Title : Techniques for carbon dioxide sequestration and the way forward
Abstract:
The combustion of fossil fuels releases large quantities of Carbon Dioxide (CO₂) into the atmosphere, driving global warming and producing measurable shifts in climate patterns worldwide. In response, researchers and policymakers have intensified efforts to reduce emissions and remove CO₂ from the air, with Carbon Capture and Sequestration (CCS) emerging as a central strategy. CCS encompasses a range of approaches—pre-combustion, oxy-fuel combustion, and post-combustion capture—each with distinct technical and economic trade-offs. Among these, post-combustion capture is particularly attractive for near-term deployment because it can be retrofitted to existing power plants and industrial facilities, enabling rapid emissions reductions without the need for wholesale redesign of combustion systems. Post-combustion systems typically rely on chemical solvents, solid sorbents, or membranes to separate CO₂ from flue gas; the choice of capture medium strongly influences capital cost, energy penalty, and operational complexity.
Solid adsorption using porous materials has gained attention for its potential to lower costs and simplify integration. Activated carbon stands out for its low production cost, abundant precursors, and tunable pore structure, making it a promising candidate for large-scale post-combustion capture. Activated carbon’s advantages include robustness, ease of regeneration, and resilience to moisture and contaminants commonly present in flue gas. However, its CO₂ selectivity and uptake capacity can be lower than those of more engineered materials. Zeolites and zeolitic imidazolate frameworks (ZIFs), members of the broader Metal-Organic Framework (MOF) family, often exhibit superior selectivity and higher adsorption capacities due to precisely defined pore chemistries and high surface areas. These materials can achieve more efficient separation at lower regeneration energies, but their higher synthesis costs, sensitivity to humidity, and scale-up challenges currently limit widespread adoption.
A pragmatic pathway forward combines material innovation with systems engineering: improving low-cost sorbents like activated carbon through surface functionalization, hybridizing sorbents to balance cost and performance, and optimizing process cycles to reduce energy penalties. Equally important are lifecycle assessments and techno-economic analyses that account for precursor sourcing, regeneration energy, durability, and end-of-life impacts. Finally, capture must be paired with secure, long-term storage or utilization pathways—geologic sequestration, mineralization, or carbon-utilization technologies—to ensure permanence. This review synthesizes current CCS concepts, compares sorbent classes, and outlines research priorities aimed at delivering scalable, sustainable, and cost-effective solutions for atmospheric CO₂ removal.
