Carbon Capture and Sequestration: Transforming Emissions into Action
Carbon capture is not just about reducing emissions-it’s about creating a circular carbon economy. By converting CO₂ into useful products, we can turn a waste stream into a resource.
The demand for effective strategies to mitigate the alarming rise in global greenhouse gas emissions has become more critical than ever. Carbon capture and sequestration (CCS) is one of the most promising technological solutions to reducing atmospheric carbon dioxide (CO₂) buildup. Since industrial sectors are responsible for almost 40% of global CO₂ emissions, CCS provides a scientifically sound approach to capturing emissions at their origin and safely storing the extracted carbon to prevent it from re-entering the atmosphere. It explores the foundational concepts of the technology, presents quantitative metrics on costs and performance, assesses the benefits and drawbacks based on empirical research, and discusses potential future developments considering the current trends in technology and policy.
Carbon Capture Technologies.
CCS is typically divided into three key stages: capture, transportation, and storage (or utilisation). The capture phase involves isolating CO₂ from flue gases generated during combustion. Post-combustion capture is the most developed among various methods and employs chemical solvents, primarily amines, to absorb CO₂. Although it can remove up to 90% of emissions when fully optimised, this method incurs significant energy costs, potentially reducing overall plant efficiency by 10–20%. The cost of post-combustion capture is estimated to be between US$50 and US$150 per ton of CO₂.
Pre-combustion capture, commonly used in integrated gasification combined cycle (IGCC) plants, converts fossil fuels into synthesis gas (syngas), a mixture of hydrogen and carbon monoxide, before combustion.
A water-gas shift reaction transforms the carbon monoxide into CO₂, facilitating easier capture. Studies indicate that pre-combustion systems can achieve comparable CO₂ capture rates to post-combustion methods while potentially lowering energy consumption under optimised conditions.
Oxy-fuel combustion, another promising technique, replaces air with nearly pure oxygen during combustion. This produces an exhaust stream composed almost entirely of CO₂ and water vapour, simplifying CO₂ separation; however, it also relies on energy-intensive air separation units that increase operational costs.
Direct Air Capture (DAC) is a technology that removes CO₂ directly from the atmosphere using chemical processes. The captured CO₂ can then be stored underground or reused in various applications, such as in the production of synthetic fuels. DAC is still in the early development phase, with estimated costs of several hundred dollars per ton of CO₂. However, it remains a crucial area of research due to its potential for decentralised carbon management.
Transportation of Captured Carbon Dioxide.
The effective movement of captured CO₂ is crucial in the CCS chain, as logistical limitations significantly impact the overall feasibility of CCS initiatives. Available data indicates that transporting large amounts of CO₂ via pipelines is the most cost-effective method for long-distance conveyance. Typically, pipeline systems increase costs by about US$1 to US$5 per ton of CO₂ per 100 kilometres, influenced by variables such as pipeline size, operating pressure, and geographical conditions. Real-world examples from North America and Europe have confirmed these cost projections, although they necessitate considerable initial capital investment.
In areas where pipelines are not feasible due to geographical or infrastructural limitations, shipping offers an alternative solution. Transporting liquefied CO₂ over long distances is possible; however, the process of liquefaction is energy-demanding and contributes an extra 10–15% to the total expense. Findings from pilot programs have shown that while shipping can be seamlessly integrated into global CCS systems, the additional costs involved in handling and refrigeration must be carefully considered against the advantages of flexible routing.
Storage Methods:
Geological Sequestration and Carbon Utilisation
The final stage of the CCS process, known as carbon capture, utilisation, and storage (CCUS), involves either long-term geological storage or the conversion of CO₂ into commercially viable products.
Geological storage remains the most extensively studied method for permanent CO₂ retention, with saline aquifers identified by the International Energy Agency as highly promising due to their abundance and high porosity. Studies suggest these formations could store hundreds of gigatonnes of CO₂ globally, retaining over 95% of injected CO₂ for more than 1,000 years when combined with effective monitoring techniques.
Depleted oil and gas fields also present a viable geological storage option. Data from enhanced oil recovery (EOR) projects indicate that injecting CO₂ into mature fields can enhance oil recovery by 5–15% while permanently sequestering a significant proportion of CO₂. Although EOR can partially offset capture costs, comprehensive reservoir assessments are essential to ensure long-term stability and prevent leakage risks. The conversion of CO₂ into valuable products is gaining momentum to offset CCS costs. Catalytic conversion processes have demonstrated the feasibility of transforming CO₂ into methanol, a fuel and industrial feedstock, with conversion efficiencies approaching 60% in laboratory settings. Additionally, industrial-scale trials explore mineralisation techniques that convert CO₂ into concrete aggregates, offering a dual benefit of carbon sequestration and new revenue streams. These utilisation pathways are currently in development; however, economic models suggest that large-scale adoption of these methods could substantially reduce the overall cost of CCS.
Advantages of CCS Technologies.
CCS also offers far-reaching benefits beyond reducing carbon emissions. CCS methods can achieve over 90% efficiency, thereby significantly cutting greenhouse gas emissions from high-emission industries such as cement, steel, and energy production, which account for nearly 40% of global CO₂ output.
CCS also provides a transitional solution, allowing fossil fuel-dependent industries to operate while renewable energy capacity expands. In regions where immediate decarbonisation is impractical, CCS helps curb emissions from existing power plants and industrial sites. Additionally, its widespread adoption could generate thousands of jobs in engineering, construction, and environmental monitoring.
