equipped power plants to support grid stability
• Potential for CO2 pipeline networks to influence electricity transmission planning
• Integration of CCS with smart grid technologies for optimized energy management
• Considerations for grid resilience and reliability with increased CCS deployment
• Balancing act between emissions reduction and maintaining grid stability

Future prospects and challenges

• The future of carbon capture and storage technologies depends on overcoming significant technical, economic, and policy challenges
• Continued research, development, and policy support are crucial for realizing the potential of CCS in mitigating climate change

Scalability issues

• Need for rapid deployment to meet climate targets
  • IPCC scenarios suggest 100-1000 fold increase in CCS capacity by 2050
• Challenges in scaling up from demonstration projects to commercial-scale operations
• Limited number of suitable geological storage sites in some regions
• Infrastructure requirements for large-scale CO2 transportation networks
• Supply chain constraints for specialized equipment and materials
• Workforce development needs for widespread CCS implementation

Technological barriers

• Improving energy efficiency of capture processes to reduce parasitic load
• Developing more effective and environmentally friendly solvents for post-combustion capture
• Advancing membrane technologies for more efficient gas separation
• Enhancing monitoring and verification technologies for long-term storage
• Addressing challenges in direct air capture for negative emissions
• Improving integration of CCS with industrial processes (cement, steel production)

Policy and investment needs

• Long-term policy frameworks to provide certainty for investors
• Adequate carbon pricing mechanisms to incentivize CCS adoption
• Public funding for research, development, and demonstration projects
• International cooperation for technology transfer and capacity building
• Streamlined permitting processes for CCS projects
• Addressing liability issues for long-term CO2 storage
• Developing standards and regulations for CO2 transportation and storage

Case studies

• Examining real-world carbon capture and storage projects provides valuable insights into the challenges, successes, and lessons learned in implementing this technology
• Case studies inform policy decisions and guide future project development

Notable CCS projects

• Sleipner CO2 Storage Project, Norway
  • World's first commercial CCS project, operating since 1996
  • Captures and stores 1 million tonnes of CO2 annually from natural gas processing
• Boundary Dam CCS Facility, Canada
  • First commercial-scale CCS project on a coal-fired power plant
  • Captures up to 1 million tonnes of CO2 per year since 2014
• Petra Nova Carbon Capture Project, USA
  • Largest post-combustion CO2 capture project on an existing coal-fired power plant
  • Operated from 2017 to 2020, capturing 1.6 million tonnes of CO2 annually
• Gorgon Carbon Dioxide Injection Project, Australia
  • Largest greenhouse gas mitigation project undertaken by industry
  • Aims to capture and store up to 4 million tonnes of CO2 annually from natural gas processing

Successes and failures

• Successes:
  • Demonstration of technical feasibility at commercial scale
  • Significant emissions reductions achieved in operating projects
  • Integration with enhanced oil recovery for economic viability
  • Long-term storage integrity confirmed in projects like Sleipner
• Failures:
  • Cost overruns and delays in project implementation
  • Lower-than-expected capture rates in some projects
  • Cancellation of projects due to changing economic or political conditions
  • Technical challenges in scaling up from pilot to commercial scale

Lessons learned

• Importance of government support and stable policy frameworks
• Need for comprehensive site characterization for geological storage
• Value of knowledge sharing and international collaboration
• Significance of public engagement and stakeholder communication
• Importance of integrating CCS with existing industrial processes
• Need for flexible designs to adapt to changing market conditions
• Crucial role of monitoring and verification in ensuring storage integrity
• Importance of addressing the full CCS chain (capture, transport, storage) in project planning

Alternatives and complements

• While carbon capture and storage is a significant technology for mitigating climate change, it is part of a broader portfolio of solutions
• Understanding the alternatives and complementary approaches is crucial for developing comprehensive climate policies

Direct air capture

• Removes CO2 directly from the atmosphere rather than from point sources
• Can address historical emissions and emissions from dispersed sources
• Current technologies:
  • Chemical absorption using liquid solvents
  • Solid sorbent materials
• Challenges include high energy requirements and costs
  • Current costs range from $250 to$600 per ton of CO2 captured
• Potential for negative emissions when combined with permanent storage
• Scalability limited by high land and energy requirements

Bioenergy with CCS (BECCS)

• Combines biomass energy production with carbon capture and storage
• Potential for negative emissions as CO2 is removed from the atmosphere by plants and then captured during energy production
• Applications in power generation and biofuel production
• Challenges:
  • Competition for land use with food production
  • Sustainability concerns related to large-scale biomass cultivation
  • Limited by available biomass resources
• Estimated potential to remove 2-10 gigatons of CO2 annually by 2050 (IPCC)

Reforestation vs CCS

• Reforestation and afforestation as natural carbon sequestration methods
  • Potential to sequester 0.5-3.6 gigatons of CO2 annually
• Advantages of reforestation:
  • Lower cost compared to technological solutions
  • Additional ecosystem benefits (biodiversity, soil conservation)
• Limitations of reforestation:
  • Land availability constraints
  • Vulnerability to climate change impacts (fires, droughts)
  • Slower carbon uptake compared to CCS
• CCS advantages over reforestation:
  • Higher carbon sequestration potential per unit area
  • More permanent storage of CO2
  • Applicability to industrial emissions
• Complementary approach: combining reforestation with BECCS or other CCS technologies