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Context: Germany plans carbon capture for industrial sectors, including cement, aiming for carbon neutrality by 2045, while the UAE initiated a project in November 2023 to convert air-extracted carbon into rock.

Details

• Carbon capture and storage (CCS) is a technology aimed at reducing carbon dioxide (CO2) emissions from large point sources, such as industrial facilities and power plants.
• The process involves capturing CO2 emissions and storing them underground to prevent their release into the atmosphere. While CCS has been considered by some as a potential solution to mitigate climate change, there are several challenges and concerns associated with its effectiveness and feasibility.

The CCS Process

• Capture: CO2 is separated from the emissions of power plants and industrial facilities like steel mills. This can be done through various methods, most commonly involving chemical absorption or physical separation using membranes.
• Transport: The captured CO2, now in a concentrated form, needs to travel to the storage site. Pipelines are the preferred mode for onshore transportation, while ships are used for offshore projects.
• Storage: Deep underground geological formations, either onshore or offshore, act as the final destination for CO2. These formations, like saline aquifers or depleted oil and gas reservoirs, offer secure storage with minimal risk of leakage.

CCS employs various techniques to capture carbon emissions

• Pre-combustion capture: This technology separates CO2 from the fuel stream before it is burned in power plants, typically using fossil fuels like coal or natural gas. The process involves converting the fuel into a gaseous mixture of hydrogen and carbon monoxide (syngas) through a process called gasification. Then, CO2 is captured from the syngas using chemical absorption or membrane separation techniques.
• Post-combustion capture: This technology captures CO2 from the flue gas emitted after fossil fuels are burned in power plants or industrial facilities. This is the most mature technology for CCS, but it can be less efficient than pre-combustion capture due to the additional energy required to separate CO2 from diluted flue gas.
• Oxy-fuel combustion: This technology captures high-purity CO2 from a combustion process using pure oxygen instead of air. The process burns the fuel in an oxygen-rich environment, resulting in a flue gas stream that primarily consists of CO2 and water vapour. The water vapour is then condensed and removed, leaving behind a concentrated stream of CO2 for easy capture.

Effectiveness and Concerns

• Efficiency: Operational CCS projects typically claim to be 90% efficient in capturing and storing carbon. However, studies, such as the 2022 report by the Institute for Energy Economics and Financial Analysis (IEEFA), have shown that many projects underperform or fail.
• Cost: CCS technologies are expensive. When attached to coal and gas power stations, they can be at least six times more expensive than electricity generated from wind power backed by battery storage.
• Limited Projects: Despite decades of promotion, there are only a few operational CCS projects globally. As of 2023, there were 40 operational projects capturing more than 45 metric tonnes of CO2 annually.
• Scale and Overreliance: The International Energy Agency (IEA) warns that achieving significant carbon capture to limit global temperature increases would require an inconceivable amount of resources and could lead to overreliance on technology.
• Social License: Critics, like Genevieve Gunther, argue that fossil fuel companies may use CCS not as a climate solution but as a means to enhance extraction, thus obtaining a social license to continue their operations.

Carbon Capture and Offshore Storage (CCS)
Key Points	Description
Capture Technologies	●Post-combustion: CO2 is removed after the fossil fuel has been burned. Chemical solvents are used to separate CO2 from the exhaust gases, which are then captured. ●Pre-combustion: CO2 is removed before burning the fossil fuel. The fossil fuel is partially burned to form synthetic gas, and CO2 can be captured from this exhaust stream. This method also generates hydrogen. ●Oxyfuel combustion: Fossil fuel is burned with almost pure oxygen, producing CO2 and water vapour. The water is condensed, and CO2 is separated and captured. This method is efficient but energy-intensive.
Transport	●Pipelines: Preferred method for onshore and near-shore storage. ●Ships: Used for transporting CO2 over longer distances or to offshore storage locations. ●Considerations: Distance, infrastructure availability, safety regulations.
Storage	●Depleted oil and gas reservoirs: Existing infrastructure can potentially be repurposed for CO2 storage. ●Saline formations: Deep underground rock formations with briny water, offer large storage capacity. ●Selection criteria: Geological stability, capacity, injectivity (ability to accept CO2), and risk of leakage.
Monitoring and Verification (M&V)	●Monitoring: Regular assessment of pressure, temperature, and CO2 plume movement at the storage site. ●Verification: Independent confirmation of CO2 storage and potential leakage risks. ●Technologies: Seismic monitoring, wellbore integrity checks, satellite observations.
Regulatory Framework	●Permitting process for capture facilities, transport pipelines, and storage sites. ●Liability and risk management frameworks. ●CO2 property rights and ownership during storage. ●Monitoring and reporting requirements.
Costs and Economics	●Capture technology costs: Vary depending on the chosen technology and application. ●Transport costs: Pipeline construction and operation or ship transportation fees. ●Storage costs: Site selection, well drilling, and long-term monitoring. ●Potential economic benefits: Carbon credits earned through CO2 capture and storage.
Environmental Considerations	●Energy use for capture processes: Can increase power plant emissions if not addressed with renewable energy integration. ●Leakage risks: Accidental or gradual release of stored CO2, potentially impacting ocean acidification or local ecosystems. ● Habitat considerations: Careful site selection to avoid sensitive marine environments.

 

Conclusion

• While carbon capture and storage technology holds promise, its current limitations, high costs, and concerns about efficiency and potential misuse raise questions about its ability to be a sole "silver bullet" solution in tackling climate change. Many experts emphasize the importance of a comprehensive approach, including reducing emissions at the source and transitioning to renewable energy sources, to effectively address the challenges posed by climate change 

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PRACTICE QUESTION Q.  Considering the complexities of marine ecosystems and potential changes in ocean chemistry due to CO2 injection, what research is needed to fully understand the long-term environmental consequences of large-scale offshore Carbon Capture and Offshore Storage (CCS) deployment, and how to ensure robust mitigation strategies are in place to minimize potential risks?