Integrating CCS with EOR further strengthens its economic appeal. Injecting captured CO₂ into ageing oil fields can improve extraction rates, partially offsetting CCS costs and improving financial feasibility. These environmental and economic advantages position CCS as a vital tool in achieving both national and global climate targets.
Challenges Facing CCS Deployment.
Despite its vast potential, there are also several critical challenges with CCS that must be addressed to maximise its viability. One of the main obstacles is its high cost, with capture alone estimated between US$50 and US$150 per tonne of CO₂. Factoring in transportation and storage raises the total costs further, making implementation particularly difficult for industries operating on narrow margins, especially in regions with fluctuating energy prices.
Another critical challenge is the energy penalty associated with CO₂ capture, which can reduce power plant efficiency by 10–20%. This increased fuel consumption may offset environmental benefits, particularly if additional energy demand is met through fossil fuels. Furthermore, integrating CCS into existing industrial processes increases operational complexity and costs. There are also technical barriers to developing and maintaining transportation infrastructure. Pipelines require corrosion-resistant materials and continuous monitoring to prevent leaks, which pose both environmental and financial risks. In maritime transport, additional energy demands for liquefaction and refrigeration further complicate cost-benefit considerations. Regulatory uncertainty, including inconsistencies in liability, permitting processes, and safety standards across different regions, further hampers the deployment of CCS. For instance, unclear accountability for CO₂ leakage after storage site closure discourages private sector investment due to the associated risks. Feasibility studies highlight regulatory ambiguities as a major obstacle to the large-scale adoption of CCS.
Public acceptance is equally crucial, as concerns over the safety of CO₂ storage—including potential leakage and induced seismic activity—have been reflected in case studies and surveys. Critics also argue that CCS could divert investments from renewable energy, particularly in regions with strong environmental advocacy. Addressing these concerns requires transparent risk communication, stringent safety monitoring, and successful pilot projects to build public trust.
CCS is also cost-intensive. Storage costs are largely influenced by geological conditions and post-injection monitoring and typically range from US$10 to US$30 per tonne.
However, research indicates that economies of scale can significantly reduce this—thereby making CCS more competitive with other carbon reduction strategies—provided supportive policies are in place. Achieving these efficiencies will require substantial initial investment and strong regulatory backing, particularly through carbon pricing and financial incentives.
Strategies for Reducing CCS Costs
Significant research and policy efforts are focused on mitigating the challenges of the high costs and energy demands of CCS. Technological advancements play a key role, and there are intensive studies into innovative solvents, membranes, and catalysts aimed at enhancing CO₂ absorption efficiency while reducing the energy required for solvent regeneration. Emerging methods such as chemical and calcium looping have shown promising results, potentially lowering energy costs by up to 30% compared to conventional capture techniques.
Modular and prefabricated systems are also being developed to streamline installation and reduce capital expenditure. Recent demonstration projects indicate that modular systems can halve installation time, significantly lowering the overall cost per tonne of CO₂ captured.
Meanwhile, integrating DAC with renewable energy offers a decentralised approach to CCS, although current estimates suggest that DAC remains substantially more expensive than point-source capture.
Policy measures are also crucial in making CCS more financially viable. Implementing carbon pricing mechanisms—whether through taxation or cap-and-trade schemes—can internalise the environmental cost of CO₂ emissions, making CCS investments more attractive.
Regions with established carbon pricing frameworks have already seen increased investment in low-carbon technologies, including CCS. Additionally, financial incentives such as subsidies, tax relief, and loan guarantees can help offset the high upfront costs that remain a key barrier for many industries.
Strategic deployment models, such as CCUS hubs, are also being explored as ways to drive down costs further.
By centralising infrastructure and enabling multiple emitters to share capture, transport, and storage facilities, these hubs distribute fixed costs more efficiently. This approach enhances the economic viability of individual projects while fostering industry collaboration, accelerating the large-scale adoption of CCS.
Future Prospects of CCS.
The future of CCS is closely linked to global energy policies and technological progress. As nations work towards net-zero emissions by mid-century, CCS is expected to play a key role in climate strategies. Policy developments such as the U.S. Inflation Reduction Act have injected significant funding into CCS, demonstrating strong governmental support for it. Efforts like this, along with international climate agreements, are likely to drive further investment in CCS infrastructure and research.
Advancements in technology are also expected to lower both costs and energy demands. Research into improved capture materials and storage methods, along with more efficient transportation systems, should reduce the cost per tonne of CO₂. Additionally, carbon utilisation—converting captured CO₂ into marketable products—could make CCS financially viable. Innovations in catalytic conversion, for instance, may enable large-scale production of synthetic fuels or methanol to offset operational expenses.
Furthermore, integrating CCS with renewable energy and storage solutions could enhance energy resilience, particularly in regions where renewables alone are insufficient. Collaboration between academia, industry, and government will be crucial in scaling these innovations, ensuring CCS can deliver meaningful emissions reductions on a global scale.
Synergia Takeaways:
• CCS is a scientifically validated and economically promising strategy to mitigate climate change by capturing CO₂ at its source, transporting it safely, and either sequestering it in geological formations or converting it into valuable products.
• Data from pilot projects, cost analyses, and energy studies show that CCS can reduce emissions significantly, although it faces technological and economic challenges. With global policies increasingly targeting net-zero emissions, CCS is set to become a central element of climate mitigation efforts.
• Its integration with renewable energy systems, advancements in carbon utilisation, and supportive policy frameworks enhance its potential. Continued investments in research and innovative system design are critical to transforming industrial practices and lowering greenhouse gas emissions.
